下鶴 倫人 (シモヅル ミチト)
| 獣医学研究院 獣医学部門 環境獣医科学分野 | 准教授 |
| Ｏｎｅ Ｈｅａｌｔｈリサーチセンター | 准教授 |
Last Updated :2025/04/25
■研究者基本情報
Researchmap個人ページ
ホームページURL
J-Global ID
■経歴
経歴
委員歴
- 2025年04月 - 現在
札幌市環境影響評価審議会委員 - 2024年04月 - 現在
日本クマネットワーク, 副代表 - 2023年04月 - 現在
知床世界自然遺産地域科学委員会ヒグマワーキンググループ委員 - 2021年04月 - 現在
ヒグマの会, 理事, その他 - 2021年04月 - 現在
日本獣医学会 野生動物分科会, 副会長 - 2019年04月 - 現在
日本野生動物医学会, 学術誌編集委員 - 2019年01月 - 現在
日本動物行動学会, 副編集長, 学協会 - 2014年04月 - 現在
日本獣医学会, 評議員, 学協会 - 2011年04月 - 現在
日本野生動物医学会, 評議員, 学協会 - 2018年04月 - 2024年03月
日本クマネットワーク, 事務局長, その他 - 2021年04月 - 2023年03月
Frontiers in Physiology / Physio-logging, Review Editor - 2014年04月 - 2021年03月
日本獣医学会, 野生動物分科会 事務局・会計, 学協会 - 2010年04月 - 2013年03月
日本野生動物医学会, 幹事（広報）, 学協会
■研究活動情報
受賞
- 2024年09月, 日本獣医学会, 日本獣医学会賞
One Healthへの貢献を目指した、野生動物を対象とした生理・生態学的研究 - 2023年09月, 日本哺乳類学会, 最優秀発表賞
ヒグマにおける毛根DNAのメチル化レベルを指標とした年齢推定の試み
中村 汐里、山﨑 淳平、松本 直也、萩野 恭伍、坂元 秀行、山中 正実、中西 将尚、神保 美渚、柳川 洋二郎、伊藤 英之、坪田 敏男、下鶴 倫人 - 2023年03月, 日本生態学会, ポスター賞最優秀賞
血液を用いてヒグマの年齢を推定する ～DNAメチル化率を指標として～
中村汐里、山﨑淳平、松本直也、 伊藤英之、村山美穂、 斉惠元、木下こづえ、山中正実、 栁川洋二郎、佐鹿万里子、坪田敏男、下鶴倫人 - 2022年10月, 日本獣医学会, 優秀発表賞（野生動物学分科会）
ヒグマにおける血液DNAのメチル化率を指標とした年齢推定の試み
中村汐里、山﨑淳平、松本直也、伊藤英之、村山美穂、斉惠元、木下こづえ、山中正実、柳川洋二郎、佐鹿万里子、坪田敏男、下鶴倫人 - 2021年08月, 日本哺乳類学会, 優秀発表賞
知床半島のオスヒグマにおける生涯の採食戦略
神保美渚、白根ゆり、梅村佳寛、石名坂豪、中西将尚、葛西真輔、白栁正隆、宇野裕之、佐鹿万里子、坪田敏男、下鶴倫人 - 2020年04月, 羅臼町, 感謝状
ヒグマ対策におけるDNA分析の協力に対する感謝状
下鶴 倫人 - 2016年09月, 日本哺乳類学会, 優秀発表賞
知床半島におけるヒグマの移動分散様式の解明
白根ゆり;山中正実;中西將尚;石名坂豪;能勢峰;葛西真輔;白柳正隆;増田泰;釣賀一二三;間野勉;藤本靖;長田雅裕;佐鹿万里子;坪田敏男;下鶴倫人 - 2012年09月, 日本哺乳類学会, 最優秀ポスター賞
知床半島ルシャ地域におけるヒグマの個体モニタリング調査の試み
森脇潤;下鶴倫人;山中正実;中西将尚;増田泰;藤本靖;坪田敏男
論文
- Patterns of intestinal parasite prevalence in brown bears (Ursus arctos) revealed by a 3-year survey on the Shiretoko Peninsula, Hokkaido, Japan
Mizuki Moriyoshi, Naoki Hayashi, Nariaki Nonaka, Ryo Nakao, Masami Yamanaka, Toshio Tsubota, Michito Shimozuru
International Journal for Parasitology: Parasites and Wildlife, 101048, 101048, Elsevier BV, 2025年02月, ［最終著者, 責任著者］
研究論文（学術雑誌） - Epidemiological Survey of Canine Distemper Virus Infection: Exploring the Link Between Virus Spread and Invasive Raccoon (Procyon lotor) Population Growth in Hokkaido, Japan
Miku Minamikawa, Mebuki Ito, Anastasiia Kovba, Yumi Kobayashi, Go Abe, Takanori Kooriyama, Ken Maeda, Michito Shimozuru, Toshio Tsubota, Mariko Sashika
Integrative Zoology, Wiley, 2024年12月
研究論文（学術雑誌）, ABSTRACT
Invasive raccoons (Procyon lotor) naturalized in Hokkaido, Japan, potentially spreading infectious diseases. Canine distemper virus infection is a serious epizootic disease, for which the raccoon is one of the hosts. We investigated the virus's prevalence in Hokkaido's wild raccoons, using 611 serum samples collected from captured raccoons in 2007–2012, 2021, and 2022. Higher seropositivity rates were confirmed in 2007 (32.7%), 2021 (46.4%), and 2022 (46.8%) than in 2008–2012 (0.00%–6.06%), suggesting the occurrence of an epidemic in 2007, 2021, and 2022 and its disappearance in 2008–2012. However, the infection status has recently changed, with high seropositivity rates consecutively confirmed in 2021 and 2022. Logistic regression analysis was performed to investigate the relationships among the catch per unit effort (an index of animal population density), host and environmental factors, and antibody status. The catch per unit effort correlated with seropositivity in 2007. As for environmental factors, the forest area ratio had a weak influence on seroprevalence in 2007; however, the residential area ratio had a clear influence on seroprevalence in 2021 and 2022. The epidemic occurred in forested areas in 2007; nonetheless, recent raccoon population growth and habitat expansion may have caused widespread infections even around residential areas in 2021 and 2022. Continuous monitoring of the infection and reinforcement of raccoon control programs are necessary to avoid serious damage through disease transmission to sympatric native raccoon dog (Nyctereutes procyonoides) and fox (Vulpes vulpes) populations, as well as health consequences for domestic dogs (Canis familiaris). - Regulation of mitochondrial metabolism by hibernating bear serum: Insights into seasonal metabolic adaptations
Mohamed Elfeky, Ayumi Tsubota, Michito Shimozuru, Toshio Tsubota, Kazuhiro Kimura, Yuko Okamatsu-Ogura
Biochemical and Biophysical Research Communications, 736, 150510, 150510, Elsevier BV, 2024年12月
研究論文（学術雑誌） - Seasonal infestation patterns of ticks on Hokkaido sika deer (Cervus nippon yesoensis).
Kotaro Shimizu, Michito Shimozuru, Masami Yamanaka, Genta Ito, Ryo Nakao, Toshio Tsubota
Parasitology, 1, 9, 2024年11月15日, ［国際誌］
英語, 研究論文（学術雑誌）, Ticks prefer specific feeding sites on a host that are influenced by host–tick and tick–tick interactions. This study focused on the spatiotemporal distribution of ticks in Hokkaido sika deer, an important tick host in Hokkaido, Japan. Tick sampling was performed on the sika deer in the Shiretoko National Park between June and October 2022. Ticks were collected from 9 different body parts of the deer to compare their attachment site preferences. Interspecific and intraspecific relationships among ticks were examined using co-occurrence analysis. The collected ticks were nymphal and adult stages of 4 species: Ixodes ovatus, Ixodes persulcatus, Haemaphysalis japonica and Haemaphysalis megaspinosa. Seasonal variations in tick burden were observed, with I. persulcatus and I. ovatus peaking in June and declining towards October; H. japonica showing low numbers in July and August and increasing from September; and H. megaspinosa appearing from September onwards with little variation. Attachment site preferences varied among species, with a significant preference for the pinna in I. ovatus and I. persulcatus. Haemaphysalis japonica was mainly found on the body and legs between June and August, and shifted to the pinna from September. Haemaphysalis megaspinosa showed a general preference for areas other than the legs. Co-occurrence analysis revealed positive, negative and random co-occurrence patterns among the tick species. Ticks of the same genus and species exhibited positive co-occurrence patterns; I. ovatus showed negative co-occurrence patterns with Haemaphysalis spp. This study revealed the unique attachment site preferences and distinct seasonal distributions of tick species in the Hokkaido sika deer. - Environmental and host factors underlying tick-borne virus infection in wild animals: Investigation of the emerging Yezo virus in Hokkaido, Japan
Mebuki Ito, Miku Minamikawa, Anastasiia Kovba, Hideka Numata, Tetsuji Itoh, Takuma Ariizumi, Asako Shigeno, Yuki Katada, Shiho Niwa, Yurie Taya, Yuto Shiraki, Gita Sadaula Pandey, Nariaki Nonaka, Ryo Nakao, Ryosuke Omori, Yuma Ohari, Norikazu Isoda, Michito Shimozuru, Toshio Tsubota, Keita Matsuno, Mariko Sashika
Ticks and Tick-borne Diseases, 15, 6, 102419, 102419, Elsevier BV, 2024年11月
研究論文（学術雑誌） - Environmental and host factors underlying tick infestation in invasive raccoons (Procyon lotor) in Hokkaido, Japan
Mebuki Ito, Miku Minamikawa, Anastasiia Kovba, Hideka Numata, Tetsuji Itoh, Yuki Katada, Shiho Niwa, Yurie Taya, Yuto Shiraki, Gita Sadaula Pandey, Samuel Kelava, Nariaki Nonaka, Ryo Nakao, Ryosuke Omori, Yuma Ohari, Norikazu Isoda, Michito Shimozuru, Toshio Tsubota, Keita Matsuno, Mariko Sashika
Ticks and Tick-borne Diseases, 15, 6, 102389, 102389, Elsevier BV, 2024年11月
研究論文（学術雑誌） - Epidemiology and molecular characterization of Mycobacterium tuberculosis including a drug-resistant strain associated with mortality of Asian elephants in Nepal 2019-2022.
Arjun Pandit, Jeewan Thapa, Amir Sadaula, Yasuhiko Suzuki, Chie Nakajima, Susan K Mikota, Naresh Subedi, Bijaya Kumar Shrestha, Michito Shimozuru, Bhawana Shrestha, Bijendra Raya, Sanjay Chaudhary, Sarad Paudel, Toshio Tsubota
Tuberculosis (Edinburgh, Scotland), 148, 102550, 102550, 2024年07月26日, ［国際誌］
英語, 研究論文（学術雑誌）, Tuberculosis (TB) is an emerging threat to the survival of elephants in Nepal. We investigated the lung tissue samples from nine elephants that died from 2019 to 2022 in Nepal using culture, conventional PCR, and loop-mediated isothermal amplification (LAMP) and then performed genotyping of five PCR-positive isolates to understand the possible transmission dynamics of Mycobacterium tuberculosis (Mtb). Results showed that two-thirds (6/9) of elephants were confirmed to be infected from Mtb by LAMP, 5/9 by PCR, and 4/9 by culture. Genotyping of Mtb isolates showed that elephants were infected with the Indo-Oceanic and Beijing lineages including an isoniazid-resistant Beijing lineage. MIRU-VNTR-based phylogeny, gyrA, and katG sequencing showed the possibility of ongoing transmission of Indo-Oceanic lineages and likely transmission of the drug-resistant Beijing lineage from human to elephant. Implementation of comprehensive surveillance and preventive measures are urgently needed to address this zoonotic disease and protect elephants from TB in Nepal. - No Evidence of SARS‐CoV‐2 Infection in Urban Wildlife of Hokkaido, Japan
Anastasiia Kovba, Naganori Nao, Michito Shimozuru, Mariko Sashika, Chihiro Takahata, Kei Sato, Keiya Uriu, Masami Yamanaka, Masanao Nakanishi, Genta Ito, Mebuki Ito, Miku Minamikawa, Kotaro Shimizu, Koichi Goka, Manabu Onuma, Keita Matsuno, Toshio Tsubota
Transboundary and Emerging Diseases, 2024, 1, Wiley, 2024年01月
研究論文（学術雑誌）, Various domestic and wildlife species have been found susceptible to and infected with SARS‐CoV‐2, the causative agent of COVID‐19, around the globe, raising concerns about virus adaptation and transmission to new animal hosts. The virus circulation in the white‐tailed deer population in North America has further called to action for virus surveillance in the wildlife. Here, we report on the first SARS‐CoV‐2 survey of wild animals in Japan, where frequent wildlife invasions of urban areas have occurred due to the limited predation, field abandonment, the increase of human acclimatization. Genetic testing using nasal swabs and serological screening have been conducted for sika deer, brown bears, raccoons, and raccoon dogs captured in Hokkaido prefecture from the end of the Delta variant wave to the spread of the Omicron variant, between March 2022 and February 2023. No viral RNA was detected in raccoons (0/184), sika deer (0/107), and brown bears (0/14) indicating that the virus was unlikely to spread within the population of these animal species. Among 171 raccoons, 20 raccoon dogs, 100 sika deer, and 13 brown bears, one raccoon, one brown bear, and two deer tested positive in the antibodies screening with multispecies SARS‐CoV‐2 N‐protein ELISA. Still, ELISA‐positive samples tested negative in three other serological tests, emphasizing the importance of confirming serological screening results. Our results suggested that SARS‐CoV‐2 was unlikely to spillback from humans to wildlife in Hokkaido during the study period, with the emergence of new variants, continuous surveillance is of utmost importance. - アライグマをセンチネルとしたダニ媒介性ウイルスのマダニからの伝播リスク評価
伊藤 萌林, 松野 啓太, 南川 未来, 重野 麻子, 有泉 拓馬, 伊藤 哲治, コウバ・アナスタシア, 沼田 栄花, 大森 亮介, 尾針 由真, 中尾 亮, 下鶴 倫人, 坪田 敏男, 佐鹿 万里子
日本野生動物医学会誌, 28, Suppl., 208, 208, 日本野生動物医学会, 2023年12月
日本語 - Age estimation based on blood DNA methylation levels in brown bears.
Shiori Nakamura, Jumpei Yamazaki, Naoya Matsumoto, Miho Inoue-Murayama, Huiyuan Qi, Masami Yamanaka, Masanao Nakanishi, Yojiro Yanagawa, Mariko Sashika, Toshio Tsubota, Hideyuki Ito, Michito Shimozuru
Molecular ecology resources, 2023年03月23日, ［最終著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Age is an essential trait for understanding the ecology and management of wildlife. A conventional method of estimating age in wild animals is counting annuli formed in the cementum of teeth. This method has been used in bears despite some disadvantages, such as high invasiveness and the requirement for experienced observers. In this study, we established a novel age estimation method based on DNA methylation levels using blood collected from 49 brown bears of known ages living in both captivity and the wild. We performed bisulfite pyrosequencing and obtained methylation levels at 39 cytosine-phosphate-guanine (CpG) sites adjacent to 12 genes. The methylation levels of CpGs adjacent to four genes showed a significant correlation with age. The best model was based on DNA methylation levels at just four CpG sites adjacent to a single gene, SLC12A5, and it had high accuracy with a mean absolute error of 1.3 years and median absolute error of 1.0 year after leave-one-out cross-validation. This model represents the first epigenetic method of age estimation in brown bears, which provides benefits over tooth-based methods, including high accuracy, less invasiveness, and a simple procedure. Our model has the potential for application to other bear species, which will greatly improve ecological research, conservation, and management. - クマの冬眠の生理・代謝機構 〜如何に太り, 如何に痩せるか〜
下鶴倫人
低温科学, 81, 181, 189, 2023年03月, ［査読有り］, ［招待有り］, ［筆頭著者, 最終著者, 責任著者］
研究論文（学術雑誌） - The dynamics of the microbiome in Ixodidae are shaped by tick ontogeny and pathogens in Sarawak, Malaysian Borneo.
Alice C C Lau, Wessam Mohamed Ahmed Mohamed, Ryo Nakao, Manabu Onuma, Yongjin Qiu, Nobuyoshi Nakajima, Michito Shimozuru, Jayasilan Mohd-Azlan, Mohamed Abdallah Mohamed Moustafa, Toshio Tsubota
Microbial genomics, 9, 2, 2023年02月, ［国際誌］
英語, 研究論文（学術雑誌）, Tick-borne diseases have recently been considered a potential emerging public health threat in Malaysia; however, fundamental studies into tick-borne pathogens and microbiome appear limited. In this study, six tick species (Ixodes granulatus, Haemaphysalis hystricis, Haemaphysalis shimoga, Dermacentor compactus, Dermacentor steini and Dermacentor atrosignatus) collected from two primary forests and an oil palm plantation in Sarawak, Malaysian Borneo, were used for microbiome analysis targeting bacterial 16S rDNA using next-generation sequencing (NGS). In addition, bacterial species were further characterized in conventional PCRs to identify potential pathogens. Sequences generated from NGS were first filtered with the Decontam package in R before subsequent microbial diversity analyses. Alpha and beta analyses revealed that the genus Dermacentor had the highest microbial diversity, and H. shimoga significantly differed in microbial composition from other tick species. Alpha and beta diversities were also significantly different between developmental stages of H. shimoga. Furthermore, we observed that some bacterial groups were significantly more abundant in certain tick species and developmental stages of H. shimoga. We tested the relative abundances using pairwise linear discriminant analysis effect size (LEfSe), which also revealed significant microbial composition differences between Borrelia-positive and Borrelia-negative I. granulatus ticks. Finally, pathogenic and potentially pathogenic bacteria circulating in different tick species, such as Rickettsia heilongjiangensis, Ehrlichia sp., Anaplasma sp. and Bartonella spp. were characterized by PCR and sequencing. Moreover, Coxiella and Francisella-like potential symbionts were identified from H. shimoga and D. steini, respectively. More studies are required to unravel the factors associated with the variations observed in this study. - Regulation of protein and oxidative energy metabolism are down-regulated in the skeletal muscles of Asiatic black bears during hibernation
Mitsunori Miyazaki, Michito Shimozuru, Yu Kitaoka, Kenya Takahashi, Toshio Tsubota
Scientific Reports, 12, 1, Springer Science and Business Media LLC, 2022年11月16日
研究論文（学術雑誌）, Abstract
Hibernating animals exhibit an unexplained physiological characteristic of skeletal muscles being atrophy resistance, in which case muscle mass and strength remain almost unchanged both before and after hibernation. In this study, we examined the alterations in the regulatory systems of protein and energy metabolism in the skeletal muscles of Asiatic black bears during hibernation. Skeletal muscle samples (vastus lateralis muscle) were collected from identical individuals (n = 8) during the active (July) and hibernating (February) periods, while histochemical and biochemical analyses were performed. We observed no significant alterations in body weight, muscle fiber size, and fiber type composition during the active and hibernating periods, indicating that the skeletal muscles of bears are very well preserved during hibernation. In hibernating bear skeletal muscles, both regulatory pathways of muscle protein synthesis (Akt/mechanistic target of rapamycin and mitogen-activated protein kinase systems) and proteolysis (ubiquitin–proteasome and autophagy systems) were down-regulated. Gene expression levels of factors regulating oxidative metabolism were also decreased in hibernating bear skeletal muscles. This is likely an adaptive strategy to minimize the energy wasting of amino acids and lipids during hibernation, which is accompanied by a prolonged period of disuse and starvation. - Detection of a Babesia sp. genotype closely related to marsupial-associated Babesia spp. in male Haemaphysalis shimoga from Sarawak, Malaysian Borneo.
Alice Cc Lau, Yongjin Qiu, Mohamed Abdallah Mohamed Moustafa, Ryo Nakao, Michito Shimozuru, Manabu Onuma, Nobuyoshi Nakajima, Mariko Sashika, Jayasilan Mohd-Azlan, Toshio Tsubota
The Journal of veterinary medical science, 84, 11, 1469, 1473, 2022年09月16日, ［査読有り］, ［国内誌］
英語, 研究論文（学術雑誌）, In this study, Babesia screening was conducted in 55 rodents and 160 tick samples collected from primary forests and an oil palm plantation in Sarawak, Malaysian Borneo. PCR targeting the 18S ribosomal DNA revealed the presence of Babesia spp. DNA detected in two questing male Haemaphysalis shimoga ticks collected from the oil palm plantation. Sequence analysis revealed that both sequences were identical and had 98.6% identity to a Babesia macropus sequence obtained from Eastern grey kangaroos (Macropus giganteus) in Australia. Phylogenetic tree revealed clustering with marsupial-associated Babesia spp. in the Babesia sensu stricto clade. Whether or not H. shimoga is the competent vector and the importance of the Babesia sp. detected in this study warrants more investigation. - Estimation of breeding population size using DNA‐based pedigree reconstruction in brown bears
Michito Shimozuru, Mina Jimbo, Keisuke Adachi, Kei Kawamura, Yuri Shirane, Yoshihiro Umemura, Tsuyoshi Ishinazaka, Masanao Nakanishi, Mayu Kiyonari, Masami Yamanaka, Yukihiro Amagai, Ayaho Ijuin, Tomoki Sakiyama, Shinsuke Kasai, Takane Nose, Masataka Shirayanagi, Hifumi Tsuruga, Tsutomu Mano, Toshio Tsubota, Keita Fukasawa, Hiroyuki Uno
Ecology and Evolution, 12, 9, Wiley, 2022年09月, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌） - Anthelmintic Baiting of Foxes against Echinococcus multilocularis in Small Public Area, Japan.
Kohji Uraguchi, Takao Irie, Hirokazu Kouguchi, Azusa Inamori, Mariko Sashika, Michito Shimozuru, Toshio Tsubota, Kinpei Yagi
Emerging infectious diseases, 28, 8, 1677, 1680, 2022年08月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, We distributed anthelmintic baits on a university campus in Japan inhabited by foxes infected with Echinococcus multilocularis to design an effective baiting protocol for small public areas. High-density baiting can reduce the risk for human exposure to the parasite to near zero. However, monthly baiting is recommended to maintain this effect. - Diet selection and asocial learning: Natal habitat influence on lifelong foraging strategies in solitary large mammals
Mina Jimbo, Tsuyoshi Ishinazaka, Yuri Shirane, Yoshihiro Umemura, Masami Yamanaka, Hiroyuki Uno, Mariko Sashika, Toshio Tsubota, Michito Shimozuru
Ecosphere, 13, 7, Wiley, 2022年07月, ［査読有り］, ［責任著者］
研究論文（学術雑誌） - Semen collection by urethral catheterization and electro-ejaculation with different voltages, and the effect of holding temperature and cooling rate before cryopreservation on semen quality in the Japanese macaque (Macaca fuscata).
