Researcher Database

Hitoshi Suzuki
Faculty of Environmental Earth Science Environmental Biology Ecological Genetics
Professor

Researcher Profile and Settings

Affiliation

  • Faculty of Environmental Earth Science Environmental Biology Ecological Genetics

Job Title

  • Professor

Degree

  • Doctor of Philosophy

J-Global ID

Research Interests

  • 分子進化学   遺伝子多様性   生物地理学   

Research Areas

  • Life sciences / Evolutionary biology
  • Life sciences / Genetics
  • Life sciences / Biodiversity and systematics

Association Memberships

  • 日本遺伝学会   日本動物学会   日本哺乳類学会   Society for Molecular Biology and Evolution   International Mammalian Genome Society   American Society of Mammalogists   

Research Activities

Published Papers

  • Aoki Daisuke, Kinoshita Gohta, Kryukov Alexey P, Nishiumi Isao, Lee Sang-Im, Suzuki Hitoshi
    JOURNAL OF ORNITHOLOGY 159 (4) 1087 - 1097 0021-8375 2018/10 [Refereed][Not invited]
  • Bawm Saw, Kakisaka Keita, Thu May June, Chel Hla Myet, Oo Yamon, Min Nyunt, Soe Nyein Chan, Win Shwe Yee, Htun Lat Lat, Win Mar Mar, Suzuki Hitoshi, Nakao Ryo, Katakura Ken
    PARASITOLOGY RESEARCH 117 (10) 3361 - 3364 0932-0113 2018/10 [Refereed][Not invited]
  • Thomson Vicki, Wiewel Andrew, Chinen Aldo, Maryanto Ibnu, Sinaga M. H, How Ric, Aplin Ken, Suzuki Hitoshi
    ZOOTAXA 4459 (3) 431 - 452 1175-5326 2018/08/16 [Refereed][Not invited]
  • Miyu Isobe, Mitsuo Nunome, Ken Katakura, Hitoshi Suzuki
    Journal of Molecular Evolution 86 (5) 312 - 323 0022-2844 2018/06/01 [Refereed][Not invited]
     
    We investigated evolutionary trends of the 5S ribosomal RNA gene in the house mouse, Mus musculus. First, we assessed the 5S cluster and copy numbers in eight laboratory strains by pulsed-field gel electrophoresis. The copy numbers in seven lines were estimated to be around 130–170 copies per cluster, with 63 copies in the remaining strain, implying that the copy number can change drastically and has been maintained under certain evolutionary constraints at ~ 140 copies. Second, we addressed the frequency of meiotic recombination mediated by the 5S cluster by performing a mating experiment with laboratory strains, and found that the 5S cluster did not accelerate recombination events. Third, we surveyed recombination events of the 5S-containing chromosome region in wild mice from the Japanese Islands, where the two subspecies lineages, M. m. castaneus and M. m. musculus, are historically mingled, and found that the influence of the 5S cluster on meiotic recombination was limited. Finally, we examined the nucleotide diversity of six genes in the neighboring regions of the 5S cluster and found reduced genetic diversity in the regions on both sides of the cluster, suggesting the involvement of either positive or background selection in the population-level sequence similarity of the 5S clusters. Therefore, the mouse 5S genes are considered to be evolving toward sequence similarity within a given cluster by certain intrachromosomal mechanisms and toward sharing of a specific 5S cluster within a population by certain selective processes.
  • Multiple conserved elements structuring inverted repeats in mammal coat color-related gene Asip
    Yuki Sakuma, Masatoshi Matsunami, Toyoyuki Takada, Hitoshi Suzuki
    Zoological Science 2018 [Refereed][Not invited]
  • Shoichi Sasamori, Andrew S. Wiewel, Vicki A. Thomson, Motoko Kobayashi, Katsushi Nakata, Hitoshi Suzuki
    ZOOLOGICAL SCIENCE 34 (6) 513 - 522 0289-0003 2017/12 [Refereed][Not invited]
     
    The occurrence of black fur, or melanism, in many mammalian species is known to be linked to DNA sequence variation in the agouti signaling protein (Asip) gene, which is a major determinant of eumelanin and pheomelanin pigments in coat color. We investigated 38 agouti (i.e., banded wildtype) and four melanistic Rattus rattus species complex (RrC) lineage II specimens from Okinawa Island, Ryukyu Islands, Japan, for genetic variation in three exons and associated flanking regions in the Asip gene. On Okinawa, a predicted loss-of-function mutation caused by a cysteine to serine amino acid change at p.124C>S (c.370T>A) in the highly conserved functional domain of Asip was found in melanistic rats, but was absent in agouti specimens, suggesting that the p.124C>S mutation is responsible for the observed melanism. Phylogeographic analysis found that Asip sequences from Okinawan RrC lineage II, including both agouti and melanistic specimens, differed from: 1) both agouti and melanistic RrC lineage I from Otaru, Hokkaido, Japan, and 2) agouti RrC lineages I and II from South Australia. This suggests the possibility of in-situ mutation of the Asip gene, either within the RrC lineage II population on Okinawa or in an unsampled RrC lineage II population with biogeographic links to Okinawa, although incomplete lineage sorting could not be ruled out.
  • Takashi Kuwayama, Mitsuo Nunome, Gohta Kinoshita, Kuniya Abe, Hitoshi Suzuki
    BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY 122 (3) 661 - 674 0024-4066 2017/11 [Refereed][Not invited]
     
    In this study, phylogenetic analysis of relatively long sequences of mitochondrial DNA (4225 bp) in the Japanese house mouse Mus musculus provides the first evidence that both southern Asian subspecies of Mus musculus castaneus (CAS) and northern Asian subspecies of Mus musculus musculus (MUS) arrived in Japan through rapid population expansion events, from Southern China similar to 4000 years ago and the Korean Peninsula similar to 2000 years ago, respectively. Nuclear DNA haplotype structure analyses targeting a chromosome region with two different tract sizes, 1 and 5 Mb, consisting of nine and six tandemly arranged markers, respectively, yielded a possible average fragment length of 170 kb of CAS haplotypes in the MUS background genome in northern Japan, providing a rough estimate of its elapsed time of 815 generations under an assumption of continued backcrossing. Less frequent and shortened CAS-like haplotypes specific to Japan were detected, suggesting ancient introduction prior to the appearance of the South Chinese CAS in Japan. Our analyses also showed sporadic appearance of long fragments (2-5 Mb) from the west European subspecies Mus musculus domesticus, indicating contemporary stowaway introduction. Overall, multiple overseas introductions, and the time-lagged inter-subspecies genetic admixture, probably resulted in the heterogeneous state of Japanese wild mice.
  • Kaori Hanazaki, Morihiko Tomozawa, Yutaro Suzuki, Gohta Kinoshita, Masanobu Yamamoto, Tomohisa Irino, Hitoshi Suzuki
    ZOOLOGICAL SCIENCE 34 (3) 201 - 210 0289-0003 2017/06 [Refereed][Not invited]
     
    Reliable estimates of evolutionary rates of mitochondrial DNA might allow us to build realistic evolutionary scenarios covering broad time scales based on phylogenetic inferences. In the present study, we sought to obtain estimates of evolutionary rates in murine rodents using calibrations against historical biogeographic events. We first assumed that land-bridge-like structures that appeared intermittently at glacial maxima with 100,000-year intervals shaped the divergence patterns of cytochrome b (Cytb) sequences (1140 bp) of the larger Japanese wood mouse Apodemus speciosus. The comparison of sequences from peripheral remote islands that are separated from one another by deep straits allowed us to estimate mitochondrial DNA evolutionary rates (substitutions/site/million years) to be 0.027 to 0.036, with presumed calibrations from 140,000, 250,000, 350,000, and 440,000 years ago. Second, we addressed rapid expansion events inferred from analyses of the Cytb sequences of the lesser Japanese wood mouse A. argenteus. We detected five expansion signals in the dataset and established three categories based on the expansion parameter tau values: 3.9, 5.6-5.7, and 7.8-8.1. Considering that the climate became warmer 15,000, 53,000, and 115,000 years ago after preceding periods of rapid cooling, we calculated evolutionary rates to be 0.114, 0.047, and 0.031, respectively. This preliminary concept of the evolutionary rates on a time scale from 15,000 to 440,000 years ago for the wood mouse should be refined and tested in other species of murine rodents, including mice and rats.
  • Yuki Sakuma, Marie C. Ranorosoa, Gohta Kinoshita, Hiroyuki Shimoji, Kimiyuki Tsuchiya, Satoshi D. Ohdachi, Satoru Arai, Chihiro Tanaka, Hajanirina Ramino, Hitoshi Suzuki
    MAMMAL STUDY 41 (3) 131 - 140 1343-4152 2016/09 [Refereed][Not invited]
     
    Variability in the coat color of the house mouse, Mus musculus, provides an opportunity to study the evolution of phenotypes in this species. Here we associated genetic variations with coat color in seven mice from Madagascar that had identical M. m. gentilulus mitochondrial DNA sequences. The entire coding region of the 948-base pair (bp) coat-color-related gene, Mc1r, was shown to have no nonsynonymous changes. However, analyses of the two exon-1 promoter regions-termed 1A (317 bp) and 1B (499 bp)-from a second gene, Asip, which is also involved in the evolution of coat color, revealed two distinct haplotypes in each region. Associations between Asip promoter regions and dorsal color were ambiguous; however, two ventral color types-light and dark gray-were associated with the haplotypes of 1A, as determined by clustering analysis. Notably, the haplotype of the light gray animals was identical to the Asip A(w) allele that is associated with white bellies.
  • Yutaro Suzuki, Morihiko Tomozawa, Yuki Koizumi, Kimiyuki Tsuchiya, Hitoshi Suzuki
    BMC EVOLUTIONARY BIOLOGY 15 1471-2148 2015/09 [Refereed][Not invited]
     
    Background: Determining reliable evolutionary rates of molecular markers is essential in illustrating historical episodes with phylogenetic inferences. Although emerging evidence has suggested a high evolutionary rate for intraspecific genetic variation, it is unclear how long such high evolutionary rates persist because a recent calibration point is rarely available. Other than using fossil evidence, it is possible to estimate evolutionary rates by relying on the well-established temporal framework of the Quaternary glacial cycles that would likely have promoted both rapid expansion events and interisland dispersal events. Results: We examined mitochondrial cytochrome b (Cytb) and control region (CR) gene sequences in two Japanese wood mouse species, Apodemus argenteus and A. speciosus, of temperate origin and found signs of rapid expansion in the population from Hokkaido, the northern island of Japan. Assuming that global warming after the last glacial period 7-10 thousand years before present (kyr BP) was associated with the expansion, the evolutionary rates (sites per million years, myr) of Cytb and CR were estimated as 11-16 % and 22-32 %, respectively, for A. argenteus, and 12-17 % and 17-24 %, respectively, for A. speciosus. Additionally, the significant signature of rapid expansion detected in the mtDNA sequences of A. speciosus from the remaining southern main islands, Honshu, Shikoku, and Kyushu, provided an estimated Cytb evolutionary rate of 3.1 %/site/myr under the assumption of a postglacial population expansion event long ago, most probably at 130 kyr BP. Bayesian analyses using the higher evolutionary rate of 11-17 %/site/myr for Cytb supported the recent demographic or divergence events associated with the Last Glacial Maximum. However, the slower evolutionary rate of 3.1 %/site/myr would be reasonable for several divergence events that were associated with glacial periods older than 130 kyr BP. Conclusions: The faster and slower evolutionary rates of Cytb can account for divergences associated with the last and earlier glacial maxima, respectively, in the phylogenetic inference of murine rodents. The elevated evolutionary rate seemed to decline within 100,000 years.
  • Sayaka Kodama, Mitsuo Nunome, Kazuo Moriwaki, Hitoshi Suzuki
    BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY 114 (4) 778 - 794 0024-4066 2015/04 [Refereed][Not invited]
     
    We examined genetic variation in house mice from India and Pakistan, a predominant part of the predicted homeland of this species and also the territory of the subspecies Mus musculus castaneus (CAS), using a nuclear marker for seven tandemly arranged genes (Fanca-Spire2-Tcf25-Mc1r-Def8-Afg3l1-Dbndd1) and compared them with those previously determined for mice from other parts of Eurasia. Construction of a network with the concatenate sequences yielded three distinct clusters representing the three major subspecies groups: CAS, Mus musculus domesticus (DOM) and Mus musculus musculus (MUS). STRUCTURE analysis provided evidence for further subdivision of CAS into two main haplogroups within the Indian subcontinent. Single-gene networks revealed not only gene-specific architecture for subgrouping in CAS, but also allelic exchange among subspecies. These results suggest the earlier onset of allopatric divergence in the predicted homeland (the Middle East and Indian subcontinent) and subsequent intermittent admixing via gene flow across the CAS haplogroups and among the three subspecies groups. A comparison of the levels of nucleotide diversity among the gene regions revealed a less divergent state in the chromosome region containing Mc1r and its adjacent genes, indicative of a selective sweep, suggesting the involvement of natural selection in the Mc1r allelic variation.(c) 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 778-794.
  • Dhananjoy S. Chingangbam, Joykumar M. Laishram, Hitoshi Suzuki
    GENES & GENETIC SYSTEMS 90 (1) 21 - 30 1341-7568 2015/02 [Refereed][Not invited]
     
    The Indian subcontinent and Southeast Asia are hotspots of murine biodiversity, but no species from the Arakan Mountain system that demarcates the border between the two areas has been subjected to molecular phylogenetic analyses. We examined the mitochondrial cytochrome b gene sequences in six murine species (the Rattus rattus species complex, R. norvegicus, R. nitidus, Berylmys manipulus, Niviventer sp. and Mus musculus) from Manipur, which is located at the western foot of the mountain range. The sequences of B. manipulus and Niviventer sp. examined here were distinct from available congeneric sequences in the databases, with sequence divergences of 10-15%. Substantial degrees of intrapopulation divergence were detected in R. nitidus and the R. rattus species complex from Manipur, implying ancient habitation of the species in this region, while the recent introduction by modern and prehistoric human activities was suggested for R. norvegicus and M. musculus, respectively. In the nuclear gene Mc1r, also analyzed here, the R. rattus species complex from Manipur was shown to possess allelic sequences related to those from the Indian subcontinent in addition to those from East Asia. These results not only fill gaps in the phylogenetic knowledge of each taxon examined but also provide valuable insight to better understand the biogeographic importance of the Arakan Mountain system in generating the species and genetic diversity of murine rodents.
  • Hitoshi Suzuki, Lyudmila V. Yakimenko, Daiki Usuda, Liubov V. Frisman
    Genes and Environment 37 (1) 20  1880-7062 2015 [Refereed][Not invited]
     
    Here we describe recent advances in our understanding of the natural history of the house mouse, Mus musculus, with a focus on the genetic characteristics of the home territories and how this relates to prehistoric eastward movements from the predicted source areas. Recent studies of mitochondrial and nuclear gene sequences provide insight into the ancient divergence of the three subspecies groups, M. m. castaneus (CAS), M. m. domesticus (DOM), and M. m. musculus (MUS), with inferred natural habits (homelands) in central (Iran, Afghanistan, Pakistan, and India), western (western Iran), and northern (central Asia) areas, respectively. Our mitochondrial DNA and nuclear gene analyses indicate that only one local lineage of CAS extended its range via historical rapid expansion at two different times to Southeast Asia and East Asia, including Japan and southern Sakhalin. This is suggestive of a rapid range expansion of CAS out of its homeland, perhaps associated with the spread of agricultural practices in Asia. The subspecies group MUS now occurs in a large portion of northern Eurasia from eastern Europe in the West to the Japanese Islands in the East, including Uzbekistan, Kazakhstan, southern Siberia, northern China, and Korea, showing divergent patterns in terms of Mus musculus genetics, particularly in relation to nuclear gene sequences, allozymes (e.g., hemoglobin), morphological characteristics, and cytogenetic C-banding patterns. In this review article, we explain the complex spatial patterns of MUS. We postulate that two historical dispersal events took place, from two different source areas, and tentatively assign the taxon names "musculus" and "wagneri" to the two populations, which are associated with distinct genetic modules.
  • Shumpei P. Yasuda, Chandika D. Gamage, Nobuo Koizumi, Sanae Nishio, Rie Isozumi, Kenta Shimizu, Takaaki Koma, Takako Amada, Hitoshi Suzuki, Kumiko Yoshimatsu, Jiro Arikawa
    Genes and Genetic Systems 89 (2) 71 - 80 1880-5779 2014/09/01 [Refereed][Not invited]
     
    We examined genetic variation in black rats (the Rattus rattus complex) from Kandy District, Sri Lanka using mitochondrial cytochrome b (cytb, 1140 bp) and nuclear melanocortin 1 receptor (Mc1r, 954 bp) gene sequences together with database sequences. We confirmed the existence of two divergent mitochondrial lineages in Sri Lankan black rats, with genetic distance of 2.2% and estimated divergence time of 0.3 million years ago. Because one lineage is unique to the island and the other is closely related to R. rattus populations on the Indian subcontinent, two migration events of R. rattus from the subcontinent are inferred, one ancient and one recent. Mc1r analyses revealed 12 haplotypes among the Sri Lankan black rats. A median-joining network together with other availablesequences separated the 12 haplotypes into two groups, one unique to the island and the other related to previously reported R. rattus sequences. Notably, most individuals possessed various combinations of both haplotype groups which had no association with the cytb clades. These results imply that old and new R. rattuslineages are now intermingled as a result of hybridization in Sri Lanka. Specimensof the lesser bandicoot rat (Bandicota bengalensis) collected from Sri Lanka (n = 24) were shown to have no genetic variability in the cytb sequence. Our results indicate that the two most abundant groups of commensal rats in Sri Lanka, black rats and lesser bandicoot rats, are the product of contrasting evolutionary histories on different timescales.
  • Hiromitsu Kono, Masaru Tamura, Naoki Osada, Hitoshi Suzuki, Kuniya Abe, Kazuo Moriwaki, Kunihiro Ohta, Toshihiko Shiroishi
    DNA RESEARCH 21 (3) 315 - 326 1340-2838 2014/06 [Refereed][Not invited]
     
    PR/SET domain containing 9 (Prdm9) mediates histone modifications such as H3K4me3 and marks hotspots of meiotic recombination. In many mammalian species, the Prdm9 gene is highly polymorphic. Prdm9 polymorphism is assumed to play two critical roles in evolution: to diversify the spectrum of meiotic recombination hotspots and to cause male hybrid sterility, leading to reproductive isolation and speciation. Nevertheless, information about Prdm9 sequences in natural populations is very limited. In this study, we conducted a comprehensive population survey on Prdm9 polymorphism in the house mouse, Mus musculus. Overall M. musculus Prdm9 displays an extraordinarily high level of polymorphism, particularly in regions encoding zinc finger repeats, which recognize recombination hotspots. Prdm9 alleles specific to various M. musculus subspecies dominate in subspecies territories. Moreover, introgression into other subspecies territories was found for highly divergent Prdm9 alleles associated with t-haplotype. The results of our phylogeographical analysis suggest that the requirement for hotspot diversity depends on geographical range and time span in mouse evolution, and that Prdm9 polymorphism has not been maintained by a simple balanced selection in the population of each subspecies.
  • Enoki S, Shimizu A, Hayashi C, Imanishi H, Hashizume O, Mekada K, Suzuki H, Hashimoto T, Nakada K, Hayashi J
    Experimental animals / Japanese Association for Laboratory Animal Science 63 (1) 21 - 30 1341-1357 2014 [Refereed][Not invited]
  • H. Suzuki, M. Nunome, G. Kinoshita, K. P. Aplin, P. Vogel, A. P. Kryukov, M-L Jin, S-H Han, I. Maryanto, K. Tsuchiya, H. Ikeda, T. Shiroishi, H. Yonekawa, K. Moriwaki
    HEREDITY 111 (5) 375 - 390 0018-067X 2013/11 [Refereed][Not invited]
     
