Researcher Database

Munetaka Shimizu
Faculty of Fisheries Sciences Marine Life Science Marine Chemical Resource Development
Associate Professor

Researcher Profile and Settings


  • Faculty of Fisheries Sciences Marine Life Science Marine Chemical Resource Development

Job Title

  • Associate Professor


Research funding number

  • 90431337

J-Global ID

Research Interests

  • 成長   サケ科魚類   ホルモン   インスリン様成長因子   内分泌   組換え蛋白   cDNAクローニング   発現量測定   生理   結合蛋白   発現解析   

Research Areas

  • Life sciences / Aquaculture

Academic & Professional Experience

  • 2017/03 - Today Hokkaido University Faculty of Fisheries Sciences
  • 2006/08 - 2017/02 Hokkaido University Faculty of Fisheries Sciences


  • 1993/04 - 1997/03  Hokkaido University
  • 1991/04 - 1993/03  Hokkaido University
  • 1987/04 - 1991/03  Hokkaido University  School of Fisheries Sciences

Association Memberships


Research Activities

Published Papers

  • Shotaro Suzuki, Eisuke Takahashi, Tom Ole Nilsen, Nobuto Kaneko, Hirokazu Urabe, Yuki Ugachi, Etsuro Yamaha, Munetaka Shimizu
    AQUACULTURE 526 0044-8486 2020/09 [Refereed][Not invited]
    We induced season independent smolts in masu salmon (Oncorhynchus masou) by rearing juveniles under an advanced photoperiod (AP) in which LD15:9 was interrupted by LD9:15 from June for 4 months. AP fish showed higher degree of skin slivering from November than fish reared under a simulated natural photoperiod (SNP) and became larger in length and lower in condition factor in January. Gill Na+,K+-ATPase in AP fish started increasing in November and peaked in December to typical spring smolt levels while it remained low in SNP fish. In addition, AP fish had higher hypo-osmoregulatory ability than SNP fish, as judged by the lower serum sodium and chloride concentrations 48 h after seawater transfer. Serum levels of insulin-like growth factor (IGF)-I and IGF-binding protein (IGFBP)-1b, components of the somatotropic axis, in AP fish peaked in November and January, respectively. Serum IGFBP-1b levels were increased 48 h after transfer to 70% seawater in both groups, suggesting that it is not a quantitative index of hypo-osmoregulatory ability in the short-term but a marker of osmotic stress. The present study showed that off-season smolts could be induced in underyearling masu salmon by a square-wave photoperiod, and off-season smolts showed morphological and physiological changes comparable to yearling spring smolts. Increased levels of circulating IGF-I and IGFBP-1b in smolting fish suggest that these endocrine parameters are involved in the smoltification process.
  • Bernat Morro, Pablo Balseiro, Amaya Albalat, Simon Mackenzie, Cindy Pedrosa, Tom O. Nilsen, Shotaro Suzuki, Munetaka Shimizu, Harald Sveier, Marnix Gorissen, Lars O. E. Ebbesson, Sigurd O. Handeland
    AQUACULTURE 519 0044-8486 2020/03 [Refereed][Not invited]
  • Tharmini Kalananthan, Koji Murashita, Ivar Ronnestad, Mitsumasa Ishigaki, Kota Takahashi, Marta S. Silva, Yuki Wakabayashi, Floriana Lai, Munetaka Shimizu, Tom O. Nilsen, Enrique Pino Martinez, Ana S. Gomes
    FRONTIERS IN PHYSIOLOGY 11 1664-042X 2020/02 [Refereed][Not invited]
    The orexigenic agouti-related protein (AgRP) and the anorexigenic pro-opiomelanocortin (POMC) are crucial players in the control of feed intake in vertebrates, yet their role in teleosts has not been fully established. Triplicate groups of Atlantic salmon (Salmo salar) post smolts were subjected to (1) fasting for 3 days (fast) and (2) normal feeding (fed), resulting in a significant (p < 0.05) upregulation of hypothalamic agrp1 transcripts levels in the fast group. Moreover, the mRNA abundance of agrp1 was significantly (p < 0.05) correlated with the stomach dry weight content. Corresponding inverse patterns were observed for pomca2, albeit not statistically significant. No significant differences were found for the other paralogues, agrp2 and pomca1 and b, between fed and fast groups. The significant correlation between stomach fullness and agrp1 mRNA expression suggests a possible link between the stomach filling/distension and satiety signals. Our study indicates that hypothalamic agrp1 acts as an orexigenic signal in Atlantic salmon.
  • Nobuto Kaneko, Tom Ole Nilsen, Hanae Tanaka, Akihiko Hara, Munetaka Shimizu
    Insulin-like growth factor binding protein (IGFBP)-1a is one of three major circulating forms in salmon and induced under catabolic conditions. However, there is currently no immunoassay available for this form because of a lack of standard and specific antibodies. We developed a time-resolved fluoroimmunoassay (TR-FIA) for salmon IGFBP-1a using recombinant protein for labeling, an assay standard, and production of antiserum. The TR-FIA had a low cross-reactivity (3.6%) with IGFBP-1b, another major form in the circulation. Fasting for 4 wk had no effect on serum immunoreactive (total) IGFBP-1a levels in yearling masu salmon, whereas 6-wk fasting significantly increased it. There was a significant, but weak, negative relationship between serum total IGFBP-1a level and individual growth rate (r(2) = 0.12, P = 0.01). We next developed a ligand immuno-functional assay (LIFA) using europium-labeled IGF-I to quantify intact IGFBP-1a. In contrast to total IGFBP-1a, serum intact IGFBP-1a levels increased after 4 wk of fasting, and refeeding for 2 wk restored it to levels similar to those of the fed control. Serum intact IGFBP-1a levels showed a significant negative correlation with individual growth rate (r(2) = 0.52, P < 0.001), which was as good as that of IGFBP-1b. Our findings using newly developed TR-FIA and LIFA suggest that regulation of intact IGFBP-1a levels has an important effect on growth in salmon and that intact IGFBP-1a is a negative index of salmon growth.
  • Nobuto Kaneko, Meredith L. Journey, Chrys M. Neville, Marc Trudel, Brian R. Beckman, Munetaka Shimizu
    FISH PHYSIOLOGY AND BIOCHEMISTRY 45 (6) 1867 - 1878 0920-1742 2019/12 [Refereed][Not invited]
    Monitoring the growth of salmon during their early marine phase provides insights into prey availability, and growth rates may be linked to risks of size-dependent mortality. However, the measurement of growth rate is challenging for free-living salmon in the ocean. Insulin-like growth factor (IGF)-I is a growth-promoting hormone that is emerging as a useful index of growth in salmon. In addition, laboratory-based studies using coho salmon have shown that one of circulating IGF-binding proteins (IGFBPs), IGFBP-1b, is induced by fasting and thus could be used as an inverse index of growth and/or catabolic state in salmon. However, few studies have measured plasma levels of IGFBP-1b in salmon in the wild. We measured plasma IGFBP-1b levels for postsmolt coho salmon collected in the Strait of Georgia and surrounding waters, British Columbia, Canada, and compared regional differences in IGFBP-1b to ecological information such as seawater temperature and stomach fullness. Plasma IGFBP-1b levels were the highest in fish from Eastern Johnstone Strait and relatively high in Queen Charlotte Strait and Western Johnstone Strait, which was in good agreement with the poor ocean conditions for salmon hypothesized to occur in that region. The molar ratio of plasma IGF-I to IGFBP-1b, a theoretical parameter of IGF-I availability to the receptor, discriminated differences among regions better than IGF-I or IGFBP-1b alone. Our data suggest that plasma IGFBP-1b reflects catabolic status in postsmolt coho salmon, as highlighted in fish in Eastern Johnston Strait, and is a useful tool to monitor negative aspects of salmon growth in the ocean.