Noboru Takaesu, Chihiro Kanno, Kosuke Sugimoto, Masashi Nagano, Akihisa Kaneko, Yoriko Indo, Hiroo Imai, Hirohisa Hirai, Munehiro Okamoto, Mariko Sashika, Michito Shimozuru, Seiji Katagiri, Toshio Tsubota, Yojiro Yanagawa
The Journal of veterinary medical science, 84, 3, 429, 438, 2022年03月15日, ［査読有り］, ［国内誌］
英語, 研究論文（学術雑誌）, In the Japanese macaque, semen has been collected by electro-ejaculation (EE), using the higher voltage stimuli compared to other species including genus Macaca. Semen coagulates immediately after ejaculation, which makes difficult to produce high-quality semen for artificial insemination. Recently, semen collection using urethral catheterization (UC) has been reported in carnivore and this technique may allow semen collection without coagulation in a less invasive manner. Further, the temporal preservation temperature and cooling rate of semen during cryopreservation affect post thawing sperm quality. In this study, to improve semen quality and quantity, as well as the animal welfare, semen collection was performed by EE with high (5-15 V) or low (3-6 V) voltage, UC and a combination of the two (EE-UC). It has been suggested that a high voltage is necessary for semen collection, but 10 V stimulation was effective enough and 15 V is for additional sperm collection. Also, liquid semen was collected by EE-UC and this could increase the total number of sperm. Further, to improve the post thawing sperm motility, semen was kept at four temperatures (4, 15, 25 and 37°C) for 60 min, and processed with two cooling procedures (slow cooling before second dilution and fast cooling after second dilution). Holding semen at 25°C and fast cooling after the second dilution maintained progressive motile sperm rate. The present results will contribute to the improvement of semen collection and animal welfare of Japanese macaques. - Habitat occupancy of sloth bear Melursus ursinus in Chitwan National Park, Nepal
Rajan Prasad Paudel, Rabin Kadariya, Babu Ram Lamichhane, Naresh Subedi, Mariko Sashika, Michito Shimozuru, Toshio Tsubota
ECOLOGY AND EVOLUTION, 12, 3, WILEY, 2022年03月, ［査読有り］
英語, 研究論文（学術雑誌）, Mammals have experienced a massive decline in their populations and geographic ranges worldwide. The sloth bear, Melursus ursinus (Shaw, 1791), is one of many species facing conservation threats. Despite being endangered in Nepal, decades of inattention to the situation have hindered their conservation and management. We assessed the distribution and patterns of habitat use by sloth bears in Chitwan National Park (CNP), Nepal. We conducted sign surveys from March to June, 2020, in 4 x 4 km grids (n = 45). We collected detection/non-detection data along a 4-km trail that was divided into 20 continuous segments of 200 m each. We obtained environmental, ecological, and anthropogenic covariates to understand determinants of sloth bear habitat occupancy. The data were analyzed using the single-species single-season occupancy method, with a spatially correlated detection. Using repeated observations, these models accounted for the imperfect detectability of the species to provide robust estimates of habitat occupancy. The model-averaged occupancy estimate for the sloth bear was 69% and the detection probability was 0.25. The probability of habitat occupancy by sloth bears increased with the presence of termites and fruits and in rugged, dry, open, undisturbed habitats. Our results indicate that the sloth bear is elusive, functionally unique, and widespread in CNP. Future conservation interventions and action plans aimed at sloth bear management must adequately consider their habitat requirements. - Ovulatory follicle size investigated by ultrasonography and single artificial insemination with ovulation induction in the Japanese macaque (Macaca fuscata)
Takaesu, Noboru, Minami, Masako, Nagano, Masashi, Kaneko, Akihisa, Indo, Yoriko, Imai, Hiroo, Hirai, Hirohisa, Sashika, Mariko, Shimozuru, Michito, Okamoto, Munehiro, Katagiri, Seiji, Tsubota, Toshio, Yanagawa, Yojiro
70, 1, 5, 17, 2022年02月, ［査読有り］
研究論文（学術雑誌） - Diel and monthly activity pattern of brown bears and sika deer in the Shiretoko Peninsula, Hokkaido, Japan
Kei KAWAMURA, Mina JIMBO, Keisuke ADACHI, Yuri SHIRANE, Masanao NAKANISHI, Yoshihiro UMEMURA, Tsuyoshi ISHINAZAKA, Hiroyuki UNO, Mariko SASHIKA, Toshio TSUBOTA, Michito SHIMOZURU
Journal of Veterinary Medical Science, 84, 8, 1146, 1156, Japanese Society of Veterinary Science, 2022年, ［査読有り］, ［最終著者, 責任著者］
研究論文（学術雑誌） - Supplementing cultured human myotubes with hibernating bear serum results in increased protein content by modulating Akt/FOXO3a signaling.
Mitsunori Miyazaki, Michito Shimozuru, Toshio Tsubota
PloS one, 17, 1, e0263085, 2022年, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Hibernating bears remain in their dens for 5-7 months during winter and survive without eating or drinking while staying inactive. However, they maintain their physical functions with minimal skeletal muscle atrophy and metabolic dysfunction. In bears, resistance to skeletal muscle atrophy during hibernation is likely mediated by seasonally altered systemic factors that are independent of neuromuscular activity. To determine whether there are components in bear serum that regulate protein and energy metabolism, differentiated human skeletal muscle cells were treated with bear serum (5% in DMEM/Ham's F-12, 24 h) collected during active summer (July) and hibernating winter (February) periods. The serum samples were collected from the same individual bears (Ursus thibetanus japonicus, n = 7 in each season). Total protein content in cultured skeletal muscle cells was significantly increased following a 24 h treatment with hibernating bear serum. Although the protein synthesis rate was not altered, the expression of MuRF1 protein, a muscle-specific E3 ubiquitin ligase was significantly decreased along with a concomitant activation of Akt/FOXO3a signaling. Increased levels of insulin-like growth factor-1 (IGF-1) were also observed in hibernating bear serum. These observations suggest that protein metabolism in cultured human myotubes may be altered when incubated with hibernating bear serum, with a significant increase in serum IGF-1 and diminished MuRF1 expression, a potential target of Akt/FOXO3a signaling. A protein sparing phenotype in cultured muscle cells by treatment with hibernating bear serum holds potential for the development of methods to prevent human muscle atrophy and related disorders. - Dining from the coast to the summit: Salmon and pine nuts determine the summer body condition of female brown bears on the Shiretoko Peninsula.
Yuri Shirane, Mina Jimbo, Masami Yamanaka, Masanao Nakanishi, Fumihiko Mori, Tsuyoshi Ishinazaka, Mariko Sashika, Toshio Tsubota, Michito Shimozuru
Ecology and evolution, 11, 10, 5204, 5219, 2021年05月, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Body condition in mammals fluctuates depending on energy intake and expenditure. For brown bears (Ursus arctos), high-protein foods facilitate efficient mass gain, while lipids and carbohydrates play important roles in adjusting dietary protein content to optimal levels to maximize energy intake. On the Shiretoko Peninsula, Hokkaido, Japan, brown bears have seasonal access to high-lipid pine nuts and high-protein salmon. To assess seasonal and annual fluctuation in the body condition of adult female brown bears in relation to diet and reproductive status, we conducted a longitudinal study in a special wildlife protection area on the Shiretoko Peninsula during 2012-2018. First, analyses of 2,079 bear scats revealed that pine nuts accounted for 39.8% of energy intake in August and salmon accounted for 46.1% in September and that their consumption by bears varied annually. Second, we calculated the ratio of torso height to torso length as an index of body condition from 1,226 photographs of 12 adult females. Results indicated that body condition continued to decline until late August and started to increase in September when salmon consumption increased. In addition, body condition began to recover earlier in years when consumption of both pine nuts and salmon was high. Furthermore, females with offspring had poorer body condition than solitary females, in particular in late August in years with low salmon consumption. Our findings suggest that coastal and subalpine foods, which are unique to the Shiretoko Peninsula, determine the summer body condition of female brown bears, as well as their survival and reproductive success. - SPECIFIC MOLECULAR DETECTION OF PIROPLASMS AND CHARACTERIZATION OF β-TUBULIN FOR A NOVEL BABESIA SPECIES IN SIKA DEER (CERVUS NIPPON YESOENSIS)
Mohamed Abdallah Mohamed Moustafa, Jason L. Anders, Wessam Mohamed Ahmed Mohamed, Kyunglee Lee, Elzahara Elbaz, Mariko Sashika, Ryo Nakao, Michito Shimozuru, Toshio Tsubota
Journal of Zoo and Wildlife Medicine, 52, 1, American Association of Zoo Veterinarians, 2021年04月01日, ［査読有り］
研究論文（学術雑誌） - Changes in liver microRNA expression and their possible regulatory role in energy metabolism-related genes in hibernating black bears
Kazuhei Nishida, Michito Shimozuru, Yuko Okamatsu-Ogura, Mitsunori Miyazaki, Tsukasa Soma, Mariko Sashika, Toshio Tsubota
JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMS AND ENVIRONMENTAL PHYSIOLOGY, 191, 2, 397, 409, SPRINGER HEIDELBERG, 2021年03月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, Hibernating bears survive up to 6 months without feeding while yet maintaining metabolic homeostasis. We previously reported expression changes in energy metabolism-related genes in the liver of hibernating Japanese black bears. The present study examined the role of microRNAs in the regulation of hepatic gene expression during hibernation. The quantitative analyses revealed significant increases in the expression of 4 microRNAs (miR-221-3p, miR-222-3p, miR-455-3p, and miR-195a-5p) and decreases of 2 microRNAs (miR-122-5p and miR-7a-1-5p) during hibernation. RNA sequencing and in silico target prediction regarding 3 upregulated microRNAs (miR-221-3p, miR-222-3p and miR-455-3p) found 13 target mRNAs with significantly decreased expression during hibernation. The transfection of microRNA mimics into cells showed that miR-222 and miR-455 reduced solute carrier family 16 member 4 (SLC16A4) and fatty acid synthase (FASN) mRNA expression, respectively. Our results suggest that the increased levels of hepatic miRNA during hibernation (miR-222-3p and miR-455-3p) negatively regulate the expression of targeted genes predicted to be involved in the transport of energy source and de novo fatty acid synthesis, is consistent with a regulatory role of these miRNAs in energy metabolism in hibernating black bears. - Amblyomma testudinarium infestation on a brown bear (Ursus arctos yesoensis) captured in Hokkaido, a northern island of Japan.
Ryo Nakao, Kohei Shinjo, Tomoki Sakiyama, Shohei Ogata, Kodai Kusakisako, Gohta Kinoshita, Doaa Naguib, Elisha Chatanga, Wessam Mohamed Ahmed Mohamed, Mohamed Abdallah Mohamed Moustafa, Keita Matsuno, Takuya Ito, Nariaki Nonaka, Mariko Sashika, Toshio Tsubota, Michito Shimozuru
Parasitology international, 80, 102209, 102209, 2021年02月, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, The tick Amblyomma testudinarium Koch, 1844 (Acari: Ixodidae) is known as a vector of several pathogens such as Rickettsia tamurae and severe fever with thrombocytopenia syndrome (SFTS) virus. This tick species is present in many Asian countries, including Japan, where its distribution is limited to the warm areas of Kanto region and the southwestern region. The present study reports the recovery of a partially engorged A. testudinarium from a wild brown bear captured in Shari town, Hokkaido. In addition to morphological identification, the specimen was genetically characterized by the complete mitochondrial genome sequencing. The results showed that the length of the obtained mitogenome is 14,835 bp that encodes 13 protein-coding, two ribosomal RNA (rRNA) (12S and 16S), and 22 transfer RNA genes with two non-coding control regions. The phylogenetic analysis indicated that our sample clustered with A. testudinarium from Nara, Japan, but separated from A. testudinarium from China. Although the introduction of the tick through livestock transportation cannot be ruled out, the detection of A. testudinarium in Hokkaido prefecture, which is separated from the main island where A. testudinarium is present in the south, may suggest the introduction by migratory birds. This study provides important insights on the distribution and host range of A. testudinarium. This will be useful for the future taxonomic analysis of ticks based on the complete mitogenome sequencing. To our knowledge, this is the northernmost detection point of the tropical tick A. testudinarium. - Predation impacts of invasive raccoons on rare native species.
Sakura Oe, Mariko Sashika, Ayako Fujimoto, Michito Shimozuru, Toshio Tsubota
Scientific reports, 10, 1, 20860, 20860, 2020年11月30日, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, In Japan, there are concerns that invasive alien raccoons prey on rare native species during their spawning season from late winter to early summer. We investigated raccoon predation impact by examining the predation presence using DNA metabarcoding and extent of predation on rare native species using stable isotope analysis. We captured raccoons in Hokkaido, Japan from April to August in 2018 and 2019. We analysed raccoon faeces and gastric contents by DNA metabarcoding to detect the rare native Hokkaido salamander and Japanese crayfish. Hokkaido salamanders were detected from gastric contents, but Japanese crayfish were not detected in any samples. Stable isotope analysis of raccoon muscle samples and the Bayesian mixing model were used to estimate each food resource's contribution to the raccoon diet. Animal food resources accounted for 70% of total consumed food. The foraging ratios of amphibians and crustaceans were about 9% and 5%, respectively. Raccoons have been found to use amphibians at a higher rate than previously reported, including a rare endangered species, the Hokkaido salamander. Hokkaido salamander and Japanese crayfish spawn in the spring, and increased predation pressure by raccoons may directly impact populations of these rare native species. - Molecular detection of apicomplexan protozoa in Hokkaido brown bears (Ursus arctos yesoensis) and Japanese black bears (Ursus thibetanus japonicus).
Mohamed Abdallah Mohamed Moustafa, Ayaka Sasaki, Michito Shimozuru, Ryo Nakao, Mariko Sashika, Koji Yamazaki, Shinsuke Koike, Junpei Tanaka, Hiroo Tamatani, Masami Yamanaka, Tsuyoshi Ishinazaka, Toshio Tsubota
Parasitology research, 119, 11, 3739, 3753, 2020年11月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Many tick-borne pathogens (TBPs) are present in wildlife. The objective of this study is to reveal the role of wild bears in maintaining TBPs. A total of 49 brown bears (Ursus arctos yesoensis) from Hokkaido, and 18 Japanese black bears (Ursus thibetanus japonicus) from Tochigi, and 66 Japanese black bears from Nagano were examined by two molecular methods, reverse line blot (RLB) hybridization, and nested PCR. A total of 5 TBPs (Hepatozoon ursi, Babesia sp. UR2-like group, Cytauxzoon sp. UR1, Babesia sp. UR1, and Babesia microti) were detected from bear blood DNA samples. B. microti was detected from blood DNA samples of Japanese black bear for the first time, with the prevalence of 6.0% (5/84). Out of detected pathogens, H. ursi, Babesia sp. UR2-like pathogens, and Cytauxzoon sp. UR1 were considered as three of the most prevalent TBPs in bears. The prevalence of H. ursi were significantly higher in Japanese black bear (0% vs 96.4%) while that of Babesia sp. UR2-like group was higher in Hokkaido brown bears (89.8% vs 40.5%). The prevalence of Babesia sp. UR1 were significantly higher in Japanese black bears from Tochigi (44.4%), comparing with those from Nagano (18.2%). The prevalence of the detected TBPs were significantly higher in adult bears, comparing with those in younger bears. The present study suggests that Japanese bear species contribute in the transmission of several TBPs in Japan. The expanding distribution of bears might cause the accidental transmission of TBPs to humans and domestic animals. - Utilizing attached hard ticks as pointers to the risk of infection by Babesia and Theileria species in sika deer (Cervus nippon yesoensis), in Japan.
Elzahara Elbaz, Mohamed Abdallah Mohamed Moustafa, Kyunglee Lee, Alice Lau Ching Ching, Michito Shimozuru, Mariko Sashika, Ryo Nakao, Sabry Ahmed El-Khodery, Toshio Tsubota
Experimental & applied acarology, 82, 3, 411, 429, 2020年11月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Ticks are hematophagous ectoparasites that have a significant impact on their animal hosts. Along with mosquitoes, they are the main arthropod vectors of disease agents in domestic animals, wildlife and humans. To investigate the occurrence and prevalence of piroplasmids in ticks, DNA was extracted from 519 hard ticks collected from 116 hunted Hokkaido sika deer (Cervus nippon yesoensis). The success of the DNA extraction was confirmed by touchdown PCR targeting the mitochondrial 16S rDNA gene of ticks. Touchdown PCR and reverse line blot (RLB) hybridization targeting the 18S rRNA gene were used to detect 14 piroplasm species. All hard ticks parasitizing Hokkaido sika deer were identified as belonging to the genera Ixodes and Haemaphysalis. In total 163 samples (31.4%) were positive for Babesia and Theileria spp. among tick species according to RLB hybridization. Tick DNA hybridized to the oligonucleotide probes of Theileria sp. Thrivae (27.0% of ticks; 140/519), Theileria capreoli (10.6%; 55/519), Babesia divergens-like (1.7%; 9/519), Babesia sp. (Bab-SD) (0.6%; 3/519), Babesia microti U.S. (0.4%; 2/519), and B. microti Hobetsu (0.4%; 2/519). The partial sequencing and phylogenetic analyses of the 18S rRNA gene confirmed the RLB hybridization results. Further investigations are needed to reveal the epidemiology and respective vectors of these pathogens. - Detection of Borreliaburgdorferi Sensu Lato and Relapsing Fever Borrelia in Feeding Ixodes Ticks and Rodents in Sarawak, Malaysia: New Geographical Records of Borrelia yangtzensis and Borrelia miyamotoi.
Alice C C Lau, Yongjin Qiu, Mohamed Abdallah Mohamed Moustafa, Ryo Nakao, Michito Shimozuru, Manabu Onuma, Jayasilan Mohd-Azlan, Toshio Tsubota
Pathogens (Basel, Switzerland), 9, 10, 2020年10月15日, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Members of the Borrelia burgdorferi sensu lato (Bbsl) complex are etiological agents of Lyme disease (LD), and Borrelia miyamotoi is one of the relapsing fever Borrelia (RFB). Despite the serological evidence of LD in Malaysia, there has been no report from Sarawak, Malaysian Borneo. Thus, this study aimed to detect and characterize Borrelia in rodents and Ixodes ticks from primary forests and an oil palm (OP) plantation in Sarawak. Borrelia yangtzensis (a member of the Bbsl complex) was detected in 43.8% (14/32) of Ixodes granulatus; most of the positive ticks were from the OP plantation (13/14). Out of 56 rodents, B. yangtzensis was detected in four Rattus spp. from the OP plantation and B. miyamotoi was detected in one rodent, Sundamys muelleri, from the primary forest. Further, the positive samples of B. yangtzensis were randomly selected for multilocus sequence analysis (MLSA). The MLSA results of successfully amplified tick samples revealed a clustering with the sequences isolated from Japan and China. This study is the first evidence of B. miyamotoi, a known human pathogen in Malaysia, and B. yangtzensis, which is circulating in ticks and rodents in Sarawak, Malaysian Borneo, and presenting a new geographical record of the Borrelia spp. - Maternal human habituation enhances sons' risk of human-caused mortality in a large carnivore, brown bears.
Michito Shimozuru, Yuri Shirane, Masami Yamanaka, Masanao Nakanishi, Tsuyoshi Ishinazaka, Shinsuke Kasai, Takane Nose, Masataka Shirayanagi, Mina Jimbo, Hifumi Tsuruga, Tsutomu Mano, Toshio Tsubota
Scientific reports, 10, 1, 16498, 16498, 2020年10月05日, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Human habituation of large carnivores is becoming a serious problem that generates human-wildlife conflict, which often results in the removal of animals as nuisances. Although never tested, human habituation potentially reduces the fitness of adult females by reducing their offspring's survival as well as their own, due to an increased likelihood of human-caused mortality. Here, we tested this hypothesis in brown bears inhabiting Shiretoko National Park, Japan. We estimated the frequency of human-caused mortality of independent young (aged 1-4 years) born to mothers living in areas with different maternal levels of human habituation and different proximities to areas of human activity. The overall mortality rate was higher in males than in females, and in females living near a town than those in a remote area of park. Surprisingly, more than 70% of males born to highly habituated mothers living around a remote wildlife protection area were killed by humans; this proportion is greater than that for males born to less-habituated mothers living in almost the same area. The current study clarified that interactions among maternal human habituation, birthplace (proximity to town), age, and sex determine the likelihood of human-caused mortality of brown bears at an early stage of life. - Hair growth in brown bears and its application to ecological studies on wild bears
Mina Jimbo, Naoya Matsumoto, Hideyuki Sakamoto, Yojiro Yanagawa, Yoshiko Torii, Masami Yamanaka, Tsuyoshi Ishinazaka, Yuri Shirane, Mariko Sashika, Toshio Tsubota, Michito Shimozuru
MAMMAL STUDY, 45, 4, 337, 345, MAMMALOGICAL SOC JAPAN, 2020年10月, ［査読有り］, ［責任著者］
英語, 研究論文（学術雑誌）, Hair biomarkers have been widely used to study wildlife physiology and ecology. To apply this technique to practical studies, detailed information on hair growth is needed for each study species. This study measured hair growth patterns, including growth rate, periods of growth and shedding, and hair bulb structural changes in the brown bear. Hair growth was examined monthly in captive bears, and gross observations of fur were performed in wild bears. Guard hairs grew from late April to early October at an approximate rate of 0.5 mm/day for captive bears, and from late May to late September at an approximate rate of 0.7 mm/day for wild bears. Underfur began growing in August and continued into winter. The growth periods for intermediate hairs began at different times and lasted 3-5 months, depending on individuals. Most shedding was complete by August, and all shedding was complete by the end of September. Hair bulbs were classified into three types: white spheres (WS-type), black hooks (BH-type), and white hooks (WH-type). This classification can be used to discriminate between previous year's hair (WS-type) and current year's hair (BH-type or WH-type). The current findings will enhance the understanding of brown bear ecology in the wild. - Genetic population structure of invasive raccoons (Procyon lotor) in Hokkaido, Japan: Unique phenomenon caused by pet escape or abandonment.