    We examined the sequence variation of mitochondrial DNA control region and cytochrome b gene of the house mouse (Mus musculus sensu lato) drawn from ca. 200 localities, with 286 new samples drawn primarily from previously unsampled portions of their Eurasian distribution and with the objective of further clarifying evolutionary episodes of this species before and after the onset of human-mediated long-distance dispersals. Phylogenetic analysis of the expanded data detected five equally distinct clades, with geographic ranges of northern Eurasia (musculus, MUS), India and Southeast Asia (castaneus, CAS), Nepal (unspecified, NEP), western Europe (domesticus, DOM) and Yemen (gentilulus). Our results confirm previous suggestions of Southwestern Asia as the likely place of origin of M. musculus and the region of Iran, Afghanistan, Pakistan, and northern India, specifically as the ancestral homeland of CAS. The divergence of the subspecies lineages and of internal sublineage differentiation within CAS were estimated to be 0.37-0.47 and 0.14-0.23 million years ago (mya), respectively, assuming a split of M. musculus and Mus spretus at 1.7 mya. Of the four CAS sublineages detected, only one extends to eastern parts of India, Southeast Asia, Indonesia, Philippines, South China, Northeast China, Primorye, Sakhalin and Japan, implying a dramatic range expansion of CAS out of its homeland during an evolutionary short time, perhaps associated with the spread of agricultural practices. Multiple and non-coincident eastward dispersal events of MUS sublineages to distant geographic areas, such as northern China, Russia and Korea, are inferred, with the possibility of several different routes.
  • Hitoshi Suzuki
    GENES & GENETIC SYSTEMS 88 (3) 155 - 164 1341-7568 2013/06 [Refereed][Not invited]
     
    The purpose of this article is to provide basic knowledge about the Mc1r-Asip system that promotes the evolution of coat color in mammals, and to stimulate genetic, ecological, and phylogeographic studies focusing on color variation in natural populations. The topics reviewed herein include: the genetic system of the Mc1r and Asip genes related to phenotypic variation; the evolutionary implications of the genetic features recorded in their nucleotide sequences; and the validity of surveys in the wild of genetic variations in coat color, which would facilitate a better understanding of the genetic system, ecological meaning, natural history, and taxonomic reevaluation of species and local populations.
  • Takashi Kirihara, Akio Shinohara, Kimiyuki Tsuchiya, Masashi Harada, Alexey P. Kryukov, Hitoshi Suzuki
    ZOOLOGICAL SCIENCE 30 (4) 267 - 281 0289-0003 2013/04 [Refereed][Not invited]
     
    We assessed dispersal and vicariant events in four species of Japanese moles in the genera Mogera and Euroscaptor to better understand the factors shaping intra-and interspecific differentiation in Japanese moles. We used the combined viewpoints of molecular phylogeny and historical geology using nucleotide sequences of mitochondrial (cytochrome b; Cytb) and nuclear (A2ab, Bmp4, Tcf25, vWf) genes. The divergence times estimated from the molecular data were verified with available geological data on the chronology of fluctuations in sea level in the Korea Strait, assuming sequential migration and speciation events. This produced possible migration times of 5.6, 3.5, 2.4, and 1.3 million years ago for four species of Japanese moles, Euroscaptor mizura, Mogera tokudae, M. imaizumii, and M. wogura, respectively. For the western Japanese mole M. wogura, Cytb sequences revealed four major phylogroups with strong geographic affinities in southwestern Central Honshu (I), western Honshu/Shikoku (II), Kyushu/westernmost Honshu (III), and Korea/Russian Primorye (IV). The nuclear gene sequences supported the distinctiveness of phylogroups I and IV, indicating long, independent evolutionary histories. In contrast, phylogroups II and III were merged into a single geographic group based on the nuclear gene data. Intraspecific divergences in M. imaizumii and M. tokudae were rather apparent in Cytb but not in nuclear gene sequences. The results suggest that repeated dispersal events have occurred between the Asian continent and the Japanese Islands, and intensive vicariant events associated with abiotic and biotic factors have created higher levels of species and genetic diversities in moles occurring on the Japanese Islands.
  • Gohta Kinoshita, Mitsuo Nunome, Sang-Hoon Han, Hirofumi Hirakawa, Hitoshi Suzuki
    ZOOLOGICAL SCIENCE 29 (11) 776 - 785 0289-0003 2012/11 [Refereed][Not invited]
     
    We examined the phylogenetic status and history of the mountain hare Lepus timidus in and around Hokkaido using mitochondrial cytochrome b (cyt b) sequences from 158 samples from Hokkaido and 14 from Sakhalin, as well as four samples from the Korean hare, L. coreanus. The phylogenetic analysis of the cyt b sequences generated in this study and obtained from DNA databases showed the clear genetic specificity of the Hokkaido lineage as a clade. The Hokkaido lineage was estimated to have diverged from the other conspecific and L. coreanus lineages 0.46 and 0.30 million years ago (Mya), respectively. These results suggest that the common ancestor of the mitochondrial lineage in Hokkaido and Korea inhabited Far East Asia before colonization by the present continental lineages of L. timidus, including the Sakhalin population. We estimated the time of the most recent common ancestor of the Hokkaido population to be 0.17 Mya, and found two distinct haplogroups within the island. One group had greater genetic diversity (mean number of pairwise differences: pi = 0.0188 +/- 0.0108) and appears to have expanded from the west to the entire island of Hokkaido. The other had lower genetic diversity (pi = 0.0038 +/- 0.0037) and its distribution was concentrated in the east. These contrasting west/east trends indicate that the Hokkaido population was fragmented in the past, and then subsequently expanded. Our study suggests that Hokkaido was an important refugium for boreal species in the far eastern region, and allowed the formation of various population genetic structures within the island.
  • Jun J. Sato, Mieczyslaw Wolsan, Francisco J. Prevosti, Guillermo D'Elia, Colleen Begg, Keith Begg, Tetsuji Hosoda, Kevin L. Campbell, Hitoshi Suzuki
    MOLECULAR PHYLOGENETICS AND EVOLUTION 63 (3) 745 - 757 1055-7903 2012/06 [Refereed][Not invited]
     
    We analyzed a concatenated (8492 bp) nuclear-mitochondrial DNA data set from 44 musteloids (including the first genetic data for Lyncodon patagonicus) with parsimony, maximum likelihood, and Bayesian methods of phylogenetic and biogeographic inference and two Bayesian methods of chronological inference. Here we show that Musteloidea emerged approximately 32.4-30.9 million years ago (MYA) in Asia, shortly after the greenhouse-icehouse global climate shift at the Eocene-Oligocene transition. During their Oligocene radiation, which proceeded wholly or mostly in Asia, musteloids diversified into four primary divisions: the Mephitidae lineage separated first, succeeded by Ailuridae and the divergence of the Procyonidae and Mustelidae lineages. Mustelidae arose approximately 16.1 MYA within the Mid-Miocene Climatic Optimum, and extensively diversified in the Miocene, mostly in Asia. The early offshoots of this radiation largely evolved into badger and marten ecological niches (Taxidiinae, Melinae, Mellivorinae, Guloninae, and Helictidinae), whereas the later divergences have adapted to other niches including those of weasels, polecats, minks, and otters (Mustelinae, Ictonychinae, and Lutrinae). Notably, and contrary to traditional beliefs, the morphological adaptations of badgers, martens, weasels, polecats, and minks each evolved independently more than once within Mustelidae. Ictonychinae (which is most closely related to Lutrinae) arose approximately 9.5-8.9 MYA, most likely in Asia, where it diverged into the Old World Ictonychini (Vormela, Poecilictis, Ictonyx, and Poecilogale) and New World Lyncodontini (Lyncodon and Galictis) lineages. Ictonychini presumably entered Africa during the Messinian Salinity Crisis (at the Miocene-Pliocene transition), which interposed the origins of this clade (approximately 6.5-6.0 MYA) and its African Poecilictis-Ictonyx-Poecilogale subclade (approximately 4.8-4.5 MYA). Lyncodontini originated approximately 2.9-2.6 MYA at the Pliocene-Pleistocene transition in South America, slightly after the emergence of the Panamanian land bridge that provided for the Great American Biotic Interchange. As the genera Martes and Ictonyx (as currently circumscribed) are paraphyletic with respect to the genera Gulo and Poecilogale, respectively, we propose that Pekania and Poecilictis be treated as valid genera and that "Martes" pennanti and "Ictonyx" libyca, respectively, be assigned to these genera. (c) 2012 Elsevier Inc. All rights reserved.
  • Yoshikazu Kambe, Katsushi Nakata, Shumpei P. Yasuda, Hitoshi Suzuki
    GENES & GENETIC SYSTEMS 87 (1) 29 - 38 1341-7568 2012/02 [Refereed][Not invited]
     
    We examined pelage color variation in wild populations of black rats (the Rattus rattus species complex) in the Yambaru forest area, northern Okinawa Island, Ryukyu Archipelago, Japan. Our field study revealed that 8.7% (38/438) and 0.2% (4/2500) of rats exhibited two types of coat color: white spotting and melanism, respectively. Using 34 representative animals, the phylogeography of the population was inferred using a nuclear gene marker, i.e., sequences (954 bp) of the melanocortin-1 receptor (Mc1r) gene responsible for the melanistic form in black rats. Four sequences from Okinawa were characterized as R. tanezumi, the Asian strain of black rat. Notably, neither of the phenotypic characters of white spotting or melanism was associated with the Mc1r haplotypes. Analysis of mitochondrial cytochrome b (Cytb) sequences (1140 bp) revealed that four haplotypes recovered from Okinawa clustered with the clade of R. tanezumi and differed by one or more bases from haplotypes at other localities in Japan and Asian countries. Thus, both variants may have arisen in the native rat population of Okinawa without interaction with the lineage of R. rattus, which exhibits a worldwide distribution and displays such coat color variants. The Yambaru population of black rats has thus experienced its own evolutionary history in allopatry for a substantial period of time (e.g., 10,000 years), which has preserved valuable genetic polymorphisms and will be useful for assessing the ecological consequences of genetic variation in natural populations.
  • Akio Shinohara, Hitoshi Suzuki, Kimiyuki Tsuchiya, Ya-Ping Zhang, Jing Luo, Xue-Long Jiang, Ying-Xiang Wang, Kevin L. Campbell
    ZOOLOGICAL SCIENCE 21 (12) 1177 - 1185 0289-0003 2004/12 [Refereed][Not invited]
     
    We sequenced the cytochrome b gene from two little-studied mammal species from the highlands of Southwest China, the long-tailed mole Scaptonyx fusicaudus and the gracile shrew-like mole Uropsilus gracilis. This data was used to examine the phylogenetic relationships among 19 talpid species within the family Talpidae (Mammalia: Eulipotyphla). Cytochrome b gene trees supported a basal placement of shrew-like moles (Uropsilus) within the Talpidae, and suggested that fossorial specializations arose twice during talpid evolution. To assess the evolutionary relationships of moles endemic to this region, we additionally sequenced the 12S rRNA gene and the nuclear recombination-activating gene-1 from eight and ten East Asian taxa, respectively. Analyses of these single and concatenated data sets suggested that East Asian shrew moles diverged prior to the evolution of fossorial Eurasian moles. However, we were unable to determine whether semi-fossorial shrew moles are monophyletic. In contrast, fossorial Eurasian genera (Talpa, Mogera and Euroscaptor) were consistently found to form a monophyletic clade, with Mogera and Euroscaptor representing sister taxa. Furthermore, this fossorial clade grouped with the semi-aquatic Desmana, although with fairly low (35-62%) bootstrap support. Mogera imaizumii was found to be more closely related to M. wogura than to M. tokudae. This implies that the ancestors of these three species entered Japan from the Asian continent in this order via a series of migration events, suggesting that the Japanese Islands have played an important role in preserving mole lineages from ancient to recent times.
  • MA Iwasa, H Suzuki
    ZOOLOGICAL SCIENCE 20 (10) 1305 - 1313 0289-0003 2003/10 [Refereed][Not invited]
     
    Differences in the nuclear ribosomal DNA (rDNA), mitochondrial DNA (mtDNA), cytochrome b (Cytb), and Y chromosomal Sry genes were used to assess intra- and interspecific relationships in two Japanese red-backed voles, Eothenomys andersoni and E. smithii, focusing on areas where the two species might come into contact. In the Kii Peninsula, southwestern Honshu, which contains an allopatric population of E. andersoni isolated from its main range, the rDNA-RFLP data provide robust evidence of past mutual interspecific gene introgression, while the Cytb and Sry sequences were specific to this population. In central Honshu, where E andersoni and E smithii inhabit higher and lower altitudes, respectively, with a narrow sympatric zone, the rDNA-RFLP and Sty variation was specific for each species, while introgression of the mtDNA from E. smithii to E andersoni was seen. These complex patterns in the gene markers are consistent with our previous notions derived from sex chromosome variation. Our previous and present data strongly suggest that the evolution of these vole species, which are morphologically and cytogenetically distinct, involves complex genetic interactions and the resultant combinations of genes are sometimes peculiar, mainly due to the Cytb haplotypes. However, phylogenetic analysis using a combination of maternal, paternal, and biparental markers has proven useful for understanding the evolutionary history given the complex phylogenetic background.
  • A Shinohara, KL Campbell, H Suzuki
    MOLECULAR PHYLOGENETICS AND EVOLUTION 27 (2) 247 - 258 1055-7903 2003/05 [Refereed][Not invited]
     
    A rich variety of anatomical and physiological specializations has enabled members of the family Talpidae (moles, shrew moles, and desmans) to exploit a diverse range of habitats: terrestrial, semi-aquatic, aquatic/fossorial, semi-fossorial, and fossorial. While numerous morphological and biochemical studies pertaining to the origin and radiation of the Talpidae have been completed, phylogenetic hypotheses remain controversial. To address this shortcoming we sequenced the mitochondrial DNA cytochrome b gene (1140 bp) from 29 individuals spanning 12 talpid species. Phylogenetic trees incorporating 12 New and Old World genera (18 species; all 3 extant subfamilies) were then constructed using NJ, MP, ML, and NJ-ML (NJ with ML parameters) methods. Our results provide molecular support for a mononphyletic Talpidae, and suggest that the 12 genera are clustered into seven major clades; (1) Asiatic shrew-like moles (Uropsilus), (2) North American aquatic/fossorial moles (Condylura), (3) North American fossorial moles (Parascalops, Scalopus, and Scapanus), (4) North American semni-fossorial shrew moles (Neurotrichus), (5) Japanese semi-fossorial shrew moles (Dymecodon and Urotrichus), (6) European semi-aquatic desmans (Desmana), and (7) Eurasian fossorial moles (Euroscaptor, Mogera, and Talpa). None of these groupings comprised mole species from both continents. In fact, North American moles and shrew moles do not appear to have specific affinities with Asian moles and shrew moles, respectively. Although low bootstrap support was generally found for evolutionary nodes uniting the major talpid clades, all gene trees constructed identified fossorial North American and Eurasian mole lineages as nonmonophyletic groups, suggesting subterranean specializations arose independently at least twice during the evolution of the Talpidae. Additionally, our data set provides molecular support for a basal divergence and long independent history of Uropsilus from the main talpid line, and refutes the traditional taxonomic status and secondarily basal phylogenetic placement of the subfamily Desmaninae within the Talpidae. (C) 2002 Elsevier Science (USA). All rights reserved.
  • JJ Sato, T Hosoda, M Wolsan, K Tsuchiya, M Yamamo, H Suzuki
    ZOOLOGICAL SCIENCE 20 (2) 243 - 264 0289-0003 2003/02 [Refereed][Not invited]
     
    Phylogenetic relationships among 20 species-group taxa of Mustelidae, representing Mustelinae (Mustela, Martes, Gulo), Lutrinae (Enhydra), and Melinae (Meles), were examined using nucleotide sequences of the nuclear interphotoreceptor retinoid binding protein (IRBP) and mitochondrial cytochrome b genes. Neighbor-joining and maximum-parsimony phylogenetic analyses on these genes separately and combined were conducted. While IRBP performed better than cytochrome b in recovering more-inclusive clades, cytochrome b demonstrated more resolving power in recovering less-inclusive clades. Strong support was found for a close affinity of Enhydra with Mustela to the exclusion of Martes and Gulo (causing Mustelinae to be paraphyletic); the most-basal position of Mustela vison within Mustela, followed by Mustela erminea; an association of Mustela lutreola, Mustela itatsi, Mustela sibirica, and the subgenus Putorius (including Mustela putorius and Mustela eversmanii), to the exclusion of Mustela nivalis and Mustela altaica; and a basal position of Mustela itatsi to a clade containing Mustela sibirica and Putorius. Whereas cytochrome b strongly supported Mustela lutreola as the sister species to Putorius, IRBP strongly supported its basal placement to the Mustela itatsi-Mustela sibirica-Putorius clade. The low level of sequence divergence in cytochrome b between Mustela lutreola and Putorius is therefore a result of interspecific mitochondrial introgression between these taxa, rather than a recent origin of Mustela lutreola in a close relationship to Putorius. Time estimates inferred from IRBP and cytochrome b for mustelid divergence events are mostly in agreement with the fossil record.
  • K Serizawa, H Suzuki, MA Iwasa, K Tsuchiya, MV Pavlenko, Kartavtseva, IV, GN Chelomina, NE Dokuchaev, SH Han
    BIOCHEMICAL GENETICS 40 (5-6) 149 - 161 0006-2928 2002/06 [Refereed][Not invited]
     
    Apodemus peninsulae is a field mouse that inhabits the broad-leafed forests of temperate Eurasia. We examined the mitochondrial cytochrome b gene in 57 individuals of A. peninsulae from northeastern Asia, including Siberia, Primorye, Magadan region, Sakhalin, Hokkaido, and the Korean Peninsula. The genealogy of the mitochondrial DNA (mtDNA) in A. peninsulae was shown to have substantial geographic affinity, suggesting geographic architecture of northeastern Asia, including the islands of Sakhalin and Hokkaido, played important roles on the cladogenesis. Taking into account the presence of region-specific anciently divergent mtDNA types, three parts of the regions of Primorye, Siberia, and the Korean Peninsula can be denoted as refugia for A. peninsulae during the substantial period of the Quaternary glacial ages. Among the geographic regions examined, Primorye is likely to be the most influential one, from which the mtDNA is thought to have migrated to the neighboring regions of Sakhalin, Hokkaido, the Magadan region, and Siberia during the evolution of this species.
  • F Yamada, M Takaki, H Suzuki
    GENES & GENETIC SYSTEMS 77 (2) 107 - 116 1341-7568 2002/04 [Refereed][Not invited]
     
    We determined mitochondrial 12S ribosomal RNA (rRNA) and cytochrome b (cyt b) gene sequences in three leporid species of Japan, the Amami rabbit Pentalagus furnessi from the Ryukyu Islands, the Japanese hare Lepus brachyurus from Honshu, and a Japanese form of the mountain hare Lepus timidus ainu from Hokkaido. We compared the sequences with those of other taxa of leporids available in databases. Phylogenetic trees of the 12S rRNA gene sequences indicated that the lineage of P. furnessi diversified during the generic radiation of the leporids at an ancient time, which was estimated to have been the middle Miocene. Cyt-b gene trees revealed that the lineage of L. brachyurus branched off at an early stage in the speciation of Lepzts, probably at the beginning of the Pliocene. The cyt b sequences of L. t. aims were somewhat distinct from those of continental conspecific populations; this lineage divergence is likely to have occurred during the middle or late Pleistocene. The results show that the three regions of the Japanese archipelago, Ryukyu, Honshu-Shikoku-Kyushu, and Hokkaido, now preserve their own leporid taxa, each with a different extent of genetic endemicity. It is possible that the zoogeographic traits of the Japanese leporids are a consequence of the evolutionary dynamics of leporids in East Asia, in that the radiation centers of leporids are likely to have shifted from tropical, through temperate, to arctic zones.
  • L. V. Frisman, I. V. Kartavtseva, M. V. Pavlenko, V. A. Kostenko, H. Suzuki, M. Iwasa, K. Nakata, F. B. Chernyavskii
    Genetika 38 (5) 655 - 664 0016-6758 2002 [Refereed][Not invited]
     
    Thirteen enzyme systems and three nonenzyme proteins were electrophoretically analyzed in red-backed voles of the genus Clethrionomys. In total, 25 loci were interpreted. Gene-geographic variation was studied and indices of genetic variability and differentiation were determined. By the distribution of electrophoretic variants of hemoglobin, C. rutilus was shown to be divided into two geographical groups (northern and southern). A low level of genetic differentiation was revealed in the island isolates of C. rutilus and C. rufocanus. Separation of C. rufocanus, C. rex, and C. sicotanensis into a superspecies complex was confirmed. A study of differential G- and C-banding on C. rutilus and C. rufocanus chromosomes did not reveal intraspecific variation of autosomes. In these species, karyotypes of voles from Kamchatka Peninsula were studied for the first time. They appeared to be morphologically similar to the karyotypes continental voles by both autosomes and sex chromosomes.
  • Iwasa MA, Suzuki H
    Chromosome research : an international journal on the molecular, supramolecular and evolutionary aspects of chromosome biology 10 (5) 419 - 428 0967-3849 2002 [Refereed][Not invited]
  • M Motokawa, H Suzuki, M Harada, LK Lin, K Koyasu, S Oda
    ZOOLOGICAL SCIENCE 17 (4) 497 - 504 0289-0003 2000/05 [Refereed][Not invited]
     
    Phylogenetic relationships among the East Asian species of the genus Crocidura (Mammalia, Insectivora, Soricidae) were inferred from the partial sequences (402 base pairs) of the mitochondrial cytochrome b gene. Six species of Crocidura and one representative of another insectivoran genus Suncus were examined. In the neighbor joining tree, four distinct lineages were recognized: C. lasiura from northeastern China and Korea, and C. dsinezumi from the main-islands of Japan; C. attenuata from Taiwan; C. watasei from the Amami and Okinawa Groups, and S. murinus from the Miyako Group; and C. suaveolens from Tsushima and Taiwan, and C. sibirica from Central Asia in Russian territory. All these lineages excluding C. lasiura and C. dsinezumi were also recognized by the maximum parsimony analysis. Clustering of C. watasei with S. murinus suggested the non-monophyly of the genus Crocidura as of the present definition. Biogeographical implications of the present results were also discussed.