  • Effect of different photoperiod regimes on the smoltification and seawater adaptation of seawater-farmed rainbow trout (Oncorhynchus mykiss): Insights from Na+,K+-ATPase activity and transcription of osmoregulation and growth regulation genes
    Morro B, Balseiro P, Albalat A, Pedrosa C, Mackenzie S, Nakamura S, Shimizu M, Nilsen TO, Sveier H, Ebbesson LO, Handeland SO
    Aquaculture 507 282 - 292 2019/04 [Refereed][Not invited]
  • Kaneko N, Torao M, Koshino Y, Fujiwara M, Miyakoshi Y, Shimizu M
    General and comparative endocrinology 0016-6480 2019/01 [Refereed][Not invited]
  • Cleveland Beth M, Yamaguchi Ginnosuke, Radler Lisa M, Shimizu Munetaka
    SCIENTIFIC REPORTS 8 2045-2322 2018/10/30 [Refereed][Not invited]
  • Inatani Yu, Ineno Toshinao, Sone Shiori, Matsumoto Naoto, Uchida Katsuhisa, Shimizu Munetaka
    JOURNAL OF FISH BIOLOGY 93 (3) 490 - 500 0022-1112 2018/09 [Refereed][Not invited]
  • Balseiro Pablo, Moe Oyvind, Gamlem Ingrid, Shimizu Munetaka, Sveier Harald, Nilsen Tom O, Kaneko Nobuto, Ebbesson Lars, Pedrosa Cindy, Tronci Valentina, Nylund Are, Handel, Sigurd O
    JOURNAL OF FISH BIOLOGY 93 (3) 567 - 579 0022-1112 2018/09 [Refereed][Not invited]
  • Tanaka H, Oishi G, Nakano Y, Mizuta H, Nagano Y, Hiramatsu N, Ando H, Shimizu M
    General and comparative endocrinology 257 184 - 191 0016-6480 2018/02 [Refereed][Not invited]
  • Munetaka Shimizu, Walton W. Dickhoff
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 252 150 - 161 0016-6480 2017/10 [Refereed][Not invited]
    Insulin-like growth factor binding proteins (IGFBPs) play crucial roles in regulating the availability of IGFs to receptors and prolong the half-lives of IGFs. There are six IGFBPs present in the mammalian circulation with IGFBP-3 being most abundant. In mammals IGFBP-3 is the major carrier of circulating IGFs, facilitated by forming a ternary complex with IGF and an acid-labile subunit (ALS). IGFBP-1 is generally inhibitory to IGF action by preventing it from interacting with its receptors. In teleosts, the third-round of vertebrate whole genome duplication created paralogs of each IGFBP, except IGFBP-4. In the fish circulation, three major IGFBPs are typically detected at molecular ranges of 20-25, 28-32 and 40-50 kDa. However, their identities are not well established. Three major circulating IGFBPs in Chinook salmon have been identified through protein purification and cDNA cloning. Salmon 28- and 22-kDa IGFBPs are coorthologs of IGFBP-1, termed IGFBP-1a and-1b, respectively. They are induced under catabolic conditions such as stress and fasting but their responses are somewhat different, with IGFBP-1b being the most sensitive of the two. Cortisol stimulates production and secretion of these IGFBP-1 subtypes while, unlike in mammals, insulin may not be a primary suppressor. Salmon 41-kDa IGFBP, a major carrier of IGF-I, is not IGFBP-3, as might be expected extrapolating from mammals, but is in fact IGFBP-2b. Salmon IGFBP-2b levels in plasma are high when fish are fed, and GH treatment increases its circulating levels similar to mammalian IGFBP-3. These findings suggest that salmon IGFBP-2b acquired the role and regulation similar to mammalian IGFBP-3. Multiple replications of fish IGFBPs offer a unique opportunity to investigate molecular evolution of IGFBPs. (C) 2017 Published by Elsevier Inc.
  • Natsumi Taniyama, Nobuto Kaneko, Yu Inatani, Yasuyuki Miyakoshi, Munetaka Shimizu
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 236 146 - 156 0016-6480 2016/09 [Refereed][Not invited]
    Insulin-like growth factor (IGF)-I, IGF-binding protein (IGFBP)-1 and RNA/DNA ratio are endocrine and biochemical parameters used as growth indices in fish, however, they are subjected to environmental modulation. Chum salmon (Oncorhynchus keta) migrate from freshwater (FW) to seawater (SW) at fry/juvenile stage weighing around 1 g and suffer growth-dependent mortality during the early phase of their marine life. In order to reveal environmental modulation of the IGF/IGFBP system and establish a reliable growth index for juvenile chum salmon, we examined effects of SW transfer and fasting on IGF-I, IGFBP-1 and RNA/DNA ratio, and correlated them to individual growth rate. Among serum IGF-I, liver and muscle igf-1, igfbp-1a, igfbp-1b and RNA/DNA ratio examined, muscle RNA/DNA ratio and muscle igfbp-1a responded to SW transfer. Serum IGF-I, liver igf-1 and liver RNA/DNA ratio were sensitive to nutritional change by being reduced in 1 week in both FW and SW while muscle igf-1 was reduced 2 weeks after fasting. In contrast, igfbp-1a in both tissues was increased by 2 weeks of fasting and igfbp-1b in the liver of SW fish was increased in 1 week. These results suggest that the sensitivity of igf-1 and igfbp-1s to fasting differs between tissues and subtypes, respectively. When chum salmon juveniles in SW were marked and subjected to feeding or fasting, serum IGF-I showed the highest correlation with individual growth rate. Liver igfbp-1a and -1b, and muscle igf-1 exhibited moderate correlation coefficients with growth rate. These results show that serum IGF-I is superior to the other parameters as a growth index in juvenile chum salmon in term of its stability to salinity change, high sensitivity to fasting and strong relationship with growth rate. On the one hand, when collecting blood from chum salmon fry/juveniles is not practical, measuring liver igfbp-1a and -1b, or/and muscle igf-1 is an alternative. (C) 2016 Elsevier Inc. All rights reserved.
  • Tomonori Kuwada, Tetsuya Tokuhara, Munetaka Shimizu, Goro Yoshizaki
    FISHERIES SCIENCE 82 (1) 59 - 71 0919-9268 2016/01 [Refereed][Not invited]