Minami W Okuyama, Michito Shimozuru, Mariko Nakai, Emi Yamaguchi, Kei Fujii, Ken-Ichiro Shimada, Tohru Ikeda, Toshio Tsubota
Scientific reports, 10, 1, 8108, 8108, 2020年05月15日, ［査読有り］, ［筆頭著者］, ［国際誌］
英語, Phylogeographic studies can resolve relationships between genetic population structure of organisms and geographical distributions. Raccoons have become feral in Japan, and in Hokkaido island, they have been rapidly increasing in number and spreading since the 1970s. We analyzed mitochondrial (mtDNA) and microsatellite DNA to understand the current phylogenetic distribution and invasive founder events. Overall, Hokkaido raccoons maintained high genetic diversity (i.e., the level of heterozygosity was comparable to the original habitat, North America). Based on mtDNA distribution and microsatellite diversity, Hokkaido raccoons were divided into six management units. However, mtDNA haplotype distributions and genetic structures based on microsatellites did not always correspond to each other (e.g., two geographically and genetically separated populations showed similar mtDNA distributions). In addition, a high degree of genetic admixture was observed in every unit, and the degree of genetic differentiation was low even between regions separated by long distances. Compared with other countries in Europe where genetic distribution of introduced raccoons is more clearly structured, the current results represent a unique and complex phenomenon of pet escape/abandonment in Hokkaido: i.e., genetically related colonies were introduced into multiple regions as founder events, resulting in the current state in which raccoons are not clearly genetically differentiated even 40 years after introduction. - Hibernating bear serum hinders osteoclastogenesis in-vitro.
Alireza Nasoori, Yuko Okamatsu-Ogura, Michito Shimozuru, Mariko Sashika, Toshio Tsubota
PloS one, 15, 8, e0238132, 2020年, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Bears do not suffer from osteoporosis during hibernation, which is associated with long-term inactivity, lack of food intake, and cold exposure. However, the mechanisms involved in bone loss prevention have scarcely been elucidated in bears. We investigated the effect of serum from hibernating Japanese black bears (Ursus thibetanus japonicus) on differentiation of peripheral blood mononuclear cells (PBMCs) to osteoclasts (OCs). PBMCs collected from 3 bears were separately cultured with 10% serum of 4 active and 4 hibernating bears (each individual serum type was assessed separately by a bear PBMCs), and differentiation were induced by treatment with macrophage colony stimulating factor (M-CSF) and receptor activator of NF-kB ligand (RANKL). PBMCs that were cultured with the active bear serum containing medium (ABSM) differentiated to multi-nucleated OCs, and were positive for TRAP stain. However, cells supplemented with hibernating bear serum containing medium (HBSM) failed to form OCs, and showed significantly lower TRAP stain (p < 0.001). On the other hand, HBSM induced proliferation of adipose derived mesenchymal stem cells (ADSCs) similarly to ABSM (p > 0.05), indicating no difference on cell growth. It was revealed that osteoclastogenesis of PBMCs is hindered by HBSM, implying an underlying mechanism for the suppressed bone resorption during hibernation in bears. In addition, this study for the first time showed the formation of bears' OCs in-vitro. - Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears.
Yuri Shirane, Fumihiko Mori, Masami Yamanaka, Masanao Nakanishi, Tsuyoshi Ishinazaka, Tsutomu Mano, Mina Jimbo, Mariko Sashika, Toshio Tsubota, Michito Shimozuru
PeerJ, 8, e9982, 2020年, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Body condition is an important determinant of health, and its evaluation has practical applications for the conservation and management of mammals. We developed a noninvasive method that uses photographs to assess the body condition of free-ranging brown bears (Ursus arctos) in the Shiretoko Peninsula, Hokkaido, Japan. First, we weighed and measured 476 bears captured during 1998-2017 and calculated their body condition index (BCI) based on residuals from the regression of body mass against body length. BCI showed seasonal changes and was lower in spring and summer than in autumn. The torso height:body length ratio was strongly correlated with BCI, which suggests that it can be used as an indicator of body condition. Second, we examined the precision of photograph-based measurements using an identifiable bear in the Rusha area, a special wildlife protection area on the peninsula. A total of 220 lateral photographs of this bear were taken September 24-26, 2017, and classified according to bear posture. The torso height:body/torso length ratio was calculated with four measurement methods and compared among bear postures in the photographs. The results showed torso height:horizontal torso length (TH:HTL) to be the indicator that could be applied to photographs of the most diverse postures, and its coefficient of variation for measurements was <5%. In addition, when analyzing photographs of this bear taken from June to October during 2016-2018, TH:HTL was significantly higher in autumn than in spring/summer, which indicates that this ratio reflects seasonal changes in body condition in wild bears. Third, we calculated BCI from actual measurements of seven females captured in the Rusha area and TH:HTL from photographs of the same individuals. We found a significant positive relationship between TH:HTL and BCI, which suggests that the body condition of brown bears can be estimated with high accuracy based on photographs. Our simple and accurate method is useful for monitoring bear body condition repeatedly over the years and contributes to further investigation of the relationships among body condition, food habits, and reproductive success. - Male reproductive input, breeding tenure, and turnover in high-density brown bear populations on the Shiretoko Peninsula, Hokkaido, Japan.
Michito Shimozuru, Yuri Shirane, Mina Jumbo, Masami Yamanaka, Masanao Nakanishi, Tsuyoshi Isinazaka, Shinsuke Kasai, Takane Nose, Yasushi Fujimoto, Hifumi Tsuruga, Tsutomu Mano, Toshio Tsubota
Canadian Journal of Zoology, 98, 3, 175, 185, Canadian Science Publishing, 2020年, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌）, Male reproductive behavior has not been thoroughly investigated in large, non-social mammals. We studied male reproductive input using field observations and microsatellite DNA data for the brown bear (Ursus arctos yesoensis Lydekker, 1897) population in a special wildlife protection area on the Shiretoko Peninsula in Hokkaido, Japan. We identified the father of 82 offspring born between 2006 and 2018 from 54 litters produced by 20 females and revealed that they were sired by a total of 19 males. Overall, paternity was distributed relatively evenly among different males, although litter production tended to be skewed to a few bears in some years. Male breeding tenure varied among individuals, but most tenures were within the range of 1 to 6 years. Human-caused mortality, mostly occurring near human residential areas, induced male turnover, indicating that the special wildlife protection area located in the inner part of the Shiretoko Peninsula is not free from human impact. The frequency of successful reproduction was highest in 10- to 14-year-old bears, which is consistent with the period when males reach physical maturity. These results contribute to an understanding of breeding systems in large solitary mammals and to appropriate conservation and management strategies for brown bear populations. - PMab-241 Specifically Detects Bear Podoplanin of Lymphatic Endothelial Cells in the Lung of Brown Bear.
Junko Takei, Shinji Yamada, Satoru Konnai, Tsuyoshi Ishinazaka, Michito Shimozuru, Mika K Kaneko, Yukinari Kato
Monoclonal antibodies in immunodiagnosis and immunotherapy, 38, 6, 282, 284, 2019年12月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Podoplanin (PDPN)/T1alpha is utilized as a specific marker of lymphatic endothelial cells or type I alveolar cells of lung. Therefore, sensitive and specific monoclonal antibodies (mAbs) detecting PDPN are necessary for immunohistochemical analyses, especially using formalin-fixed paraffin-embedded tissues. Recently, we developed an anti-bear PDPN (bPDPN) mAb, PMab-247, which is useful for immunohistochemical analyses to detect both lymphatic endothelial cells and type I alveolar cells of lung. However, it is difficult to distinguish lymphatic endothelial cells from type I alveolar cells in the bear lung. In this study, we showed that a novel anti-bPDPN mAb, PMab-241 stained only lymphatic endothelial cells, not type I alveolar cells of the lung in immunohistochemical analyses. These findings suggest that PMab-241 could be useful for staining lymphatic endothelial cells specifically in the bear lung tissues. - Comparison of feeding habits and habitat use between invasive raccoons and native raccoon dogs in Hokkaido, Japan.
Aya Osaki, Mariko Sashika, Go Abe, Kohei Shinjo, Ayako Fujimoto, Mariko Nakai, Michito Shimozuru, Toshio Tsubota
BMC ecology, 19, 1, 35, 35, 2019年09月11日, ［査読有り］, ［国際誌］
英語, BACKGROUND: In Japan, invasive raccoons cause severe ecological and social problems by transmitting pathogens to humans, livestock, and native species, causing substantial crop damage, and competing with native species. Possible competition between invasive raccoons and native raccoon dogs is of concern in Japan because Japanese raccoon dogs have a limited distribution and are native only to Japan and the two species have similar characteristics. We assessed potential competition between raccoons and raccoon dogs by comparing feeding habits and habitat use. RESULTS: Both species were captured in Hokkaido, Japan from 2004 to 2017. More raccoons were captured close to agricultural land at the forest periphery (70.1%, 358/511); conversely, more raccoon dogs were captured in the forest core (74.9%, 253/338). Feeding habits were then examined by fecal analysis and stable isotope analyses. Fecal analysis revealed both species to be opportunistic omnivores that consumed easily found food items. However, raccoon feces contained more crops, whereas raccoon dog feces contained more insects, reflecting the different locations in which the species were trapped. Moreover, stable isotope ratios were significantly higher in raccoons than raccoon dogs (Corn has the highest carbon stable isotope (δ13C) value, and amphibians and reptiles are high in nitrogen stable isotope (δ15N); forest resources such as insects and wild fruits are low in δ13C and δ15N). CONCLUSIONS: We conclude that both species ate similar food types, but their food preferences appeared to differ. Raccoon and raccoon dog habitat use also differed, possibly because the two species inhabited areas where they could easily obtain their preferred foods. Therefore, the current feeding habits and habitat use of raccoons do not appear to overlap sufficiently with those of raccoon dogs to impact the latter. The results of this study, particularly the stable isotope data, may provide a useful precedent for future studies of competition in medium-sized mammals, particularly canids. - Sex-biased dispersal and inbreeding avoidance in Hokkaido brown bears
Shirane, Yuri, Shimozuru, Michito, Yamanaka, Masami, Tsuruga, Hifumi, Nakanishi, Masanao, Ishinazaka, Tsuyoshi, Nose, Takane, Kasai, Shinsuke, Shirayanagi, Masataka, Masuda, Yasushi, Fujimoto, Yasushi, Mano, Tsutomu, Sashika, Mariko, Tsubota, Toshio
JOURNAL OF MAMMALOGY, 100, 4, 1317, 1326, OXFORD UNIV PRESS INC, 2019年07月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, Natal dispersal likely plays an important role in avoiding inbreeding among large carnivores. We tested the hypothesis that male-biased dispersal reduces close inbreeding by limiting the spatial overlap of opposite-sex pairs of close relatives in brown bears (Ursus arctos) in the Shiretoko Peninsula, Hokkaido, Japan. We genotyped 837 individuals collected in 1998-2017 at 21 microsatellite loci and performed parentage analysis. To calculate natal dispersal distance, we considered the site where the mother was identified as the birthplace of her offspring, and the site where the offspring were identified as their dispersed place. As predicted, we found that dispersal distances were significantly greater for males (12.4 km +/- 1.0) than for females (7.7 km +/- 0.9), and those for males increased from 3 years old, indicating that males begin to disperse around the time sexual maturation begins. Relatedness decreased with distance among pairs of females, and the mean relatedness was significantly higher between pairs of females than between pairs of males or between female-male pairs within 3 km. Closely related female-male pairs rarely (5-6%) resided in close proximity (< 3 km), compared with pairs of closely related females. Our study revealed that the potential for close inbreeding was low in Hokkaido brown bears because males are effective dispersers. - Incidence of Multiple Paternity and Inbreeding in High-Density Brown Bear Populations on the Shiretoko Peninsula, Hokkaido, Japan.
Shimozuru M, Shirane Y, Tsuruga H, Yamanaka M, Nakanishi M, Ishinazaka T, Kasai S, Nose T, Masuda Y, Fujimoto Y, Mano T, Tsubota T
The Journal of heredity, 110, 3, 321, 331, Oxford University Press (OUP), 2019年05月, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌） - Mixed Mycobacterium tuberculosis Lineage Infection in 2 Elephants, Nepal.
Paudel S, Nakajima C, Mikota SK, Gairhe KP, Maharjan B, Subedi S, Poudel A, Sashika M, Shimozuru M, Suzuki Y, Tsubota T
Emerging infectious diseases, 25, 5, 1031, 1032, CENTERS DISEASE CONTROL & PREVENTION, 2019年05月, ［査読有り］
英語, Tuberculosis in elephants is primarily caused by Mycobacterium tuberculosis. We identified mixed M. tuberculosis lineage infection in 2 captive elephants in Nepal by using spoligotyping and large sequence polymorphism. One elephant was infected with Indo-Oceanic and East African-Indian (CAS-Delhi) lineages; the other was infected with Indo-Oceanic and East Asian (Beijing) lineages. - Skeletal muscles of hibernating black bears show minimal atrophy and phenotype shifting despite prolonged physical inactivity and starvation.
Mitsunori Miyazaki, Michito Shimozuru, Toshio Tsubota
PloS one, 14, 4, e0215489, 2019年, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Hibernating mammals experience prolonged periods of torpor and starvation during winter for up to 5-7 months. Though physical inactivity and malnutrition generally lead to profound loss of muscle mass and metabolic dysfunction in humans, hibernating bears show limited muscle atrophy and can successfully maintain locomotive function. These physiological features in bears allow us to hypothesize that hibernating bears uniquely alter the regulation of protein and energy metabolism in skeletal muscle which then contributes to "muscle atrophy resistance" against continued physical inactivity. In this study, alteration of signaling pathways governing protein and energy metabolisms was examined in skeletal muscle of the Japanese black bear (Ursus thibetanus japonicus). Sartorius muscle samples were collected from bear legs during late November (pre-hibernation) and early April (post-hibernation). Protein degradation pathways, through a ubiquitin-proteasome system (as assessed by increased expression of murf1 mRNA) and an autophagy-dependent system (as assessed by increased expression of atg7, beclin1, and map1lc3 mRNAs), were significantly activated in skeletal muscle following hibernation. In contrast, as indicated by a significant increase in S6K1 phosphorylation, an activation state of mTOR (mammalian/mechanistic target of rapamycin), which functions as a central regulator of protein synthesis, increased in post-hibernation samples. Gene expression of myostatin, a negative regulator of skeletal muscle mass, was significantly decreased post-hibernation. We also confirmed that the phenotype shifted toward slow-oxidative muscle and mitochondrial biogenesis. These observations suggest that protein and energy metabolism may be altered in skeletal muscle of hibernating bears, which then may contribute to limited loss of muscle mass and efficient energy utilization. - High genetic diversity and distinct ancient lineage of Asiatic black bears revealed by non-invasive surveys in the Annapurna Conservation Area, Nepal
Kadariya, R, Shimozuru, M, Maldonado, J.E, Moustafa, M.A.M, Sashika, M, Tsubota, T
PloS one, in press, 12, e0207662, PUBLIC LIBRARY SCIENCE, 2018年12月, ［査読有り］, ［筆頭著者］
英語, 研究論文（学術雑誌）, Asiatic black bears (Ursus thibetanus) have a widespread distribution in mountain landscapes, and are considered vulnerable globally, but are low-priority species for conservation in Nepal. Habitat fragmentation, illegal hunting, and human-bear conflict are the major threats to Asiatic black bears across their global range. Having an adequate level of genetic variation in a population helps with adapting to rapidly changing environments, and thus is important for the long-term health of bear populations. Accordingly, we conducted non-invasive surveys of bear populations in the Annapurna Conservation Area (ACA) to elucidate genetic diversity, genetic structure, and the phylogenetic relationship of Asiatic black bears from this region of Nepal to other subspecies. To assess levels of genetic diversity and population genetic structure, we genotyped eight microsatellite loci using 147 samples, identifying 60 individuals in an area of approximately 525 km(2). We found that the Asiatic black bear population in the ACA has maintained high levels of genetic diversity (H-E = 0.76) as compared to other bear populations from range countries. We did not detect a signature of population substructure among sampling localities and this suggests that animals are moving freely across the landscape within the ACA. We also detected a moderate population size that may increase with the availability of suitable habitat in the ACA, so bear-related conflict should be addressed to ensure the long-term viability of this expanding bear populations. Primers specific to bears were designed to amplify a 675 bp fragment of the mitochondrial control region from the collected samples. Three haplotypes were observed from the entire conservation area. The complete mitochondrial genome (16,771 bp), the first obtained from wild populations of the Himalayan black bear (U. t. laniger), was also sequenced to resolve the phylogenetic relationships of closely related subspecies of Asiatic black bears. The resulting phylogeny indicated that Himalayan black bear populations in Nepal are evolutionary distinct from other known subspecies of Asiatic black bears. - Sex-biased natal dispersal in Hokkaido brown bears revealed through mitochondrial DNA analysis
Shirane Yuri, Shimozuru Michito, Yamanaka Masami, Tsuruga Hifumi, Hirano Saiko, Nagano Natsuo, Moriwaki Jun, Nakanishi Masanao, Ishinazaka Tsuyoshi, Nose Takane, Kasai Shinsuke, Shirayanagi Masataka, Masuda Yasushi, Fujimoto Yasushi, Osada Masahiro, Akaishi Masao, Mano Tsutomu, Masuda Ryuichi, Sashika Mariko, Tsubota Toshio
EUROPEAN JOURNAL OF WILDLIFE RESEARCH, 64, 6, Springer Science and Business Media LLC, 2018年12月, ［査読有り］, ［責任著者］
研究論文（学術雑誌） - Evaluation of body condition using body mass and chest girth in brown bears of Hokkaido, Japan (Ursus arctos yesoensis)
Jun Moriwaki, Ryosuke Omori, Michito Shimozuru, Hifumi Tsuruga, Tsutomu Mano, Toshio Tsubota
Japanese Journal of Veterinary Research, 66, 2, 71, 81, Hokkaido University, 2018年05月01日, ［査読有り］
英語, 研究論文（学術雑誌）, Chest girth and body mass of 3,576 brown bears (Ursus arctos yesoensis) harvested for conflict management in Hokkaido, Japan during 1991-2012 were used to establish methods to assess body condition and to compare the body condition of bears by sex, month, year, and reproductive status. The body mass was estimated based on the chest girth in cases with no measurements of the bear body mass. Using the measured and estimated body mass, a growth curve by age was demonstrated to ascertain the mean asymptotical body mass (245 kg for males, 114 kg for females) and ages at 95% asymptotic body mass (14.2 years for males, 7.1 years for females). The body condition value of bears was evaluated as body mass difference (kg) between the individual body mass and the standard body mass as estimated from the growth curve. Body condition value changed seasonally with a low in summer and the highest in the autumnal hyperphagic period. Female body condition value was higher than the males during September. Fluctuation in annual body condition value was found for females
however, there was no difference between solitary adult females and females with offspring (cubs, yearlings, or offspring of unknown age). No significant fluctuation was found for males. Our body condition evaluation method using chest girth and body mass of brown bears is useful to elucidate different trends across sex, year, and season. - Testosterone-related and seasonal changes in sebaceous glands in the back skin of adult male brown bears (Ursus arctos)
Jumpei Tomiyasu, Yojiro Yanagawa, Yoshikazu Sato, Michito Shimozuru, Masashi Nagano, Motoki Sasaki, Hideyuki Sakamoto, Naoya Matsumoto, Kohei Kobayashi, Mitsunori Kayano, Shingo Haneda, Motozumi Matsui
Canadian Journal of Zoology, 96, 3, 205, 211, Canadian Science Publishing, 2018年, ［査読有り］
英語, 研究論文（学術雑誌）, Adult male brown bears (Ursus arctos Linnaeus, 1758) display tree-marking behavior to chemically signal their dominance throughout the nondenning period, and this behavior peaks during the breeding season. Within the scent-marking sequence, back rub is a core marking posture. The present study investigated (i) seasonal changes in sebaceous glands in the back skin of brown bears and (ii) the relationship between those changes and testosterone levels. Back skin tissue samples and blood were collected from captive adult intact and castrated males during prebreeding, transitional, breeding, and postbreeding seasons, which were concurrent with back skin observations. In intact males, during the transitional and breeding seasons, an oily secretion from the back skin was observed along with enlarged sebaceous glands. The plasma testosterone concentrations during the transitional and breeding seasons were increased compared with the pre- and post-breeding seasons. Secretions and enlarged sebaceous glands were not found in castrated males, and the plasma testosterone concentrations remained at baseline levels. Oily secretions of the back skin glands that appear more abundant during the breeding season are rubbed against trees. Changes in size and volume of sebaceous glands, and thus their secreting capacity, are likely testosterone-regulated. - First molecular detection and characterization of Hepatozoon and Sarcocystis spp. in field mice and voles from Japan
Mohamed Abdallah Mohamed Moustafa, Michito Shimozuru, Wessam Mohamed, Kyle Rueben Taylor, Ryo Nakao, Mariko Sashika, Toshio Tsubota
PARASITOLOGY RESEARCH, 116, 8, 2321, 2325, SPRINGER, 2017年08月, ［査読有り］