Books etc

  • カラス類の系統進化史
    北海道大学出版会 2010
  • Natural history of crows
    Hokkaido University Press 2010
  • 『保全遺伝学』<小池裕子,松井正文編>
    東京大学出版会 2003

MISC

  • Morihiko Tomozawa, Mitsuo Nunome, Hitoshi Suzuki, Hirotake Ono  BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY  113-  (2)  522  -535  2014/10  [Not refereed][Not invited]
     
    To infer the evolutionary mechanism of phenotypic variation among isolated island populations, we investigated coat colour and genetic variation in the large Japanese field mouse (Apodemus speciosus) on the Izu Islands (Ohshima, Niijima, Kouzushima, and Miyakejima). Coat colour in the most remote population (Miyakejima) was unique and significantly darker than that in the other populations. Ohshima that is closest to the source population showed variation in coat colour within its population. Phylogeographical analyses using mitochondrial and microsatellite markers suggested that the island populations (except Kouzushima) were founded sequentially from the closest Ohshima to remote Niijima and Miyakejima during or before the penultimate interglacial period. Secondary gene flow from the source population was rare and occurred only for the closest (Ohshima) population. In addition, we found that an amino acid mutation in the Agouti signalling protein gene (Asip) was associated with coat colour variation among the island populations. The mutation was rare in the source population but completely fixed in the Miyakejima population. The phenotypic and genetic variation suggested that severe reduction of genetic variation and changes in allele frequency as a result of sequential colonization (i.e. the founder effect) had significant effects on colour polymorphism. The findings of the present study suggest that the founder effect, in addition to natural selection, facilitated the morphological changes below the species level over a relatively long time scale.(c) 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 522-535.
  • Hiroshi Sasaki, Kyoko Ohta, Toshiki Aoi, Shigeki Watanabe, Tetsuji Hosoda, Hitoshi Suzuki, Mikiko Abe, Kazuhiro Koyasu, Syuji Kobayashi, Sen-ichi Oda  MAMMAL STUDY  39-  (3)  133  -139  2014/09  [Not refereed][Not invited]
     
    The vertical distribution of introduced Siberian weasels Mustela,sibirica and endemic Japanese weasels M. itatsi in the Seburi Mountains in Kyushu, Japan, was examined from October 1996 to February 1998. Siberian weasels occurred near villages with paddy and cultivated fields, whereas Japanese weasels occurred in grasslands and plantations. The dispersion of yearlings destabilized the distributions of both weasel species. The horizontal distribution of both species throughout Japan was examined by means of collection of dead specimens and by trapping from March 1998 to March 2002. The eastern boundary of the distribution of the Siberian weasel was Fukui, Nagano, and Aichi prefectures; however, the distribution is expanding slowly eastward. The Siberian weasel cannot invade new habitats that lack nearby villages in Seburi, and cannot expand its range in the eastern area of Aichi, where Japanese weasels are dominant. The presence of the Japanese weasel likely prevents expansion of the distribution of the Siberian weasel.
  • Akio Shinohara, Shin-ichiro Kawada, Nguyen Truong Son, Chihiro Koshimoto, Hideki Endo, Dang Ngoc Can, Hitoshi Suzuki  JOURNAL OF MAMMALOGY  95-  (3)  455  -466  2014/06  [Not refereed][Not invited]
     
    The diversity of fossorial moles in East and Southeast Asia is contained in the 2 species-rich genera Mogera (8 species) and Euroscaptor (8 or more species), and the 3 monospecific genera Scapanulus, Scaptochirus, and Parascaptor. To better understand the evolution and biogeography of these fossorial moles, we conducted molecular phylogenetic analyses using mitochondrial cytochrome-b (Cytb; 1,140 base pairs [bp]) and 12S rRNA (approximately 830 bp) and nuclear recombination activating gene 1 (Ragl; 1,010 bp) gene sequences from 5 species of Euroscaptor, 6 of Mogera, and the single species of Scaptochirus. Phylogenetic estimates revealed 5 distinct lineages of East and Southeast Asian fossorial moles: Mogera, Scaptochirus, Euroscaptor mizura, E. parvidens, and E. malayana-E. klossi-E. longirostris. Our results support the monophyly of Mogera but not Euroscaptor, indicating a need for taxonomic revision of the latter genus. We hypothesize that Mogera originated in the central portion of its range and then dispersed to peripheral islands, such as Taiwan and the Japanese Islands. The fragmented distribution of Southeast Asian Euroscaptor presumably arose from habitat competition (invasion) from Mogera species, long-range dispersal, vicariance events, or a combination of these, explaining the high species richness of fossorial moles in this region.
  • Alexey Kryukov, Liudmila Spiridonova, Sumio Nakamura, Elisabeth Haring, Hitoshi Suzuki  ZOOLOGICAL SCIENCE  29-  (8)  484  -492  2012/08  [Not refereed][Not invited]
     
    The jungle crow Corvus macrorhynchos Wagler, 1827, and the carrion crow Corvus corone L., 1758, are two closely related species with similar ecological requirements that occupy wide distribution ranges in the Palearctic. We studied patterns of their genetic variation by using sequences of the mitochondrial cytochrome b gene. Corvus macrorhynchos demonstrates a low level of variation and differentiation throughout its range, except for a highly diverged population of Cheju Island (Korea). The haplotype network shows two haplogroups. The island group comprises populations of Sakhalin, Hokkaido, Honshu, and Kyushu, while the haplotypes of Taiwan and Ryukyu Islands proved to be closer to the mainland group, which also includes populations from the Primorye, Khabarovsk, Amur, and Magadan regions in the Russian Far East. This pattern allowed us to develop a phylogeographic hypothesis regarding the two modes of settling of the island populations. Concerning C. corone, the presence of two distinct haplogroups was confirmed within the range of C. c. orientalis. Both haplogroups are found within the same populations in Kamchatka and North Sakhalin, which implies secondary contacts there. Populations of C. corone are found to be rather stable in the western parts of its range, while in the Far East populations experienced recent growth, as was observed for C. macrorhynchos in general. The two species appear to have passed through different evolutionary scenarios.
  • 桑山崇, 布目三夫, 鈴木仁  タクサ  (32)  7  -12  2012/02/20  [Not refereed][Not invited]
  • Kuwayama Takashi, Nunome Mitsuo, Suzuki Hitoshi  タクサ : 日本動物分類学会誌  (32)  7  -12  2012/02/20  [Not refereed][Not invited]
     
    In this review article, we describe a recently developed method that explores past introgressive hybridization following secondary contact, focusing on recombination signals along a certain chromosome portion, such as 200 kb, 1 Mb, or 5 Mb. In a case of 200 kb segment, for example, we determined nucleotide sequences in eight gene region (〜500 bp) being separated at 20-30 kb interval and assessed its haplotype structures. This allows us to estimate the time since hybridization has occurred, assuming that the lengths of introgressed segments reflect the times of generation. We applied this method to capture missed evolutionary episodes of the house mouse Mus musculus occurring in the Japanese Islands, where different subspecies lineages are known to be mingled. We detected the recombinant haplotypes not only between north Eurasian (M. m. musculus) and East Asian (M. m. castaneus) lineages but also between north Eurasian and East European (M. m. domesticus) lineages, with relatively shorter and longer introgressed segments, respectively. These results suggest that the Japanese wild mice with the genetic background of M. m. musculus experienced ancient and recent genetic introgression with M. m. castaneus and M. m. domesticus, respectively. Further efforts would be needed to improve the method, aiming at establishment of ways to fully utilize the genetic information related to recombination events in molecular phylogeographic study.
  • Shumpei P. Yasuda, Manami Iwabuchi, Haruka Aiba, Shusaku Minato, Kunihiro Mitsuishi, Kimiyuki Tsuchiya, Hitoshi Suzuki  ZOOLOGICAL SCIENCE  29-  (2)  111  -120  2012/02  [Not refereed][Not invited]
     
    We previously revealed the presence of six genetically distinct matrilineal populations of the Japanese dormouse Glirulus japonicus in the distribution range of Honshu, Shikoku, and Kyushu islands. In this study, we extended this analysis using mitochondrial cytochrome b gene sequences (n = 96) and Y-chromosome-specific SRY gene sequences (n = 22) from individuals collected from Honshu, Shikoku, Kyushu, and Oki Dogo I. The cytochrome b sequence data allowed us to define precise geographic ranges of the six previously known and three newly found distinct matrilineal lineages: northeastern Honshu (I), east-central Honshu (II), west-central Honshu and the Kii Peninsula (III), the western part of Honshu (IV), Shikoku (V), westernmost Honshu and Kyushu (VI), the northern part of central Honshu (VII), the southern part of central Honshu (VIII), and Oki Dogo I. (IX). Our inference of geographic borders suggests that regions of lower and higher altitudes in the mountain systems played important roles in driving the hosting and separation of lineages, respectively. Six matrilineal lineages (I, II, V, VI, VIII, and XI) were shown to possess their own SRY haplotypes, while lineages III and IV shared one haplotype. These data together with our previous observation of nuclear ribosomal RNA gene variation indicate advanced populational subdivision in this species. It is thus evident that each of the populations, including those living at high latitudes and in limited geographic spaces, have survived for several million years. A specific ability to tolerate cold may have permitted G. japonicus to preserve anciently diverged lineages in each locality.
  • SATO Jun J, HOSODA Tetsuji, KRYUKOV Alexey P, KARTAVTSEVA Irina V, SUZUKI Hitoshi  Mammal Study  36-  (4)  209  -220  2011/12/01  [Not refereed][Not invited]
  • Ken P. Aplin, Hitoshi Suzuki, Alejandro A. Chinen, R. Terry Chesser, Jose ten Have, Stephen C. Donnellan, Jeremy Austin, Angela Frost, Jean Paul Gonzalez, Vincent Herbreteau, Francois Catzeflis, Julien Soubrier, Yin-Ping Fang, Judith Robins, Elizabeth Matisoo-Smith, Amanda D. S. Bastos, Ibnu Maryanto, Martua H. Sinaga, Christiane Denys, Ronald A. Van den Bussche, Chris Conroy, Kevin Rowe, Alan Cooper  PLOS ONE  6-  (11)  e26357  2011/11  [Not refereed][Not invited]
     
    The Black Rat (Rattus rattus) spread out of Asia to become one of the world's worst agricultural and urban pests, and a reservoir or vector of numerous zoonotic diseases, including the devastating plague. Despite the global scale and inestimable cost of their impacts on both human livelihoods and natural ecosystems, little is known of the global genetic diversity of Black Rats, the timing and directions of their historical dispersals, and the risks associated with contemporary movements. We surveyed mitochondrial DNA of Black Rats collected across their global range as a first step towards obtaining an historical genetic perspective on this socioeconomically important group of rodents. We found a strong phylogeographic pattern with well-differentiated lineages of Black Rats native to South Asia, the Himalayan region, southern Indochina, and northern Indochina to East Asia, and a diversification that probably commenced in the early Middle Pleistocene. We also identified two other currently recognised species of Rattus as potential derivatives of a paraphyletic R. rattus. Three of the four phylogenetic lineage units within R. rattus show clear genetic signatures of major population expansion in prehistoric times, and the distribution of particular haplogroups mirrors archaeologically and historically documented patterns of human dispersal and trade. Commensalism clearly arose multiple times in R. rattus and in widely separated geographic regions, and this may account for apparent regionalism in their associated pathogens. Our findings represent an important step towards deeper understanding the complex and influential relationship that has developed between Black Rats and humans, and invite a thorough re-examination of host-pathogen associations among Black Rats.
  • Yoshikazu Kambe, Tsutomu Tanikawa, Yasuharu Matsumoto, Morihiko Tomozawa, Ken P. Aplin, Hitoshi Suzuki  ZOOLOGICAL SCIENCE  28-  (8)  560  -567  2011/08  [Not refereed][Not invited]
     
    We examined nucleotide changes that underlie coat color variation in Black Rats (the Rattus rattus species complex), which show polymorphism in dorsal fur color, including either grayish brown (agouti) or black (melanistic) forms. We examined the full coding sequence of a gene known to produce melanism in other vertebrates-melanocortin-1-receptor gene Mc1r (954 bp) -using samples of both R. rattus (with 2n = 38) and its close relative Asian Black Rat (R. tanezumi; 2n = 42). We used 61 specimens from Japan with karyotype-known individuals and four samples from Pakistan. We found 11 allele sequences and constructed a network tree that shows two distinct clusters, with allelic segregation according to karyotype and by inference, representing the two species. We found that a nucleotide substitution from G to A at site 280, producing an amino acid change from glutamic acid to lysine, was associated with the dominant trait of the melanistic form of the coat color in R. rattus. Notably, the derived SNP 280A was found in a single allele, with the ancestral SNP 280G present in seven alleles. By contrast, all three alleles for R. tanezumi retain the ancestral SNP 280G. These results suggest a possible recent origin of melanism in R. rattus.
  • T. Hosoda, J. J. Sato, L. -K. Lin, Y. -J. Chen, M. Harada, H. Suzuki  CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE  89-  (6)  559  -569  2011/06  [Not refereed][Not invited]
     
    Phylogenetic relationships among species of the family Mustelidae were examined using the combined nucleotide sequences of the three mitochondrial genetic loci (cytochrome b (MT-CYB; 1140 bp), NADH dehydrogenase subunit 2 (MT-ND2; 1044 bp), and displacement loop (MT-DLOOP; 540 bp)), with special emphasis on the phylogenetic history of four Taiwanese mustelid species: Martes flavigula (Boddaert, 1785), Melogale moschata (Gray, 1831), Mustela nivalis L., 1766, and Mustela sibirica Pallas, 1773. Maximum likelihood phylogenetic analysis of the combined sequences of the mitochondrial genetic loci produced a topology largely congruent with that of previous studies at the species level. Analyses of intra-specific genetic variations revealed two Melogale moschata individuals from Taiwan and Vietnam that showed genetic distances comparable with interspecific variations within the mustelid lineages. Furthermore, Mustela nivalis, recently discovered in Taiwan, was not as genetically differentiated from other continental conspecific individuals as a previous morphological survey suggested. Divergence time estimations for the mustelid lineages of Taiwan and the Eurasian continent by the Bayesian relaxed molecular clock approach suggested multiple colonization of Taiwan by mustelids from the continent during the Pleistocene, creating a hierarchical pattern of endemism based on the differential isolation history of the mustelid species in Taiwan.
  • Mitsuo Nunome, Harumi Torii, Rikyu Matsuki, Gohta Kinoshita, Hitoshi Suzuki  ZOOLOGICAL SCIENCE  27-  (9)  746  -754  2010/09  [Not refereed][Not invited]
     
    We performed a phylogeographic analysis of the Japanese hare, Lepus brachyurus, using the mitochondrial cytochrome b gene (1140 bp). In total, 119 haplotypes were recovered from 197 samples isolated from 82 localities on three main islands of the Japanese archipelago: Honshu, Sikoku, Kyushu, Sado Island and the Oki Islands. Results showed two distinct clades at a genetic distance of 3.5%, equivalent to an estimated 1.2 million years. The two clades, encompassing seven sub-clades, showed an apparent geographic affinity to Kyushu, Shikoku and the nearby area of Honshu (southern group) by one clade, whereas the other clade covered the remaining area of Honshu (northern group). The landscape shape interpolation analysis exhibited a higher genetic diversity in the southern parts of central Honshu (northern group) and Shikoku and Kyushu regions (southern group), suggesting the existence of multiple geographical origins of population expansion in each clade. The Bayesian skyline plot analysis showed that lineage diversifications occurred about 0.35, 0.20 and 0.05 million years ago (Mya), which coincide closely with the glacial-interglacial cycles during the Pleistocene. Therefore, we suggest that the Japanese hare population once inhabited northern and southern refugia, and subsequently developed several populations through local demographic fluctuations. The present day demarcation in the northern and southern geographic groups is considered to be a temporal remnant of Pleistocene population dynamics and the geographic boundary between them could move or fade away in time.
  • Morihiko Tomozawa, Hiroshi Tomida, Hitoshi Suzuki, Kimiyuki Tsuchiya  MAMMAL STUDY  35-  (2)  93  -97  2010/06  [Not refereed][Not invited]
     
    A phylogeographic study of the large Japanese wood mouse, Apodemus speciosus, on Sado Island, Japan, was performed based on sequences of the mitochondrial cytochrome b gene (1,140 bp). Our previous study covered the entire species range and suggested that the mice on Sado Island are monophyletic, exhibiting two well diverged lineages throughout the island. The present data also supported two lineages (the average number of nucleotide difference was 11.4), showing a weak phylogeographic structure. Given the high sequence divergence observed, we assumed historically subdivided populations within the island. Bayesian coalescent analysis supported a dual-population model rather than that of one large population. The times to most recent common ancestor of all sequences were 293,000 years ago [ka; 95% highest probability density (HPD) 85-634 ka] and 292 ka (HPD 102-605 ka) for the one- and dual-population models, respectively. These results suggest that the populations have undergone repeated separations and reconnections, rather than being subdivided completely through time. Our results are in accordance with other paleogeographic and phylogeographic evidence from the island. The present study highlighted a unique system of producing and maintaining genetic diversity and suggested prehistoric colonization of the A. speciosus population on Sado Island, thus supporting the ancient origin of the mammalian fauna of Sado Island.
  • Mitsuo Nunome, Chikako Ishimori, Ken P. Aplin, Kimiyuki Tsuchiya, Hiromichi Yonekawa, Kazuo Moriwaki, Hitoshi Suzuki  MOLECULAR ECOLOGY  19-  (12)  2474  -2489  2010/06  [Not refereed][Not invited]
     