    The present study retrospectively examined relationships between growth trajectory and smolting in order to identify the key regulators in commencement of smolting using groups of all-female homozygous clonal amago salmon. We found that (1) regardless of specific growth rate, the majority of fish above the threshold size (12-13 g) by the end of the decision window (early fall) became smolt in the future; (2) even if fish smaller than the threshold size during the decision window exceeded that size afterwards, they were not recruited to smolt; (3) smolting of fish that attained sufficient size during the decision window could not be suppressed by subsequent restriction of growth rate; (4) smaller fish that had not attained the threshold size during the decision window could not smoltify, even though they showed faster growth rates than that of future smolt during/after the decision window. Taken together, these findings indicated that fish mass by the end of the decision window was responsible for the determination of whether individual amago salmon could smoltify or not and that the faster growth rates observed in future smolt after the decision window occurred as a result of commitment of smoltification.
  • Ernst M. Hevroy, Christian K. Tipsmark, Sofie C. Remo, Tom Hansen, Miki Fukuda, Thomas Torgersen, Vibeke Vikesa, Pal A. Olsvik, Rune Waagbo, Munetaka Shimizu
    A comparative experiment with Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) postsmolts was conducted over 35 days to provide insight into how growth, respiration, energy metabolism and the growth hormone (GH) and insulin-like growth factor 1 (IGF-1) system are regulated at elevated sea temperatures. Rainbow trout grew better than Atlantic salmon, and did not show reduced growth at 19 degrees C. Rainbow trout kept at 19 degrees C had increased blood hemoglobin concentration compared to rainbow trout kept at 13 degrees C, while salmon did not show the same hemoglobin response due to increased temperature. Both species showed reduced length growth and decreased muscle glycogen stores at 19 degrees C. Circulating IGF-1 concentration was higher in rainbow trout than in Atlantic salmon, but was not affected by temperature in either species. Plasma IGF-binding protein 1b (IGFBP-1b) concentration was reduced in Atlantic salmon reared at 19 degrees C after 15 days but increased in rainbow trout at 19 degrees C after 35 days. The igfbp1b mRNA level in liver showed a positive correlation to plasma concentrations of glucose and IGFBP-1b, suggesting involvement of this binding protein in carbohydrate metabolism at 19 degrees C. At this temperature muscle igfbp1a mRNA was down-regulated in both species. The muscle expression of this binding protein correlated negatively with muscle igf1 and length growth. The plasma IGFBP-1b concentration and igfbp1b and igfbp1a expression suggests reduced muscle igf1 signaling at elevated temperature leading to glucose allostasis, and that time course is species specific due to higher thermal tolerance in rainbow trout. (C) 2015 Elsevier Inc. All rights reserved.
  • Miki Fukuda, Nobuto Kaneko, Kohei Kawaguchi, Ernst M. Hevroy, Akihiko Hara, Munetaka Shimizu
    In salmon plasma/serum, three major insulin-like growth factor binding proteins (IGFBPs) are consistently detected at 22-, 28- and 41-kDa. The 22-kDa form has been identified as IGFBP-1b and shown to increase under catabolic conditions. We developed a competitive time-resolved fluoroimmunoassay (TR-FIA) for salmon IGFBP-1b. Purified salmon IGFBP-1b was used for biotin-labeling, assay standard and antiserum production. The TR-FIA did not cross-react with the 41-kDa form (IGFBP-2b) but showed 3% cross-reactivity with the 28-kDa form (IGFBP-1a). It measured IGFBP-1b levels as low as 0.4 ng/ml, and ED80 and ED20 were 0.9 and 24.6 ng/ml, respectively. There appears to be little interference by IGF-I. Using the TR-FIA, serum IGFBP-1b levels were measured in individually-tagged underyearling masu salmon fed or fasted for 5 weeks, or fasted for 3 weeks followed by refeeding for 2 weeks. Fasting for 3 weeks significantly increased circulating IGFBP-1b levels, while it returned to the basal levels after prolonged fasting for additional 2 weeks. Serum IGFBP-1b level negatively correlated with body weight, condition factor, specific growth rate and serum IGF-I level. During parr-smolt transformation of masu salmon, average circulating IGFBP-1b levels were the highest in May. There was a positive correlation between serum IGFBP-1b and IGF-I, which is in contrast to that in the fasting/feeding experiment. IGFBP-1b also showed a positive relationship with gill Na+, K+-ATPase activity. These results suggest that the relationship between circulating IGFBP-1b and IGF-I during smoltification differs from that during fasting and IGFBP-1b may play a role in the development of hypoosmoregulatory ability. (C) 2015 Elsevier Inc. All rights reserved.
  • Nobuto Kaneko, Natsumi Taniyama, Yu Inatani, Yuta Nagano, Makoto Fujiwara, Mitsuru Torao, Yasuyuki Miyakoshi, Munetaka Shimizu
    FISH PHYSIOLOGY AND BIOCHEMISTRY 41 (4) 991 - 1003 0920-1742 2015/08 [Refereed][Not invited]
    Chum salmon (Oncorhynchus keta) migrate to the ocean in their first spring, and growth during early marine life is critical for survival. We examined the validity of circulating IGF-I and muscle RNA/DNA ratio as indices of growth rate using individually tagged juvenile chum salmon fed or fasted for 10 days. Serum IGF-I level was highly, positively correlated with individual growth rate. Muscle RNA/DNA ratio also showed a positive correlation, but its relation was not as high as that of IGF-I. We next measured these physiological parameters in chum salmon juveniles caught at river, estuary, port and nearshore of the northeastern Hokkaido, Japan, from May to June in 2013 and 2014, respectively. In both years, there was a trend that serum IGF-I levels were high in nearshore fish and low in river/estuarine fish in June. In contrast, muscle RNA/DNA ratio showed no clear temporal and spatial patterns. The present study shows that circulating IGF-I can be used as a growth index in juvenile chum salmon. Monitoring growth status using serum IGF-I suggests that growth of juvenile chum salmon in the survey area was activated when they left the coast.
  • Nobuto Kaneko, Anai Iijima, Takahiro Shimomura, Takuro Nakajima, Haruka Shimura, Hajime Oomori, Hirokazu Urabe, Akihiko Hara, Munetaka Shimizu
    FISHERIES SCIENCE 81 (4) 643 - 652 0919-9268 2015/07 [Refereed][Not invited]
    We compared profiles of serum insulin-like growth factor (IGF)-I levels during smoltification of masu salmon reared under different environments, hatcheries and growth histories. Masu salmon from the Kenichi River in Hokkaido showed a sharp increase in serum IGF-I from April to May, followed by a peak of gill Na+,K+-ATPase (NKA) activity. Fish at Kumaishi Hatchery had an IGF-I profile similar to that of the river fish, while the increase in gill NKA was lower. At Shimamaki Hatchery, interval feeding during winter appeared to suppress the spring IGF-I peak. At Kumaishi Hatchery, a difference in size during smoltification affected IGF-I levels at release, but the numbers of adults that returned to the release site were not significantly different. In the following year, three release groups differing in winter size and/or spring growth (Large-High, Large-Low and Small-High) were created. Large-High and Small-High fish showed a higher IGF-I peak than Large-Low fish in April, while smolt-to-adult return of Large-High fish was highest. These results suggest that in smolting masu salmon in freshwater, circulating IGF-I level alone is not a predictor of long-term survival in seawater. However, since growth history in freshwater affected the smolt-to-adult return, optimizing rearing conditions is a critical component of hatchery releases for masu salmon.