英語, 研究論文（学術雑誌）, Sarcocystis and Hepatozoon species are protozoan parasites that are frequently detected in domestic and wild animals. Rodents are considered common intermediate and paratenic hosts for several Sarcocystis and Hepatozoon species. Here, blood DNA samples from a total of six rodents, including one Myodes rutilus, one Myodes rufocanus, and four Apodemus speciosus, collected from Hokkaido, Japan, were shown by conventional PCR of the 18S ribosomal RNA (rRNA) gene to contain Sarcocystis and Hepatozoon DNA. Sequencing of the DNA detected one Sarcocystis sp. in the M. rufocanus sample and two different Hepatozoon spp. in the M. rutilus and A. speciosus samples. Phylogenetic analysis showed that the detected Sarcocystis sp. sequence grouped with GenBank Sarcocystis sequences from rodents, snakes, and raccoons from Japan and China. The 18S rRNA partial gene sequences of both detected Hepatozoon spp. clustered with GenBank Hepatozoon sequences from snakes, geckos and voles in Europe, Africa, and Asia. This study provides evidence that wild rodents have a role in the maintenance of Sarcocystis and Hepatozoon species on the island of Hokkaido. - Reproductive parameters and cub survival of brown bears in the Rusha area of the Shiretoko Peninsula, Hokkaido, Japan
Michito Shimozuru, Masami Yamanaka, Masanao Nakanishi, Jun Moriwaki, Fumihiko Mori, Masakatsu Tsujino, Yuri Shirane, Tsuyoshi Ishinazaka, Shinsuke Kasai, Takane Nose, Yasushi Masuda, Toshio Tsubota
PLOS ONE, 12, 4, PUBLIC LIBRARY SCIENCE, 2017年04月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, servation and management of wildlife. In this study, we investigated the demographic parameters, including age of primiparity, litter size, inter-birth interval, reproductive rate, and cub survival rate, of Hokkaido brown bears (Ursus arctos yesoensis) in the Rusha area on the Shiretoko Peninsula, Hokkaido, Japan, based on a long-term, individual-based monitoring survey. A total of 15 philopatric females were observed nearly every year from 2006 to 2016, and these observations were used to estimate reproductive parameters. The mean age of primiparity was 5.3 +/- 0.2 (SE) years (n = 7, 95% CI = 5.0-5.6). We observed 81 cubs in 46 litters from 15 bears. Litter size ranged from one to three cubs, and averaged 1.76 +/- 0.08 (SE) cubs/litter (95% CI = 1.61-1.91). Inter-birth intervals ranged from 1 to 4 years, and the mean value was estimated as 2.43 (95% CI = 2.16-2.76) and 2.53 (95% CI = 2.26-2.85) years in all litters and in litters that survived at least their first year, respectively. The reproductive rate was estimated from 0.70 to 0.76 young born/year/reproductive adult female, depending on the method of calculation. The cub survival rate between 0.5 and 1.5 years ranged from 60 to 73%. Most cub disappearances occurred in July and August, suggesting that cub mortality is mainly due to poor nutrition in the summer. All reproductive parameters observed in the Rusha area on the Shiretoko Peninsula fell within the range reported in Europe and North America, and were among the lowest or shortest age of primiparity, litter size, and inter-birth intervals, and ranked at a high level for reproductive rate. - 知床半島先端部地区におけるヒグマ個体群の保護管理、および、羅臼町住民生活圏へ与える影響に関する研究
下鶴倫人, 山中正実
知床博物館研究報告特別号, 2, 95, 120, 2017年, ［査読有り］, ［招待有り］, ［筆頭著者, 責任著者］
日本語 - Molecular identification and characterization of piroplasm species in Hokkaido sika deer (Cervus nippon yesoensis), Japan
Elzahara Elbaz, Mohamed Abdallah Mohamed Moustafa, Kyunglee Lee, Wessam Ahmed Mohamed Mohamed, Ryo Nakao, Michito Shimozuru, Mariko Sashika, Emad Elsayed Ahmed Younis, Sabry Ahmed El-Khodery, Toshio Tsubota
TICKS AND TICK-BORNE DISEASES, 8, 5, 802, 807, ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2017年, ［査読有り］
英語, 研究論文（学術雑誌）, Babesia and Theileria species are tick-borne protozoan parasites that have a veterinary and zoonotic importance. In order to investigate the prevalence and genetic diversity of these parasites, a total of 269 sika deer blood DNA samples collected from Hokkaido, Japan, were examined for Babesia and Theileria species by touch-down PCR targeting the 18S rRNA gene. Reverse line blot (RLB) hybridization was then used to detect 12 piroplasm species. The results revealed that 95.5% (257/269), 94.1% (253/269), 14.1% (38/269), 87.7% (236/269) and 11.5% (31/269) of the examined PCR products hybridized with the probes which were designed to detect all Babesia and Theileria spp., all Theileria spp., all Babesia spp., Theileria sp. Thrivae and Babesia divergens-like, respectively. The 18S rRNA gene partial sequences were divided into Theileria sp. Thrivae, T. capreoli, B. divergens-like and an undescribed Babesia species. This study showed the first detection of the undescribed Babesia sp. from Japan. Therefore, more studies are required to understand the ecology of the newly detected tick-borne pathogens in Hokkaido. - Comparison of cortisol and thyroid hormones between tuberculosis-suspect and healthy elephants of Nepal
Sarad Paudel, Janine L. Brown, Sharada Thapaliya, Ishwari P. Dhakal, Susan K. Mikota, Kamal P. Gairhe, Michito Shimozuru, Toshio Tsubota
JOURNAL OF VETERINARY MEDICAL SCIENCE, 78, 11, 1713, 1716, JAPAN SOC VET SCI, 2016年11月, ［査読有り］
英語, 研究論文（学術雑誌）, We compared cortisol and thyroid hormone (T3 and T4) concentrations between tuberculosis (TB)-suspected (n=10) and healthy (n=10) elephants of Nepal. Whole blood was collected from captive elephants throughout Nepal, and TB testing was performed using the ElephantTB STAT-PAK (R) and DPP VetTB (R) serological assays that detect antibodies against Mycobacterium tuberculosis and M bovis in elephant serum. Cortisol, T3 and T4 were quantified by competitive enzyme immunoassays, and the results showed no significant differences in hormone concentrations between TB-suspect and healthy elephants. These preliminary data suggest neither adrenal nor thyroid function is altered by TB disease status. However, more elephants, including those positively diagnosed for TB by trunk wash cultures, need to be evaluated over time to confirm results. - Development and evaluation of an interferon-gamma release assay in Asian elephants (Elephas maximus)
Sarad Paudel, Marvin A. Villanueva, Susan K. Mikota, Chie Nakajima, Kamal P. Gairhe, Suraj Subedi, Nabin Rayamajhi, Mariko Sashika, Michito Shimozuru, Takashi Matsuba, Yasuhiko Suzuki, Toshio Tsubota
JOURNAL OF VETERINARY MEDICAL SCIENCE, 78, 7, 1117, 1121, JAPAN SOC VET SCI, 2016年07月, ［査読有り］
英語, 研究論文（学術雑誌）, We developed an interferon-gamma release assay (IGRA) specific for Asian elephants (Elephas maximus). Whole blood collected from forty captive Asian elephants was stimulated with three different mitogens i.e., phytohemagglutinin (PHA), pokweed mitogen (PWM) and phorbol myristate aceteate/ionomycin (PMA/I). A sandwich ELISA that was able to recognize the recombinant elephant interferon-gamma (rEIFN-gamma) as well as native interferon-gamma from the Asian elephants was performed using anti-elephant IFN-gamma rabbit polyclonal antibodies as capture antibodies and biotinylated anti-elephant IFN-gamma rabbit polyclonal antibodies as detection antibodies. PMA/I was the best mitogen to use as a positive control for an Asian elephant IGRA. The development of an Asian elephant-specific IGRA that detects native IFN-gamma in elephant whole blood provides promising results for its application as a potential diagnostic tool for diseases, such as tuberculosis (TB) in Asian elephants. - Seasonal changes in the expression of energy metabolism-related genes in white adipose tissue and skeletal muscle in female Japanese black bears
Michito Shimozuru, Akiko Nagashima, Jun Tanaka, Toshio Tsubota
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY, 196, 38, 47, ELSEVIER SCIENCE INC, 2016年06月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, Bears undergo annual cycles in body mass: rapid fattening in autumn (i.e., hyperphagia), and mass loss in winter (i.e., hibernation). To investigate how Japanese black bears (Ursus thibetanus japonicus) adapt to such extreme physiological conditions, we analyzed changes in the mRNA expression of energy metabolism-related genes in white adipose tissues and skeletal muscle throughout three physiological stages: normal activity (June), hyperphagia (November), and hibernation (March). During hyperphagia, quantitative real-time polymerase chain reaction analysis revealed the upregulation of de novo lipogenesis-related genes (e.g., fatty acid synthase and diacylglycerol O-acyltransferase 2) in white adipose tissue, although the bears had been maintained with a constant amount of food. In contrast, during the hibernation period, we observed a downregulation of genes involved in glycolysis (e.g., glucose transporter 4) and lipogenesis (e.g., acetyl-CoA carboxylase 1) and an upregulation of genes in fatty acid catabolism (e.g., carnitine palmitoyltransferase 1A) in both tissue types. In white adipose tissues, we observed upregulation of genes involved in glyceroneogenesis, including pyruvate carboxylase and phosphoenolpyruvate carboxykinase 1, suggesting that white adipose tissue plays a role in the recycling of circulating free fatty acids via re-esterification. In addition, the downregulation of genes involved in amino acid catabolism (e.g., alanine aminotransferase) and the TCA cycle (e.g., pyruvate carboxylase) indicated a role of skeletal muscle in muscle protein sparing and pyruvate recycling via the Cori cycle. These examples of coordinated transcriptional regulation would contribute to rapid mass gain during the pre-hibernation period and to energy preservation and efficient energy production during the hibernation period. (C) 2016 Elsevier Inc. All rights reserved. - Dynamics, co-infections and characteristics of zoonotic tick-borne pathogens in Hokkaido small mammals, Japan
Mohamed Abdallah Mohamed Moustafa, Kyle Taylor, Ryo Nakao, Michito Shimozuru, Mariko Sashika, Roberto Rosa, May June Thu, Annapaola Rizzoli, Toshio Tsubota
TICKS AND TICK-BORNE DISEASES, 7, 5, 922, 928, ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2016年, ［査読有り］
英語, 研究論文（学術雑誌）, Many of the emerging infectious diseases originate in wildlife and many of them are caused by vector borne pathogens. In Japan, zoonotic tick-borne pathogens (TBPs) are frequently detected in both ticks and wildlife. Here, we studied the infection rates of potentially zoonotic species, including Anaplasma, Ehrlichia, Neoehrlichia and Babesia spp., in Hokkaido's most abundant small mammals as they relate to variable extrinsic factors that might affect the infection rates of these pathogens. A total of 412 small mammals including 64 Apodemus argenteus, 219 Apodemus speciosus, 78 Myodes rufocanus, 41 Myodes rutilus, 6 Myodes rex and 4 Sorex unguiculatus were collected from Furano and Shari sites in Hokkaido, Japan, in 2010 and 2011 and were examined by multiplex PCR for TBPs. A reverse line blot hybridization (RLB) was then developed for the specific detection of 13 potentially zoonotic TBPs. A total of 4 TBPs were detected: Anaplasma sp. AP-sd, Ehrlichia muris, Candidatus Neoehrlichia mikurensis and Babesia microti. The infection rates were 4.4% (18/412), 1.2% (5/412), 13.1% (54/412) and 17.2% (71/412), respectively. The infection rates of each of the detected TBPs were significantly correlated with host small mammal species. A total of 22 (two triple and 20 double) co-infection cases were detected (5.3%). The most frequent co-infection cases occurred between Candidatus N. mikurensis and B. microti 68.2% (15/22). Further studies are required to examine human exposure to these zoonotic TBPs in Hokkaido. (C) 2016 Elsevier GmbH. All rights reserved. - Estimation of reproductive parameters and their annual variation in brown bears of Hokkaido, Japan
Jun Moriwaki, Michito Shimozuru, Hifumi Tsuruga, Tsutomu Mano, Toshio Tsubota
URSUS, 27, 2, 99, 109, INT ASSOC BEAR RESEARCH & MANAGEMENT-IBA, 2016年, ［査読有り］
英語, 研究論文（学術雑誌）, The reproductive tracts of 130 adult female brown bears (Ursus arctos) in Hokkaido, Japan, euthanized during 2010-2013 for conflict management, were examined for the presence and number of corpora lutea (CL) in the ovary and placental scars (PS) in the uterine horns. We scored PS on a 0-5 scale based on morphological features including their rim and color. They were characterized as representing either current-year parturition, as determined by accompanying cubs, or previous year parturition, as determined by accompanying yearlings. In total, 128 females were divided into 3 reproductive categories: 44 females with current-year parturition, 39 with previous-year parturition, and 45 solitary females that had not given birth for >2 years. The estimated ovulation rate was 2.21 +/- 0.55 (mean +/- SD), the implantation rate was 1.91 +/- 0.74, and the litter size was 1.54 +/- 0.51. Implantation rates were lower than ovulation rates and changed annually during 2010-2013. Systematic observation of PS and CL allowed us to evaluate the reproductive history and parameters in Hokkaido brown bears and ascertain their annual variation. - Molecular characterization and specific detection of Anaplasma species (AP-sd) in sika deer and its first detection in wild brown bears and rodents in Hokkaido, Japan
Mohamed Abdallah Mohamed Moustafa, Kyunglee Lee, Kyle Taylor, Ryo Nakao, Mariko Sashika, Michito Shimozuru, Toshio Tsubota
INFECTION GENETICS AND EVOLUTION, 36, 268, 274, ELSEVIER SCIENCE BV, 2015年12月, ［査読有り］
英語, 研究論文（学術雑誌）, A previously undescribed Anaplasma species (herein referred to as AP-sd) has been detected in sika deer, cattle and ticks in Japan. Despite being highly similar to some strains of A. phagocytophilum, AP-sd has never been detected in humans. Its ambiguous epidemiology and the lack of tools for its specific detection make it difficult to understand and interpret the prevalence of this Anaplasma species. We developed a method for specific detection, and examined AP-sd prevalence in Hokkaido wildlife. Our study included 250 sika deer (Cervus nippon yesoensis), 13 brown bears (Ursus arctos yesoensis) and 252 rodents including 138 (Apodemus speciosus), 45 (Apodemus argenteus), 42 (Myodes rufocanus) and 27 (Myodes rutilus) were collected from Hokkaido island, northern Japan, collected during 2010 to 2015. A 770 bp and 382 bp segment of the 16S rRNA and gltA genes, respectively, were amplified by nested PCR. Results were confirmed by cloning and sequencing of the positive PCR products. A reverse line blot hybridization (RLB) based on the 16S rRNA gene was then developed for the specific detection of AP-sd. The prevalence of AP-sd by nested PCR in sika deer was 51% (128/250). We detected this Anaplasma sp. for the first time in wild brown bears and rodents with a prevalence of 15% (2/13) and 2.4% (6/252), respectively. The sequencing results of the 16S rRNA and gltA gene amplicons were divergent from the selected A. phagocytophilum sequences in GenBank. Using a newly designed AP-sd specific probe for RLB has enabled us to specifically detect this Anaplasma species. Besides sika deer and cattle, wild brown bears and rodents were identified as potential reservoir hosts for AP-sd. This study provided a high throughput molecular method that specifically detects AP-sd, and which can be used to investigate its ecology and its potential as a threat to humans in Japan. (C) 2015 Elsevier B.V. All rights reserved. - Molecular characterization of Mycobacterium tuberculosis isolates from elephants of Nepal
Sarad Paudel, Susan K. Mikota, Chie Nakajima, Kamal P. Gairhe, Bhagwan Maharjan, Jeewan Thapa, Ajay Poudel, Michito Shimozuru, Yasuhiko Suzuki, Toshio Tsubota
TUBERCULOSIS, 94, 3, 287, 292, CHURCHILL LIVINGSTONE, 2014年05月, ［査読有り］
英語, 研究論文（学術雑誌）, Mycobacterium tuberculosis was cultured from the lung tissues of 3 captive elephants in Nepal that died with extensive lung lesions. Spoligotyping, TbD1 detection and multi-locus variable number of tandem repeat analysis (MLVA) results suggested 3 isolates belonged to a specific lineage of Indo-Oceanic clade, EAI5 SIT 138. One of the elephant isolates had a new synonymous single nucleotide polymorphism (SNP) T231C in the gyrA sequence, and the same SNP was also found in human isolates in Nepal. MLVA results and transfer history of the elephants suggested that 2 of them might be infected with M. tuberculosis from the same source. These findings indicated the source of M. tuberculosis infection of those elephants were local residents, presumably their handlers. Further investigation including detailed genotyping of elephant and human isolates is needed to clarify the infection route and eventually prevent the transmission of tuberculosis to susceptible hosts. (C) 2014 Elsevier Ltd. All rights reserved. - A Genetic Method for Sex Identification of Raccoons (Procyon lotor) with Using the ZFX and ZFY Genes
Minami W. Okuyama, Michito Shimozuru, Toshio Tsubota
JOURNAL OF VETERINARY MEDICAL SCIENCE, 76, 5, 773, 775, JAPAN SOC VET SCI, 2014年05月, ［査読有り］
英語, 研究論文（学術雑誌）, A genetic method for sex determination in raccoons was developed based on nucleotide differences of the zinc finger protein genes ZFX and ZFY. Four novel internal primers specific for ZFX or ZFY were designed. PCR amplification using two primer sets followed by agarose gel electrophoresis enabled sex determination. 141-bp and 447-bp bands were in both sex, and 346-bp band was specific only in male with primer set I. 345-bp and 447-bp bands were in both sex, and 141-bp band was specific only in male with primer set II, which could distinguish raccoon's electrophoresis pattern from three native carnivores in Hokkaido. This method will be useful for conservation genetics studies or biological analyses of raccoons. - Changes in the Immunolocalization of Steroidogenic Enzymes and the Androgen Receptor in Raccoon (Procyon lotor) Testes in Association with the Seasons and Spermatogenesis
Minami W. Okuyama, Michito Shimozuru, Yojiro Yanagawa, Toshio Tsubota
JOURNAL OF REPRODUCTION AND DEVELOPMENT, 60, 2, 155, 161, SOCIETY REPRODUCTION & DEVELOPMENT-SRD, 2014年04月, ［査読有り］
英語, 研究論文（学術雑誌）, The raccoon is a seasonal breeder with a mating season in the winter. In a previous study, adult male raccoons exhibited active spermatogenesis with high plasma testosterone concentrations, in the winter mating season. Maintenance of spermatogenesis generally requires high testosterone, which is produced by steroidogenic enzymes. However, even in the summer non-mating season, some males produce spermatozoa actively despite low plasma testosterone concentrations. To identify the factors that regulate testosterone production and contribute to differences in spermatogenetic activity in the summer non-mating season, morphological, histological and endocrinological changes in the testes of wild male raccoons should be known. In this study, to assess changes in the biosynthesis, metabolism and reactivity of testosterone, the localization and immunohistochemical staining intensity of four steroidogenic enzymes (P450scc, P450c17, 3 beta HSD, P450arom) and the androgen receptor (AR) were investigated using immunohistochemical methods. P450scc and P450c17 were detected in testicular tissue throughout the year. Seasonal changes in testosterone concentration were correlated with 3 beta HSD expression, suggesting that 3 beta HSD may be important in regulating the seasonality of testosterone production in raccoon testes. Immunostaining of P450arom and AR was detected in testicular tissues that exhibited active spermatogenesis in the summer, while staining was scarce in aspermatogenic testes. This suggests that spermatogenesis in the raccoon testis might be maintained by some mechanism that regulates P450arom expression in synthesizing estradiol and AR expression in controlling reactivity to testosterone. - An Enriched Rearing Environment Calms Adult Male Rat Sexual Activity: Implication for Distinct Serotonergic and Hormonal Responses to Females
Susumu Urakawa, Dai Mitsushima, Michito Shimozuru, Yasuo Sakuma, Yasuhiko Kondo
PLOS ONE, 9, 2, PUBLIC LIBRARY SCIENCE, 2014年02月, ［査読有り］
英語, 研究論文（学術雑誌）, Early life events induce alterations in neural function in adulthood. Although rearing in an enriched environment (EE) has a great impact on behavioral development, the effects of enriched rearing on sociosexual behavior remain unclear. In this study, we investigated the effects of rearing in an EE on male copulatory behavior and its underlying neurobiological mechanisms in Wistar-Imamichi rats. Three-week-old, recently weaned rats were continuously subjected to a standard environment (SE) or an EE comprised of a large cage with several objects, such as toys, tunnels, ladders, and a running wheel. After 6 weeks, rats reared in an EE (EE rats) showed decreased sexual activity compared with rats reared in a SE (SE rats). This included a lower number of ejaculations and longer latencies in three consecutive copulatory tests. In addition, EE rats showed decreased emotional responsiveness and less locomotor behavior in an open field. In a runway test, on the other hand, sexual motivation toward receptive females in EE males was comparable to that of SE males. Furthermore, following exposure to a female, increases in serotonin levels in the nucleus accumbens and the striatum were significantly suppressed in EE males, whereas dopaminergic responses were similar between the groups. Female-exposure-induced increases in the levels of plasma corticosterone and testosterone were also suppressed in EE rats compared to SE rats. These data suggest that rearing in an EE decreases male copulatory behavior, and serotonin and hormonal regulating systems may regulate the differences in sociosexual interactions that result from distinct rearing environments. - A relapsing fever group Borrelia sp similar to Borrelia lonestari found among wild sika deer (Cervus nippon yesoensis) and Haemaphysalis spp. ticks in Hokkaido, Japan
Kyunglee Lee, Ai Takano, Kyle Taylor, Mariko Sashika, Michito Shimozuru, Satoru Konnai, Hiroki Kawabata, Toshio Tsubota
TICKS AND TICK-BORNE DISEASES, 5, 6, 841, 847, ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2014年, ［査読有り］
英語, 研究論文（学術雑誌）, A relapsing fever Borrelia sp. similar to Borrelia lonestari (herein referred to as B. lonestari-like) was detected from wild sika deer (Cervus nippon yesoensis) and Haemaphysalis ticks in the eastern part of Hokkaido, Japan. The total prevalence of this Borrelia sp. in tested deer blood samples was 10.6% using conventional PCR and real-time PCR. The prevalence was significantly higher in deer fawns compared to adults (21.9% and 9.4%, respectively). Additionally, there was significant regional difference between our two sampling areas, Shiretoko and Shibetsu with 17% and 2.8% prevalence, respectively. Regional differences were also found in tick species collected from field and on deer. In the Shiretoko region, Haemaphysalis spp. were more abundant than Ixodes spp., while in Shibetsu, Ixodes spp. were more abundant. Using real-time PCR analysis, B. lonestari-like was detected from 2 out of 290 adult Haemaphysalis spp. ticks and 4 out of 76 pools of nymphs. This is the first report of a B. lonestari-like organism in Haemaphysalis spp. ticks, and the first phylogenetic analysis of this B. lonestari-like organism in Asia. Based on our results, Haemaphysalis spp. are the most likely candidates to act as a vector for B. lonestari-like; furthermore, regional variation of B. lonestari-like prevalence in sika deer may be dependent on the population distribution of these ticks. (C) 2014 Elsevier GmbH. All rights reserved. - Timing of Puberty and Its Relationship with Body Growth and Season in Male Raccoons (Procyon lotor) in Hokkaido