    Japanese house mice (Mus musculus molossinus) are thought to be a hybrid lineage derived from two prehistoric immigrants, the subspecies M. m. musculus of northern Eurasia and M. m. castaneus of South Asia. Mice of the western European subspecies M. m. domesticus have been detected in Japanese ports and airports only. We examined haplotype structuring of a 200 kb stretch on chromosome 8 for 59 mice from throughout Eurasia, determining short segments (approximate to 370-600 bp) of eight nuclear genes (Fanca, Spire2, Tcf25, Mc1r, Tubb3, Def8, Afg3l1 and Dbndd1) which are intermittently arranged in this order. Where possible we identified the subspecies origin for individual gene alleles and then designated haplotypes for concatenated alleles. We recovered 11 haplotypes among 19 Japanese mice examined, identified either as 'intact' haplotypes derived from the subspecies musculus (57.9%), domesticus (7.9%), and castaneus (2.6%), or as 'recombinant' haplotypes (31.6%). We also detected recombinant haplotypes unique to Sakhalin. The complex nature of the recombinant haplotypes suggests ancient introduction of all three subspecies components into the peripheral part of Eurasia or complicated genomic admixture before the movement from source areas. 'Intact' domesticus and castaneus haplotypes in other Japanese wild mice imply ongoing stowaway introductions. The method has general utility for assessing the history of genetic admixture and for disclosing ongoing genetic contamination.
  • Tomofumi Shimada, Ken P. Aplin, Hitoshi Suzuki  ZOOLOGICAL SCIENCE  27-  (5)  449  -459  2010/05  [Not refereed][Not invited]
     
    Mus lepidoides of central Burma (Myanmar) was described 75 years ago but has since been dismissed as a regional variant of the Indian field mouse, M. booduga. DNA sequences of multiple mitochondrial and nuclear genes from recently collected specimens, combined with a fresh morphological reassessment, reaffirm the distinctiveness of M. lepidoides from M. booduga and from all other species of Mus. Mus lepidoides is so distinct in fact that it warrants placement in its own Species Group within subgenus Mus. Molecular and morphological assessments of phylogenetic affinities converge on the exciting possibility that M. lepidoides represents the previously elusive sibling taxon to the Mus musculus Species Group. If confirmed, this relationship would provide the previously missing connection between the main radiation of subgenus Mus in Southeast and South Asia, and the radiation of the M. musculus Species Group in western Asia and Europe. We speculate that a common ancestor of M. lepidoides and the M. musculus Species Group occupied a continuous but episodic tract of xeric habitat that linked central Burma with northern India at various times during the late Pliocene and Quaternary. Further molecular and cytogenetic studies on the phylogenetic position of M. lepidoides clearly represent a high priority in mouse research.
  • Jun J. Sato, Mieczyslaw Wolsan, Shinji Minami, Tetsuji Hosoda, Martua H. Sinaga, Kozue Hiyama, Yasunori Yamaguchi, Hitoshi Suzuki  MOLECULAR PHYLOGENETICS AND EVOLUTION  53-  (3)  907  -922  2009/12  [Not refereed][Not invited]
     
    Few species have been of more disputed affinities than the red or lesser panda (Ailurus fulgens), an endangered endemic Southeast Asian vegetarian member of the placental mammalian order Carnivora. This peculiar carnivoran has mostly been classified with raccoons (Procyonidae) or bears (Ursidae), grouped with the giant panda (Ailuropoda melanoleuca) in their own family, or considered a separate lineage of equivocal ancestry. Recent molecular studies have indicated a close affinity of the red panda to a clade of procyonids and mustelids (weasels, otters, martens, badgers, and allies), but have failed to unambiguously resolve the position of this species relative to mephitids (skunks and stink badgers). We examined the relationship of the red panda to other extant species of the carnivoran suborder Caniformia using a set of concatenated similar to 5.5-kb sequences from protein-coding exons of five nuclear genes. Bayesian, maximum likelihood, and parsimony phylogenetic analyses strongly supported the red panda as the closest living relative of a clade containing Procyonidae and Mustelidae to the exclusion of Mephitidae. These three families together with the red panda (which is classified here as a single extant species of a distinct family, Ailuridae) compose the superfamily Musteloidea, a clade strongly supported by all our phylogenetic analyses as sister to the monophyletic Pinnipedia (seals, sea lions, walruses). The approximately unbiased, Kishino-Hasegawa, and Templeton topology tests rejected (P < 0.05) each of all possible alternative hypotheses about the relationships among the red panda and mephitids, procyonids, and mustelids. We also estimated divergence times for the red panda's lineage and ones of other caniform taxa, as well as the ages of the first appearance datums for the crown and total clades of musteloids and the total clades of the red panda, mephitids, procyonids, and mustelids. Bayesian relaxed molecular-clock analysis using combined information from all sampled genes yielded a similar to 42-Myr timescale to caniform evolution and provided evidence of five periods of increased diversification. The red panda's lineage and those of other extant musteloid families are estimated to have diverged during a 3-Myr interval from the mid-Early Oligocene to near the Early/Late Oligocene boundary. We present fossil evidence that extends the early adaptive radiation of the total clade of musteloids to the Eocene-Oligocene transition and also suggests Asia as a center of this radiation. (C) 2009 Elsevier Inc. All rights reserved.
  • YAMADA Fumio, SUZUKI Hitoshi, KUROIWA Asato, MURATA Chie  Honyurui Kagaku (Mammalian Science)  49-  (1)  133  -135  2009/06/30  [Not refereed][Not invited]
  • Tomofumi Shimada, Jun J. Sato, Ken P. Aplin, Hitoshi Suzuki  GENES & GENETIC SYSTEMS  84-  (3)  225  -231  2009/06  [Not refereed][Not invited]
     
    Sequences from ten species of Mus (Rodentia, Muridae) of the melanocortin-1 receptor (Mc1r) gene (945 bp), which plays a key role in coat color determination, were compared with an existing Mc1r dataset (ca. 498 bp) from 12 species of Mustela and Martes (Carnivora, Mustelidae). The dN/dS ratio (omega) was estimated at 0.19 for Mus and 0.35 for the mustelids, using a likelihood-based one-ratio model with empirical codon frequencies. Running the model with equal codon frequencies gave a dramatic increase in omega for the mustelids (1.02) but not for Mus (0.31), indicating stronger codon usage bias in Mc1r among mustelids. When omega was estimated with the free-ratio model, significantly accelerated rates of amino acid replacement (nearly 1 in omega) were seen in several regions of the Mus phylogeny, such as in the ancestral subgeneric lineages, possibly associated with ecological niche shifting. Our results suggest that both functional constraints on coat color variation and selective constraints on codon usage bias have participated in structuring Mc1r gene sequences. Furthermore, they suggest that these contrasting influences have acted differentially in Mus and the mustelid lineages, and also differentially during the course of evolution within the genus Mus.
  • S. P. Yasuda, A. A. Nakayama, M. Iwabuchi, S. Minato, K. Tsuchiya, H. Suzuki  MOLECULAR ECOLOGY RESOURCES  9-  (2)  569  -571  2009/03  [Not refereed][Not invited]
     
    Eight microsatellite markers were developed for the Japanese dormouse (Glirulus japonicus), a natural monument and near-threatened species in Japan. The markers amplify in individuals from all of the mitochondrial lineages detected in a previous study. Numerous polymorphisms were detected in specimens from a local population in central Honshu (11-21 alleles per locus; n = 31) and from the entire distribution range of the species (19-41 alleles per locus; n = 152). These microsatellites will be useful in conservation genetic studies of G. japonicus.
  • Mozaic genome structure of multiple subspecies in the Japanese wild mouse Mus musculus.
    The Wild Mammals of Japan.  180  -181  2009  [Not refereed][Not invited]
  • A molecular phylogenetic view of mammals in the “three-story museum” of Hokkaido, Honshu, and Ryukyu Islands.
    The Wild Mammals of Japan.  261  -263  2009  [Not refereed][Not invited]
  • Sutou Shizuyo, Suzuki Hitoshi, Tsuchiya Kimiyuku  Taikai Program Yoshisyu of the Environmental Mutagen Society of Japan  (37)  2008/11/20  [Not refereed][Not invited]
  • 鈴木 仁  遺伝  62-  (6)  60  -66  2008/11  [Not refereed][Not invited]
  • Hitoshi Suzuki, Maria Grazia Filippucci, Galina N. Chelomina, Jun J. Sato, Keiko Serizawa, Eviatar Nevo  BIOCHEMICAL GENETICS  46-  (5-6)  329  -346  2008/06  [Not refereed][Not invited]
     
    Sequences of the mitochondrial cyt b gene and nuclear IRBP, RAGI, 17, and vWF genes were used to assess the evolutionary history of major lineages of Apodemus, in particular to better understand dispersal between Asia and Europe. Our data show eight extant lineages of Late Tertiary origin: Apodemus agrarius, A. semotus, A. peninsulae, A. speciosus, A. argenteus, A. gurkha, A. mystacinus, and A. sylvaticus. Monophyly of two European lineages (A. mystacinus and A. sylvaticus) and four Asian lineages (A. agrarius, A. semotus, A. peninsulae, and A. speciosus) was confirmed with high bootstrap support. Together with literature data, the available molecular data depict three crucial evolutionary events: (1) initial wide dispersal and subsequent radiation around 6 million years ago, (2) region-specific radiations in Europe and southern China around 2 million years ago, and (3) westward dispersal of A. agrarius to Europe in the Late Quaternary.
  • Akio Shinohara, Shin-Ichiro Kawada, Masashi Harada, Kazuhiro Koyasu, Sen-Ichi Oda, Hitoshi Suzuki  Mammal Study  33-  (2)  77  -82  2008/06  [Not refereed][Not invited]
  • Morihiko Tomozawa, Hitoshi Suzuki  ZOOLOGICAL SCIENCE  25-  (3)  273  -285  2008/03  [Not refereed][Not invited]
     
    A phylogeographic analysis was performed on Japanese endemic wood mice (Apodemus speciosus) using nuclear interphotoreceptor retinol binding protein (IRBP) gene sequences (1,152 bp), together with previously published mitochondrial cytochrome b (cyt b) data. In the IRBP analysis, 40 haplotypes were recovered from 84 individuals by statistical and subcIoning methods. Substantial sequence variation was determined from the IRBP data (pi=0.0047), and no significant evidence of recombination was detected. From the phylogenetic analysis, the 40 haplotypes fell into two major groups with geographic associations, irrespective of the karyotype groups (2n=46 and 2n=48), yielding a trend of central (Hokkaido, Honshu, Shikoku, Kyushu, and Sado) and peripheral (Izu, Oki, Tsushima, and Satsunan Is.) groupings. This geographic pattern is similar to that observed in the cyt b data, with a different insular grouping of Sado, Hokkaido, Izu, and Satsunan islands, and also to that of morphological features. In both gene data sets, nested clade analyses revealed allopatric fragmentation in the "peripheral island clades" and range expansion in the "central island clades:" A mismatch analysis using cyt b data also suggested expansion of the central islands clade. Thus, the trend of central vs. peripheral structuring may be attributable to past demographic dynamics in the two distinct haplotype clades, such as range expansion of one clade in the central area of the Japanese Islands, leaving the other clade in the periphery.
  • SHIMADA Tomofumi, APLIN Ken P, JOGAHARA Takamichi, LIN Liang-Kong, HERBRETEAU Vincent, GONZALEZ Jean-Paul, SUZUKI Hitoshi  Journal of the Mammalogical Society of Japan  32-  (2)  49  -62  2007/12/01  [Not refereed][Not invited]
     
    We investigated genetic variation in mitochondrial cytochrome b within the long-tailed rice field mouse, Mus caroli Bonhote, 1902, across its entire geographic range in Southeast and East Asia with a view to: 1) assessing the pattern and causality of phylogeographic structure in a terrestrial small mammal from continental Southeast Asia; and 2) distinguishing genuine insular relics from cases of human-assisted translocation. We identified five main mtDNA lineages which show a similar level of differentiation as the subspecies of M. musculus and probably diverged during the Middle Pleistocene. Two of the lineages are restricted to large islands (Taiwan and Java) and their existence is explicable in terms of regional palaeogeographic factors including changes in sea level and climate. The remaining lineages are distributed in different regions on mainland Southeast Asia but vicariant explanations are inappropriate given the relatively short time frame. Dispersal across barriers followed by local differentiation probably explains the observed phylogeographic patterning on the mainland. A close genetic link between Okinawan M. caroli and populations in Laos confirms previous suggestions that people carried this species to the Ryukyu Archipelago. However, more intensive regional sampling is needed to identify a precise source area.
  • Mitsuo Nunome, Shumpei P. Yasuda, Jun J. Sato, Peter Vogel, Hitoshi Suzuki  ZOOLOGICA SCRIPTA  36-  (6)  537  -546  2007/11  [Not refereed][Not invited]
     
    We examined phylogenetic relationships among six species representing three subfamilies, Glirinae, Graphiurinae and Leithiinae with sequences from three nuclear protein-coding genes (apolipoprotein B, APOB; interphotoreceptor retinoid-binding protein, IRBP; recombination-activating gene 1, RAG1). Phylogenetic trees reconstructed from maximum-parsimony (MP), maximum-likelihood (ML) and Bayesian-inference (BI) analyses showed the monophyly of Glirinae (Glis and Glirulus) and Leithiinae (Dryomys, Eliomys and Muscardinus) with strong support, although the branch length maintaining this relationship was very short, implying rapid diversification among the three subfamilies. Divergence time estimates were calculated from ML (local clock model) and Bayesian-dating method using a calibration point of 25 Myr (million years) ago for the divergence between Glis and Glirulus, and 55 Myr ago for the split between lineages of Gliridae and Sciuridae on the basis of fossil records. The results showed that each lineage of Graphiuros, Glis, Glirulus and Muscardinus dates from the Late Oligocene to the Early Miocene period, which is mostly in agreement with fossil records. Taking into account that warm climate harbouring a glirid-favoured forest dominated from Europe to Asia during this period, it is considered that this warm environment triggered the prosperity of the glirid species through the rapid diversification. Glirulus japonicas is suggested to be a relict of this ancient diversification during the warm period.
  • S. P. Yasuda, S. Minato, K. Tsuchiya, H. Suzuki  JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH  45-  (2)  155  -162  2007/05  [Not refereed][Not invited]
     
    The sequences of the mitochondrial cytochrome b gene and restriction site variation in the spacer region of the nuclear ribosomal RNA gene [rDNA-restriction fragment length polymorphism (RFLP)] were analysed to determine the phylogeographic structure of the Japanese dormouse (Glirulus japonicus), which is threatened by deforestation and has been designated an endangered species in Japan. The phylogenetic tree of cytochrome b grouped G. japonicus into six geographical populations: north-eastern Honshu (I), central Honshu (II), west-central Honshu/Kii Peninsula (III), western Honshu (IV), Shikoku (V), and westernmost Honshu/Kyushu (VI); the genetic distances among these groups suggest divergence in the Late Tertiary. The lineage of group VI was located at the basal position in the phylogenetic tree, followed by the radiation of the other lineages. An rDNA-RFLP analysis of 15 restriction sites roughly supported such genetic isolation; groups I, II, III, IV, V and VI have five, two, one, one, one and four unique restriction sites, respectively, revealing four geographic groups as cryptic species: I, II, III + IV + V and VI. Our results reveal the ancient divergences of the local population, which has a complicated evolutionary history, and should be useful in developing a framework for the conservation of this species.
  • Rediscovery of Mus nitidulus Blyth, 1859 (Rodentia, Muridae), an endemic murine rodent of the central basin of Myanmar
    Zootaxa  1498-  45  -68  2007  [Not refereed][Not invited]
  • Masahiro A. Iwasa, Chizu Kawakubo, Kimiyuki Tsuchiya, Hitoshi Suzuki  ZOOLOGICAL SCIENCE  23-  (11)  955  -961  2006/11  [Not refereed][Not invited]
     
    The lesser Japanese mole, Mogera imaizumii, recognized by Motokawa and Abe (1996), occurs in eastern Honshu, western Honshu and Shikoku. Mitochondrial and nuclear DNA were analyzed for mole samples from eastern Honshu to elucidate intraspecific differentiation. Analyses of sequences of the mitochondrial cytochrome b gene (Cytb) and of a restriction fragment length polymorphism of the nuclear 28S ribosomal RNA gene spacer (rDNA-RFLP) revealed two genetic types, partially corresponding to Hutterer's (1993) taxa, M. wogura (= M. imaizumii) and M. minor. Most samples showed either of two combinations of mitochondrial / nuclear gene types. However, two specimens showed a different combination. This incongruent combination of mitochondrial and nuclear genes might have derived, in part, from an introgression event between genetically differentiated populations after secondary contact during the evolutionary history of the lesser Japanese mole in eastern Honshu.
  • M Terashima, S Furusawa, N Hanzawa, K Tsuchiya, A Suyanto, K Moriwaki, H Yonekawa, H Suzuki  HEREDITY  96-  (2)  128  -138  2006/02  [Not refereed][Not invited]
     
    We examined intraspecies genetic variation in house mice (Mus musculus molossinus) from the northern third of the Japanese Islands, in order to obtain evidence of the history of mouse colonization that might have shaped the current genetic diversity. We extended the previous sampling of mitochondrial cytochrome b sequence and added information from the Y-linked Sry gene and ribosomal RNA gene surveys. We distinguish mitochondrial haplotypes characteristic of the North Asian musculus subspecies group ( involving M. m. musculus and M. m. molossinus) as 'MUS', and that of the Southeast Asian castaneus subspecies group as 'CAS' ( although the mice resemble MUS morphologically). There was a clear geographic partition of MUS and CAS types into southern and northern Hokkaido, respectively. Conversely, on Tohoku, the MUS and CAS types were interspersed without clear geographic subdivision. In contrast to the mtDNA data, all Hokkaido and Tohoku mice examined were found to possess a unique type for the Y-linked Sry gene, specific to Korea and Japan. Restriction site analysis of nuclear rDNA probe showed a consistent distribution of MUS and CAS types, as major and minor components, respectively, in the Hokkaido and Tohoku mice. These data support the previous notion that the Hokkaido and Tohoku mice experienced genetic hybridization between primary residents of CAS origin and MUS newcomers arriving via a southern route. The invasion of the MUS type could correspond with the evidence for arrival of prehistoric peoples. There are, however, alternative interpretations, including genetic admixture between MUS arriving by a southern route and CAS from a northern route.
  • Jun J. Sato, Mieczyslaw Wolsan, Hitoshi Suzuki, Tetsuji Hosoda, Yasunori Yamaguchi, Kozue Hiyama, Mari Kobayashi, Shinji Minami  ZOOLOGICAL SCIENCE  23-  (2)  125  -146  2006/02  [Not refereed][Not invited]
     