  • Takuro Nakajima, Haruka Shimura, Miyuki Yamazaki, Yasuhiro Fujioka, Kazuhiro Ura, Akihiko Hara, Munetaka Shimizu
    Landlocking of salmon relaxes selective pressures on hypoosmoregulatory ability (seawater adaptability) and may lead to the abandonment of its physiological system. However, little is known about the mechanism and consequence of the process. Biwa salmon is a strain/subspecies of Oncorhynchus masou that has been landlocked in Lake Biwa for an exceptionally long period (about 500,000 years) and has low ability to adapt to seawater. We compared activity of gill Na+, K+-ATPase (NKA) of Biwa salmon with those of anadromous strains of the same species (masu and amago salmon) during downstream migration periods and after exogenous hormone treatment. Gill NKA activity in anadromous strains increased during their migration periods, while that in Biwa salmon remained low. However, treatments of Biwa salmon with growth hormone (GH) and cortisol increased gill NKA activity. Cortisol treatment also improved the whole body seawater adaptability of Biwa salmon. Receptors for GH and cortisol responded to hormonal treatments, whereas their mRNA levels during downstream migration period were essentially unchanged in Biwa salmon. Circulating levels of cortisol in masu salmon showed a peak during downstream migration period, while no such increase was seen in Biwa salmon. The present results indicate that Biwa salmon can improve its seawater adaptability by exogenous hormonal treatment, and hormone receptors are capable of responding to the signals. However, secretion of the endogenous hormone (cortisol) was not activated during the downstream migration period, which explains, at least in part, their low ability to adapt to seawater.
    Comp Biochem Physiol A 165 (2) 191 - 198 1095-6433 2013/06 [Refereed][Not invited]
  • Ernst M. Hevroy, Christine Hunskar, Stefan de Gelder, Munetaka Shimizu, Rune Waagbo, Olav Breck, Harald Takle, Sissel Sussort, Tom Hansen
    Growth regulation in adult Atlantic salmon (1.6 kg) was investigated during 45 days in seawater at 13, 15, 17, and 19 A degrees C. We focused on feed intake, nutrient uptake, nutrient utilization, and endocrine regulation through growth hormone (GH), insulin-like growth factors (IGF), and IGF-binding proteins (IGFBP). During prolonged thermal exposure, salmon reduced feed intake and growth. Feed utilization was reduced at 19 A degrees C after 45 days compared with fish at lower temperatures, and body lipid storage was depleted with increasing water temperature. Although plasma IGF-1 concentrations did not change, 32-Da and 43-kDa IGFBP increased in fish reared at a parts per thousand currency sign17 A degrees C, and dropped in fish reared at 19 A degrees C. Muscle igf1 mRNA levels were reduced at 15 and 45 days in fish reared at 15, 17, and 19 A degrees C. Muscle igf2 mRNA levels did not change after 15 days in response to increasing temperature, but were reduced after 45 days. Although liver igf2 mRNA levels were reduced with increasing temperatures after 15 and 45 days, temperature had no effect on igf1 mRNA levels. The liver igfbp2b mRNA level, which corresponds to circulating 43-kDa IGFBP, exhibited similar responses after 45 days. IGFBP of 23 kDa was only detected in plasma in fish reared at 17 A degrees C, and up-regulation of the corresponding igfbp1b gene indicated a time-dependent catabolic response, which was not observed in fish reared at 19 A degrees C. However, higher muscle ghr mRNA levels were detected in fish at 17 and 19 A degrees C than in fish at lower temperatures, indicating lipolytic regulation in muscle. These results show that the reduction of muscle growth in large salmon is mediated by decreased igf1 and igf2 mRNA levels in addition to GH-associated lipolytic action to cope with prolonged thermal exposure. Accordingly, 13 A degrees C appears to be a more optimal temperature for the growth of adult Atlantic salmon at sea.
  • David C. Metzger, J. Adam Luckenbach, Munetaka Shimizu, Brian R. Beckman
    Feeding, fasting and re-feeding is a common experimental paradigm for studying growth endocrinology. Herein we demonstrate dynamic changes in the livers of coho salmon under these conditions and how changes in liver composition can influence quantification and interpretation of liver gene expression data. A three-week fast resulted in decreases in hepatosomatic index (liver size), liver glycogen content, and liver DNA concentration. In addition, significant differences were found in liver transcript levels from fed and fasted fish for the reference genes, arp and ef1a, when these were normalized to total RNA. We took the additional step of normalizing reference gene transcript levels to the liver homogenate RNA/DNA ratio to account for differences in RNA yield/cell and the number of cells sampled, normalizing to transcript number per cell rather than transcript number per unit RNA. After this additional step no significant differences in liver transcript levels of reference genes were found. The significance of these results was illustrated by normalizing liver transcript levels of insulin-like growth factor 1 (igf1) to ef1a transcript levels or ef1a transcript levels by RNA/DNA. The different normalization strategies resulted in differing patterns of change in igf1 transcript levels between fed and fasted fish. The novelty of this work rests in a two-step normalization process, attempting to account for both 1) technical errors in reverse transcription and qPCR reactions, and 2) biological variance in liver samples. Published by Elsevier Inc.
  • Takahiro Shimomura, Takuro Nakajima, Moeri Horikoshi, Anai Iijima, Hirokazu Urabe, Shinya Mizuno, Naoshi Hiramatsu, Akihiko Hara, Munetaka Shimizu
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 2 178 (2) 427 - 435 0016-6480 2012/09 [Refereed][Not invited]