Minami W. Okuyama, Michito Shimozuru, Go Abe, Mariko Nakai, Mariko Sashika, Ken-Ichiro Shimada, Nobuhiro Takahashi, Daisuke Fukui, Ryohei Nakamura, Toshio Tsubota
JOURNAL OF REPRODUCTION AND DEVELOPMENT, 59, 4, 361, 367, SOCIETY REPRODUCTION & DEVELOPMENT-SRD, 2013年08月, ［査読有り］
英語, 研究論文（学術雑誌）, The raccoon (Procyon lotor), indigenous to North America, has naturalized in Japan as an invasive alien species, having been introduced into the country in the 1970s. In Hokkaido, the northernmost island of Japan, feral raccoons have been increasing in number and spreading throughout the island. The age at the onset of puberty for raccoons is important for estimating individual lifetime reproductive success and population growth. The present study investigated the timing of and potential factors affecting the onset of puberty in male raccoons in Hokkaido. External characteristics and histology of testes were studied in 151 male feral raccoons and in 1 captive juvenile. For the majority of feral yearling raccoons, prepubertal development began in May, and spermatozoa production began in October prior to their second mating season. However, some larger juveniles attained puberty during the juvenile period. The captive juvenile, which was fed throughout the winter, attained puberty only 11 months after birth. These results suggest that if male raccoons can achieve enough body growth before the first mating season, puberty can be attained early. In both juveniles and yearlings, spermatozoa production was only observed after autumn. This timing coincided with the recrudescence of seasonally active spermatogenesis in adult males. Therefore, attaining puberty in male raccoons appears to require both adequate body nutrient development and several environmental factors that control seasonal testicular changes. - Pregnancy during hibernation in Japanese black bears: effects on body temperature and blood biochemical profiles
Michito Shimozuru, Ruriko Iibuchi, Takuro Yoshimoto, Akiko Nagashima, Jun Tanaka, Toshio Tsubota
JOURNAL OF MAMMALOGY, 94, 3, 618, 627, ALLIANCE COMMUNICATIONS GROUP DIVISION ALLEN PRESS, 2013年06月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, Bears from the family Ursidae are the only terrestrial mammals that go through gestation, parturition, and lactation during hibernation. This is the 1st study to examine the influence of reproductive status (i.e., nonpregnant, pseudopregnant, or pregnant) on body temperature and blood biochemical profiles in hibernating black bears. Pregnant bears appeared to have higher and more stable body temperatures (37-38 degrees C) than nonpregnant ones (34-36 degrees C) during pregnancy, which was followed by a rapid drop to levels comparable to those of nonpregnant individuals after parturition. In midpregnancy (i.e., January), pregnant bears had higher blood glucose and lower triglyceride concentrations than did nonpregnant ones, whereas blood concentrations of free fatty acids, glycerol, and ketone bodies did not differ significantly. Plasma urea, creatinine, and urea/creatinine levels were significantly lower in pregnant bears than in nonpregnant ones. Pseudopregnant bears showed similar changes in body temperature and blood profiles to pregnant ones, but blood glucose levels in January were significantly lower than those in pregnant bears. These results suggest that pregnant bears maintain homeothermic conditions and supply nutrients to the fetus by stimulating thermogenesis, gluconeogenesis, and urea recycling during hibernation. In addition, these physiological changes appear to be mainly caused by corpus luteum-derived factors (e.g., progesterone) but also were facilitated by placental factors. - Differential Tick Burdens May Explain Differential Borrelia afzelii and Borrelia garinii Infection Rates among Four, Wild, Rodent Species in Hokkaido, Japan
Kyle R. Taylor, Ai Takano, Satoru Konnai, Michito Shimozuru, Hiroki Kawabata, Toshio Tsubota
JOURNAL OF VETERINARY MEDICAL SCIENCE, 75, 6, 785, 790, JAPAN SOC VET SCI, 2013年06月, ［査読有り］
英語, 研究論文（学術雑誌）, The ecologies of Lyme disease Borrelia spp. are very specific to location, as they are dependent upon the spirochete species and genotypes, the vectors and the host vertebrates present. In Hokkaido, Japan, where two human pathogenic, Lyme disease Borrelia spp. are present, and human cases are reported annually, the ecologies have been poorly studied. Our goal was to determine whether variation in borrelial infection rates among rodent species sharing an environment, is due to immunological or ecological differences. To this end, we examined the relationships between tick burden and borrelial infection, by including examination of agreement between nested PCR, as a test for infection, and serology, as a test for exposure. We collected 868 rodents, comprised of four species commonly found in Hokkaido, and tested for infection rates with Borrelia spp. using PCR for the borrelial flaB gene, seroprevalence of Borrelia afzelii and Borrelia garinii using ELISA, and attachment of ticks by direct counts. We noted a correlation between differential nymph and larval burdens and the borrelial infection rates found among the four rodent species. Furthermore, there was significant correlation between infection and seroprevalence of B. afzelii and B. garinii (P<0.01), between infection and Ixodes persulcatus nymph burden (P<0.01), and between seroprevalence and I. persulcatus nymph burden (P<0.01). The close agreement among rodent species seroprevalences with infection rates and tick burdens suggest the differences in infection rates of Borrelia spp. may largely be a direct consequence of differential exposure to vectors. - Borrelia miyamotoi Infections among Wild Rodents Show Age and Month Independence and Correlation with Ixodes persulcatus Larval Attachment in Hokkaido, Japan
Kyle R. Taylor, Ai Takano, Satoru Konnai, Michito Shimozuru, Hiroki Kawabata, Toshio Tsubota
VECTOR-BORNE AND ZOONOTIC DISEASES, 13, 2, 92, 97, MARY ANN LIEBERT INC, 2013年02月, ［査読有り］
英語, 研究論文（学術雑誌）, To clarify how Borrelia miyamotoi is maintained in the environment in Hokkaido, we examined Ixodes persulcatus for its prevalence among wild rodents and its tick vector by detecting a portion of the borrelial flaB gene in rodent urinary bladder and blood samples, and from whole ticks. We compared B. miyamotoi infection rates to Borrelia garinii and Borrelia afzelii, which are human Lyme disease pathogens also carried by wild rodents, and which are transmitted by the same vector tick. Whereas B. garinii and B. afzelii showed age dependence of infection rates among wild rodents (18.4% and 9.9% among adults and 6.0% and 3.4% among sub-adults, respectively) when looking at urinary bladder samples, B. miyamotoi infection rates were not age dependent for either blood (4.2% among adults, and 7.9% among sub-adults) or urinary bladder samples (1.0% among adults, and 1.7% among sub-adults). Moreover, while B. garinii and B. afzelii infection rates showed increases across months (June, July [p < 0.05] and August [p < 0.01] had higher rates than in May for adult rodents with B. garinii, and July and August had higher rates than in May [p < 0.01] for adult rodents with B. afzelii), B. miyamotoi infection rates did not show significant month dependence. These differences in month and age dependence led us to suspect that B. miyamotoi may not develop persistent infections in wild rodents, as B. garinii and B. afzelii are thought to. Furthermore, we examined the extent of rodent exposure to I. persulcatus nymphs and larvae throughout most of the tick's active season (May through September), and determined that B. miyamotoi infection rates in sub-adult rodents were correlated with larval burden (p < 0.01), suggesting that larvae may be very important in transmission of B. miyamotoi to wild rodents. - Parasitology of five primates in Mahale Mountains National Park, Tanzania
Takanori Kooriyama, Hideo Hasegawa, Michito Shimozuru, Toshio Tsubota, Toshisada Nishida, Takashi Iwaki
PRIMATES, 53, 4, 365, 375, SPRINGER JAPAN KK, 2012年10月, ［査読有り］
英語, 研究論文（学術雑誌）, Parasitological surveillance in primates has been performed using coprological observation and identification of specimens from chimpanzees (Pan troglodytes schweinfurthii) in Mahale Mountains National Park, Tanzania (Mahale). In this study, we conducted coprological surveillance to identify the fauna of parasite infection in five primate species in Mahale: red colobus (Procolobus badius tephrosceles), red-tailed monkeys (Cercopithecus ascanius schmidti), vervet monkeys (Cercopithecus aethiops pygerythrus), yellow baboons (Papio cynocephalus), and chimpanzees. Fecal samples were examined microscopically, and parasite identification was based on the morphology of cysts, eggs, larvae, and adult worms. Three nematodes (Oesophagostomum spp., Strongyloides sp., and Trichuris sp.), Entamoeba coli, and Entamoeba spp. were found in all five primate species. The following infections were identified: Bertiella studeri was found in chimpanzees and yellow baboons; Balantidium coli was found in yellow baboons; three nematodes (Streptopharagus, Primasubulura, an undetermined genus of Spirurina) and Dicrocoeliidae gen. sp. were found in red-tailed monkeys, vervet monkeys, and yellow baboons; Chitwoodspirura sp. was newly identified in red colobus and red-tailed monkeys; Probstmayria gombensis and Troglocorys cava were newly identified in chimpanzees, together with Troglodytella abrassarti; and Enterobius sp. was newly identified in red colobus. The parasitological data reported for red colobus, vervet monkeys, and yellow baboons in Mahale are the first reports for these species. - Changes in expression of hepatic genes involved in energy metabolism during hibernation in captive, adult, female Japanese black bears (Ursus thibetanus japonicus)
Michito Shimozuru, Akari Kamine, Toshio Tsubota
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY, 163, 2, 254, 261, ELSEVIER SCIENCE INC, 2012年10月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, Hibernating bears survive up to 6 months without feeding by utilizing stored body fat as fuel. To investigate how bears maintain energy homeostasis during hibernation, we analyzed changes in mRNA expression of hepatic genes involved in energy metabolism throughout the hibernation period in captive, adult, female Japanese black bears (Ursus thibetanus japonicus). Real-time PCR analysis revealed down-regulation of glycolysis(e.g.. glucokinase). amino acid catabolism- (e.g., alanine aminotransferase) and de novo lipogenesis-related genes (e.g., acetyl-CoA carboxylase 1), and up-regulation of gluconeogensis- (e.g., pyruvate carboxylase), beta-oxidation- (i.e., uncoupling protein 2) and ketogenesis-related genes (i.e., 3-hydroxy-3-methylglutary-CoA synthase 2), during hibernation, compared to the active period (June). In addition, we found that glycolysis-related genes (i.e., glucokinase and pyruvate kinase) were more suppressed in the early phase of hibernation (January) compared to the late phase (March). One week after the commencement of feeding in April, expression levels of most genes returned to levels comparable to those seen in June, but beta-oxidation-related genes were still up-regulated during this period. These results suggest that the modulation of gene expression is not static, but changes throughout the hibernation period. The transcriptional modulation during hibernation represents a unique physiological adaptation to prolonged fasting in bears. (C) 2012 Elsevier Inc. All rights reserved. - Changes in expression of hepatic genes involved in lipid metabolism during prehibernation period in captive adult female Japanese black bears (Ursus thibetanus japonicus)
Michito Shimozuru, Kamine Akari, Toshio Tsubota
CANADIAN JOURNAL OF ZOOLOGY, 90, 8, 945, 954, CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS, 2012年08月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, Body fat accumulation in the prehibernation period is crucial for survival and reproduction during hibernation for bears. Bear body mass increases rapidly during their autumnal hyperphagia phase, which is attributed not only to an increase in food availability, but also to physiological changes in lipid metabolism. To test this hypothesis, we investigated changes in blood biochemical values and mRNA expression levels of hepatic genes involved in lipid metabolism during the active period (June, August, October, and November) in Japanese black bears (Ursus thibetanus japonicus Schlegel, 1857), which were fed a constant ration throughout this period. Blood biochemical analysis revealed that plasma triglyceride concentrations decreased in October and November, implying that peripheral triglyceride uptake was accelerated in autumn. The liver was sampled by needle biopsy. Real-time polymerase chain reaction (PCR) analysis revealed that mRNA expressions of enzymes involved in glycolysis (glucokinase), as well as fatty acid and triglyceride synthesis (ATP-citrate lyase, acetylCoA carboxykinase 1, fatty acid synthase, and diacylglycerol O-acyltransferase 2), increased in November, which suggests that hepatic lipogenesis becomes accelerated during the hyperphagia phase. These results suggest that lipid metabolism is seasonally controlled even without changes in food intake. These physiological changes seen in the prehibernation period would contribute to the rapid mass gain necessary for hibernation. - Effects of intramuscular administration of tiletamine-zolazepam with and without sedative pretreatment on plasma and serum biochemical values and glucose tolerance test results in Japanese black bears (Ursus thibetanus japonicus)
Akari Kamine, Michito Shimozuru, Haruki Shibata, Toshio Tsubota
AMERICAN JOURNAL OF VETERINARY RESEARCH, 73, 8, 1282, 1289, AMER VETERINARY MEDICAL ASSOC, 2012年08月, ［査読有り］
英語, 研究論文（学術雑誌）, Objective-To establish a safe anesthetic protocol with little effect on blood biochemical values and IV glucose tolerance test (IVGTT) results in Japanese black bears (Ursus thibetanus japonicus).
Animals-16 captive female Japanese black bears (5 to 17 years of age).
Procedures-Bears were randomly assigned to 4 treatment groups (4 bears/group) in which various treatment combinations were administered via blow dart: tiletamine HCI and zolazepam HCI (9 mg/kg) alone (TZ), TZ (6 mg/kg) and acepromazine maleate (0.1 mg/kg), TZ (6 mg/kg) and butorphanol tartrate (0.3 mg/kg), or TZ (3 mg/kg) and medetomidine HCI (40 mu g/kg). Glucose injection for the IVGTT was started 130 minutes after TZ administration. Blood samples were obtained before, at, and intermittently after glucose injection for measurement of biochemical variables as well as plasma glucose and serum insulin concentrations during the IVGTT Rectal temperature, pulse rate, and respiratory rate were assessed every 15 minutes during the experiment.
Results-Induction and maintenance of anesthesia were safely achieved with little adverse effect on cardiopulmonary function when each of the 4 anesthetic regimens was used, although mild hypothermia was induced. No difference was evident between treatment groups in blood biochemical values. Blood glucose and insulin concentration profiles during the IVGTT were similar among the bears given TZ, with or without acepromazine or butorphanol, but hyperglycemia and hypoinsulinemia developed in bears given TZ with medetomidine.
Conclusions and Clinical Relevance-All 4 anesthetic regimens yielded chemical restraint without affecting clinical and biochemical values in bears, but medetomidine appeared to affect IVGTT results. For this reason, medetomidine should not be used when anesthetizing bears for IVGTTs. (Am J Vet Res 2012;73:1282-1289) - Seasonal Changes in Spermatogenesis and Peripheral Testosterone Concentration in Raccoons (Procyon lotor) in Hokkaido
Minami W. Okuyama, Michito Shimozuru, Nobuhiro Takahashi, Daisuke Fukui, Ryohei Nakamura, Toshio Tsubota
JOURNAL OF VETERINARY MEDICAL SCIENCE, 74, 6, 727, 732, JAPAN SOC VET SCI, 2012年06月, ［査読有り］
英語, 研究論文（学術雑誌）, Feral raccoons (Procyon lotor) have been increasing in number since 1979 and are currently subject to pest control in Hokkaido. One of the reasons for the increase in numbers is thought to be the high reproductive potential of raccoons, but little is known about their reproduction. The main aim of this study was to clarify seasonal changes in spermatogenesis and peripheral testosterone concentration of raccoons in Hokkaido. In the present study, external characteristics and histology of the testis and epididymis and the plasma testosterone concentration were investigated in 68 feral, male raccoons culled for pest control and once a month in one live, captive male. The feral males exhibited seasonal changes in spermatogenesis, showing active spermatogenesis in autumn, winter and spring (October June) with noted spermatogenesis and inactive spermatogenesis in summer (July September) with lower mean levels of spermatozoa in the cauda epididymis. Even in the inactive period, spermatozoa were observed in about half of the individuals (14/26); therefore, individuals producing spermatozoa existed every month throughout the year. Testosterone concentrations were significantly high in the winter mating season. In the captive male, the testosterone concentrations were low from June to August, and spermatozoa could not be observed from July to September. These results suggest that raccoons exhibit seasonality of reproduction, but the time and duration of spermatogenetic decline varies widely among individuals. This individual variation in the inactive period is a feature of male raccoon reproduction and is unique among seasonally breeding mammals. - Changes in blood glucose and insulin responses to intravenous glucose tolerance tests and blood biochemical values in adult female Japanese black bears (Ursus thibetanus japonicus)
Akari Kamine, Michito Shimozuru, Haruki Shibata, Toshio Tsubota
JAPANESE JOURNAL OF VETERINARY RESEARCH, 60, 1, 5, 13, HOKKAIDO UNIV, 2012年02月, ［査読有り］
英語, 研究論文（学術雑誌）, The metabolic mechanisms to circannual changes in body mass of bears have yet to be elucidated. We hypothesized that the Japanese black bear (Ursus thibetanus japonicus) has a metabolic mechanism that efficiently converts carbohydrates into body fat by altering insulin sensitivity during the hyperphagic stage before hibernation. To test this hypothesis, we investigated the changes in blood biochemical values and glucose and insulin responses to intravenous glucose tolerance tests (IVGTT) during the active season (August, early and late November). Four, adult, female bears (5-17 years old) were anesthetized with 6 mg/kg TZ (tiletamine HCl and zolazepam HCl) in combination with 0.1 mg/kg acepromazine maleate. The bears were injected intravenously with glucose (0.5 g/kg of body mass), and blood samples were obtained before, at, and intermittently after glucose injection. The basal triglycerides concentration decreased significantly with increase in body mass from August to November. Basal levels of plasma glucose and serum insulin concentrations were not significantly different among groups. The results of IVGTT demonstrated the increased peripheral insulin sensitivity and glucose tolerance in early November. In contrast, peripheral insulin resistance was indicated by the exaggerated insulin response in late November. Our findings suggest that bears shift their glucose and lipid metabolism from the stage of normal activity to the hyperphagic stage in which they show lipogenic-predominant metabolism and accelerate glucose uptake by increasing the peripheral insulin sensitivity. - Evaluation of Stored Body Fat in Nuisance-killed Japanese Black Bears (Ursus thibetanus japonicus)
Atsushi Yamanaka, Makoto Asano, Masatsugu Suzuki, Toshio Mizoguchi, Toru Oi, Michito Shimozuru, Toshio Tsubota
ZOOLOGICAL SCIENCE, 28, 2, 105, 111, ZOOLOGICAL SOC JAPAN, 2011年02月, ［査読有り］
英語, 研究論文（学術雑誌）, We evaluated the stored body fat of Japanese black bears (Ursus thibetanus japonicus) killed as nuisances in Gifu and Fukushima prefectures, Japan, during 2005-2007. We employed femur marrow fat (FMF), modified kidney fat index (mKFI), and abdominal subcutaneous fat (ASF) as indices for quantitative evaluation. We examined the basic characteristics of these indices, such as seasonality, age and sex dependency, and the quantitative relationship among them. mKFI and ASF increased towards the beginning of the denning period (December), while FMF was relatively stable throughout the sampling period (July-December). In cubs, all indices showed significantly lower values than in the older age classes. There seemed to be a catabolizing order between FMF and mKFI, but not between mKFI and ASF. We also evaluated the yearly change in the indices, and discussed its relevance to the incidence of bear intrusion into human residential areas. Bears nuisance-killed in summer (July-September) 2006 had a significantly larger amount of stored body fat than those killed in summer 2007, although the number of nuisance kills was larger in 2006 than in 2007. This suggests that poor nutritional condition is not a direct cause of bear intrusion. - Estimating the success rate of ovulation and early litter loss rate in the Japanese black bear (Ursus thibetanus japonicus) by examining the ovaries and uteri
Atsushi Yamanaka, Kiyoshi Yamauchi, Tsunenori Tsujimoto, Toshio Mizoguchi, Toru Oi, Seigo Sawada, Michito Shimozuru, Toshio Tsubota
JAPANESE JOURNAL OF VETERINARY RESEARCH, 59, 1, 31, 39, HOKKAIDO UNIV, 2011年02月, ［査読有り］
英語, 研究論文（学術雑誌）, In order to develop a method for estimating the success/failure rates of reproductive processes, especially those of ovulation and neonate nurturing, in the Japanese black bear (Ursus thibetanus japonicus), we examined offspring status, corpora lutea (CLs), placental scars (PSs) and corpora albicantia (CAs) in 159 females (0-23 years old) killed as nuisances on Honshu Island of Japan during 2001-2009. PSs were found to remain in the uterus at least until November of the year of parturition. CA detectability began to decline after September of the year of parturition. Monthly and age-specific proportions of CL-present females revealed that the post-mating season starts in August, and that the age of first ovulation is 4 years. These results indicate that the success rate of ovulation (SRO: the probability that solitary/non-lactating mature females actually succeed in ovulation) can be estimated by calculating the proportion of CL-present females among >= 4-year-old females without PSs captured from August to November; the early litter loss rate (ELLR: the probability that parenting females lose all of their cubs [0-year-old offspring] before mating season) can be estimated by calculating the proportion of CL-present females among those with PSs and CAs captured in August or later. The estimated values of SRO and ELLR were 0.93 (62/67) and 0.27 (6/22), respectively. - Sex Differences in Behavioral and Corticosterone Responses to Mild Stressors in ICR Mice are Altered by Ovariectomy in Peripubertal Period