    Considerable long-standing controversy and confusion surround the phylogenetic affinities of pinnipeds, the largely marine group of "fin-footed" members of the placental mammalian order Carnivora. Until most recently, the two major competing hypotheses were that the pinnipeds have a single (monophyletic) origin from a bear-like ancestor, or that they have a dual (diphyletic) origin, with sea lions (Otariidae) derived from a bear-like ancestor, and seals (Phocidae) derived from an otter-, mustelid-, or musteloid-like ancestor. We examined phylogenetic relationships among 29 species of arctoid carnivorans using a concatenated sequence of 3228 bp from three nuclear loci (apolipoprotein B, APOB; interphotoreceptor retinoid-binding protein, IRBP; recombination-activating gene 1, RAG1). The species represented Pinnipedia (Otariidae: Callorhinus, Eumetopias; Phocidae: Phoca), bears (Ursidae: Ursus, Melursus), and Musteloidea (Mustelidae: Mustela, Enhydra, Melogale, Martes, Gulo, Meles; Procyonidae: Procyon; Ailuridae: Ailurus; Mephitidae: Mephitis). Maximum parsimony, maximum likelihood, and Bayesian inference phylogenetic analyses of separate and combined datasets produced trees with largely congruent topologies. The analyses of the combined dataset resulted in well-resolved and well-supported phylogeny reconstructions. Evidence from nuclear DNA evolution presented here contradicts the two major hypotheses of pinniped relationships and strongly suggests a single origin of the pinnipeds from an arctoid ancestor shared with Musteloidea to the exclusion of Ursidae.
  • GN Chelomina, H Suzuki  ZOOLOGICHESKY ZHURNAL  85-  (2)  219  -234  2006/02  [Not refereed][Not invited]
     
    The analysis of peculiarities of molecular organization, evolution and phylogeny of two protein-coding genes (nDNA IRBP gene (1140 bp) and mtDNA cyt B gene (1150 bp)) was carried out for seven wood mouse species belonging to the West-Palaearctic genus Sylvaemus (S. sylvaticus, S. flavicollis, S. ponticus, S. fulvipectus, S. uralensis, S. alpicola and S. mystacinus) to clear up their phylogenetic relationships and develop, suitable phylogeographyc concept. Intra-, interspecific and intergeneric genetic distances - absolute and corrected according to Kimura's two parameter options - were computed. The distribution of different types of mutations (transitions, transversions, homoplasies, synonymous and nonsynonymous) in all codon positions and for each gene as a whole was characterized. For each molecular marker pheno- and phylogenetic relationships (UPGMA, NJ, MP, and ML from the software package PAUP) were reconstructed. A satisfactory stability of the system of phylogenetic relationships in the wood mice designed by different methods for each molecular marker was shown. At the same time, some differences between molecular phylogenies of nuclear and mitochondrial DNA regions were revealed. The analysis of matriarchal relationships specified a high probability of monophyly for the subgenus Sylvaemus while the data on a nuclear gene give worse support of monophyly and demonstrate its polytomy. This discrepancy is widely discussed. A new phylogeographic concept of the genus Sylvaemus is proposed. It assumes the differentiation of three main phylogenetic lines represented by recent S. fulvipectus, S. uralensis, and a group of the species "sylvaticus" (S. sylvaticus, S.flavicollis, S. ponticus, and S. alpicola) in the territory of Central and Asia Minor between the Miocene and the Pliocene, as well as their colonization of the European continent through various geographical areas.
  • D Astuti, N Azuma, H Suzuki, S Higashi  ZOOLOGICAL SCIENCE  23-  (2)  191  -198  2006/02  [Not refereed][Not invited]
     
    Blood and tissue samples of 40 individuals including 27 parrot species (15 genera; 3 subfamilies) were collected in Indonesia. Their phylogenetic relationships were inferred from 907 bp of the mitochondrial cytochrome-b gene, using the maximum-parsimony method, the maximum-likelihood method and the neighbor-joining method with Kimura two-parameter distance. The phylogenetic analysis revealed that (1) cockatoos (subfamily Cacatuinae) form a monophyletic sister group to other parrot groups; (2) within the genus Cacatua, C. goffini and C. sanguinea form a sister group to a clade containing other congeners; (3) subfamily Psittacinae emerged as paraphyletic, consisting of three clades, with a clade of Psittaculirostris grouping with subfamily Loriinae rather than with other Psittacinae; (4) lories and lorikeets (subfamily Loriinae) emerged as monophyletic, with Charmosyna placentis a basal sister group to other Lorlinae, which comprised the subclades Lorius; Trichoglossus+Eos; and Chalcopsitta+Pseudeos.
  • M Terashima, S Furusawa, N Hanzawa, K Tsuchiya, A Suyanto, K Moriwaki, H Yonekawa, H Suzuki  HEREDITY  96-  (2)  128  -138  2006/02  [Not refereed][Not invited]
     
    We examined intraspecies genetic variation in house mice (Mus musculus molossinus) from the northern third of the Japanese Islands, in order to obtain evidence of the history of mouse colonization that might have shaped the current genetic diversity. We extended the previous sampling of mitochondrial cytochrome b sequence and added information from the Y-linked Sry gene and ribosomal RNA gene surveys. We distinguish mitochondrial haplotypes characteristic of the North Asian musculus subspecies group ( involving M. m. musculus and M. m. molossinus) as 'MUS', and that of the Southeast Asian castaneus subspecies group as 'CAS' ( although the mice resemble MUS morphologically). There was a clear geographic partition of MUS and CAS types into southern and northern Hokkaido, respectively. Conversely, on Tohoku, the MUS and CAS types were interspersed without clear geographic subdivision. In contrast to the mtDNA data, all Hokkaido and Tohoku mice examined were found to possess a unique type for the Y-linked Sry gene, specific to Korea and Japan. Restriction site analysis of nuclear rDNA probe showed a consistent distribution of MUS and CAS types, as major and minor components, respectively, in the Hokkaido and Tohoku mice. These data support the previous notion that the Hokkaido and Tohoku mice experienced genetic hybridization between primary residents of CAS origin and MUS newcomers arriving via a southern route. The invasion of the MUS type could correspond with the evidence for arrival of prehistoric peoples. There are, however, alternative interpretations, including genetic admixture between MUS arriving by a southern route and CAS from a northern route.
  • Evidence from nuclear DNA sequences sheds light on the phylogenetic relationships of Pinnipedia: Single origin with affinity to Musteloidea.
    Zoological Science  23-  191  -198  2006  [Not refereed][Not invited]
  • Suzuki Junko, Terasaki Asako, Suzuki Hiroshi, Ohashi Kazuyo  Zoological science  22-  (12)  2005/12/25  [Not refereed][Not invited]
  • Sakamoto Sachiko, Terasaki Asako, Suzuki Hiroshi, Ohashi Kazuyo  Zoological science  22-  (12)  2005/12/25  [Not refereed][Not invited]
  • SUZUKI Hitoshi  The Journal of animal genetics  33-  (1)  39  -46  2005/12/01  [Not refereed][Not invited]
  • SHINOHARA Akio, CAMPBELL Kevin L, SUZUKI Hitoshi  Journal of the Mammalogical Society of Japan  30-  S19  -S24  2005/12/01  [Not refereed][Not invited]
     
    Japanese talpid moles exhibit a remarkable degree of species richness and geographic complexity, and as such, have attracted much research interest by morphologists, cytogeneticists, and molecular phylogeneticists. However, a consensus hypothesis pertaining to the evolutionary history and biogeography of this group remains elusive. Recent phylogenetic studies utilizing nucleotide sequences have provided reasonably consistent branching patterns for Japanese talpids, but have generally suffered from a lack of closely related South-East Asian species for sound biogeographic interpretations. As an initial step in achieving this goal, we constructed phylogenetic trees using publicly accessible mitochondrial and nuclear sequences from seven Japanese taxa, and those of related insular and continental species for which nucleotide data is available. The resultant trees support the view that four lineages (Euroscaptor mizura, Mogera tokuade species group [M. tokudae and M. etigo], M. imaizumii, and M. wogura) migrated separately, and in this order, from the continental Asian mainland to Japan. The close relationship of M. tokudae and M. etigo suggests these lineages diverged recently through a vicariant event between Sado Island and Echigo plain. The origin of the two endemic lineages of Japanese shrew-moles, Urotrichus talpoides and Dymecodon pilirostris, remains ambiguous. Further analyses on intra-species diversity are necessary to fully solve the evolutionary histories of Japanese moles and shrew-moles.
  • NAITOH Yukako, IWASA Masahiro A, OHDACHI Satoshi D, HAN Sang-Hoon, SUZUKI Hitoshi  Journal of the Mammalogical Society of Japan  30-  (2)  101  -107  2005/12/01  [Not refereed][Not invited]
     
    We estimated phylogenetic relationships among shrews of the Sorex caecutiens/shinto group (Eulipotyphla, Soricidae) from various locations through its range, based on restriction fragment length polymorphism (RFLP) analysis of the nuclear ribosomal RNA gene (rDNA) spacer region. Seven rDNA-RFLP repetitive types (repetypes) were recognized among 15 shrews examined. Restriction patterns of Sorex caecutiens Laxmann, 1788 and S. shinto Thomas, 1905 were distinguishable from each other, but the separation was not statistically supported in the maximum parsimony analysis. The RFLP repetype from Cheju Island was close to that of S. caecutiens from the Eurasian continent, indicating that the shrew of Cheju should be classified as S. caecutiens. Within S. caecutiens, there were two alternative phylogenetic hypotheses. According to a parsimonious tree and a simple network, the Hokkaido population was regarded to be derived from the Sakhalin population, which in turn was derived from the continental population. Alternatively, it was inferred that the continent and Hokkaido populations were firstly separated from the ancestral population, and then shrews from both populations immigrated into Sakhalin and hybridization occurred there. The latter hypothesis seems to be more plausible because it is more congruent with a previous mitochondrial phylogeny.
  • SP Yasuda, P Vogel, K Tsuchiya, SH Han, LK Lin, H Suzuki  CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE  83-  (11)  1411  -1420  2005/11  [Not refereed][Not invited]
     
    We examined sequence variation in the mitochondrial cytochrome b gene (1140 bp, n = 73) and control region (842-851 bp, n = 74) in the Eurasian harvest mouse (Micromys minutus (Pallas, 1771)), with samples drawn from across its range, from Western Europe to Japan. Phylogeographic analyses revealed region-specific haplotype groupings combined with overall low levels of inter-regional genetic divergence. Despite the enormous intervening distance, European and East Asian samples showed a net nucleotide divergence of only 0.36%. Based on an evolutionary rate for the cytochrome b gene of 2.4%(.)(site(.)lineage(.)million years)(-1), the initial divergence time of these populations is estimated at around 80 000 years before present. Our findings are consistent with available fossil evidence that has recorded repeated cycles of extinction and recolonization of Europe by M. minutus through the Quaternary. The molecular data further suggest that recolonization occurred from refugia in the Central to East Asian region. Japanese haplotypes of M. minutus, with the exception of those from Tsushima Is., show limited nucleotide diversity (0.15%) compared with those found on the adjacent Korean Peninsula. This finding suggests recent colonization of the Japanese Archipelago, probably around the last glacial period, followed by rapid population growth.
  • AA Chinen, H Suzuki, KP Aplin, K Tsuchiya, S Suzuki  GENES & GENETIC SYSTEMS  80-  (5)  367  -375  2005/10  [Not refereed][Not invited]
     
    We conducted a pilot survey of genetic diversity among 37 karyotyped individuals of the black rat Rattus rattus (sensu lato) from six localities on the Japanese Islands, using complete gene sequences of mitochondrial cytochrome b (cyt b) and nuclear interphotoreceptor retinoid binding protein (IRBP). Our sampling included two previously documented karyotypic groups: 'Oceanian' with 2n = 38 and 'Asian' with 2n = 42. Cyt b sequences for most individuals clustered according to their karyotypic groups, with an average between-group divergence of 3.8%. One exception was that individuals from Kagoshima (Kyushu Island) showed 'Asian' karyotypes combined with a cyt b haplotype that differed by a single nucleotide substitution from the haplotype of the 'Oceanian' karyotypic group. Six IRBP haplotypes were identified. They belonged to three distinct IRBP lineages (I-III), with an average inter-lineage divergence of 1%. Among homozygous individuals, these lineages showed good association with the karyotypic groups: IRBP lineage I occurred only with 'Oceanian' karyotypes, while IRBP lineages II and III both occurred with 'Asian' karyotypes. Individuals from Kagoshima all possessed IRBP of 'Asian' lineages, despite the presence of an 'Oceanian' mitochondrial type. The Chichijima population (Ogasawara Islands) featured exclusively 'Asian' karyotypes and cyt b sequences, but various combinations of all three IRBP lineages. The Kagoshima and Chichijima populations thus provide strong evidence of viable hybridization and genetic introgression between the two karyotypic groups, but with variable genetic outcomes. Our results demonstrate the potential of combined analysis of karyotypes and mitochondrial and nuclear gene sequences to elucidate the complex dispersal and population history of the black rat.
  • Shinohara A Campbell, K.L., and Suzuki, H.: "An evolutionary view on the Japanese talpids based on nucleotide sequences" Mammal Study 30 (supplement): S19-S24 (2005)*
    2005  [Not refereed][Not invited]
  • Hosoda, T., Sato, J.J., Shimada, T., Campbell, K. L., and Suzuki, H.: "Independent nonframeshift deletions in the MC1R gene are not associated with melanistic coat coloration in three mustelid lineages", Journal of Heredity, 96:607-613 (2005)*
    2005  [Not refereed][Not invited]
  • Chinen, A. A., Suzuki, H., Aplin, K. P., Tsuchiya, K., and Suzuki, S.: "Preliminary genetic characterization of two lineages of black rats (Rattus rattus sensu lato) in Japan, with evidence for introgression at several localities" Genes & Genetic Syste・・・
    2005  [Not refereed][Not invited]
     
    Chinen, A. A., Suzuki, H., Aplin, K. P., Tsuchiya, K., and Suzuki, S.: "Preliminary genetic characterization of two lineages of black rats (Rattus rattus sensu lato) in Japan, with evidence for introgression at several localities" Genes & Genetic Systems, 80:367-375 (2005)*
  • Shinohara Akio, Suzuki Hitoshi, Tsuchiya Kimiyuki, Zhang Ya-Ping, Luo Jing, Jiang Xue-Long, Wang Ying-Xiang, Campbell Kevin L  Zoological science  21-  (12)  1177  -1185  2004/12/25  [Not refereed][Not invited]
     
    We sequenced the cytochrome b gene from two little-studied mammal species from the highlands of Southwest China, the long-tailed mole Scaptonyx fusicaudus and the gracile shrew-like mole Uropsilus gracilis. This data was used to examine the phylogenetic relationships among 19 talpid species within the family Talpidae (Mammalia: Eulipotyphla). Cytochrome b gene trees supported a basal placement of shrew-like moles (Uropsilus) within the Talpidae, and suggested that fossorial specializations arose twice during talpid evolution. To assess the evolutionary relationships of moles endemic to this region, we additionally sequenced the 12S rRNA gene and the nuclear recombination-activating gene-1 from eight and ten East Asian taxa, respectively. Analyses of these single and concatenated data sets suggested that East Asian shrew moles diverged prior to the evolution of fossorial Eurasian moles. However, we were unable to determine whether semi-fossorial shrew moles are monophyletic. In contrast, fossorial Eurasian genera (Talpa, Mogera and Euroscaptor) were consistently found to form a monophyletic clade, with Mogera and Euroscaptor representing sister taxa. Furthermore, this fossorial clade grouped with the semiaquatic Desmana, although with fairly low (35-62%) bootstrap support. Mogera imaizumii was found to be more closely related to M. wogura than to M. tokudae. This implies that the ancestors of these three species entered Japan from the Asian continent in this order via a series of migration events, suggesting that the Japanese Islands have played an important role in preserving mole lineages from ancient to recent times.
  • Terasaki Asako, Suzuki Hiroshi, Suzuki Junko, Hiruta Jin, Ogasawara Michio, Ohashi Kazuyo  Zoological science  21-  (12)  2004/12/25  [Not refereed][Not invited]
  • H Suzuki, T Shimada, M Terashima, K Tsuchiya, K Aplin  MOLECULAR PHYLOGENETICS AND EVOLUTION  33-  (3)  626  -646  2004/12  [Not refereed][Not invited]
     
    We sequenced mitochondrial (cytochrome b, 12S rRNA) and nuclear (IRBP, RAG1) genes for 17 species of the Old World murine genus Mus, drawn primarily from the Eurasian subgenus Mus. Phylogenetic analysis of the newly and previously available sequences support recognition of four subgenera within Mus (Mus, Coelomys, Nannomys, and Pyromys), with an unresolved basal polytomy. Our data further indicate that the subgenus Mus contains three distinct 'species groups': (1) a Mus booduga Species Group, also including Mus terricolor and Mus fragilicauda (probably also Mus famulus); (2) a Mus cervicolor Species Group, also including Mus caroli and Mus cookii; and (3) a Mus musculus Species Group, also including Mus macedonicus, Mus spicilegus, and Mus spretus. Species diversity in Eurasian Mus is probably explicable in terms of several phases of range expansion and vicariance, and by a propensity within the group to undergo biotope transitions. IRBP and RAG1 molecular clocks for Mus date the origin of subgenera to around 5-6 mya and the origin of Species Groups within subgenus Mus to around 2-3 mya. The temporal pattern of evolution among Eurasian Mus is more complex than that within the Eurasian temperate genus Apodemus. (C) 2004 Elsevier Inc. All rights reserved.
  • J Luo, DM Yang, H Suzuki, YX Wang, WJ Chen, KL Campbell, YP Zhang  MOLECULAR PHYLOGENETICS AND EVOLUTION  33-  (2)  349  -362  2004/11  [Not refereed][Not invited]
     
    Oriental voles of the genus Eothenomys are predominantly distributed along the Southeastern shoulder of the Qinghai-Tibetan Plateau. Based on phylogenetic analyses of the mitochondrial cytochrome b gene (1143 bp) obtained from 23 specimens (eight species) of Oriental voles collected from this area, together with nucleotide sequences from six specimens (two species) of Japanese red-backed voles (Eothenomys andersoni and Eothenomys smithii) and five species of the closely related genus Clethrionomys, we revised the systematic status of Eothenomys. We also tested if vicariance could explain the observed high species diversity in this area by correlating estimated divergence times to species distribution patterns and corresponding paleo-geographic events. Our results suggest that: (1) the eight species of Oriental voles form a monophyletic group with two distinct clades, and that these two clades should be considered as valid subgenera-Eothenomys and Anteliomys; (2) Eothenomys eleusis and Eothenomys miletus are not independent species; (3) Japanese red-backed voles are more closely related to the genus Clethrionomys than to continental Asian Eothenomys taxa; and (4) the genus Clethriomomys as presently defined, is paraphyletic. In addition, the process of speciation of Oriental voles appears to be related to the Trans-Himalayan formation via three recent uplift events of the Qinghai-Tibetan Plateau within the last 3.6 million years, as well as to the effects of the mid-Quaternary ice age. (C) 2004 Elsevier Inc. All rights reserved.
  • H Suzuki, SP Yasuda, M Sakaizumi, S Wakana, M Motokawa, K Tsuchiya  GENES & GENETIC SYSTEMS  79-  (3)  165  -176  2004/06  [Not refereed][Not invited]
     