    We established profiles of insulin-like growth factor (IGF)-I mRNA in the liver, gill and white muscle and circulating IGF-I during smoltification of hatchery-reared masu salmon, and compared with that of gill Na+,K+-ATPase (NKA) activity. Gill NKA activity peaked in May and dropped in June. Liver igf1 mRNA was high in March and decreased to low levels thereafter. Gill igf1 increased from March, maintained its high levels during April and May and decreased in June. Muscle igf1 mRNA levels were relatively high during January and April when water temperature was low. Serum IGF-I continuously increased from March through June. Serum IGF-I during March and May showed a positive correlation with NKA activity, although both were also related to fish size. These parameters were standardized with fork length and re-analyzed. As a result, serum IGF-I and gill igf1 were correlated with NKA activity. On the other hand, samples from desmoltification period (June) that had high serum IGF-I levels and low NKA activity disrupted the relationship. Expression of two IGF-I receptor (igf1r) subtypes in the gill decreased in June, which could account for the disruption by preventing circulating IGF-I from acting on the gill and retaining it in the blood. The present study suggests that the increase in gill NKA activity in the course of smoltification of masu salmon was supported by both endocrine and local IGF-I, and the decrease during desmoltification in freshwater was due at least in part to the down-regulation of gill IGF-I receptors. (C) 2012 Elsevier Inc. All rights reserved.
  • Munetaka Shimizu, Keisuke Kishimoto, Teppei Yamaguchi, Yusuke Nakano, Akihiko Hara, Walton W. Dickhoff
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 174 (2) 97 - 106 0016-6480 2011/11 [Refereed][Not invited]
    Circulating insulin-like growth factor binding proteins (IGFBPs) play pivotal roles in stabilizing IGFs and regulating their availability to target tissues. In the teleost circulation, three major IGFBPs are typically detected by ligand blotting with molecular masses around 20-25, 28-32 and 40-45 kDa. However, their identity is poorly established and often confused. We previously identified salmon 22- and 41-kDa forms as IGFBP-1 and -2b, respectively. In the present study, we cloned the cDNA of 28-kDa IGFBP from Chinook salmon (Oncorhynchus tshawytscha) as well as rainbow trout (Oncorhynchus mykiss) based on the partial N-terminal amino acid sequence of purified protein and identified it as an ortholog of IGFBP-1. Structural and phylogenetic analyses revealed that the 28-kDa IGFBP is more closely related to human IGFBP-1 and zebrafish IGFBP-1 a than the previously identified salmon IGFBP-1 (i.e. 22-kDa IGFBP). We thus named salmon 28- and 22-kDa forms as IGFBP-la and -1b, respectively. Salmon IGFBP-la contains a potential PEST region involved in rapid protein turnover and phosphorylation sites typically found in mammalian IGFBP-1, although the PEST and phosphorylation scores are not as high as those of human IGFBP-1. There was a striking difference in tissue distribution patterns between subtypes; Salmon igfbp-1a was expressed in a variety of tissues while igfbp-1b was almost exclusively expressed in the liver, suggesting that IGFBP-la has more local actions. Direct seawater exposure (osmotic stress) of Chinook salmon parr caused increases in both IGFBP-1s in plasma, while IGFBP-1b appeared to be more sensitive. The presence of two co-orthologs of IGFBP-1 in the circulation in salmon, and most likely in other teleosts, provides a good opportunity to investigate subfunction partitioning of duplicated IGFBP-1 during postnatal growth. (C) 2011 Elsevier Inc. All rights reserved.
  • Munetaka Shimizu, Seira Suzuki, Moeri Horikoshi, Akihiko Hara, Walton W. Dickhoff
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 171 (3) 326 - 331 0016-6480 2011/05 [Refereed][Not invited]
    In vertebrates, most circulating insulin-like growth factor (IGF) is bound to multiple forms of IGF-binding proteins (IGFBPs) that differ both structurally and functionally. In mammals, the largest reservoir of IGF in the circulation comes from a large (150 kDa) ternary complex comprised of IGF bound to IGFBP-3, which is bound to an acid label subunit (ALS), and this variant of IGFBP is regulated by growth hormone (GH) and feed intake. Although multiple variants of IGFBPs ranging from 20 to 50 kDa have been found in fishes, no ternary complex is present and it has been assumed that the majority of circulating IGF is bound to fish IGFBP-3. Consistent with this assumption is previous work in salmon showing the presence of a 41-kDa IGFBP that is stimulated by GH, decreases with fasting and increases with feeding. However, the hypothesis that the salmon 41-kDa IGFBP is structurally homologous to mammalian IGFBP-3 has not been directly tested. To address this issue, we cloned cDNAs for several Chinook salmon IGFBPs, and found that the cDNA sequence of the 41-kDa IGFBP is most similar to that of mammalian IGFBP-2 and dissimilar to IGFBP-3. We found an additional IGFBP (termed IGFBP-2a) with high homology to mammalian IGFBP-2. These results demonstrate that salmon 41-kDa IGFBP is not IGFBP-3, but a paralog of IGFBP-2 (termed IGFBP-2b). Salmon IGFBP-2s are also unique in terms of having potential N-glycosylation sites and splice variants. Additional research on non-mammalian IGFBPs is needed to fully understand the molecular/functional evolution of the IGFBP family and the significance of the ternary complex in vertebrates. (C) 2011 Elsevier Inc. All rights reserved.
  • Munetaka Shimizu, Kathleen A. Cooper, Walton W. Dickhoff, Brian R. Beckman
    Shimizu M, Cooper KA, Dickhoff WW, Beckman BR. Postprandial changes in plasma growth hormone, insulin, insulin-like growth factor (IGF)-I, and IGF-binding proteins in coho salmon fasted for varying periods. Am J Physiol Regul Integr Comp Physiol 297: R352-R361, 2009. First published May 27, 2009; doi:10.1152/ajpregu.90939.2008.-We examined postprandial changes in circulating growth hormone (GH), insulin, insulin-like growth factor (IGF)-I, and IGF-binding proteins (IGFBPs) in yearling coho salmon under different feeding regimes. Fish were initially fasted for 1 day, 1 wk, or 3 wk. Fasted fish were then fed, and blood was collected at 4-h intervals over 26 h. After the various periods of fasting, basal levels of insulin were relatively constant, whereas those of IGF-I, IGFBPs and GH changed in proportion to the duration of the fast. A single meal caused a rapid, large increase in the circulating insulin levels, but the degree of the increase was influenced by the fasting period. IGF-I showed a moderate increase 2 h after the meal but only in the regularly fed fish. Plasma levels of 41-kDa IGFBP were increased in all groups within 6 h after the single meal. The fasting period did not influence the response of 41-kDa IGFBP to the meal. IGFBP-1 and GH decreased after the meal to the same extent among groups regardless of the fasting period. The present study shows that insulin and IGF-I respond differently to long (weeks)- and short (hours)-term nutritional changes in salmon; insulin maintains its basal level but changes acutely in response to food intake, whereas IGF-I adjusts its basal levels to the long-term nutritional status and is less responsive to acute nutritional input. IGFBPs maintain their sensitivity to food intake, even after prolonged fasting, suggesting their critical role in the nutritional regulation of salmon growth.
  • Toshiaki Fujita, Haruhisa Fukada, Munetaka Shimizu, Naoshi Hiramatsu, Akihiko Hara