Mami Aoki, Michito Shimozuru, Takefumi Kikusui, Yukari Takeuchi, Yuji Mori
ZOOLOGICAL SCIENCE, 27, 10, 783, 789, ZOOLOGICAL SOC JAPAN, 2010年10月, ［査読有り］
英語, 研究論文（学術雑誌）, Among rodents, females are generally considered to be highly responsive in terms of emotionality under stressful conditions, and have higher corticosterone levels and activity. In this study, we examined sex differences in mice by evaluating anxiety behaviors and corticosterone responses to mild stressors. In our first experiment, we analyzed the behavioral and corticosterone responses to the elevated plus-maze test and open-field test in male and female mice, and compared sex differences. Principal component analysis (PCA) was used to investigate the correlation of these responses between males and females. The corticosterone level was higher in females under both basal and stressed conditions. In the behavioral response, higher locomotor activity was seen in females in the elevated plus-maze test. PCA showed little association among anxiety behavior, locomotor activity, and corticosterone secretion. In our second experiment, we examined the activational effects of sex steroids on the corticosterone response to the elevated plus-maze test by gonadectomizing male and female mice and using testosterone or estrogen capsules as hormonal replacements. Sex differences at the basal corticosterone level were not altered by the hormonal milieu in adults, however the higher corticosterone level of females in response to stress was diminished by ovariectomy, although replacement with neither testosterone nor estrogen had any effect. These results suggest that the sex difference in novelty exposure observed in the form of a greater hypothalamic-pituitary-adrenal (HPA) axis response in female ICR mice is controlled by ovary-derived factors in adults. - 【クマの保全医学の研究動向】ニホンツキノワグマにおける精子形成の季節変化の制御機序
飯渕 るり子, 加味根 あかり, 下鶴 倫人, 坪田 敏男
獣医畜産新報, 63, 5, 371, 374, 文永堂出版(株), 2010年05月
日本語, 本論は、筆頭著者が4年間の博士論文研究として行った、雄ツキノワグマの精子形成の季節性と、その季節性を形成する繁殖生理メカニズムについてとりまとめたものである。精子形成が開始される冬眠中を中心として、繁殖関連ホルモンの動態や精巣におけるテストステロン合成の変化に関与する因子について、先行研究なども含めて紹介する。(著者抄録) - Localization of Five Steroidogenic Enzyme mRNAs in Japanese Black Bear (Ursus thibetanus japonicus) Testes During the Mating Season by In Situ Hybridization
Ruriko Iibuchi, Michito Shimozuru, Akari Kamine, Junko Nio-Kobayashi, Toshihiko Iwanaga, Toshio Tsubota
JOURNAL OF REPRODUCTION AND DEVELOPMENT, 56, 2, 236, 242, SOCIETY REPRODUCTION & DEVELOPMENT-SRD, 2010年04月, ［査読有り］
英語, 研究論文（学術雑誌）, The Japanese black bear (Ursus thibetanus japonicus) is a typical seasonal breeder that has a mating season in early summer. Spermatogenesis and testicular steroidogenesis are known to develop and regress annually; however, its molecular mechanism has not yet been investigated. In the present study, we clarified the mRNA sequence of 5 steroidogenic enzymes (P450scc, 3 beta HSD, P450c17, 17 beta HSD3 and P450arom) using RT-PCR and RACE methods and the localization of these gene expressions in the bear testis using an in situ hybridization technique. The amino acid sequence deduced from each mRNA sequence had high homology with the corresponding sequences of other species and possessed a motif typical of the P450 family or short chain alcohol dehydrogenase family. Expression of P450scc, 3 beta HSD and P450c17 mRNA in interstitial tissue indicated that conversion from cholesterol to androstenedione occurs in Leydig cells. On the other hand, the mRNA of 17 beta HSD3, which plays a central role in synthesizing testosterone, was detected not only in the interstitium but also inside the seminiferous tubules, along the basement membrane. P450arom mRNAs were distributed in the seminiferous tubules. These results suggest the possibility of testosterone and estradiol-17 beta synthesis inside the seminiferous tubules in the bear testis. We expect that the results of this study will be useful for further investigation of the molecular mechanism of steroidogenic seasonality in the bear testis. - Changes in plasma gonadotropins, inhibin and testosterone concentrations and testicular gonadotropin receptor mRNA expression during testicular active, regressive and recrudescent phase in the captive Japanese black bear (Ursus thibetanus japonicus)
Ruriko Iibuchi, Akari Kamine, Michito Shimozuru, Junko Nio-Kobayashi, Gen Watanabe, Kazuyoshi Taya, Toshio Tsubota
JAPANESE JOURNAL OF VETERINARY RESEARCH, 57, 4, 185, 196, HOKKAIDO UNIV, 2010年02月, ［査読有り］
英語, 研究論文（学術雑誌）, Male Japanese black bears (Ursus thibetanus japonicus) have an explicit reproductive cycle. The objective of this study was to clarify the variation of plasma testosterone, FSH, inhibin, LH levels and testicular gonadotropin receptor mRNA expression of male bears associated with their testicular activity. Notably, this study investigated peripheral FSH concentration and localization of gonadotropin receptor mRNAs for the first time in male bears. Blood and testicular tissue samples were taken from captive, mature, male Japanese black bears during testicular active, regressive and recrudescent phases. Plasma hormone concentrations were measured by immunoassays, and gonadotropin receptor mRNA expression in the testis was investigated by in situ hybridization technique and also by real-time PCR. There were significant variations in plasma testosterone and inhibin concentrations. Changes in FSH concentration preceded these hormones with a similar tendency. Hormones started to increase during denning, and achieved the highest values at the end of the recrudescent phase for FSH and in the active phase for testosterone and inhibin. These changes in hormone concentrations were accompanied by testicular growth. In situ hybridization analysis revealed that FSH and LH receptor mRNA was possibly expressed in Sertoli cells and Leydig cells, respectively, as they are in other mammals. However, neither plasma LH concentration nor testicular gonadotropin receptor mRNA expression level varied significantly among the sampling months. These results suggest that FSH, inhibin and testosterone have roles in testicular activity in male bears. This study provides important endocrine information for comprehending seasonal reproductivity in male Japanese black bears. - Change in body weight of mothers and neonates and in milk composition during denning period in captive Japanese black bears (Ursus thibetanus japonicus)
Ruriko Iibuchi, Noriko Nakano, Tadashi Nakamura, Tadasu Urashima, Michito Shimozuru, Tetsuma Murase, Toshio Tsubota
JAPANESE JOURNAL OF VETERINARY RESEARCH, 57, 1, 13, 22, HOKKAIDO UNIV, 2009年05月, ［査読有り］
英語, 研究論文（学術雑誌）, Japanese black bears, Ursus thibetanus japonicus, have been classified as a vulnerable species so that data on reproduction are needed to maintain and/or extend their population. They are known to have a peculiar style of reproduction, giving birth to their neonates and raising them during denning, a period of complete fasting. In this study, we investigated the metabolic rate and milk composition of mother bears raising neonates, and the changes in body weight of the neonates under captive conditions. Seven female bears kept in dens were weighed once a month, and the amount of energy they used was calculated. From birth, cubs were also weighed and their growth rate was determined. In addition, the milk composition was analyzed to investigate its characteristics. As a result, it was found that mother bears used 34% more energy than did solitary females. There was no significant difference in the energy used for nursing whether they had single or twin cubs. On the other hand, the body weight gain of single cubs was significantly higher than that of twin cubs, suggesting that the growth of the cubs was highly affected by the suppression of mother's energy consumption during the fasting period. The milk had high fat and low sugar concentrations. This indicates that mother bears used the fat accumulated prior to denning for their main energy source when raising cubs. Considering all results together, Japanese black bears showed remarkable efficiency in the use of energy for reproduction during the fasting period. - Sequences and Polymorphisms of the Canine Monoamine Transporter Genes SLC6A2, SLC6A3, and SLC6A4 among Five Dog Breeds
Sayaka Arata, Niwako Ogata, Michito Shimozuru, Yukari Takeuchi, Yuji Mori
JOURNAL OF VETERINARY MEDICAL SCIENCE, 70, 9, 971, 975, JAPAN SOC VET SCI, 2008年09月, ［査読有り］
英語, 研究論文（学術雑誌）, Monoamine transporters have roles to regulate the monoamine concentrations in synaptic clefts in the central nervous system and are the targets of antidepressants and psychostimulants. They include transporters for norepinephrine, dopamine and serotonin, which are encoded by the SLC6A2, SLC6A3, and SLC6A4 genes, respectivily. We sequenced the full lengths of the coding regions of these genes for dogs and identified four single nucleotide polymorphisms (SNPs) in SLC6A2 and four in SLC6A3. One SLC6A3 SNP was non-synonymous and caused an amino acid substitution front threonine to serine. The genotype frequencies of these polymorphisms differed significantly among five breeds with different behavioral traits, suggesting that novel SLC6A2 and SLC6A3 SNPs would provide additional useful information for behavioral genetic studies in dogs. - Effects of isolation-rearing on the development of social behaviors in male Mongolian gerbils (Meriones unguiculatus)
Michito Shimozuru, Takefumi Kikusui, Yukari Takeuchi, Yuji Mori
PHYSIOLOGY & BEHAVIOR, 94, 3, 491, 500, PERGAMON-ELSEVIER SCIENCE LTD, 2008年06月, ［査読有り］, ［筆頭著者］
英語, 研究論文（学術雑誌）, Social isolation has been shown to modify behavioral patterns and neuroendocrine function in many species. In this study, we examined the influence of post-weaning social isolation on the behavioral development and fecal testosterone and corticosterone levels of male Mongolian gerbils. In Experiment 1, isolation-reared (IR) males spent more time engaged in social-sniffing. IR males also showed more aggressive and anxiety-related behaviors than group-reared males (GR; three animals per cage). In Experiment 2, a screen-divided-reared condition (SDR) was examined in addition to GR (two males per cage) and IR males. In the SDR group, two subjects were separated by a wire mesh screen allowing for sensory communication and limited physical contact but not direct social interactions. SDR males showed similar patterns in sniffing and anxiety-related behaviors to IR males; however, an increase in aggression was not observed. No differences in fecal testosterone and corticosterone levels were found among males in different rearing conditions. These results suggest that post-weaning social isolation affects behavioral development without affecting testosterone and corticosterone levels. The behavioral changes observed may therefore be regulated by different mechanisms; increases in social-sniffing and anxiety-related behaviors may be caused by the deprivation of direct social interactions, whereas the enhancement of aggressive behaviors may be caused by the lack of sensory stimulation and limited physical contact with other individuals. (C) 2008 Elsevier Inc. All rights reserved. - Early weaning decreases play-fighting behavior during the postweaning developmental period of Wistar rats
Michito Shimozuru, Yuka Kodama, Takefumi Kikusui, Yukari Takeuchi, Yuji Mori
DEVELOPMENTAL PSYCHOBIOLOGY, 49, 4, 343, 350, JOHN WILEY & SONS INC, 2007年05月, ［査読有り］, ［筆頭著者］
英語, 研究論文（学術雑誌）, We examined the influence of early weaning on the development of play-fighting behaviors and anxiety status in Wistar rats. Pups were divided into two groups, those weaned at postnatal day (PD) 16 (early-weaned group) and those weaned at PD30 (normally weaned group), and were housed in pairs of the same sex. Playful interactions were measured for each pair once a week from 4 to 7 weeks of age. Thereafter during early adulthood, all the rats were subjected to the elevated plus-maze test. The frequencies of pinning and playful attack were less in the early-weaned group than in the normally weaned group. In the elevated plus-maze test, rat pups in the early-weaned group had higher anxiety levels. The results showed that deprivation of mother-pup interactions during the preweaning period decreases affiliative interactions between cage mates, including play-fighting behaviors during the postweaning developmental period, and increases anxiety levels during early adulthood. (c) 2007 Wiley Periodicals, Inc. - Discrimination of individuals by odor in male Mongolian gerbils, Meriones unguiculatus
Michito Shimozuru, Takefumi Kikusui, Yukari Takeuchi, Yuji Mori
ZOOLOGICAL SCIENCE, 24, 5, 427, 433, ZOOLOGICAL SOC JAPAN, 2007年05月, ［査読有り］, ［筆頭著者］
英語, 研究論文（学術雑誌）, The ability to discriminate among individuals plays a fundamental role in the establishment of social relationships in animals. We examined how Mongolian gerbils (Meriones unguiculatus) discriminate among individuals using odor. In the first experiment, the ability of male gerbils to discriminate among five odor sources from different individuals was investigated using a habituation-dishabituation paradigm. After male gerbils had been habituated to a scent from one individual, they were exposed to familiar and unfamiliar scents from different donors simultaneously. Where urine and ventral gland secretions were used, the subjects spent more time investigating novel odors than familiar ones, suggesting that they were able to discriminate individual differences in these odor sources. However, with the scents of feces and saliva, they could detect, but could not discriminate individual differences; with scent from inside the pinnae, they could not even detect. In the second experiment, we tested whether cross-habituation occurred between the scents of urine and ventral gland secretions. A male was exposed repeatedly to urine from one of two familiar donor males during four habituation trials, and was then exposed to the ventral gland secretions from two donors simultaneously. The subject males spent more time investigating scents of ventral gland secretions, but there was no difference in the investigation time between ventral gland scents from the two donors. These results suggest that male gerbils discriminate among individuals using odors from urine and ventral gland secretions and that cross-habituation may not occur between these scents during social-memory formation. - Scent-marking and sexual activity may reflect social hierarchy among group-living male Mongolian gerbils (Meriones unguiculatus)
Michito Shimozuru, Takefumi Kikusui, Yukari Takeuchi, Yuji Mori
PHYSIOLOGY & BEHAVIOR, 89, 5, 644, 649, PERGAMON-ELSEVIER SCIENCE LTD, 2006年12月, ［査読有り］, ［筆頭著者］
英語, 研究論文（学術雑誌）, Social hierarchy plays an important role in the lives of gregarious species. We investigated how social hierarchy between male Mongolian gerbils (Meriones unguiculatus) housed together before sexual maturity affected their scent-marking behavior, endocrine status and physical traits as adults. The social rank between paired males was assessed based on sexual activity in adulthood at 18 and 20 weeks of age. In most cases, the male that showed higher sexual activity at IS weeks also exhibited greater sexual performance at 20 weeks, suggesting a precedence relationship between paired males regarding reproductive opportunity. Sexually active males scent-marked more often than their cage mate, particularly after a sexual experience. No significant differences in physical traits (e.g., the weight of the ventral gland, testes and adrenal glands) or endocrine status (e.g., fecal testosterone and corticosterone levels) were found between the two males. These findings suggest that social rank between familiar males formed during cohabitation, and rank was closely correlated with scent-marking activity, but not with endocrine status. (c) 2006 Elsevier Inc. All rights reserved. - Social-defeat stress suppresses scent-marking and social-approach behaviors in male Mongolian gerbils (Meriones unguiculatus)
Michito Shimozuru, Takefumi Kikusui, Yukari Takeuchi, Yuji Mori
PHYSIOLOGY & BEHAVIOR, 88, 4-5, 620, 627, PERGAMON-ELSEVIER SCIENCE LTD, 2006年07月, ［査読有り］, ［筆頭著者］
英語, 研究論文（学術雑誌）, In many species, social-defeat stress induces behavioral changes in subordinate individuals. The present study examined how social-defeat stress affected scent-marking and approach behaviors in male Mongolian gerbils and whether socially defeated males selectively avoided dominant males. in Experiment 1, each of 11 gerbils was defeated by a dominant gerbil during a short social confrontation (10 min in total). For Experiment 2, the same animals were used two weeks after the end of Experiment 1. Each subject was again similarly defeated, but the two gerbils were then kept in the same cage, separated by a wire mesh for 24 h. Behavioral changes in socially defeated males were observed after social defeat; both experiments were replicated three times. After acute social defeat in Experiment 1, male gerbils did not change their scent-marking activity and frequently approached the dominant males. In contrast, males decreased scent-marking activity and approach behavior toward dominant males in Experiment 2. The amount of time defeated males approached unfamiliar males was also reduced, suggesting that social-defeat stress reduces scent-marking motivation and conspecific approach behavior rather than inducing social avoidance toward a specific individual. These findings showed that the severity of social-defeat stress is an important factor in subsequent behavioral changes in male Mongolian gerbils. (c) 2006 Elsevier Inc. All rights reserved. - Alarm pheromone increases defensive and risk assessment behaviors in male rats
Y Kiyokawa, M Shimozuru, T Kikusui, Y Takeuchi, Y Mori
PHYSIOLOGY & BEHAVIOR, 87, 2, 383, 387, PERGAMON-ELSEVIER SCIENCE LTD, 2006年02月, ［査読有り］
英語, 研究論文（学術雑誌）, Previously, we reported that alarm pheromone released from the perianal region of male rats aggravated stress-induced hyperthermia and increased Fos expression in the vomeronasal pathway and stress-related nuclei in pheromone-recipient rats. However, the alarm property of this pheromone in terms of behavior modification is still unclear. We recently found that this alarm pheromone could be trapped in water. Based on this finding, we developed an experimental paradigm to assess the effect of alarm pheromone on recipient behavior. Male Wistar rats were acclimatized for 5 min to an open field, where two pieces of filter paper soaked with 750 mu l of either pheromone-containing water or vehicle water were attached to the wall. Then, a small "hiding box" was placed in one corner of the field and the behavioral responses of the subject rat were recorded for 10 subsequent minutes. Exposure to alarm pheromone significantly increased defensive and risk assessment behaviors and decreased exploratory and grooming behaviors compared to the vehicle control group, indicating the alarm property of the pheromone. In addition, the comparison with previous results suggests that the alarm pheromone released from the perianal region of the male rat increases anxiety in recipients, rather than evoking a stereotyped autonomic response. (c) 4 2005 Elsevier Inc. All rights reserved.
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(公社)日本獣医学会, 日本語 - ネコ目動物3種における尿道カテーテル挿入による精子採取
高江洲昇, 伊藤真輝, 菅原里沙, 柳川洋二郎, 永野昌志, 佐鹿万里子, 下鶴倫人, 坪田敏男, 日本獣医学会学術集会講演要旨集, 157th, 547, 547, 2014年08月11日
(公社)日本獣医学会, 日本語 - 北海道のsika deerおよびHaemaphysalis属ダニより検出されたRF Borrelia属(A RF Borrelia sp. found among wild sika deer and Haemaphysalis ticks in Hokkaido)
李 景利, 高野 愛, Taylor Kyle, 佐鹿 万里子, 下鶴 倫人, 今内 覚, 川端 寛樹, 坪田 敏男, 日本獣医学会学術集会講演要旨集, 157回, 548, 548, 2014年08月
(公社)日本獣医学会, 英語 - 腎臓周囲脂肪および大腿骨骨髄内脂肪を用いたヒグマの栄養状態評価
森真理子, 佐鹿万里子, 下鶴倫人, 坪田敏男, 間野勉, 日本哺乳類学会大会プログラム・講演要旨集, 2014, 2014年 - 知床半島ルシャ地区におけるヒグマの繁殖様式に関する研究
下鶴倫人, 森脇潤, 山中正実, 中西將尚, 石名坂豪, 葛西真輔, 能勢峰, 増田泰, 坪田敏男, 日本獣医学会学術集会講演要旨集, 157th, 548, 548, 2014年
(公社)日本獣医学会, 日本語 - アライグマ精巣組織における精子形成調節機構の解析 ステロイド代謝およびテストステロン感受性との関連性の解明
奥山 みなみ, 下鶴 倫人, 坪田 敏男, The Journal of Reproduction and Development, 59, Suppl., j104, j104, 2013年08月
(公社)日本繁殖生物学会, 日本語 - 北海道の野生下におけるボレリア種の維持、小型哺乳類とダニの関係について(On the maintenance of Borrelia spp. among wildlife in Hokkaido: the relationship between small mammals and ticks)
カイル・テイラー, 川端 寛樹, 今内 覚, 下鶴 倫人, 高野 愛, 坪田 敏男, 衛生動物, 64, 2, 112, 112, 2013年06月
日本衛生動物学会, 英語 - ヒグマにとって厳しかった夏-2012年,知床半島での事例-
下鶴倫人, 森脇潤, 山中正実, 中西將尚, 石名坂豪, 葛西真輔, 白柳正隆, 能勢峰, 増田泰, 坪田敏男, 霊長類研究, 29, Supplement, 2013年 - 知床半島ルシャ地域におけるヒグマの血縁関係解析
森脇潤, 下鶴倫人, 山中正実, 中西將尚, 永野夏生, 増田泰, 藤本靖, 坪田敏男, 霊長類研究, 29, Supplement, 2013年 - 尿道カテーテル法を応用したニホンザルの精液採取
高江洲昇, 柳川洋二郎, 永野昌志, 兼子明久, 今井啓雄, 岡本宗裕, 下鶴倫人, 坪田敏男, 日本野生動物医学会大会・講演要旨集, 19th, 72, 2013年
日本語 - ダニによる寄生および感染症と生物多様性保全 北海道における齧歯類の動態とボレリア細菌種の感染率(Rodent dynamics and Borrelia spp. infection rates in Hokkaido)
Taylor Kyle, 高野 愛, 川端 寛樹, 下鶴 倫人, 坪田 敏男, 日本獣医学会学術集会講演要旨集, 153回, 181, 181, 2012年03月
(公社)日本獣医学会, 英語 - 道東・標津町における携帯電話を活用したリアルタイム通信によるヒグマ行動追跡
坪田敏男, 平野沙衣子, 藤本靖, 上野洋一, 長田雅裕, 郡山尚紀, 下鶴倫人, 日本生態学会大会講演要旨集, 58th, 211, 2011年03月08日
日本語 - ツキノワグマからのCytauxzoon原虫の検出と分離
陳内 理生, 前橋 克彦, 平田 晴之, 岩崎 いづみ, 中嶋 瑠衣, 藤澤 幸平, 寺田 裕, 下鶴 倫人, 坪田 敏男, 石原 智明, 獣医寄生虫学会誌, 9, 2, 168, 168, 2011年03月
日本獣医寄生虫学会, 日本語 - ツキノワグマからのCytauxzoon原虫の検出と分離
陳内 理生, 前橋 克彦, 平田 晴之, 岩崎 いづみ, 中嶋 瑠衣, 藤澤 幸平, 寺田 裕, 下鶴 倫人, 坪田 敏男, 石原 智明, 日本獣医学会学術集会講演要旨集, 150回, 192, 192, 2010年09月
(公社)日本獣医学会, 日本語 - ニホンツキノワグマにおける冬眠前の脂肪蓄積メカニズム (特集 クマの保全医学の研究動向)
加味根 あかり, 下鶴 倫人, 坪田 敏男, 獣医畜産新報, 63, 5, 367, 370, 2010年05月
文永堂出版, 日本語 - エゾシカにおけるPAGを用いた早期妊娠診断方法の検討
柳川 洋二郎, 宮澤 千鶴, 松浦 友紀子, 下鶴 倫人, Noelita Melo de Sousa, Beckers Jean-Francis, 片桐 成二, 坪田 敏男, 北海道獣医師会雑誌, 53, 8, 109, 109, 2009年08月
(公社)北海道獣医師会, 日本語 - 若手研究者によるクマの保全医学研究 雌の繁殖成功に関わる脂肪蓄積のメカニズムとその役割 ニホンツキノワグマにおける冬眠前の脂肪蓄積に関する代謝メカニズムの解明
加味根 あかり, 中村 幸子, 飯渕 るり子, 山中 淳史, 柴田 治樹, 下鶴 倫人, 坪田 敏男, 日本獣医学会学術集会講演要旨集, 147回, 193, 193, 2009年03月
(公社)日本獣医学会, 日本語 - 若手研究者によるクマの保全医学研究 雄の季節繁殖性のメカニズムと人工繁殖 ツキノワグマにおける精子形成の季節変化とその制御機構
飯渕 るり子, 岩永 敏彦, 下鶴 倫人, 坪田 敏男, 日本獣医学会学術集会講演要旨集, 147回, 194, 194, 2009年03月
(公社)日本獣医学会, 日本語 - ニホンツキノワグマ(Ursus thibetanus japonicus)における精巣内ステロイド代謝酵素mRNA発現の季節変化
飯渕 るり子, 岩永 敏彦, 下鶴 倫人, 坪田 敏男, The Journal of Reproduction and Development, 54, Suppl., j70, j70, 2008年08月
(公社)日本繁殖生物学会, 日本語 - Effects of isolation rearing on the development of social behavior and central neurotrophin levels in male Mongolian gerbils
Michito Shimozuru, Takefumi Kikusui, Yukari Takeuchi, Yuji Mori, NEUROSCIENCE RESEARCH, 58, S231, S231, 2007年, ［査読有り］
ELSEVIER IRELAND LTD, 英語, 研究発表ペーパー・要旨（国際会議） - OC-04 豊かな環境飼育は新奇環境下での雄ラット性行動亢進を減弱する(日本動物心理学会第67回大会発表要旨)
浦川将, 近藤保彦, 美津島大, 下鶴倫人, 佐久間康夫, 動物心理学研究, 57, 2, 121, 121, 2007年
日本動物心理学会, 日本語 - ラットにおける早期離乳による社会的遊び行動の減少と不安傾向の増大
岩佐 高志, 児玉 有加, 下鶴 倫人, 菊水 健史, 武内 ゆかり, 森 裕司, 動物心理学研究, 56, 2, 131, 131, 2006年12月
日本動物心理学会, 日本語 - ラット警報フェロモンの不安関連行動および神経内分泌反応に対する影響
清川 泰志, 下鶴 倫人, 菊水 健史, 武内 ゆかり, 森 裕司, 日本内分泌学会雑誌, 81, 2, 396, 396, 2005年09月
(一社)日本内分泌学会, 日本語 - 離乳後の社会的隔離操作がスナネズミの社会行動および神経内分泌機構に及ぼす影響
下鶴 倫人, 菊水 健史, 武内 ゆかり, 森 裕司, 日本獣医学会学術集会講演要旨集, 140回, 192, 192, 2005年08月
(公社)日本獣医学会, 日本語 - Influences of social rank on scent-marking behavior and endocrine status in male Mongolian gerbils.