    We examined the gene sequences of mitochondrial cytochrome b (cyt b) in two Japanese wood mouse species, Apodemus speciosus (n = 89) and A. argenteus (n = 46), which are distributed on the four main islands of Japan (Hokkaido, Honshu, Shikoku, and Kyushu) and on the small islands surrounding them. Apodemus speciosus, the larger of the two species, showed substantial genetic variation, with a maximum of 3% sequence divergence, and remarkable phylogenetic subdivision with two major clades. One clade represents haplotypes from a central region, including Honshu, Shikoku, Kyushu, and their adjacent islands; the other clade includes haplotypes from Hokkaido and the peripheral islands, forming four subclades: a) Hokkaido, b) Sado Island, c) Satsunan Islands, and d) the Izu Islands. Sequence divergence among the four subclades was 1.0 to 1.5%, implying that A. speciosus colonized these geographic regions 0.2 to 0.3 million years ago, assuming a substitution rate of 2.4% per million years. The population on the Izu Islands has preserved haplotypes that are distinct from those in any other region, providing good evidence for the natural colonization of the volcanic islands of the Izu Islands. The cyt b sequence variation had no relation to the karyotypic dimorphism for the eastern (2n = 48) and western (2n = 46) geographic groups, between which a strict border exists at central Honshu. On the other hand, Apodemus argenteus, the smaller of the two species, showed a similar level of sequence divergence (maximum of 3%) but no substantial geographic differentiation: populations in Hokkaido, Sado, and Yakushima shared similar haplotypes with each of the central populations, suggesting that genetic exchanges occurred among the localities in the last 0.15 million years. The apparent genetic structure of the mitochondrial DNA found in the A. speciosus population might be caused solely by long-term existence in insular regions, presumably due to ecological superiority relative to A. argenteus.
  • Sato Jun J, Hosoda Tetsuji, Wolsan Mieczyslaw, Suzuki Hitoshi  Zoological science  31-  (1)  111  -118  2004/01/25  [Not refereed][Not invited]
     
    Phylogenetic relationships among the ferret-badger Melogale moschata, the skunk Mephitis mephitis, and 21 other arctoid carnivorans, representing Mustelidae (Mustelinae: Mustela, Martes, Gulo; Lutrinae: Enhydra; Melinae: Meles), Procyonidae (Procyon), and Ursidae (Ursus, Melursus), were evaluated through maximum-parsimony phylogenetic analysis of concatenated partial nucleotide sequences of the nuclear recombination-activating gene 1 (RAG1) and gene encoding interphotoreceptor retinoid-binding protein (IRBP). The analysis strongly supports Melogale as more closely related to a musteline-lutrine clade (containing Mustela and Enhydra) than to Meles or another musteline clade containing Martes and Gulo (causing Melinae and Mustelinae, as traditionally circumscribed, to be nonmonophyletic). This, together with known morphological and karyological evidence for nonmeline affinities of Melogale, justify the exclusion of the ferret-badgers from the monophyletic Melinae. Therefore, we recommend that Melogale be classified in a distinct mustelid subfamily, the monotypic Helictidinae. Our analysis also strongly supports an outgroup position of the skunks to a clade containing Procyonidae and the nonmephitine Mustelidae (causing Mustelidae, as traditionally circumscribed, to be paraphyletic). This position of the skunks agrees with results of most previous genetic studies. However, it is contradicted by known morphological evidence from both living and fossil taxa, as well as genetic evidence from protein electrophoresis. These consistently support the traditional placement of the skunks within the monophyletic Mustelidae (recently in a close relationship to Lutrinae). Therefore, we consider the recent elevation of the skunks to the level of family as premature, and recommend that this clade be left at the subfamily level (Mephitinae) within the family Mustelidae, pending further evidence.
  • Kryukov, A., Iwasa, M. A., Kakizawa, R., Suzuki, H., Pinsker, W., and Haring, E.:"Synchronic east-west divergence in azure-winged magpies (Cyanopica cyanus) and magpies (Pica pica)" Journal of Zoological Systematics and Evolutionary Research, 42:342-35・・・
    2004  [Not refereed][Not invited]
     
    Kryukov, A., Iwasa, M. A., Kakizawa, R., Suzuki, H., Pinsker, W., and Haring, E.:"Synchronic east-west divergence in azure-winged magpies (Cyanopica cyanus) and magpies (Pica pica)" Journal of Zoological Systematics and Evolutionary Research, 42:342-351 (2004)*
  • Suzuki, H., Yasuda, S. P., Sakaizumi, M., Wakana, S., Motokawa M., and Tsuchiya, K.:"Differential geographic patterns of mitochondrial DNA variation in two sympatric species of Japanese wood mice, Apodemus speciosus and A. argenteus" Genes and Genetic・・・
    2004  [Not refereed][Not invited]
     
    Suzuki, H., Yasuda, S. P., Sakaizumi, M., Wakana, S., Motokawa M., and Tsuchiya, K.:"Differential geographic patterns of mitochondrial DNA variation in two sympatric species of Japanese wood mice, Apodemus speciosus and A. argenteus" Genes and Genetic Systems, 79:165-176 (2004)*
  • 2004  [Not refereed][Not invited]
     
    Sato, J. J., and Suzuki, H.: "Phylogenetic relationships and divergence times of the genus Tokudaia within Murinae (Muridae; Rodentia) inferred from the nucleotide sequences encoding the mitochondrial cytochrome b gene and nuclear recombination-activating gene 1 and interphotoreceptor retinoid-binding protein" Canadian Journal of Zoology, 82:1343-1351 (2004)*
  • Shinohara, A., Suzuki, H., Tsuchiya, K., Zhang, Y.-P., Luo, J., Jiang, X.-L., Wang Y.-X., and Campbell, K. L.:"Evolution and biogeography of talpid moles from Continental East Asia and the Japanese Islands inferred from mitochondrial and nuclear gene s・・・
    2004  [Not refereed][Not invited]
     
    Shinohara, A., Suzuki, H., Tsuchiya, K., Zhang, Y.-P., Luo, J., Jiang, X.-L., Wang Y.-X., and Campbell, K. L.:"Evolution and biogeography of talpid moles from Continental East Asia and the Japanese Islands inferred from mitochondrial and nuclear gene sequences" Zoological Science, 21:1177-1185 (2004)*
  • Furuta Ryoko, Oshima Koji, Morikawa Nao, Suzuki Hiroshi, Terasaki Asako, Ohashi Kazuyo  Zoological science  20-  (12)  2003/12/25  [Not refereed][Not invited]
  • Iwasa Masahiro A, Suzuki Hitoshi  Zoological science  20-  (10)  1305  -1313  2003/10/25  [Not refereed][Not invited]
     
    Differences in the nuclear ribosomal DNA (rDNA), mitochondrial DMA (mtDNA), cytochrome b (Cytb), and Y chromosomal Sry genes were used to assess intra- and interspecific relationships in two Japanese red-backed voles, Eothenomys andersoni and E. smithii, focusing on areas where the two species might come into contact. In the Kii Peninsula, southwestern Honshu, which contains an allopatric population of E. andersoni isolated from its main range, the rDNA-RFLP data provide robust evidence of past mutual interspecific gene introgression, while the Cytb and Sry sequences were specific to this population. In central Honshu, where E andersoni and E. smithii inhabit higher and lower altitudes, respectively, with a narrow sympatric zone, the rDNA-RFLP and Sryvariation was specific for each species, while introgression of the mtDNA from E smithiito E. andersoniwas seen. These complex patterns in the gene markers are consistent with our previous notions derived from sex chromosome variation. Our previous and present data strongly suggest that the evolution of these vole species, which are morphologically and cytogenetically distinct, involves complex genetic interactions and the resultant combinations of genes are sometimes peculiar, mainly due to the Cytb haplotypes. However, phylogenetic analysis using a combination of maternal, paternal, and biparental markers has proven useful for understanding the evolutionary history given the complex phylogenetic background.
  • TARASHIMA Mie, SUYANT Agustinus, TSUCHIYA Kimiyuki, MORIWAKI Kazuo, JIN Mei-lei, SUZUKI Hitoshi  Journal of the Mammalogical Society of Japan  28-  (1)  67  -72  2003/06/01  [Not refereed][Not invited]
     
    We examined intraspecific genetic variation in the mitochondrial cytochrome b gene (1140 bp) in the Okinawa mouse, Mus caroli (Rodentia, Muridae), from Okinawa, Taiwan, Hainan, Yunnan (southern China), Thailand, Vietnam and Java, to better understand their evolutionary history and human impact on dispersal and colonization by the mice. Populations from each of the seven localities had distinctive mitochondrial DNA sequences. The genetic distances, ranging from 0.015 to 0.045 (0.033 on average), were comparable with inter-subspecies differences in the house mouse Mus musculus (0.024). Assuming that nucleotide substitutions occur at a constant rate of 0.024/million years/lineage for mitochondrial DNA, the divergence of in M. caroli is estimated to have occurred 0.3-0.9 million years ago. The relatively great extent of intraspecific mitochondrial DNA variation in this taxon, and the spatial mode of variation suggest that M. caroli is genetically structured in space, to a considerable extent. Our data imply that local insular populations of M. caroli have been separated for long evolutionary periods, and that the scattered distribution patterns in the insular domains are due to historical shrinkage of appropriate areas of habitat, rather than to recent establishment of dispersed local populations by inadvertent human introductions.
  • Sato Jun J, Hosoda Tetsuji, Wolsan Mieczyslaw, Tsuchiya Kimiyuki, Yamamoto Masahiko, Suzuki Hitoshi  Zoological science  20-  (2)  243  -264  2003/02/25  [Not refereed][Not invited]
     
    Phylogenetic relationships among 20 species-group taxa of Mustelidae, representing Mustelinae (Mustela, Martes, Gulo), Lutrinae (Enhydra), and Melinae (Meles), were examined using nucleotide sequences of the nuclear interphotoreceptor retinoid binding protein (IRBP) and mitochondrial cytochrome b genes. Neighbor-joining and maximum-parsimony phylogenetic analyses on these genes separately and combined were conducted. While IRBP performed better than cytochrome b in recovering more-inclusive clades, cytochrome b demonstrated more resolving power in recovering less-inclusive clades. Strong support was found for a close affinity of Enhydra with Mustela to the exclusion of Martes and Gulo (causing Mustelinae to be paraphyletic) ; the most-basal position of Mustela vison within Mustela, followed by Mustela erminea ; an association of Mustela lutreola, Mustela itatsi, Mustela sibirica, and the subgenus Putorius (including Mustela putorius and Mustela eversmanii), to the exclusion of Mustela nivalis and Mustela altaica ; and a basal position of Mustela itatsi to a clade containing Mustela sibirica and Putorius. Whereas cytochrome b strongly supported Mustela lutreola as the sister species to Putorius, IRBP strongly supported its basal placement to the Mustela itatsi-Mustela sibirica-Putorius clade. The low level of sequence divergence in cytochrome b between Mustela lutreola and Putorius is therefore a result of interspecific mitochondrial introgression between these taxa, rather than a recent origin of Mustela lutreola in a close relationship to Putorius. Time estimates inferred from IRBP and cytochrome b for mustelid divergence events are mostly in agreement with the fossil record.
  • Sato, J. J., Hosoda, T., Wolsan, M., Tsuchiya, K., Yamamoto, Y. and Suzuki, H.: "Phylogenetic relationships and divergence times among mustelids (Mammalia: Carnivora) based on nucleotide sequences of the nuclear interphotoreceptor retinoid binding prot・・・
    2003  [Not refereed][Not invited]
     
    Sato, J. J., Hosoda, T., Wolsan, M., Tsuchiya, K., Yamamoto, Y. and Suzuki, H.: "Phylogenetic relationships and divergence times among mustelids (Mammalia: Carnivora) based on nucleotide sequences of the nuclear interphotoreceptor retinoid binding protein and mitochondrial cytochrome b genes", Zoological Science, 20: 243-264 (2003)*
  • Shinohara, A., Campbell, K.L. and Suzuki, H.: "Molecular phylogenetic relationships of moles, shrew-moles and desmans from the New and Old Worlds", Mol. Phylogenet. Evol., 27: 247-258 (2003)*
    2003  [Not refereed][Not invited]
  • Suzuki, H., Sato, J. J., Tsuchiya, K., Luo, J., Zhang Y-P., Wang, Y-X., Jiang X-L.: "Molecular phylogeny of wood mice (Apodemus, Muridae) in East Asia" Biological Journal of the Linnean Society, 80: 469-481 (2003)*
    2003  [Not refereed][Not invited]
  • Terashima, M., Suyanto, A., Tsuchiya, T., Moriwaki, K., Jin, M.-L., and Suzuki , H.: "Geographic variation of Mus caroli from East and Southeast Asia based on mitochondrial cytochrome b gene sequences", Mammal Study, 28: 67-72 (2003)*
    2003  [Not refereed][Not invited]
  • Iwasa, M. A. and Suzuki, H. "Intra- and interspecific genetic complexity of two Eothenomys species in Honshu, Japan", Zool. Sci., 20: 1305-1313 (2003)*
    2003  [Not refereed][Not invited]
  • SH Han, MA Iwasa, SD Ohdachi, HS Oh, H Suzuki, K Tsuchiya, H Abe  ACTA THERIOLOGICA  47-  (4)  369  -379  2002/12  [Not refereed][Not invited]
     
    Molecular phylogeny of crocidurine shrews (Insectivora, Soricidae) in northeastern Asia was investigated to confirm the taxonomic status of unidentified specimens of Crocidura from Cheju Island, South Korea. Phylogenetic trees were constructed by neighbor-joining (NJ) and maximum likelihood (ML) methods, based on mitochondrial cytochrome b gene sequences (402 base pairs) of 37 individuals of seven crocidurine species and three unidentified specimens from 31 localities mainly in northeastern Asia. Phylogenetic position of the three unidentified specimens from Cheju Island were compared with those of Suncus marinus, C. attenuata, C. dsinezumi, C. lasiura, C. sibirica, C. suaveolens, and C. walasei. Both in NJ and ML trees, the three unidentified specimens were included in the cluster of C. dsinezumi and were obviously different from C. suaveolens on Cheju Island, Thus, the present investigation demonstrated that both C. suaveolens and C. dsinezumi exist on Cheju Island.
  • 鈴木 仁  哺乳類科学  42-  (1)  88  -90  2002/06  [Not refereed][Not invited]
  • Frisman, L. V., Kartavtseva, I. V., Pavlenko, M. V., Kostenko, V. A., Suzuki, H. Iwasa, M., Nakata, K. and Chernyavskii F. B.: "Gene-geographic variation and genetic differentiation in red-backed voles of the genus Clethrionomys (Rodentia, Cricetidae) ・・・
    2002  [Not refereed][Not invited]
     
    Frisman, L. V., Kartavtseva, I. V., Pavlenko, M. V., Kostenko, V. A., Suzuki, H. Iwasa, M., Nakata, K. and Chernyavskii F. B.: "Gene-geographic variation and genetic differentiation in red-backed voles of the genus Clethrionomys (Rodentia, Cricetidae) from the region of the Sea of Okhotsk", Russian Journal of Genetics, 38:538-547 (2002)*
  • Iwasa, M. A. and Suzuki, H.: "Evolutionary significance of chromosome changes in northeastern Asiatic red-backed voles inferred with the aid of intron 1 sequences of the G6pd gene", Chromosome Research, 10:419-428 (2002)*
    2002  [Not refereed][Not invited]
  • Iwasa MA. Kartavtseva IV. Dobrotvorsky AK. Panov VV. and Suzuki H.: "Local differentiation of Clethrionomys rutilus in northeastern Asia inferred from mitochondrial gene sequences", Mammalian Biology, 67:157-166 (2002)*
    2002  [Not refereed][Not invited]
  • Iwasa. M. A., Kryukov. A. P. , Kakizawa, R. and Suzuki, H.: "Local differentiation of mitochondrial gene of jungle crow, Corvus macrorhynchos (Corvidae), in East and South Asia", Journal of Yamashina Institute of Ornithology, 34: 66-72 (2002)*
    2002  [Not refereed][Not invited]
  • Serizawa, K., Suzuki, H., Iwasa, A. I., Tsuchiya, K., Pavlenko, M. V., Kartavtseva, I. V., Chelomina, G. N., Dokuchaev, N. and Han, S.H.: "A spatial aspect on mitochondrial DNA genealogy in Apodemus peninsulae from East Asia", Biochemical Genetics, 40・・・
    2002  [Not refereed][Not invited]
     
    Serizawa, K., Suzuki, H., Iwasa, A. I., Tsuchiya, K., Pavlenko, M. V., Kartavtseva, I. V., Chelomina, G. N., Dokuchaev, N. and Han, S.H.: "A spatial aspect on mitochondrial DNA genealogy in Apodemus peninsulae from East Asia", Biochemical Genetics, 40: 149-161 (2002)*
  • 2002  [Not refereed][Not invited]
     
    Yamada, F., Takaki, M. and Suzuki, H.: "Molecular phylogeny of Japanese Leporidae, the Amami rabbit Pentalagus furnessi, the Japanese hare Lepus brachyurus, and the mountain hare Lepus timidus, inferred from mitochondrial DNA sequences", Genes and Genetic System, 77: 107-116 (2002)*
  • Motokawa Masaharu, Harada Masashi, Wu Yi, Lin Liang-Kong, Suzuki Hitoshi  Zoological science  18-  (8)  1153  -1160  2001/11/01  [Not refereed][Not invited]
     
    Conventional and G-banded karyotypes of Crocidura attenuata Milne-Edwards, 1872 from Guangdong, southern China, are reported. The diploid chromosome number (2n) varied from 35 to 38 among specimens, while thd fundamental arm number (FN) consistently was 54. Of the autosomes, 14 pairs including four meta- or submetacentric, three subtelocentric, and seven acrocentric pairs showed no variation in all specimens, whereas the remaining pairs showed Robertsonian polymorphism. The X and Y chromosomes were medium sized submetacentric and small acrocentric chromosomes, respectively. These karyotypes differ from that of C. attenuate from Taiwan, which has 40 chromosomes with 56 arms. Such differences are largely attributable to a non-Robertsonian rearrangement, where both 2n and FN values are different from each other. The largest metacentric pair observed in karyotypes from Guangdong may have resulted from the centromere-telomere translocation between an acrocentric and a subtelocentric pairs of karyotype homologous to that from Taiwan. Both morphometric difference and sequence divergence in mitochondrial cytochrome b gene between samples from Guangdong and Taiwan was relatively small. However, the non-Robertsonian rearrangement assumed between karyotypes of the shrews from Guangdong and Taiwan suggest that they are reproductively isolated from each other. The eastern continental and Taiwanese populations therefore may represent different species under the names, C. attenuata (sensu stricto), and C. tanakae Kuroda, 1938, respectively.
  • 本川 雅治, 原田 正史, 呉 毅, 林 良恭, 鈴木 仁  タクサ : 日本動物分類学会誌  (11)  2001/08/20  [Not refereed][Not invited]
  • Iwasa, M. A., Ohdachi, S., Han, S-H., Oh, H-S., Abe, H. and Suzuki, H.: "Karyotype and RFLP of the nuclear rDNA of the Crocidura sp. on Cheju Island, South Korea", Mammalia, 65: 451-459 (2001)*
    2001  [Not refereed][Not invited]
  • MUNECHIKA Isao, OKADA Ayumi, ROBERT Nadia, SUZUKI Hitoshi  Nihon Chikusan Gakkaiho  71-  (6)  572  -578  2000/11/25  [Not refereed][Not invited]
     
    Examination of restriction site length polymorphism (RFLP) in the nuclear ribosomal RNA (rDNA) gene in four species of jungle fowl showed that a Sac I site in the external spacer region exists in the three jungle fowl, Gallus sonnerati, G. lafayettei and G. varius but is entirely absent in the domestic fowl, G. gallus. In order to understand the phylogenetic meaning, an interspecific survey on restriction site variation in 4 species of Gallus and 20 related genera that belong to 12 species of the same family Phasianidae and 8 species of the families Meleagrididae, Tetoraonidae, Odontophoridae, Numididae, Megapodidae and Cracidae that belong to the order Galliformes was performed. A Sac I fragment of 2.7kb in length was observed consistently in the members of Phasianidae, except for G. gallus, Phasianus versicolor and Lophophorus impeyanus using the Southern blot survey with the 18S mouse rDNA probe. On the other hand, the length of Sac I fragments in the other species of outgroups differed from that of the common type of Phasianidae. Our data thus indicated that the presence of the Sac I site in the spacer region was a common feature of the ancestral branch of the family Phasianidae and that the site had differentiated until it was lost in G. gallus during the course of speciation. It is suggested, therefore, that the absence of the Sac I site may be a convenient diagnostic marker of G. gallus in surveys of genetic backgrounds in stocks of domestic fowl as well as populations of jungle fowl.
  • T Hosoda, H Suzuki, M Harada, K Tsuchiya, SH Han, YP Zhang, AP Kryukov, LK Lin  GENES & GENETIC SYSTEMS  75-  (5)  259  -267  2000/10  [Not refereed][Not invited]
     