    FISHERIES SCIENCE 74 (5) 1198 - 1200 0919-9268 2008/10 [Refereed][Not invited]
  • Toshiaki Fujita, Haruhisa Fukada, Munetaka Shimizu, Naoshi Hiramatsu, Akihiko Hara
    MOLECULAR REPRODUCTION AND DEVELOPMENT 75 (7) 1217 - 1228 1040-452X 2008/07 [Refereed][Not invited]
    Three cDNAs, each encoding a different choriogenin (Chg), were isolated from a female masu salmon (Oncorhynchus masou) liver cDNA library. Two of the cDNA clones, Chg H alpha and Chg H beta, showed a close relationship and contained the typical domains of zona pellucida (ZP) B genes in fish, namely proline and glutamine rich repeats, a trefoil factor family domain, and a ZP domain. Specific antibodies against recombinant Chg H products (rmH alpha and rmH beta) were generated to elucidate the relationship between the Chg H cDNAs and two types of serum Chg H protein, which were previously purified and characterized, and designated as very-high -molecular-weight vitelline envelope-related protein (vhVERP) and Chg H of masu salmon. The immunobiochemical analyses revealed that the Chg H alpha and Chg H beta clones encoded vhVERP and Chg H proteins, respectively. The third cDNA clone (Chg L) appeared to be a ZPC gene and, by mapping the N-terminal sequence of purified Chg L, was shown to encode serum Chg L protein. Various types of heteromultimer of the three Chgs were identified immunologically as high molecular weight chorion components, indicating the involvement of complex heterodimerization of multiple Chgs in the construction of chorion architecture in masu salmon.
  • Haruna Amano, Toshiaki Fujita, Naoshi Hiramatsu, Munetaka Shimizu, Sayumi Sawaguch, Takahiro Iatsubara, Hirohiko Kagawa, Masaki Nagae, Craig V. Sullivan, Akihiko Hara
    JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL GENETICS AND PHYSIOLOGY 307A (6) 324 - 341 1932-5223 2007/06 [Refereed][Not invited]
    Seven yolk proteins (YPs), four large lipoproteins (YPs1-4) and three minor yolk components (YPs5-7) including one phosphoprotein (YP7), were purified from extracts of vitellogenic ovaries of gray mullet (Mugil cephalus) by combinations of hydroxylapatite, ion exchange, immunoadsorbent, and gel filtration chromatography. The molecular masses of native Y-P1, YP2, YP3, and YP4 were estimated to be 330, 325, 335, and 570 kDa, respectively. The tertiary structures of YP1, YP2, and YP3 revealed by sodium dodecyl sulfate polyacrylamide gel electrophoresis were typical of teleost lipovitellins (Lvs), consisting of a heavy chain (similar to 110, similar to 99, and similar to 97 kDa, respectively) and a light chain (similar to 30, similar to 29, and similar to 21.5 kDa, respectively), while YP4 exhibited a heavy chain (similar to 110 kDa) and two more polypeptide bands (similar to 70 and similar to 54kDa). Mapping of N-terminal peptide sequences of the purified YPs to the primary structure of multiple mullet vitellogenins (Vgs) deduced from their respective complete cDNAs, which were cloned and sequenced, conclusively identified YP1, YP2, and YP3 as Lvs derived from mullet VgA, VgB, and VgC, respectively. The fourth YP (YP4) appeared to be a proteolytic variant consisting of Lv and phosvitin components of VgA. Two other YPs (YP5 and YP6) were identified as beta'-components derived from VgA and VgB based on their structures and common, but not identical, antigenicity to salmonid beta'-component, while purified YP7, a phosphoprotein with a high content of serine residues, was identified as a phosvitin derived from VgB. This is the first report, of which we are aware, on purification and molecular classification of three distinct forms of Lv from any oviparous vertebrate.
    Environ Sci (Tokyo) 14 (2) 95 - 108 0915-955X 2007 [Refereed][Not invited]
  • M Shimizu, BR Beckman, A Hara, WW Dickhoff
    JOURNAL OF ENDOCRINOLOGY 188 (1) 101 - 110 0022-0795 2006/01 [Refereed][Not invited]
    Fish plasma/serum contains multiple IGF binding proteins (IGFBPs), although their identity and physiological regulation are poorly understood. In salmon plasma, at least three IGFBPs with molecular masses of 22, 28 and 41 kDa are detected by Western ligand blotting. The 22 kDa IGFBP has recently been identified as a homolog of mammalian IGFBP-1. In the present study, an RIA for salmon IGFBP-l was established and regulation of IGFBP-1 by food intake and temperature, and changes in IGFBP-1 during smoltification, were examined. Purified IGFBP-1 from serum was used for as a standard, for tracer preparation and for antiserum production. Cross-linking I-125-labelled IGFBP-1 with salmon IGF-I eliminated interference by IGFs. The RIA had little cross-reactivity with salmon 28 and 41 kDa IGFBPs (<0.5%) and measured IGFBP-1 levels as low as 0.1 ng/ml. Fasted fish had significantly higher IGFBP-1 levels than fed fish (21.6 +/- 4.6 vs 3.0 +/- 2.2 ng/ml). Plasma IGFBP-1 was measured in individually tagged 1-year-old coho salmon reared for 10 weeks under four different feeding regimes as follows: high constant (2% body weight/day), medium constant (1% body weight/day), high variable (2% to 0.5% body weight/day) and medium variable (1% to 0.5% body weight/day). Fish fed with the high ration had lower IGFBP-1 levels than those fed with the medium ration. Circulating IGFBP-1 increased following a drop in feeding ration to 0.5% and returned to the basal levels when feeding ration was increased. Another group of coho salmon were reared for 9 weeks under different water temperatures (11 or 7 degrees C) and feeding rations (1.75, 1 or 0.5% body weight/day). Circulating IGFBP-1 levels were separated by temperature during the first 4 weeks; a combined effect of temperature and feeding ration was seen in week 7; only feeding ration influenced IGFBP-1 level thereafter. These results indicate that IGFBP-1 is responsive to moderate nutritional and temperature changes. There was a clear trend that circulating IGFBP-1 levels were negatively correlated with body weight, condition factor (body weight/body length(3) x 100), growth rates and circulating 41 kDa IGFBP levels but not IGF-I levels. During parr-smolt transformation of coho salmon, IGFBP-1 levels showed a transient peak in late April, which was opposite to the changes in condition factor. Together, these findings suggest that salmon IGFBP-1 is inhibitory to IGF action. In addition, IGFBP-1 responds to moderate changes in dietary ration and temperature, and shows a significant negative relationship to condition factor.
  • Y Fujiwara, H Fukada, M Shimizu, A Hara
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 143 (3) 267 - 277 0016-6480 2005/09 [Refereed][Not invited]