M Shimozuru, H Yamaguchi, T Kikusui, Y Takeuchi, Y Mori, HORMONES AND BEHAVIOR, 46, 1, 122, 122, 2004年06月
ACADEMIC PRESS INC ELSEVIER SCIENCE, 英語, 研究発表ペーパー・要旨（国際会議） - 社会的飼育環境下におけるスナネズミの社会的順位と行動学的・内分泌学的特性との関連性
下鶴 倫人, 菊水 健史, 武内 ゆかり, 森 裕司, 日本獣医学会学術集会講演要旨集, 137回, 160, 160, 2004年03月
(公社)日本獣医学会, 日本語 - IP035 スナネズミのにおいによる個体識別行動
下鶴 倫人, 菊水 健史, 武内 ゆかり, 森 裕司, 動物心理学研究, 53, 2, 117, 117, 2003年12月25日
日本動物心理学会, 日本語 - スナネズミの社会的序列をめぐる行動変化の解析
下鶴 倫人, 菊水 健史, 武内 ゆかり, 森 裕司, 日本獣医学会学術集会講演要旨集, 136回, 227, 227, 2003年09月
(公社)日本獣医学会, 日本語
書籍等出版物
- 行動生物学辞典
上田, 恵介, 岡ノ谷, 一夫, 菊水, 健史, 坂上, 貴之, 辻, 和希, 友永, 雅己, 中島, 定彦, 長谷川, 寿一, 松島, 俊也
東京化学同人, 2013年11月, 9784807908370, 637p, 日本語, ［分担執筆］
講演・口頭発表等
- Possibility of behavior modeling of brown bear using collar with video camera and tri-axis accelerometer
Yui Nemoto, Michito Shimozuru, Yuri Shirane, Mina Jimbo, Masanao Nakanishi, Ishinazaka T, Masami Yamanaka
The 7th International Bio-logging Science Symposium, ポスター発表
2021年10月19日 - 2021年10月23日 - Habitat Occupancy of Sloth bears in Chitwan National Park, Nepal
Rajan PP, Kadariya R, Lamichhane B, Subedi N, Shimozuru M, Sashika M, Tsubota T
The 14th Asian Society of Conservation Medicine, The 27th Japanese Society of Zoo and Wildlife Medicine, 2021 Joint Conference, 口頭発表（一般）
2021年09月21日 - 2021年09月24日 - An investigation of restricted mountain climbing and salmon fishing among female brown bears with dependent young in Hokkaido, Japan
Yuri Shirane, Mina Jimbo, Masami Yamanaka, Masanao Nakanishi, Yoshihiro Umemura, Tsuyoshi Ishinazaka, Toshio Tsubota, Michito Shimozuru
The 14th Asian Society of Conservation Medicine, The 27th Japanese Society of Zoo and Wildlife Medicine, 2021 Joint Conference, 口頭発表（一般）
2021年09月21日 - 2021年09月24日 - Maternal human habituation, birthplace, and sex affect brown bear mortality in the Shiretoko National Park, Hokkaido, Japan
Shimozuru M, Shirane Y, Yamanaka M, Nakanishi M, Ishinazaka T, Kasai S, Nose T, Shirayanagi M, Jimbo M, Tsuruga H, Mano T, Tsubota T
27th International conference on Bear Research and Management, ポスター発表
2021年09月14日 - 2021年09月23日 - Effects of seasonal and annual variations in diet on the body condition of Hokkaido brown bears
Shirane Y, Yamanaka M, Nakanishi M, Ishinazaka T, Jimbo M, Sashika M, Tsubota T, Shimozuru M
27th International conference on Bear Research and Management, ポスター発表
2021年09月14日 - 2021年09月23日 - Annual, regional, and intraspecific variation in Hokkaido brown bear diet: Insights from hair stable isotope analysis
Jimbo M, Shirane Y, Yamanaka M, Ishinazaka T, Nakanishi M, Nose T, Umemura Y, Uno H, Sashika M, Tsubota T, Shimozuru M
27th International conference on Bear Research and Management, ポスター発表
2021年09月14日 - 2021年09月23日 - Ecology and genetic diversity of sloth bear (Melursus ursinus) in Nepal
Paudel RP, Shimozuru M, Kadariya R, Subedi N, Sashika M, Tsubota T
27th International conference on Bear Research and Management, ポスター発表
2021年09月14日 - 2021年09月23日 - 知床世界自然遺産地域におけるニホンジカの個体群特性の評価（予報）
宇野裕之, 長雄一, 亀井利活, 上野真由美, 石名坂豪, 山中正実, 雨谷教弘, 下鶴倫人
日本哺乳類学会2021年度大会, ポスター発表
2021年08月28日 - 2021年08月31日 - 知床半島における自動撮影カメラの画像を用いたヒグマの栄養状態の評価の試みについて（予報）
山中正実, 白根ゆり, 下鶴倫人, 神保美渚, 梅村佳寛, 雨谷教弘, 石名坂豪, 坪田敏男, 宇野裕之
日本哺乳類学会2021年度大会, ポスター発表
2021年08月28日 - 2021年08月31日 - ハイマツ球果とカラフトマスがメス成獣ヒグマの夏から初秋の栄養状態を左右する
白根ゆり, 神保美渚, 山中正実, 中西将尚, 石名坂豪, 坪田敏男, 下鶴倫人
日本哺乳類学会2021年度大会, ポスター発表
2021年08月28日 - 2021年08月31日 - 知床半島のオスヒグマにおける生涯の採食戦略
神保美渚, 白根ゆり, 梅村佳寛, 石名坂豪, 中西将尚, 葛西真輔, 白栁正隆, 宇野裕之, 佐鹿万里子, 坪田敏男, 下鶴倫人
日本哺乳類学会2021年度大会, ポスター発表
2021年08月28日 - 2021年08月31日 - 知床半島ヒグマ個体群におけるDNA血縁解析に基づく成獣個体数の推定
下鶴倫人, 足立圭輔, 神保美渚, 川村圭, 白根ゆり, 梅村佳寛, 中西将尚, 石名坂豪, 雨谷教弘, 山中正実, 釣賀一二三, 間野勉, 坪田敏男, 深澤圭太, 宇野裕之
日本哺乳類学会2021年度大会, ポスター発表
2021年08月28日 - 2021年08月31日 - Hibernating bear serum leads to increased protein content in human skeletal muscle cells
Mitsunori Miyazaki, Michito Shimozuru, Toshio Tsubota
13th International Hibernation Symposium, ポスター発表
2021年08月01日 - 2021年08月05日 - Regulation of energy metabolism-related genes by liver microRNAs in hibernating Japanese black bears
Michito Shimozuru, Kazuhei Nishida, Yuko Okamatsu-Ogura, Mitsunori Miyazaki, Tsukasa Soma, Toshio Tsubota
16th International Hibernation Symposium, ポスター発表
2021年08月01日 - 2021年08月05日 - 知床半島におけるヒグマの食性の個体差と地域性
神保美渚, 白根ゆり, 梅村佳寛, 新庄康平, 中西將尚, 石名坂豪, 宇野裕之, 佐鹿万里子, 坪田敏男, 下鶴倫人
第68回日本生態学会大会, 2021年03月17日, 口頭発表（一般） - Detection of Borrelia in rodents and Ixodes ticks in Sarawak, Malaysia
Lau, C. C. A, Qiu, Y, Moustafa, M. A. M, Nakao, R, Shimozuru, M, Onuma, M, Mohd-Azlan, J, Tsubota, T
The 13th International Virtual Conference of Asian Society of Conservation Medicine, ポスター発表
2020年10月24日 - 2020年10月25日 - 北海道斜里町においてエゾヒグマより採集されたタカサゴキララマダニの一例
下鶴倫人, 新庄康平, 崎山智樹, 小方昌平, 草木迫浩大, 木下豪太, Wessam Mohamed Ahmed Mohamed・Mohamed Abdallah Mohamed Moustafa, 松野啓太, 伊東拓也, 野中成晃, 佐鹿万里子, 坪田敏男, 中尾亮
口頭発表（一般）
2020年09月08日 - 2020年09月10日 - DNA解析に基づくヒグマの個体群特性の解明
下鶴倫人
第68回日本生態学会大会, 2020年03月18日, シンポジウム・ワークショップパネル（指名） - ヒグマ体毛の伸長様式と同位体濃縮係数の算出
神保美渚, 松本直也, 坂元秀行, 石名坂豪, 栁川洋二郎, 佐鹿万里子, 坪田敏男, 下鶴倫人
第67回日本生態学会大会, 2020年03月05日, ポスター発表 - 知床半島に生息するヒグマにおけるY染色体ハプロタイプの地理的分布
足立圭輔, 下鶴倫人, 白根ゆり, 山中正実, 中西將尚, 石名坂豪, 葛西真輔, 能勢峰, 神保美渚, 釣賀一二三, 間野勉, 藤本靖, 坪田敏男
第67回日本生態学会大会, 2020年03月05日, ポスター発表 - 知床半島におけるエゾシカ新生子の死亡に与えるヒグマの影響の検討
山中正実, 下鶴倫人, 白根ゆり, 清成真由, 中西將尚, 石名坂豪, 宇野裕之, 神保美渚, 葛西真輔, 能勢峰, 梅村佳寛
日本哺乳類学会2019年度大会, 2019年09月18日, ポスター発表 - 夏期の食物環境の変動がヒグマの栄養状態に与える影響の解明
白根ゆり, 山中正実, 中西將尚, 石名坂豪, 神保美渚, 佐鹿万里子, 坪田敏男, 下鶴倫人
日本哺乳類学会2019年度大会, 2019年09月18日, ポスター発表 - 人に馴れた母グマの子は駆除されやすいか？ 知床国立公園に生息するヒグマの人為的捕殺率に影響を与える要因．
下鶴倫人, 白根ゆり, 山中正実, 中西將尚, 石名坂豪, 葛西真輔, 能勢峰, 白柳正隆, 神保美渚, 釣賀一二三, 間野勉, 坪田敏男
日本哺乳類学会2019年度大会, 2019年09月18日, 口頭発表（一般） - ヒグマはオスに偏った出生地分散により近親交配を回避する
下鶴倫人, 白根ゆり, 釣賀一二三, 山中正実, 中西將尚, 石名坂豪, 葛西真輔, 能勢峰, 間野勉, 坪田敏男
第161回日本獣医学会学術集会, 2018年09月11日, 日本語, 口頭発表（一般）
つくば, ［国内会議］ - 知床半島ヒグマ個体群におけるマルチプルパターニティと近親交配の発生率
下鶴倫人, 白根ゆり, 釣賀一二三, 山中正実, 中西將尚, 石名坂豪, 葛西真輔, 能勢峰, 増田泰, 間野勉, 坪田敏男
日本哺乳類学会2018年度大会, 2018年09月07日, 日本語, 口頭発表（一般）
信州大学, ［国内会議］ - 北海道立自然公園野幌森林公園におけるアライグマ（Procyon lotor）およびエゾタヌキ（Nyctereutes procyonoides albus）の食性と生息地比較に関する研究
尾﨑彩, 佐鹿万里子, 下鶴倫人, 坪田敏男
日本哺乳類学会2018年度大会, 2018年09月07日, 日本語, 口頭発表（一般）
信州大学, ［国内会議］ - Specific Molecular detection of piroplasms and characterization of a beta-tubulin gene for a novel Babesia species in Sika deer (Cervus nippo yesoensis)
Moustafa, M. A. M, Elbaz, E, Lee, K, Shimozuru, M, Sashika, M, Tsubota, T
The 2018 Wildlife Disease Association Conference, 2018年08月05日, 英語, ポスター発表
［国際会議］ - 国後島のヒグマのシンプルな食性－知床半島・白糠丘陵に生息するヒグマとの比較
中下留美子, 小林喬子, 伊藤哲治, 中村秀次, 飯島勇人, 増田泰, ログンツェフA, 大泰司紀之, 下鶴倫人, 秦彩夏, 釣賀一二三, 山中正実, 佐藤喜和
第65会日本生態学会大会, 2018年03月16日, 日本語, ポスター発表
帯広, ［国内会議］ - Natal dispersal pattern of brown bears in Shiretoko Peninsula, eastern Hokkaido, Japan
Shirane, Y, Yamanaka, M, Nakanishi, M, Ishinazaka, T, Nose, T, Kasai, S, Shirayanagi, M, Masuda, Y, Tsuruga, H, Mano, T, Fujimoto, Y, Osada, M, Moustarfa, MAM, Sashika, M, Tsubota, T, Shimozuru, M
2017年11月12日, 英語, 口頭発表（一般）
［国際会議］ - Occurrence rate of multiple paternity and inbreeding in the brown bear population in the Shiretoko Peninsula, Hokkaido, Japan.
Shimozuru, M, Shirane, Y, Tsuruga, H, Yamanaka, M, Nakanishi, M, Moriwaki, J, Ishinazaka, T, Kasai, S, Nose, T, Masuda, Y, Mano, T, Tsubota, T
25th International Conference of Bear Research and Management, 2017年11月12日, International Bear Association, 英語, ポスター発表
キト、エクワドル, ［国際会議］ - Changes in body temperature and heart rate during hibernation in captive male and female Japanese black bears (Ursus thibetanus japonicus).
Tsubota, T, Yamazaki, K, Sashika, M, Moustafa, M. A. M, Shimozuru, M
25th International Conference of Bear Research and Managemen, 2017年11月12日, International Bear Association, 英語, 口頭発表（一般）
キト、エクワドル, ［国際会議］ - 知床半島におけるヒグマの肥満度を左右する夏期の食物と軋轢発生への影響の検討
山中正実, 下鶴倫人, 白根ゆり, 中西將尚, 森文彦, 石名坂豪, 増田泰
野生生物と社会学会第23会大会, 2017年11月03日, 日本語, ポスター発表
帯広, ［国内会議］ - ヒグマは匂いで個体の違い・発情・非発情を区別できるか：背部脂腺から分泌される油脂性物質による嗅覚コミュニケーションの検討
豊島尚章, 成瀬泰平, 松本直也, 冨安洵平, 下鶴倫人, 佐藤喜和
日本哺乳類学会2017年度大会, 2017年09月08日, 日本語, ポスター発表
［国内会議］ - 知床半島ルシャ地区におけるヒグマの繁殖特性 —長期追跡調査に基づく繁殖指標の算出—
下鶴倫人, 山中正実, 中西將尚, 白根ゆり, 石名坂豪, 葛西真輔, 能勢峰, 増田泰, 坪田敏男
日本哺乳類学会2017年度大会, 2017年09月08日, 日本語, 口頭発表（一般）
富山, ［国内会議］ - キツネ用駆除薬ベイトを用いたエキノコックス症対策-小面積地域への摘要-
浦口宏二, 入江隆夫, 考口祐一, 八木欣平, 稲森 梓, 下鶴倫人, 坪田敏男
日本哺乳類学会2016年度大会, 2016年09月23日, 日本語, 口頭発表（一般）
つくば, ［国内会議］ - 知床半島におけるヒグマの個体群動向モニタリングの試み
山中正実, 下鶴倫人, 中西將尚, 間野勉, 白根ゆり, 増田泰
日本哺乳類学会2016年度大会, 2016年09月23日, 日本語, ポスター発表
つくば, ［国内会議］ - ヒグマは匂いで個体の違いを識別できるか：背部脂腺から分泌される油脂性物質による嗅覚コミュニケーションの検討.
豊島尚章, 成瀬泰平, 松本直也, 冨安洵平, 下鶴倫人, 佐藤喜和
日本哺乳類学会2016年度大会, 2016年09月23日, 日本語, ポスター発表
つくば, ［国内会議］ - 知床半島におけるヒグマの移動分散様式の解明
白根ゆり, 山中正実, 中西將尚, 石名坂豪, 能勢峰, 葛西真輔, 白柳正隆, 増田泰, 釣賀一二三, 間野勉, 藤本靖, 長田雅裕, 佐鹿万里子, 坪田敏男, 下鶴倫人
日本哺乳類学会2016年度大会, 2016年09月23日, 日本語, 口頭発表（一般）
つくば, ［国内会議］ - ヒグマの夏期の食物資源の豊凶が栄養状態および子の生存に与える影響
下鶴倫人, 森文彦, 白根ゆり, 山中正実, 中西將尚, 坪田敏男
日本哺乳類学会2016年度大会, 2016年09月23日, 日本語, ポスター発表
つくば, ［国内会議］ - 飼育下ツキノワグマにおける冬眠前および冬眠中の体温および心拍数の変化
坪田敏男, 鈴木信吾, 宮城太輔, 山崎晃司, 佐鹿万里子, 下鶴倫人
第22回日本野生動物医学会宮崎大会, 2016年09月16日, 日本語, 口頭発表（一般）
宮崎, ［国内会議］ - 北海道におけるアライグマの遺伝子型の地理的分布に関する研究
奥山みなみ, 下鶴倫人, 中井真理子, 藤井 啓, 山口 英美, 島田健一郎, 池田 透, 坪田敏男
第159回日本獣医学会学術集会, 2016年09月06日, 日本語, 口頭発表（一般）
藤沢, ［国内会議］ - エキノコックス症対策におけるベイト（駆虫薬入りエサ）の小面積散布について
浦口宏二, 孝口裕一, 入江隆夫, 稲森 梓, 下鶴倫人, 坪田敏男
第159回日本獣医学会学術集会, 2016年09月06日, 日本語, 口頭発表（一般）
藤沢, ［国内会議］ - Regulation of protein metabolism and muscle mass in hibernating bears: an attractive model of muscle atrophy.
Miyazaki, M, Shimozuru, M, Tsubota, T
2016年06月12日, 英語, 口頭発表（一般）
アラスカ, アメリカ合衆国, ［国際会議］ - Changes in energy metabolism in hibernating black bears: an analysis of gene expression and metabolites in liver and skeletal muscle.
Shimozuru, M, Miyazaki M, Tsubota, T
2016年06月12日, 英語, 口頭発表（一般）
アラスカ, アメリカ合衆国, ［国際会議］ - Changes in body temperature and heart rate related to hibernation in captive Japanese black bears.
Tsubota, T, Suzuki, S, Miyagi, D, Yamazaki, K, Sashika, M, Shimozuru, M
24th International Conference of Bear Research and Management, 2016年06月12日, 英語, 口頭発表（一般）
アラスカ, アメリカ合衆国, ［国際会議］ - Cross-cluster genetic exchange of the brown bear population occurs at the base of Shiretoko Peninsula.
Tsubota, T, Hirano, S, Nagano, N, Tsujino, M, Shimozuru, M, Sashika, M, Osada, M, Fujimoto, Y
5th International Wildlife Management Congress, 2015年09月27日, 英語, 口頭発表（一般）
札幌, ［国際会議］ - 北海道のエゾタヌキとアライグマにおけるイヌジステンパーウイルス感染に関する疫学調査
佐鹿万里子, 阿部 豪, 郡山尚紀, 中井真理子, 島田健一郎, 前田 健, 下鶴倫人, 坪田敏男
第158回日本獣医学会学術集会, 2015年09月07日, 日本語, 口頭発表（一般）
十和田, ［国内会議］ - ツキノワグマにおける冬眠期の皮下体温、腹腔内体温および活どう量測定の試み
鈴木信吾, 山崎晃司, 佐鹿万里子, 下鶴倫人, 坪田敏男
第158回日本獣医学会学術集会, 2015年09月07日, 日本語, 口頭発表（一般）
十和田, ［国内会議］ - Reproductive parameters and male dispersal of brown bears in the Rusha area of Shiretoko National Park, Hokkaido, Japan.
Shimozuru, M, Moriwaki, J, Yamanaka, M, Nakanishi, M, Ishinazaka, T, Kasai, S, Nose, T, Masuda, Y, Tsubota, T
5th International Wildlife Management Congress, 2015年07月26日, 英語, ポスター発表
札幌, ［国際会議］ - Tuberculosis in Asian elephants (Elephas maximus) of Nepal.
Paudel, S, Mikota, S. K, Nakajima, C, Gairhe, K. P, Poudel, A, Sashika, M, Shimozuru, M, Suzuki, Y, Tsubota, T
5th International Wildlife Management Congress, 2015年07月26日, 英語, 口頭発表（一般）
札幌, ［国際会議］ - Niche selection by microbes: Babesia and Erlichiae exhibit host preference among rodents sharing ecosystems in Hokkaido, Japan.
Moustafa, M. Jr, Taylor, K, Nakao, R, Sashika, M, Shimozuru, M, Tsubota, T
5th International Wildlife Management Congress, 2015年07月26日, 英語, 口頭発表（一般）
札幌, ［国際会議］ - Hibernating bear muscle shows slow-fiber shifting and mitochondrial biogenesis despite prolonged physical inactivity
Miyazaki, M, Shimozuru, M, Tsubota, T
Cell Symposium Exercise Metabolism, 2015年07月12日, 英語, 口頭発表（一般）
アムステルダム, ［国際会議］ - 知床半島におけるヒグマの移動分散について –知床半島ヒグマ保護管理方針に対する保護管理上の示唆–
山中正実, 下鶴倫人, 中西將尚, 増田泰, 坪田敏男
「野生生物と社会」学会第20回大会, 2014年10月31日, 英語, 口頭発表（一般）
犬山, ［国内会議］ - A relapsing fever group Borrelia sp. Similar to Borrelia lonestari found among wild sika deer (Cervus Nippon yesoensis) and Heamaphysalis spp. ticks in Hokkaido, Japan.
Lee, K, Takano, A, Taylor, K, Sashika, M, Shimozuru, M, Konnai, S, Kawabata, H, Tsubota, T
7th Asian Meeting on Zoo and Wildlife Medicine/Conservation, 2014年10月15日, 英語, 口頭発表（一般）
ハノイ, ベトナム, ［国際会議］ - Interferon-gamma release assay (IGRA) for the diagnosis of tuberculosis in Asian elephants (Elephas maximus).