    We compared partial sequences (402 bp) of the mitochondrial cytochrome b gene in 68 individuals of martens (Martes), weasels (Mustela) and their relatives from the Northern Hemisphere to identify the modes of geographic differentiation in each species. We then compared complete sequences (1140 bp) of the gene in 17 species of the family Mustelidae to know the spatial and temporal modes of speciation, constructing linearized trees with transversional substitutions for deeper lineage divergences and with transversions and transitions for younger lineages. Our data suggested that these lineages of Martes and Mustela differentiated in a stepwise fashion with five radiation stages from the generic divergences (stage I) to the intraspecific divergences (stage V), during the last 10 or 20 million years as the fossil evidence suggests. In the lineage of Martes, the first offshoots are of Martes flavigula, M. pennanti, and Gulo gulo (stage II), the second is M. foina (stage III), and the third are M. americana, M. martes, M. melampus, and M. zibellina (stage IV). The divergence of the lineages of Mustela is likely to have taken place concurrently with the radiations of the Martes. These divergence processes are attributable in part to the geographic allocation along the two continents, North America and Eurasia, as well as among peripheral insular domains, such as Taiwan and the Japanese Islands. In addition, the Eurasian continent itself was shown to have been involved in the species diversification in the martens and weasels.
  • AP Kryukov, H Suzuki  RUSSIAN JOURNAL OF GENETICS  36-  (8)  922  -929  2000/08  [Not refereed][Not invited]
     
    Distribution of mitochondrial DNA cytochrome b gene haplotypes in two crow species was examined by means of sequencing of the 336-bp gene fragment. The topology of the NJ and UPGMA trees showed that the carrion crow range was split into two parts due to the presence of significantly diverged ancestral lineage localized in the southeastern part of the range. The carrion crow populations, inhabiting a territory ranging from France to northern Sakhalin, along with interspersed hooded crow populations and hybrid Siberian populations, shared a common haplotype. The border between two carrion crow lineages revealed is located in central Sakhalin. The subdivision of two weakly differentiated lineages within the jungle crown range, also observed within this territory, coincided with the subspecies division of this species. The estimated genetic distances indicate the isolation of the subgenus Coloeus. These data also suggest the convergent similarity between the chough Pyrrhocorax pyrrhocorax and the Corvus genus, as well as the conspecificity of Corvus corone corone and C. c. cornix.
  • Iwasa Masahiro A, Utsumi Yuki, Nakata Keisuke, Kartavtseva Irina V, Nevedomskaya Irina A, Kondoh Norihisa, Suzuki Hitoshi  Zoological science  17-  (4)  477  -484  2000/05/20  [Not refereed][Not invited]
     
    The gray red-backed vole, Clethrionomys rufocanus, from Far East Asia including Sakhalin and Hokkaido is known to harbor intraspecific morphological and cytogenetic variations. Here we analyzed geographic variation in the mitochondrial cytochrome b (Cytb) gene and Y chromosome specific Sry gene by a PCR direct sequencing technique. Determination of sequences in the Cyto gene (1140 bp) in 29 individuals provided 28 haplotypes and construction of a neighbor joining tree clearly indicated that they were grouped into four major lineages, which predominated in Primorskyi territory, Kamchatska-Magadan, Sakhalin, and Hokkaido-Kuril, with 0.02-0.04 sequence divergence (Kimura's distance, all substitutions, all codon positions). The sequences for the Sry region (336-366 bp) included a variable repetitious region of microsatellites such as TG(TC)_2. In total five sequences were recognized which can be grouped into two forms, continental and insular (Sakhalin and Hokkaido) based on the presence or absence of a segment of TG(TC)_3TG(TC)_4. It was revealed that, therefore, the population of Sakhalin possessed their own type of mitochondrial DNA but the same Sry gene as Hokkaido. A similar trend can be seen in the continental populations. Our results suggested that the population of C. rufocanus in each of the geographic domains accumulated own genetic elements in part but genetic exchanges between neighboring populations occurred during the course of evolution. It is noteworthy that the insular domains, Sakhalin and Hokkaido, have played an important role in raising the amount of genetic diversity in small rodent species.
  • Motokawa Masaharu, Suzuki Hitoshi, Harada Masashi, Lin Liang-Kong, Koyasu Kazuhiro, Oda Sen-ichi  Zoological science  17-  (4)  497  -504  2000/05/20  [Not refereed][Not invited]
     
    Phylogenetic relationships among the East Asian species of the genus Crocidura (Mammalia, Insectivora, Soricidae) were inferred from the partial sequences (402 base pairs) of the mitochondrial cytochrome b gene. Six species of Crocidura and one representative of another insectivoran genus Suncus were examined. In the neighbor joining tree, four distinct lineages were recognized : C. lasiura from northeastern China and Korea, and C. dsinezumi from the main-islands of Japan ; C. attenuata from Taiwan ; C. watasei from the Amami and Okinawa Groups, and S. murinus from the Miyako Group ; and C. suaveolens from Tsushima and Taiwan, and C. sibirica from Central Asia in Russian territory. All these lineages excluding C. lasiura and C. dsinezumi were also recognized by the maximum parsimony analysis. Clustering of C. watasei with S. murinus suggested the non-monophyly of the genus Crocidura as of the present definition. Biogeographical implications of the present results were also discussed.
  • K Tsuchiya, H Suzuki, A Shinohara, M Harada, S Wakana, M Sakaizumi, SH Han, LK Lin, AP Kryukov  GENES & GENETIC SYSTEMS  75-  (1)  17  -24  2000/02  [Not refereed][Not invited]
     
    Taxonomic analysis has previously revealed that the species of moles that inhabit Japan are characterized by exceptional species richness and a high level of endemism. Here, we focused on the evolutionary history of the four Japanese mole species of the genera Euroscapter and Mogera, examining mitochondrial cytochrome b (cyt b) gene sequences and comparing them with those of continental Mogera wogura (Korean and Russian populations), M. insularis from Taiwan, and Talpa europaea and T. altaica from the western and central Eurasian continent, respectively. Our data support the idea that in a radiation center somewhere on the Eurasian continent, a parental stock evolved to modern mole-like morph and radiated several times intermittently during the course of the evolution, spreading its branches to other peripheral geographic domains at each stage of the radiation. Under this hypothesis, the four lineages of Japanese mole species, E. mizura, M. tokudae, M. imaizumii, and M. wogura, could be explained to have immigrated to Japan in this order. Mogera wogura and M. imaizumii showed substantial amounts of geographic variation and somewhat complicated distributions of the cyt b gene types. These intraspecific variations are likely to be associated with the expansion processes of moles in the Japanese Islands during the Pleistocene glacial ages.
  • Iwasa, M. A., Utsumi, Y., Nakata,K., Kartavtseva, I.V., Nevedomskaya,I.A., Kondoh, N., and Suzuki, H.: "Geographic patterns of cytochrome b and Sry gene lineages in gray red-backed vole, Clethrionomys rufocanus (Mammalia, Rodentia) from Far East Asia i・・・
    2000  [Not refereed][Not invited]
     
    Iwasa, M. A., Utsumi, Y., Nakata,K., Kartavtseva, I.V., Nevedomskaya,I.A., Kondoh, N., and Suzuki, H.: "Geographic patterns of cytochrome b and Sry gene lineages in gray red-backed vole, Clethrionomys rufocanus (Mammalia, Rodentia) from Far East Asia including Sakhalin and Hokkaido", Zoological Science 16:477-484,(2000)*
  • Hosoda, T., Suzuki,H., Harada,M., Tsuchiya,T., Han,S-H., Zhang,Y., Kryukov, A.P. and Lin, L-K.: "Evolutionary trends of the mitochondrial lineage differentiation in species of genera Martes and Mustela", Genes Genet. Syst. 75:259-267 (2000)*
    2000  [Not refereed][Not invited]
  • Tsuchiya, K., Suzuki, H., Shinohara, A., Harada, M., Wakana, S., Sakaizumi, M., Han, S-H.: "Kryukov, A.P. Molecular phylogeny of East Asian moles inferred from the sequence variation of the mitochondrial cytochrome b gene", Gene and Genetic System, 75・・・
    2000  [Not refereed][Not invited]
     
    Tsuchiya, K., Suzuki, H., Shinohara, A., Harada, M., Wakana, S., Sakaizumi, M., Han, S-H.: "Kryukov, A.P. Molecular phylogeny of East Asian moles inferred from the sequence variation of the mitochondrial cytochrome b gene", Gene and Genetic System, 75:17-24 (2000)*
  • Serizawa, K., Suzuki, H., and Tsuchiya, K.: "A phylogenetic view on species radiation in Apodemus inferred from variation of nuclear and mitochondrial genes", Biochemical Genetics, 38:27-40 (2000)*
    2000  [Not refereed][Not invited]
  • Motokawa, M., Suzuki, H., Harada, M., Lin, L-K., Koyasu, K., and Oda, S.: "Phylogenetic relationships among East Asian Crocidura (Mammalia: Insectivora) inferred from mitochondrial cytochrome b gene", Zoological Science,17:497-504 (2000)*
    2000  [Not refereed][Not invited]
  • 本川 雅治, 鈴木 仁, 原田 正史  タクサ : 日本動物分類学会誌  (7)  1999/08/20  [Not refereed][Not invited]
  • 鈴木 仁, 中田 圭亮, 長谷川 善和, 佐藤 和彦  哺乳類科学 = Mammalian Science  39-  (1)  104  -105  1999/06/30  [Not refereed][Not invited]
  • HOSODA Tetsuji, SUZUKI Hitoshi, IWASA Masahiro A, HAYASHIDA Mitsuhiro, WATANABE Shigeki, TATARA Masaya, TSUCHIYA Kimiyuki  Journal of the Mammalogical Society of Japan  24-  (1)  25  -33  1999/06/01  [Not refereed][Not invited]
     
    We examined the intra- and inter-specific genetic relationships of the Japanese marten Martes melampus and the sable M. zibellina using cytoplasmic and nuclear DNA markers. The interspecific sequence divergences in the 402 base pairs of the mitochondrial cytochrome b gene averaged 3.3%. The extent of the divergences among thirteen individuals of M. melampus collected from Honshu, Shikoku, Kyushu and Tsushima was small (≤0.5%), irrespective of their fur color variation. A somewhat higher degree of intra-specific variation (up to 1.3%) was observed among M. zibellina specimens, but the extent of inter-populational variation between Primorye, Russia, and Hokkaido, Japan, was not so high (minimum 0.2%), suggesting that there has been recent genetic communication between Hokkaido and the continent. Among the 24 restriction sites of the nuclear ribosomal DNA spacer, there was no difference within either species, however one site differed between the two species. Using these molecular markers we confirmed that an amimal from Hokkaido, showing the typical morphological characteristics of M. melampus, possessed the same genotype as M. melampus from Honshu. From these results and descriptions in the literature, we presumed that the animal in question could be a descendent of M. melampus introduced to Hokkaido from Honshu by fur farmers about 50 years earlier. Eight animals examined from Hokkaido showed no indication of hybridization between the two species.
  • SUZUKI Hitoshi, IWASA Masahiro A, ISHII Nobuo, NAGAOKA Hiroko, TSUCHIYA Kimiyuki  Journal of the Mammalogical Society of Japan  24-  (1)  43  -50  1999/06/01  [Not refereed][Not invited]
     
    We examined the geographic variation of Tokudaia osimensis through the analysis of mitochondria1 cytochrome b (cyt b) gene sequences and the restriction fragment length polymorphism (RFLP) in the nuclear ribosomal RNA gene (rDNA), using samples collected from Tokuno-shima and Amami-oshima in the Ryukyu Islands. The two populations show intrinsic karyological variation (Tokuno-shima, 2n=45; Amami-oshima, 2n=25). Sequences of the cyt b gene differed considerably between the two island populations. The extent of the sequence divergence among 1,140 bp of the gene was calculated to be 0.088 using the Kimura two parameter method, and was comparable to those between related species of rodents such as within genus Mus or Rattus. The extent of the differentiation in the rDNA-RFLP was also high. Three out of 22 restriction site variants were found to be fixed in the nuclear rDNA arrays of hundreds of copies in either one of the two island populations. These intensive inter-populational differences indicate that the two island populations may have been isolated for a considerable period of evolutionary time, probably several millions of years, despite there having been several opportunities for renewed genetic contact during the Pleistocene ice ages. Our data strongly suggest that the current taxonomic status of the populations of the two islands, Amami-oshima and Tokuno-shima, which regards them conspecific, should be reviewed.
  • IWASA Masahiro A, HAN Sang Hoon, SUZUKI Hitoshi  Journal of the Mammalogical Society of Japan  24-  (1)  35  -41  1999/06/01  [Not refereed][Not invited]
     
    The conventional and G- and Q-banded karyotypes of the Korean red-backed vole Eothenomys regulus (2n=56) are described here for the first time. The autosomes were found to be composed of 26 pairs of acrocentrics and one pair of metacentrics, as in other species of red-backed voles. Side-by-side pair-matching analysis revealed that the G-banding patterns of E. regulus were essentially identical to those of the grey red-backed vole Clethrionomys rufocanus, and therefore the karyotype of E. regulus was of a "rufocanus" type, not of a "glareolus" type, which is characterized by 1-9 translocation. The sex chromosomes of E. regulus were found to be composed of a large subtelocentric X chromosome and a medium-sized subtelocentric Y chromosome, closely resembling those of E. smithii in both size and morphology. Both X and Y sex chromosomes were indistinguishable between these species, as far as conventional staining is concerned. Further analysis indicated, however, that E. regulus' Y chromosome has a large C-band area on the terminal half of its long arm, whereas E. smithii has a large C-band area on the proximal half of its long arm. Such C-band patterning implies the involvement of the Y chromosome in paracentric inversion during the course of speciation.
  • MUNECHIKA Isao, NOZAWA Kohei, SUZUKI Hitoshi  Japanese journal of ornithology  47-  (4)  133  -138  1999/04/01  [Not refereed][Not invited]
  • 宗近 功, 野沢 康平, 鈴木 仁  日本鳥学会誌 = Japanese journal of ornithology  47-  (4)  1999/04/01  [Not refereed][Not invited]
  • Oshida Tatsuo, Tsuchiya Kimiyuki, Suzuki Hitoshi, Yanagawa Hisashi, Yoshida Michihiro C  Chromosome science  3-  (1)  29  -32  1999  [Not refereed][Not invited]
     
    Q- and C-banded karyotypes and the location of Ag-NORs were analyzed from each male specimen of the Japanese dormouse, Glirulus japonicus, obtained from different Prefectures of Nagasaki and Kumamato, and compared with those of the other specimen from Yamanashi Prefecture that have been previously reported (Oshida et al., 1997). All the specimens showed the same Q- and C-banded karyotypes with 2n=46, whereas the NOR-carrying chromosomes and the number of Ag-NORs appeared differently in each specimen, though all Ag-NORs were located in the telomeric region of each short arm of the NOR-carrying chromosomes. Ag-NORs were detected in pairs 8, 10, 19 and 22 from Nagasaki's specimen, and in pairs 8, 10, 11, and 22 from Kumamoto's, while Ag-NORs were present in pairs 8, 10 and 11 from the Yamanashi's specimen, indicating less NOR sites in the Yamanashi's specimen than the other two specimens. These results suggested specimen-specific differences in NOR-bearing chromosomes in different geographical distribution, which can provide the geographical variation of NOR locations within this species.
  • Suzuki,H., Iwasa,M.A., Ishii,N., Nagaoka,H., and Tsuchiya,K.:"The genetic status of two insular populations of the endemic spiny rat Tokudai osimensis (Rodentia, Muridae) of the Ryukyu Islands, Japan" Mammal Study, 24:43-50 (1999)*
    1999  [Not refereed][Not invited]
  • Hosoda,T., Suzuki,H., Iwasa,M.A., Hayashida,M., Watanabe,S., Tatara,M., and Tsuchiya,K.:"Genetic relationships within and between the Japanese marten Martes melampus and the sable M. zibellina, based on variation of mitochondrial DNA and nuclear riboso・・・
    1999  [Not refereed][Not invited]
     
    Hosoda,T., Suzuki,H., Iwasa,M.A., Hayashida,M., Watanabe,S., Tatara,M., and Tsuchiya,K.:"Genetic relationships within and between the Japanese marten Martes melampus and the sable M. zibellina, based on variation of mitochondrial DNA and nuclear ribosomal DNA" Mammal Study, 24:25-33 (1999)*
  • Suzuki, H., Iwasa, A. M., Harada, M., Wakana, S., Sakaizumi, M., Han, S-H., Kitahara, E., Kimura, Y., Kartavtseva, I., Tsuchiya, K.:" Molecular phylogeny of red-backed voles in Far East Asia based on variation in ribosomal and mitochondrial DNA", Journ・・・
    1999  [Not refereed][Not invited]
     
    Suzuki, H., Iwasa, A. M., Harada, M., Wakana, S., Sakaizumi, M., Han, S-H., Kitahara, E., Kimura, Y., Kartavtseva, I., Tsuchiya, K.:" Molecular phylogeny of red-backed voles in Far East Asia based on variation in ribosomal and mitochondrial DNA", Journal of Mammalogy, 80:512-521(1999)*
  • Iwasa,M.A., Han,S-H., and Suzuki,H.:"A karyological analysis of the Korean red-backed vole, Eothenomys regulus (Rodentia, Muridae), using differential staining methods", Mammal Study, 24:35-41 (1999)*
    1999  [Not refereed][Not invited]
  • NAKATA Keisuke, SUZUKI Hitoshi  Honyurui Kagaku (Mammalian Science)  38-  (1)  127  -128  1998/10/31  [Not refereed][Not invited]
  • 中田 圭亮, 鈴木 仁  哺乳類科学 = Mammalian Science  38-  (1)  1998/10/31  [Not refereed][Not invited]
  • S Sakurai, H Suzuki, S Saito, Y Konishi, K Machida, M Kohno  MICROBIOLOGY AND IMMUNOLOGY  42-  (12)  829  -836  1998  [Not refereed][Not invited]
     
    To determine the active site of exfoliative toxin B (sETB) of Staphylococcus aureus, the etb gene was cloned from an S. aureus SU strain obtained from a patient with impetigo, We prepared a frame shift mutant protein from a recombinant plasmid with a BglII linker inserted into the Tyr-155 codon of the ETB gene (pETB/BglIIL), The recombinant mutant protein (ETB/BglIIL) obtained from Escherichia coli containing pETB/BglIIL showed no toxicity in neonatal mice and no agglutination activity, The 20-kDa ETB/BglIIL contained 185 amino acid residues. Site-directed mutagenesis was used to introduce mutations at either Tyr-155, Tyr-157, Tyr-159, or Tyr-162, Substitution of any of the Tyr residues decreased exfoliative activity compared with that of native sETB (4,000 EU/ml), Substitution of Tyr-155 with a Phe (ETB/Y155) decreased activity 5-fold (800 EU/ml), Substitution of Tyr-157 with Leu (ETB/Y157) decreased activity 80-fold (50 EU/ml) and decreased agglutination titer 5-fold compared with that of native sETB (400,000), Substitution of Tyr-159 with Leu (ETB/Y159)decreased activity 4-fold (1,000 EU/ml), When both Tyr-157 and Tyr-159 were mutated (ETB/Y157-159), both toxicity and antigenicity were completely lost. On an immunodiffusion test, ETB/Y157 showed a faint precipitation line, but ETB/BglIIL and ETB/Y157-159 had no activity, showing that the Tyr-157 and Tyr-159 residues are essential for the toxicity and antigenicity of ETB.
  • Chelomina, G.N., Suzuki, H., Tsuchiya, K., Moriwaki, K., Lyapunova, E. A., and Vorontsov, N.N.: "Sequencing of the mtDNA cytochrome b gene and reconstruction of the maternal relationships of wood and field mice of the genus Apodemus (Muridae, Rodentia・・・
    1998  [Not refereed][Not invited]
     