    Two distinct yolk proteins (YP1 and YP2) were purified from the ovary of medaka, and specific antisera against YPs were generated to characterize YPs and reveal their relation to two vitellogenins (Vg1 and Vg2). The molecular masses of purified YPI and YP2 on gel filtration were 270 and 380 kDa, respectively. YPs were confirmed to be lipoproteins by staining with Sudan black. Amino acid compositions of YPI and YP2 were similar to those of Vgl and Vg2, respectively. In double immunodiffusion using anti-Vg1, a precipitin line of YPI formed a spur against the Vg1 line. YP2 and Vg2 were reacted with anti-Vg2, and a precipitin line of YP2 formed a fuse against the Vg2 line. These biochemical and immunological analyses of purified YPs revealed that YPI is lipovitellin 1 (Lv1) derived from Vg1 and YP2 is lipovitellin 2 (Lv2) derived from Vg2. Using specific antibodies against Lvs and Vgs, specific, high sensitivity chemiluminescent immunoassays (CLIAs) for two Vgs were developed to reveal basal Vg levels and response to exogenous estradiol-17 beta (E-2). The measurable range of both CLIAs was from 0.975 to 1000 ng/ml. The cross-reactivity to the alternative Vg in each CLIA was extremely low (<= 0.57%). When immature fish were immersed in water containing E2 for I h, both Vgs were induced by 0.5 mu g/L of E-2 at 24 h after treatment. Vg1 increased in a concentration-dependant manner up to 100 mu g/L E2, while Vg2 reached a plateau at 10 mu g/L of E2. The ratio of Vg1:Vg2 in E2-treated fish changed in a concentration-dependent manner from 1.5:1 to 8.5: 1. The results from E-2-treatment suggest that differential regulation may control the expression of medaka Vgs. (c) 2005 Elsevier Inc. All rights reserved.
  • T Fujita, H Fukada, M Shimizu, N Hiramatsu, A Hara
    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY 141 (2) 211 - 217 1096-4959 2005/06 [Refereed][Not invited]
    Annual changes in serum levels of two chorion precursors, choriogenin H (Chg H) and choriogenin L (Chg L), vitellogenin (Vg) and estradiol-17 beta (E2) were quantified in masu salmon, Oncorhynchus masou, using specific immunoassays. Serum Chg levels were higher than Vg during the previtellogenic growth phase when circulating E2 levels were low (similar to 0.1 ng/mL), suggesting higher sensitivity of Chg to E2. When oocyte growth shifted to the vitellogenic phase, Vg levels increased and became the most abundant in serum coincident with elevations of E2 and GSI. Chg H, Chg L and Vg peaked 1 month prior to ovulation at 0.61 +/- 0.08, 0.98 +/- 0.18 and 10.93 +/- 3.24 mg/mL, respectively. These results suggest that chorion formation by Chgs occurs prior to vitellogenesis and that the sensitivity of Chgs to low circulating E2 is closely related to the sequential events of oocyte growth. (c) 2005 Elsevier Inc. All rights reserved.
  • Munetaka Shimizu, Munetaka Shimizu, J. T. Dickey, J. T. Dickey, H. Fukada, H. Fukada, W. W. Dickhoff, W. W. Dickhoff
    Journal of Endocrinology 184 267 - 276 0022-0795 2005/01/01 [Refereed][Not invited]
    Western ligand blotting of salmon serum typically reveals three insulin-like growth factor (IGF) binding proteins (IGFBPs) at 22, 28 and 41 kDa. Physiologic regulation of the 22 kDa IGFBP is similar to that of mammalian IGFBP-1; it is increased in catabolic states such as fasting and stress. On the other hand, its molecular mass on Western ligand blotting is closest to mammalian IGFBP-4. The conflict between physiology and molecular mass makes it difficult to determine the identity of the 22 kDa IGFBP. This study therefore aimed to identify the 22 kDa IGFBP from protein and cDNA sequences. The 22 kDa IGFBP was purified from chinook salmon serum by a combination of IGF-affinity chromatography and reverse-phase chromatography. The N-terminal amino-acid sequence of the purified protein was used to design degenerate primers. Degenerate PCR with liver template amplified a partial IGFBP cDNA, and full-length cDNA was obtained by 5′- and 3-pm-rapid amplification of cDNA ends (RACE). The 1915-bp cDNA clone encodes a 23.8 kDa IGFBP, and its N-terminal amino-acid sequence matched that of purified 22 kDa IGFBP. Sequence comparison with six human IGFBPs revealed that it is most similar to IGFBP-1 (40% identity and 55% similarity). These findings indicate that salmon 22 kDa IGFBP is IGFBP-1. Salmon IGFBP-1 mRNA is predominantly expressed in the liver, and its expression levels appear to reflect circulating levels. The 3′-untranslated region of salmon IGFBP-1 mRNA contains four repeats of the nucleotide sequence ATTTA, which is involved in selective mRNA degradation. In contrast, amino-acid sequence analysis revealed that salmon IGFBP-1 does not have an Arg-Gly-Asp (RGD) integrin recognition sequence nor a Pro, Glu, Ser and Thr (PEST)-rich domain (a segment involved in rapid turnover of protein), both of which are characteristic of mammalian IGFBP-1. These findings suggest that association with the cell surface and turnover rate may differ between salmon and mammalian IGFBP-1. © 2005 Society for Endocrinology.
  • BR Beckman, M Shimizu, BA Gadberry, PJ Parkins, KA Cooper
    AQUACULTURE 241 (1-4) 601 - 619 0044-8486 2004/11 [Refereed][Not invited]
    The effect of temperature change on the relations between growth and plasma levels of insulin-like growth factor-I (IGF-I) and 41-kDa insulin-like growth factor binding protein (41-kDa IGFBP) were assessed in postsmolt coho salmon. An experiment was initiated by reducing the temperature from 11 to 7 degreesC for two groups of fish that were subsequently fed at either 0.5% or 1.0% body weight per day. Two additional groups of fish were maintained at 11 degreesC and fed either 1.0% or 1.75% body weight per day. Fish were weighed and measured, and plasma samples were obtained on four dates: 12, 27, 47, and 63 days after the temperature change. Plasma IGF-I values were significantly lower in cool water groups than warm water groups for the first sample, by the last sampling, there were no significant differences between groups. There were no significant differences between treatment groups for plasma 41-kDa IGFBP levels for the first sampling. Subsequently, significant differences in plasma 41-kDa IGFBP levels between fish fed at different levels, regardless of temperature, were found. On all dates, significant associations were found between growth, plasma IGF-1, and 41-kDa IGFBP for fish held in warm water; however, no such relations were found for fish held in cool water for the first two sampling dates. After 47 and 63 days in cool water, significant relations between growth, plasma IGF-I, and 41-kDa IGFBP were reestablished. These data suggest that associations between growth, plasma IGF-I, and 41-kDa IGFBP were disrupted by a temperature decrease for at least 4 weeks. However, significant relations were reestablished after 47 days of temperature acclimation. These results support further investigation of plasma IGF-I and 41-kDa IGFBP as growth indicators in fish. (C) 2004 Elsevier B.V. All rights reserved.
  • DA Larsen, M Shimizu, KA Cooper, P Swanson, WW Dickhoff
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 139 (1) 29 - 37 0016-6480 2004/10 [Refereed][Not invited]