Paudel, S, Villanueva, M, Mikota, S. K, Nakajima, C, Gairhe, K. P, Subedi, S, Rayamajhi, N, Sashika, M, Shimozuru, M, Suzuki, Y, Tsubota, T
7th Asian Meeting on Zoo and Wildlife Medicine/Conservation, 2014年10月15日, 英語, 口頭発表（一般）
ハノイ, ベトナム, ［国際会議］ - A RF Borrelia sp. found among wild sika deer and Haemaphysalis ticks in Hokkaido．
李 景利, 高野 愛, Taylor Kyle, 佐鹿万里子, 下鶴倫人, 今内 覚, 川端寛樹, 坪田敏男
第157回日本獣医学会学術集会, 2014年09月09日, 日本語, 口頭発表（一般）
札幌, ［国内会議］ - 知床半島ルシャ地区におけるヒグマの繁殖様式に関する研究
下鶴倫人, 森脇 潤, 山中正実, 中西將尚, 石名坂 豪, 葛西真輔, 能勢 峰, 増田 泰, 坪田敏男
第157回日本獣医学会学術集会, 2014年09月09日, 日本語, 口頭発表（一般）
札幌, ［国内会議］ - ネコ目動物３種における尿道カテーテル挿入による精子採取
高江洲 昇, 伊藤真輝, 菅原里沙, 柳川洋二郎, 永野昌志, 佐鹿万里子, 下鶴倫人, 坪田敏男
第157回日本獣医学会学術集会, 2014年09月09日, 日本語, 口頭発表（一般）
札幌, ［国内会議］ - 腎周囲脂肪および大腿骨骨髄内脂肪を用いたヒグマの栄養状態評価
森真理子, 佐鹿万里子, 下鶴倫人, 坪田敏男
日本哺乳類学会2014年度大会, 2014年09月04日, 日本語, ポスター発表
京都, ［国内会議］ - 知床半島ルシャ地区におけるヒグマの行動特性と遺伝構造
下鶴倫人
日本哺乳類学会2014年度大会, 2014年09月04日, 日本語, シンポジウム・ワークショップパネル（指名）
京都, ［国内会議］ - Molecular epidemiological study on Anaplasma phagocytophilum in sika deer (Cervus nippon) in Hokkaido, Japan.
Moustafa, M, Lee, K, Taylor, K, Sashika, M, Shimozuru, M, Tsubota, T
63rd Annual International Conference of the Wildlife Disease Association, 2014年07月26日, 英語, 口頭発表（一般）
ニューメキシコ, アメリカ合衆国, ［国際会議］ - 知床半島ルシャ地域におけるヒグマの血縁関係解析
森脇 潤, 下鶴倫人, 山中正実, 中西將尚, 永野夏生, 増田泰, 藤本 靖, 坪田敏男
日本哺乳類学会2013年度大会, 2013年09月06日, 日本語, ポスター発表
岡山, ［国内会議］ - ヒグマにとって厳しかった夏−2012年、知床半島での事例−
下鶴倫人, 森脇 潤, 山中正実, 中西將尚, 石名坂豪, 葛西真輔, 白柳正隆, 能勢 峰, 増田 泰, 坪田敏男
日本哺乳類学会2013年度大会, 2013年09月06日, 日本語, 口頭発表（一般）
岡山, ［国内会議］ - 尿道カテーテル法を応用したニホンザルの精液採取
高江洲昇, 柳川洋二郎, 永野昌志, 兼子明久, 今井啓雄, 岡本宗裕, 下鶴倫人, 坪田敏男
第19回日本野生動物医学会大会, 2013年08月31日, 日本語, 口頭発表（一般）
京都, ［国内会議］ - Characterization of Mycobacterium tuberculosis isolates from captive elephants of Nepal.
Paudel, S, Mikota, SK, Nakajima, C, Gairhe, KP, Maharjan, B, Thapa, J, Poudel, A, Shimozuru, M, Suzuki, Y, Tsubota, T
62nd International Conference of Wildlife Disease Organization, 2013年07月27日, 英語, 口頭発表（一般）
Knoxville, TN, USA, ［国際会議］ - Body temperature and blood biochemical profiles during hibernation in the Japanese black bear.
Tsubota, T, Shimozuru, M
14th International Hibernation Symposium, 2012年08月08日, 英語, 口頭発表（一般）
Semmering, Austria, ［国際会議］ - Seasonal changes in expression of energy metabolism-related genes in the liver and white adipose tissue of captive, adult, female Japanese black bears.
Shimozuru, M, Nagashima, A, Kamine, A, Tsubota, T
14th International Hibernation Symposium, 2012年08月08日, 英語, ポスター発表
Semmering, Austria, ［国際会議］ - Rodent dynamics and Borrelia spp. Infection rates in Hokkaido.
Taylor, K.R, 高野愛, 川端寛樹, 下鶴倫人, 坪田敏男
第153回日本獣医学会学術集会, 2012年03月27日, 日本語, 口頭発表（一般）
大宮, ［国内会議］ - Behavior and genetic structure of Hokkaido brown bears, Ursus arctos yesoensis in eastern Hokkaido
Hirano, S, Shimozuru, M, Tsubota, T, Fujimoto, Y, Osada, M, Ueno, H, Yamanaka, M
第59回日本生態学会大会, 2012年03月17日, 日本語, 口頭発表（一般）
大津, ［国内会議］ - DNA分析のためのダートバイオプシーによる野生ヒグマの組織標本採取の試み
山中正実, 森脇潤, 坪田敏男, 中西将尚, 下鶴倫人
第17回野生生物保護学会大会, 2011年10月14日, 日本語, ポスター発表
網走, ［国内会議］ - Changes in expression of hepatic genes involved in energy metabolism during the hibernation period in Japanese black bears
Shimozuru, M, Kamine, A, Tsubota, T
20th International Conference on Bear Research & Management, 2011年07月17日, 英語, ポスター発表
Ottawa, Canada, ［国際会議］ - 道東標津町における携帯電話を利用したリアルタイム通信によるヒグマ行動追跡
坪田敏男, 平野沙衣子, 藤本靖, 上野洋一, 長田雅裕, 郡山尚紀, 下鶴倫人
第58回日本生態学会大会, 2011年03月08日, 日本語, 口頭発表（一般）
札幌, ［国内会議］ - ニホンツキノワグマ（Ursus thibetanus unguiculatus）における排卵確率の推定
山中淳史, 山内貴義, 辻元恒徳, 溝口俊夫, 大井徹, 澤田誠吾, 下鶴倫人, 坪田敏男
第16回野生生物保護学会・日本哺乳類学会2010年度合同大会, 2010年09月17日, 日本語, 口頭発表（一般）
岐阜, ［国内会議］ - ツキノワグマからのCytauxzoon原虫の検出と分離
陣内理生, 前橋克彦, 平田晴之, 岩崎いづみ, 中嶋瑠衣, 藤澤幸平, 寺田裕, 下鶴倫人, 坪田敏男, 石原智明
第150回日本獣医学会学術集会, 2010年09月16日, 日本語, 口頭発表（一般）
帯広, ［国内会議］ - 北海道における雄アライグマの性成熟時期の解明
奥山みなみ, 福井大祐, 中村亮平, 高橋伸広, 下鶴倫人, 坪田敏男
第103回日本繁殖生物学会, 2010年09月02日, 日本語, 口頭発表（一般）
十和田, ［国内会議］ - Changes in biochemical values of captive Japanese black bears during active and hibernation phases
Kamine, A, Iibuchi, R, Shimozuru, M, Tsubota, T
19th International Conference on Bear Research & Management, 2010年05月18日, 英語, ポスター発表
Tbilisi, Georgia Republic, ［国際会議］ - ニホンツキノワグマにおける冬眠中の行動および体温変化の解析
下鶴倫人, 吉本拓郎, 坪田敏男
日本哺乳類学会2009年大会, 2009年11月21日, 英語, ポスター発表
台北、台湾, ［国際会議］ - Physiological and endocrinological mechanism for nutritional condition reproduction related to hibernation in the Japanese black bear (Ursus thibetanus japonicus)
Tsubota, T, Nakamura, S, Iibuchi, R, Kamine, A, Shimozuru, M
International Symposium on Conservation of Asiatic Black Bear, 2009年11月17日, 英語, ポスター発表
［国際会議］ - Parasite ecology of primates in Mahale Mountains National Park, Tanzania.
Kooriyama, T, Iwaki, T, Nishida, T, Shimozuru, M, Tsubota, T
The 3rd International Workshop of Asian Society of Zoo and Wildlife Medicine & The 1st Meeting of Korean Society of Zoo and Wildlife Medicine, 2009年08月18日, 英語, 口頭発表（一般）
Seoul, Korea, ［国際会議］ - Changes in plasma testosterone concentration and spermatogenesis around the mating season in juvenile and adult captive raccoons (Procyon lotor).
Okuyama, M, Fukui, D, Takahashi, N, Nakamura R, Shimozuru, M, Tsubota, T
The 3rd International Workshop of Asian Society of Zoo and Wildlife Medicine & The 1st Meeting of Korean Society of Zoo and Wildlife Medicine, 2009年08月18日, 英語, 口頭発表（一般）
Seoul, Korea, ［国際会議］ - TPR profiles, and plasma glucose and fat concentration of male Japanese black bears (Ursus thibetanus japonicus) during hibernation.
Iibuchi, R, Kamine, A, Shimozuru, M, Tsubota, T
The 3rd International Workshop of Asian Society of Zoo and Wildlife Medicine & The 1st Meeting of Korean Society of Zoo and Wildlife Medicine, 2009年08月18日, 英語, 口頭発表（一般）
Seoul, Korea, ［国際会議］ - ツキノワグマにおける精子形成の季節変化とその制御機構
飯渕るり子, 岩永敏彦, 下鶴倫人, 坪田敏男
第147回日本獣医学会学術集会, 2009年04月02日, 日本語, 口頭発表（一般）
宇都宮, ［国内会議］ - ニホンツキノワグマにおける冬眠前の脂肪蓄積に関する代謝メカニズムの解明
加味根あかり, 中村幸子, 飯渕るり子, 山中淳史, 柴田治樹, 下鶴倫人, 坪田敏男
第147回日本獣医学会学術集会, 2009年04月02日, 日本語, 口頭発表（一般）
宇都宮, ［国内会議］ - ニホンツキノワグマにおける血中グルコース動態とインスリン応答の季節変化
加味根あかり, 飯渕るり子, 柴田治樹, 下鶴倫人, 坪田敏男
第146回日本獣医学術集会, 2008年09月24日, 日本語, 口頭発表（一般）
宇都宮, ［国内会議］ - ニホンツキノワグマ（Ursus thibetanus japonicus）における冬眠中の血中代謝関連成分の変化
飯渕るり子, 加味根あかり, 下鶴倫人, 坪田敏男
第146回日本獣医学術集会, 2008年09月24日, 日本語, 口頭発表（一般）
宮崎, ［国内会議］ - ニホンツキノワグマ（Ursus thibetanus japonicus）の有害捕獲数と捕獲個体の栄養状態に関連はあるのか？
山中淳史, 浅野玄, 鈴木正嗣, 溝口俊夫, 下鶴倫人, 坪田敏男
第14回日本野生動物医学会大会, 2008年09月03日, 日本語, 口頭発表（一般）
神戸, ［国内会議］
共同研究・競争的資金等の研究課題
- 冬眠動物の“衰えない筋肉”をヒントにした新たな骨格筋萎縮予防戦略の開発
科学研究費助成事業
2022年04月01日 - 2026年03月31日
宮崎 充功, 坪田 敏男, 山口 良文, 渡邊 正知, 下鶴 倫人
日本学術振興会, 基盤研究(B), 広島大学, 22H03439 - ヒグマとシカを宿主とするマダニ媒介性感染症－感染率を決めるのは宿主かベクターか？
科学研究費助成事業
2021年04月01日 - 2024年03月31日
坪田 敏男, 佐鹿 万里子, 下鶴 倫人, 中尾 亮, MOHAMED MOUSTAFA
日本学術振興会, 基盤研究(B), 北海道大学, 21H02350 - 骨格筋萎縮耐性を獲得させる冬眠誘導性生理活性物質の探索
科学研究費助成事業
2020年07月30日 - 2023年03月31日
宮崎 充功, 坪田 敏男, 下鶴 倫人
【本研究成果のポイント】●冬眠期において採取したツキノワグマ血清と共にヒト筋肉細胞を培養すると、筋肉細胞の総タンパク質量を増加させることを明らかにした。●この筋肉細胞の総タンパク質量の増加は、冬眠期クマ血清の添加が筋タンパク質分解系を抑制することで達成される可能性を示した。●これらの成果は、長期間の不活動・栄養不良を経験し、それでもなお筋肉が衰えないという冬眠動物の特徴を説明するものであり、将来的にはヒトの寝たきり防止や効果的なリハビリテーション手法の開発につながることが期待される。
【研究成果の概要】本研究では、実験的に採取したツキノワグマ血清をヒト骨格筋培養細胞に添加するというin vitroの解析系を用いた検討を行ったところ、冬眠期クマ血清の添加により、骨格筋細胞における総タンパク質量が増加することを確認しました。また冬眠期クマ血清の添加は、タンパク質合成系の制御系であるAkt/mTOR系の制御に関与する可能性があること、またタンパク質分解系因子の一つであるMuRF1の発現量を転写因子FOXO3aの制御系を介して調節することなどを明らかにした。
【今後の研究の展開】冬眠動物は、生命維持のために一定程度のエネルギー代謝を維持しながら長期間の不活動・栄養不良を経験し、それでもなお筋肉がほとんど衰えないという、不思議な形質を備えている。本研究により、冬眠期のクマ血清に存在する「何らかの因子」がヒト骨格筋培養細胞のタンパク質代謝を制御し、筋肉量維持に貢献する可能性が示された。しかしながら、この「何らかの因子」の特定には現在も至っていない。この因子の特定を含め、冬眠動物が有する「使わなくても衰えない筋肉」という未解明の仕組みを明らかにすることで、最終的にはヒトの寝たきり防止や効果的なリハビリテーション手法の開発などが期待される。
日本学術振興会, 挑戦的研究(萌芽), 20K21769 - 増えすぎたシカはヒグマにとって恵みか災いか？ ヒグマとシカの種間関係に関する研究
科学研究費助成事業 基盤研究(C)
2019年04月 - 2022年03月
下鶴 倫人
日本学術振興会, 基盤研究(C), 北海道大学, 研究代表者, 競争的資金, 19K06833 - 遺産価値向上に向けた知床半島における大型哺乳類の保全管理手法の開発
環境研究総合推進費
2019年04月 - 2021年03月
宇野裕之(研究代表者), 下鶴倫人(サブテーマリーダー), 石名坂豪(サブテーマリーダー)
環境再生保全機構, 研究分担者, 競争的資金 - ツキノワグマにおける冬眠中の体温調節機構の解明－ふるえ産熱か非ふるえ産熱か－
科学研究費助成事業 基盤研究(B)
2017年04月01日 - 2020年03月31日
坪田 敏男, 宮崎 充功, 佐鹿 万里子, 下鶴 倫人, MOHAMED MOUSTAFA, 岡松 優子
２年目となった2018年度は、４月に研究計画について北秋田市観光課担当者と打合せを行った上で、５月より実験を開始した。昨年度オス・ツキノワグマ７頭に埋め込んだ体温、心拍数および活動量モニタリング用デバイス（DST centi-HRT ACT, STARODDI）を取り出して、データを吸い出した。７月には、去勢オス３頭（１頭はこの時に去勢手術実施）に同デバイスを胸部皮下に埋め込んだ。続いて１１月に、正常オス４頭に同デバイスおよびi-Buttonを胸部および頸部皮下に埋め込むととともに、血液および脂肪組織を採取した。さらに、１月および３月に同じ正常オス４頭より血液および脂肪組織を採取した。得られた血液を使って性ホルモン測定を行った。また、脂肪組織を使って細胞培養および非ふるえ産熱に関わる代謝系の遺伝子およびタンパク質発現について調べた。さらに、冬眠明け時期に北海道標津町にて捕殺したヒグマの頸部脂肪組織を採取して、飼育下実験と同様に、白色脂肪組織による非ふるえ産熱の有無について調べている。
日本学術振興会, 基盤研究(B), 北海道大学, 17H03936 - ヒグマに学ぶ健康 〜急激な肥満と長期の絶食を可能にする腸内細菌叢の解明〜
研究助成（一般）
2019年04月 - 2020年03月
秋山記念生命科学振興財団, 研究代表者, 競争的資金 - 知床国立公園とその周辺におけるヒグマと人の共存の道を探る調査研究
富士フィルムグリーンファンド
2017年04月 - 2019年03月
下鶴倫人
富士フィルム, 研究代表者, 競争的資金 - クマにおける冬眠中のエネルギー代謝制御に関わる血中分泌型microRNAの探索
科学研究費補助金 基盤研究（C）
2016年04月 - 2019年03月
下鶴倫人
文部科学省, 研究代表者, 競争的資金 - 地球温暖化による食物環境の変化はヒグマの生態にどのような影響を及ぼすのか？
三井物産環境基金
2015年04月 - 2018年03月
下鶴倫人
三井物産, 研究代表者, 競争的資金 - ベクターコントロールのための薬剤散布の生態系およびヒト健康に与える影響評価
科学研究費助成事業
2014年04月01日 - 2017年03月31日
池中 良徳, 石塚 真由美, 中山 翔太, 水川 葉月, 櫻井 達也, 宮原 裕一, 下鶴 倫人, 中山 翔太, 水川 葉月
WHOはハマダラカの駆除のためDDTの使用を推進しており、アフリカ等の途上国を中心に、室内残留散布として使用されている。一方、DDTは難分解性で環境中の長期間残留が知られ、発がんや内分泌撹乱などの生体影響も疑われている。当該研究では、南アフリカ共和国・クワズルナタール州をベクターコントロールモデル地域とし、DDT・IRSの潜在的な毒性リスク評価を行った。
ニワトリ、ラット、野生鳥類の卵のを採取し、その分析を行った結果、いずれの試料からも極めて高濃度のDDT蓄積が観察された。本研究結果は、環境負荷が小さいとされるDDT・IRSにおける、潜在的な毒性影響および環境リスクの存在を示唆していた。
日本学術振興会, 基盤研究(B), 北海道大学, 26304043 - 冬眠動物はなぜ寝たきりにならないのか？ －骨格筋萎縮耐性獲得の分子基盤の解明－
科学研究費助成事業 挑戦的萌芽研究
2014年04月01日 - 2017年03月31日
宮崎 充功, 坪田 敏男, 下鶴 倫人
本研究では、「冬眠」を長期間の寝たきり状態と仮定して、冬眠動物（ツキノワグマ）がどのような仕組みを利用して骨格筋量を維持しているのか、筋肉細胞の中のタンパク質や遺伝子の働きに注目して解析しました。その結果、骨格筋量の維持に影響を与える因子のうち、筋タンパク質合成を促進する命令系統が冬眠後の筋肉で活性化されていることや、筋肉が大きくなり過ぎないようリミッターの役割をしている遺伝子の働きが冬眠中に抑えられていること、などがわかりました。
日本学術振興会, 挑戦的萌芽研究, 北海道医療大学, 26560369 - 絶食・低代謝状態における繁殖生理メカニズムの解明―冬眠するクマをモデルとして―
科学研究費助成事業 基盤研究(C)
2014年04月 - 2017年03月
坪田 敏男, 佐鹿 万里子, 下鶴 倫人
北秋田市阿仁クマ牧場（くまくま園）で飼育されている５頭の成熟雌ツキノワグマを対象にして、胸部皮下に心拍・体温測定用ロガー（DST milli-HRT、Star:Oddi）を埋め込み、冬眠前から冬眠後の約６ヶ月間、心拍数および皮下体温をモニタリングした。１月には超音波画像診断装置をを使って妊娠診断を行った。特筆すべき研究成果として、妊娠個体の体温と心拍数の関係において、冬眠前時期（着床遅延期間）には両者はおよそ24時間周期の変化を示したが、冬眠導入後の胎子発育時期には高体温を維持しながら心拍数は一過性のピークを示し、出産後には体温と心拍数が同調して周期性のない数日間隔での増減を繰り返した。
日本学術振興会, 基盤研究(C), 北海道大学, 研究分担者, 26450455 - なぜクマは冬眠中に骨格筋が萎縮しないのか？ —冬眠中の筋蛋白同化／異化様式の解明—
科学研究費補助金 若手研究（Ｂ）
2014年04月 - 2016年03月
下鶴倫人
文部科学省, 研究代表者, 競争的資金 - クマはなぜ冬眠できるのか? ー冬眠中のエネルギー代謝機構の解明ー
科学研究費補助金(若手研究(B))
2011年 - 2011年
下鶴 倫人
本研究ではツキノワグマにおいて冬眠期に生じる代謝機構の変化を明らかにすることを目的し、肝臓・骨格筋・脂肪におけるエネルギー代謝関連遺伝子の発現解析を行った。この結果、冬眠中は糖新生に関与する酵素の遺伝子発現量が肝臓で増加し、一方ですべての組織において解糖および脂肪合成に関わる遺伝子発現量が低下することが明らかとなった。冬眠中の血糖値は活動期と同程度に維持されており、ケトーシスなどの代謝障害は生じていなかった。このようにクマは各組織における代謝様式を調節することで冬眠中に効率良くエネルギーを産生する仕組みを有していることが明らかとなった。
文部科学省, 若手研究(B), 北海道大学, 研究代表者, 競争的資金, 23780277 - なぜクマは肥満でも脂肪肝にならないのか?-冬眠前時期の体脂肪蓄積メカニズムの解明
科学研究費補助金(基盤研究(C))
2009年 - 2011年
坪田 敏男, 下鶴 倫人
本研究では、なぜクマは体脂肪率30～40%の肥満状態でも脂肪肝や高脂肪血症を発症しないのか、その特徴的な体脂肪蓄積メカニズムを明らかにすることを目的にして次のような実験を行った。実験は、秋田県北秋田市マタギの里阿仁クマ牧場において、5～11月にかけて月1回行った。1回の実験に4頭のツキノワグマを用いた。塩酸チレタミンと塩酸ゾラゼパムの混合薬(Zoletil 100、Virbac、フランス)9mg/kgにより不動化を行い、麻酔状態下で以下のサンプリングおよび実験を行った。なお、使用したツキノワグマは前日の夕方5:00以降は絶食状態とした。1)基底レベルの血中グルコース、インスリン、中性脂肪、コレステロールおよび遊離脂肪酸濃度を測定した。血中グルコースおよびインスリン濃度には月別の変化は見られなかったが、血中中性脂肪、コレステロールおよび遊離脂肪酸濃度は冬眠前に減少する傾向にあった。2)グルコース投与後0～180分までおよそ30分間隔で血中グルコースおよびインスリン濃度を測定した。その結果、グルコース投与後血中グルコース濃度は一過性に上昇した後、徐々に減少し180分後にはおよそ基底値まで減少した。減少のスピードに月別変化はみられなかった。一方、血中インスリン濃度はグルコース投与直後から上昇し、およそ30分でピークに達した。この時のインスリン上昇度は11月で最も著しい傾向を示した(...
文部科学省, 基盤研究(C), 北海道大学, 連携研究者, 競争的資金, 21580355 - ツキノワグマにおける冬眠に関わる自律神経機構の解明
公募型プロジェクト研究等支援経費
2008年04月 - 2009年03月
下鶴倫人
北海道大学, 研究代表者, 競争的資金