    Chelomina, G.N., Suzuki, H., Tsuchiya, K., Moriwaki, K., Lyapunova, E. A., and Vorontsov, N.N.: "Sequencing of the mtDNA cytochrome b gene and reconstruction of the maternal relationships of wood and field mice of the genus Apodemus (Muridae, Rodentia)", Russian J. Genetics 34: 529-539(1998)*
  • Sakurai, S., Suzuki, H., Saito, S., Konishi, Y., Machida, K., and Kohono, M.: "New evidence that the Tyr-157 and Tyr-159 residues of Staphylococcal exfoliative toxin B are essential for its toxicity", Micorobiol. Immunol. 42: 829-836 (1998) *
    1998  [Not refereed][Not invited]
  • MUNECHIKA Isao, WAKANA Shigeharu, SUZUKI Hitoshi  Nihon Chikusan Gakkaiho  68-  (12)  1103  -1110  1997/12/25  [Not refereed][Not invited]
     
    We studied the genetic relationships of four species of jungle fowl and the domestic fowl by the differentiation of the restriction sites in ribosomal DNA (rDNA). Almost no polymorphisms were observed, however, there were polymorphisms seen in Sac I and Pst I sites after hybridization with the 18S probe. Although a 2.7kb Sac I site was missing in the red jungle fowl and in most domestic fowl, it existed in the other three species of jungle fowl and in one line of domestic fowl. In addition, a Pst I site in the vicinity of 2.3kb was not observed in any of the jungle fowl species other than the Ceylon jungle fowl. Another Pst I site in the vicinity of 1.8kb, hybridized with the INT probe in the green jungle fowl was observed, these two bands seem to be unique to each of these species. Since most of the domestic fowl lacked the Sac I site, it is thought that the red jungle fowl, which likewise lacks the site, played a major role in the formation of the domestic fowl. However, there was one strain of domestic fowl that shared this Sac I site with the gray jungle fowl, the Ceylon jungle fowl and the green jungle fowl except the red jungle fowl, suggesting the possible involvement of jungle fowl species in the formation of the domestic fowl.
  • 関島 恒夫, 島田 卓哉, 本川 雅治, 鈴木 仁, 齊藤 隆  哺乳類科学 = Mammalian Science  36-  (2)  227  -230  1997/06/30  [Not refereed][Not invited]
  • 宗近 功, 鈴木 仁, 若菜 茂晴  日本家禽学会誌  34-  (3)  184  -188  1997/05  [Not refereed][Not invited]
  • H Suzuki, S Minato, S Sakurai, K Tsuchiya, IM Fokin  ZOOLOGICAL SCIENCE  14-  (1)  167  -173  1997/02  [Not refereed][Not invited]
     
    The Japanese dormouse, Glirulus japonicus, is the only extant lineage that represents this genus and it has been classified as a single species distributed on the three main islands of Japan, namely Honshu, Shikoku and Kyushu. However, individuals collected from Fukui, Wakayama and Kochi Prefectures (southwestern part of Japan) yielded distinctly different profiles of restriction fragments of the nuclear ribosomal DNA (rDNA) spacer from those collected from Yamanashi and Nagano Prefectures (central Japan). The estimated sequence divergence between the two groups was 2.8% on average, which corresponds to a putative divergence some two million years ago. Representing mitochondrial DNA (mtDNA) sequences, 402 bases of cytochrome b gene were determined by direct sequencing and the estimated extent of the sequence divergence between the two groups was 6.5-7%. Differences between the two geographic groups were also substantial in the sequences of about 300 base-fragments from the Y-linked, sex-determining locus, Sry. To assess the phylogenetic relationships between the Japanese dormouse and members of the family Myoxidae, we compared sequences of mitochondrial 12S rRNA gene of Japanese dormice with those of the forest dormouse (Dryomys nitedula) and the common dormouse (Muscardinus avellanarius), two continental genera thought to be closely related to the genus Glirulus. The results showed that the sequences from Japanese dormice were distinct from any sequences of the two continental species and the extent of the differences were somewhat similar to that between the rat (Rattus norvegicus) and the hamster (Mesocricetus auratus).
  • Munechika, I., Suzuki, H. and Wakana, S. : "Differentiation of Restriction Sites in Ribosomal DNA in the genus Gallus", Animal Science and Technology, 68 : 1103-1110 (1997)
    1997  [Not refereed][Not invited]
  • Munechika, I., Suzuki, H. and Wakana, S. : "Comparative Analysis of the Restriction Endocnuclease Cleavage Patterns of Mitochondrial DNA in the Genus Gallus", Japanese Poultry Science, 34 : 184-188 (1997)
    1997  [Not refereed][Not invited]
  • Kikkawa, Y., Yonekawa, H., Suzuki, H. and Amano, T. : "Analysis of Genetic Diversity of Domestic Water Buffaloes and Naoas Based on Variations in the Mitochonrdial Gene for Cytochrome b", Animal Genetics, 28 : 195-201 (1997)
    1997  [Not refereed][Not invited]
  • HAN Sang Hoon, WAKANA Shigeharu, SUZUKI Hitoshi, HIRAI Yasukazu, TSUCHIYA Kimiyuki  Journal of the Mammalogical Society of Japan  21-  (2)  125  -135  1996/12/01  [Not refereed][Not invited]
     
    Restriction fragment variations in nuclear ribosomal DNA (rDNA) spacers, and in mitochondrial DNA (mtDNA), were examined in a total of 14 individuals of the two Korean subspecies of the striped field mouse : Apodemus agrarius coreae, collected from the mainland and Jindo and Geoje islands, and A. a. chejuensis collected from Cheju Island. Analysis of heterogeneity in rDNA spacers with ten restriction enzymes, showed that the main Korean populations of A. a. coreae have a similar genetic background irrespective of their geographic locality. In the population from Cheju Island, however, an accumulation of a specific variation, a new SacI site within the internal spacer region of rDNA, was observed. In the contrast, analysis of heterogeneity of mtDNA with ten restriction enzymes, revealed that mtDNA haplotypes from the offshore islands were distinct from one another and distinct from those of the mainland, with up to 4% of sequence divergence, which corresponds to 1-2 million years of divergence time. It is suggested that certain geographic conditions, such as the existence of a large number of small islands, may help preserve various mtDNA haplotypes which diverged many millenial ago.
  • 鈴木 仁, 山田 文雄, 土屋 公幸  日本分子生物学会年会プログラム・講演要旨集  19-  1996/08/01  [Not refereed][Not invited]
  • WAKANA Shigeharu, SAKAIZUMI Mitsuru, TSUCHIYA Kimiyuki, ASAKAWA Mitsuhiko, HAN Sang Hoon, NAKATA Keisuke, SUZUKI Hitoshi  Journal of the Mammalogical Society of Japan  21-  (1)  15  -25  1996/06/01  [Not refereed][Not invited]
     
    Restriction fragment length polymorphisms (RFLPs) in nuclear ribosomal DNA (rDNA) spacers and mitochondrial DNA (mtDNA) were examined in red-backed voles collected in Hokkaido (Japan), and Korea. These voles have been classified into six species on the basis of morphological characteristics, such as dental morphology. The RFLPs of the rDNA allowed us to classify the voles into three distinct groups : rCrt (Clethrionomys rutilus), rCrf (C. rufocanus, C. sikotanensis and Eothenomys regulus) and rCrx (C. rex and C. montanus). The estimated sequence divergence between rCrt and rCrf and that between rCrf and rCrx were 4.8% and 2.3%, respectively. In the rCrf group, no major differences in mtDNA were observed among the populations from the mainland of Hokkaido, Rishiri Island, and Daikoku Islet. Similarly, in the rCrx group, mtDNA haplotypes from the mainland of Hokkaido and Rishiri I. were closely related each other, indicating that there have been genetic exchanges between the populations after speciation, or those haplotypes are derived from recent common origin. The Korean red-backed vole, which is sometimes referred to E. regulus, had rDNA identical to that of the rCrf group from Hokkaido. By contrast, the mtDNA haplotype of the Korean vole was substantially different from that of C. rufocanus in Hokkaido (8% sequence divergence). These results imply that the Korean red-backed vole and C. rufocanus in Hokkaido are very closely related and that ancestrally diverged mtDNA haplotypes have been maintained in the different geographic regions.
  • 飯塚 光司, 竹内 良範, 千場 英弘, 松田 洋一, 鈴木 仁, 太田 誠志, 緒方 秀充, 藪野 修民, 永山 俊介, 鴻野 みどり, 山田 卓三  生物教育  36-  (1)  1996/03/20  [Not refereed][Not invited]
  • 竹内 良範, 飯塚 光司, 干場 英弘, 松田 洋一, 鈴木 仁, 太田 誠志, 緒方 秀充, 藪野 修民, 永山 俊介, 鴻野 みどり, 山田 卓三  生物教育  36-  (1)  1996/03/20  [Not refereed][Not invited]
  • C Morita, K Tsuchiya, H Ueno, Y Muramatsu, A Kojimahara, H Suzuki, N Miyashita, K Moriwaki, ML Jing, XL Wu, FS Wang  MICROBIOLOGY AND IMMUNOLOGY  40-  (4)  313  -315  1996  [Not refereed][Not invited]
     
    Serum samples from 337 wild house mice (Mus musculus) from 35 sites in China, collected in 1992 and 1993, were examined for antibodies against lymphocytic choriomeningitis virus (LCMV). Ten samples from eight sites were found to contain such antibodies. Six of the eight positive sites were located in the territory of M. m. gansuensis. One of the other two sites was located in the territory of M. m. castaneus in southern China and the other site was in a habitat of M. m. castaneus which had invaded into the western end of the territory of M. m. homourus. It seems likely that LCMV is distributed in the territories of M. m. gansuensis and M. m. castaneus in China. This is the first report of detection of these antibodies in wild house mice in China and specifically in the territories of M. m. gansuensis and M. m. castaneus.
  • H. Suzuki, S. Wakana, H. Yonekawa, K. Moriwaki, S. Sakurai and E. Nevo : "Variations in ribosomal DNA and mitochondrial DNA among chromosomal species of subterranean mole rats", Mol. Biol. Evol., 13 : 85-92 (1996)*
    1996  [Not refereed][Not invited]
  • H. Suzuki, S. Sakurai and Y. Matsuda : "Rat 5S rDNA spacer sequences and chromosomal assignment of the genes to the extreme terminal region of chromosome 19", Cytogenet. Cell Genet., 72 : 1-4 (1996)*
    1996  [Not refereed][Not invited]
  • S. Wakana, M. Sakaizumi, K. Tsuchiya, M. Asakawa, S. H. Han, K. Nakata and H. Suzuki :"Phylogenetic implications of variations in rDNA and mtDNA in red-backed voles collected in Hokkaido, Japan, and in Korea", Mammal Study, 21 : 15-25 (1996)*
    1996  [Not refereed][Not invited]
  • 鈴木 仁  霊長類研究所年報  25-  104  -104  1995/11/01  [Not refereed][Not invited]
  • KATAKURA Ken, OHTOMO Hiroshi, SUZUKI Hitoshi  日本熱帯医学会雑誌  23-  1995/10/20  [Not refereed][Not invited]
  • 鈴木 仁  遺伝  49-  (9)  p53  -58,図巻頭1p  1995/09  [Not refereed][Not invited]
  • Y MAEZAWA, M YAMAUCHI, G TODA, H SUZUKI, S SAKURAI  ALCOHOLISM-CLINICAL AND EXPERIMENTAL RESEARCH  19-  (4)  951  -954  1995/08  [Not refereed][Not invited]
     
    The liver enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which are responsible for the oxidative metabolism of ethanol, are polymorphic in humans. Cytochrome P450IIE1, an ethanol-inducible isozyme of liver microsomal P450, is also important in ethanol metabolism. Genetic polymorphisms in the 5'-flanking region of the human cytochrome P45011E1 gene have recently been reported. We hypothesized that the polymorphisms of ADH, ALDH, and P45011E1 modify the susceptibility to development of alcoholism. We determined the genotypes of the ADH2, ALDH2, and P450IIE1 loci of 96 Japanese alcoholics and 60 healthy male subjects, using leukocyte DNA by the restriction fragment-length polymorphism by polymerase chain reaction. The alcoholics had significantly higher frequencies of the ADH2(1) and ALDH2(1) alleles than did the healthy subjects. No significant difference in the frequency of the P45011E1 genotype was observed between the alcoholics and the healthy subjects. In conclusion, genetic polymorphisms of the ADH and ALDH genes, but not of the P45011E1 gene, Influence the risk of developing alcoholism in Japanese.
  • S SAKURAI, H SUZUKI, K MACHIDA  MICROBIOLOGY AND IMMUNOLOGY  39-  (6)  379  -386  1995  [Not refereed][Not invited]
     
    A new system was designed to detect staphylococcal exfoliative toxin A (ETA) and B (ETB) genes by the polymerase chain reaction (PCR). The primer pairs for the ETA gene (eta) were 20 and 20-mer, and its PCR product was a 741-bp eta fragment, while the primer pairs for the ETB gene (etb) were also 20 and 20-mer, and its PCR product was a 629-bp etb fragment. When these primers were simultaneously used in the PCR, the two types of ET were clearly detected as two bands in an ETA and ETB double-producer using only one colony within 3 hr. We examined 66 strains of Staphylococcus aureus isolated from patients with staphylococcal scalded skin syndrome (SSSS) and compared the results obtained by ELISA and PCR, The same results were obtained for 56 of the strains, i.e., 30 strains were ETA producers, 20 strains were ETB producers, and 6 strains were double-producers. However, positive results were obtained for 5 of the 10 non-ET-producing strains, Two of these strains were judged by PCR as ETA producers and three as ETB producers, Thus, PCR is very sensitive and rapid in detecting ETA and ETB gene fragments in colonies isolated from patients with SSSS.
  • 鈴木 仁  霊長類研究所年報  24-  71  -72  1994/11/01  [Not refereed][Not invited]
  • SUZUKI Hitoshi  Honyurui Kagaku (Mammalian Science)  34-  (1)  67  -79  1994/10/30  [Not refereed][Not invited]
  • Watanabe Takashi, Suzuki Hitoshi, Tanba Sumio, Yokoyama Ryuzo  IEICE transactions on fundamentals of electronics, communications and computer sciences  77-  (9)  1445  -1450  1994/09/25  [Not refereed][Not invited]
     
    Contextual classification of multispectral image data in remote sensing is discussed and concretely two improved contextual classifiers are proposed. The first is the extended adaptive classifier which partitions an image successively into homogeneously distributed square regions and applies a collective classification decision to each region. The second is the accelerated probabilistic relaxation which updates a classification result fast by adopting a pixelwise stopping rule. The evaluation experiment with a pseudo LANDSAT multispectral image shows that the proposed methods give higher classification accuracies than the compound decision method known as a standard contextual classifier.
  • H SUZUKI, T HOSODA, S SAKURAI, K TSUCHIYA, MUNECHIKA, I, VP KORABLEV  JAPANESE JOURNAL OF GENETICS  69-  (4)  397  -406  1994/08  [Not refereed][Not invited]
     
    We analyzed the restriction fragment length polymorphisms in the spacer regions of ribosomal DNA (rDNA), using twelve restriction enzymes, to examine whether the Iriomote cat is related to the leopard cat (Felis bengalensis). A restriction map for each taxon was constructed and the major taxon-specific types of repeating unit (repetypes) were characterized on the basis of the arrangements of restriction sites. The Iriomote cat and the leopard cat share a common repetype but this repetype is different from that of the domestic cat (F. catus) with an estimated sequence divergence of 1.5% and from that of the ocelot (F. paradalis) with an estimated sequence divergence of 2.5%. These results indicate that, phylogenetically, the Iriomote cat is closely related to the leopard cat and that the ancestral population moved from the continent to Iriomote Island quite recently. The rDNA arrays of the leopard cat exhibit considerable intragenomic size-variation, which is thought to have emerged as a result of differences in numbers of repeated DNA segments, whereas the extent of such size-variation is much lower in the rDNA of the Iriomote cat. It appears that, even though migration of the Iriomote cat occurred relatively recently, the population has diverged to some extent from its continental counterpart, perhaps via fixation of preexistent intraspecific variations rather than by generation of new variations.
  • 鈴木 仁  霊長類研究所年報  23-  73  -73  1993/09/01  [Not refereed][Not invited]
  • Tetsuji Hosoda, Kimiyuki Tsuchiya, Tetsuji Hosoda, Hitoshi Suzuki, Takuzo Yamada  CYTOLOGIA  58-  (2)  223  -230  1993  [Not refereed][Not invited]
     
    Heterogeneity in the external spacers of the ribosomal DNA (rDNA) from eight species of terrestrial carnivores (Canidae, Mustelidae) was analyzed using twelve different restriction enzymes and cloned mouse rDNA probes. We constructed species-specific maps of restriction sites on rDNA. Based on differences in the arrangements of the restriction sites, sequence divergence among the repeating units of rDNA was estimated in order to construct a molecular-phylogenetic tree and to estimate the timing of the divergence of species. The divergence between Nyctereutes procyonoides viverrinus and Vulpes vulpes japonica was 8.4%. The sequence divergence between Mustela putorius furo versus Mustela sibirica itatsi, Mustela nivalis nivalis and Martes melampus melampus was 0.65%, 1.59% and 7.27%, respectively. © 1993, Japan Mendel Society, International Society of Cytology. All rights reserved.
  • 鈴木 仁, 桜井 進, 西村 正彦  The Japanese journal of genetics  67-  (3)  217  -232  1992/06  [Not refereed][Not invited]
  • H SUZUKI, S SAKURAI, M NISHIMURA, R KOMINAMI, K MORIWAKI  JAPANESE JOURNAL OF GENETICS  67-  (3)  217  -232  1992/06  [Not refereed][Not invited]
     
    Silver-stainability of nucleolar organizer regions (NORs) that contain genes for ribosomal RNA (rDNA) was investigated using two mouse strains, BALB/cCrSlc and MOA, and their hybrid progeny. The patterns of segregation of the rDNA clusters were analyzed in terms of chromosomal C-banding and by use of a polymorphic probe for the variable region in backcrossed N2 and N3 individuals. The results indicate that the intensity of Ag-NOR staining is stably inherited in most of the rDNA clusters, irrespective of different genetic backgrounds. In some clusters, such as those on chromosome 12 of BALB/cCrSlc, a modulation of the intensity is observed. This modulation seems to be due to compensatory activation via a change in the number of actively transcribed genes. The change from silver-negative to silver-positive staining of the NOR of chromosome 12 of BALB/cCrSlc was correlated with demethylation of the genes.

Awards & Honors

  • 日本哺乳類学会 2015年日本哺乳類学会賞
     
    受賞者: 鈴木 仁

Research Grants & Projects

  • 第三紀および第四紀の地球環境変動に伴う日本産小型哺乳類の種間及び種内の遺伝的交流の解析


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