    Among many species of salmonids, fast growing fish mature earlier than slow growing fish, and maturing males grow faster than non-maturing ones. To study the potential endocrine basis for this reciprocal relationship we examined the in vivo effects of the androgens, testosterone (T) and 11-ketotestosterone (11-KT), on plasma growth hormone (GH), insulin-like growth factor-I (IGF-I) and 41-kDa IGF binding protein (41-kDa IGFBP) (putative IGFBP-3) in coho salmon, Oncorhynchus kisutch. Immature male and female, two-year old fish (avg. wt. 31.7 +/- 0.63 g) were injected with coconut oil containing T or 11-KT at a dose of 0. 1, 0.25, or 1 mug/g body weight. Blood samples were taken 1 and 2 weeks postinjection, and analyzed by immunoassay for T, 11-KT, GH, IGF-I, and 41-kDa IGFBP. Steroid treatments elevated the plasma T and 11-KT levels to physiological ranges typical of maturing fish. Plasma IGF-I and 41-kDa IGFBP levels increased in response to both T and 11-KT in a significant and dose-dependent manner after 1 and 2 weeks, but GH levels were not altered. These data suggest that during reproductive maturation, in addition to the previously demonstrated effects of the IGFs on steroidogenesis, the gonadal steroids may in turn play a significant role in regulating IGF-I and its binding proteins in fish. The interaction between the reproductive and growth axes may provide a regulatory mechanism for bringing about the dimorphic growth patterns observed between maturing and non-maturing salmonids and other species of fish. (C) 2004 Elsevier Inc. All rights reserved.
  • T Fujita, H Fukada, M Shimizu, N Hiramatsu, A Hara
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 136 (1) 49 - 57 0016-6480 2004/03 [Refereed][Not invited]
    Previously two precursors to vitelline envelope proteins, choriogenin H (Chg H) and choriogenin L (Chg L), were identified in masu salmon, Oncorhynchus masou, and specific antisera against these two proteins were generated in rabbits. In this study, two methods of immunoassay have been developed using these specific antibodies: single radial immunodiffusion (SRID) and enzyme-linked immunosorbent assay (ELISA). Non-competitive sandwich ELISAs for Chg H and Chg L were designed using digoxigenin-labeled antibodies and purified Chgs as assay components. The working range of the ELISAs was 1-128 and 2-256 ng/ml for Chg H and Chg L, respectively. Using these immunoassays and a chemiluminescent immunoassay for vitellogenin (Vg), the changes in these three estrogen-responsive proteins were measured in the serum of masu salmon after treatment with various doses of estradiol-17beta (E-2). The changes in serum levels of Chgs and Vg in male fish differed according to the E-2 dose. When fish were given a 5 mg/kg body weight (BW) of E-2, Vg was induced to a greater extent than Chgs. By contrast, Chg levels were higher than that of Vg after a 10 tg/ kg BW of E-2 injection. A similar trend was seen in the response time to exogenous E-2. Serum Chgs were induced from 8 h after E-2 injection and reached a peak of about 5 mug/ml at 24 h. Although Vg was not detected until 8 h after E-2 injection, its levels remained considerably low at around 0.03 mug/ml, even after 24 h. Chg H was more sensitive than was Chg L to I mug/kg BW of estrogen: the long-term exposure of fish to E-2 showed that Chg H could be induced from a lower dose of E-2 than could Chg L. Taken together, these results suggest that the serum levels of Chg H, Chg L, and Vg in masu salmon are regulated by circulating levels of E-2. (C) 2003 Elsevier Inc. All rights reserved.
  • BR Beckman, M Shimizu, BA Gadberry, KA Cooper
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 135 (3) 334 - 344 0016-6480 2004/02 [Refereed][Not invited]
    The effect of different feeding levels on plasma levels of insulin-like growth factor-I (IGF-I), 41 kDa insulin-like growth factor binding protein (41 kDa IGFBP), and growth hormone (GH) were assessed in post-smolt coho salmon. Fish were fed at either stable (1 and 2% body weight/day) or varying (1-0.5-1%, 2-0.5-2% body weight/day) feeding rates and plasma was sampled from 10 fish/treatment at 2-3 week intervals over five dates from June to September, resulting in a total of 200 samples. Fish fed at higher rates grew faster and had higher plasma IGF-I and 41 kDa IGFBP levels. Plasma GH levels were variable but generally showed an inverse relationship to feeding rate. Both plasma IGF-I and 41 kDa IGFBP increased seasonally, average IGF-I levels doubled from June to September, regardless of feeding rate. On any one date both IGF-I and 41 kDa IGFBP were highly related to growth rate with regression coefficients ranging from 0.36 to 0.68 (IGF-I) and from 0.33 to 0.70 (41 kDa IGFBP). No relationship was found between IGF-I:41 kDa IGFBP ratio and individual growth rate. Overall, both feeding rate and date were important in explaining variation in IGF-I and 41 kDa IGFBP levels. Published by Elsevier Inc.
  • J Johnson, J Silverstein, WR Wolters, M Shimizu, WW Dickhoff, BS Shepherd
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 134 (2) 122 - 130 0016-6480 2003/11 [Refereed][Not invited]
    Vertebrate growth is principally controlled by growth hormone (GH) and, its intermediary, insulin-like growth factor-I (IGF-I). The actions of IGF-I are modulated by high-affinity binding proteins called insulin-like growth factor binding-proteins (IGFBPs). Channel catfish exhibit atypical responses (increased percentage body fat and reduced percentage protein) to GH treatment, despite GH-dependent IGF-I production. Among possible explanations for this atypical response to GH treatment is an unusual regulation of blood IGFBPs. In this species, there has been one report of a single 33-kDa plasma binding protein. To examine the occurrence and regulation of plasma IGFBPs in this species, two strains of channel catfish (Norris and USDA-103) were treated with weekly injections of recombinant bovine GH at different temperatures (21 degreesC versus 26 degreesC). In a separate experiment involving catfish of a different strain, endogenous GH levels were altered via injection of the GH secretogogue, bGHRH(1-29)-amide, and held in fresh water or transferred to brackish water (12 ppt). Following these treatments, the type and regulation of plasma IGFBPs in these catfish strains were examined by Western ligand blotting. We have identified five IGFBPs (19, 35, 44, 47, and >80 kDa) in catfish plasma that are differentially altered by experimental treatment and genetic lineage. Levels of the 19-kDa IGFBP were elevated in catfish of Norris and USDA-103 strains that were exposed to a higher environmental temperature (26 degreesC versus 21 degreesC), but was not seen in those animals used for the GH secretogogue/salinity study. In most vertebrates, treatment with GH increases levels of plasma IGFBP-3 (similar to40-50 kDa). In the USDA-103 and Norris catfish strains, bGH injection reduced plasma levels of the 44- and 47-kDa IGFBPs. Similarly, elevations in plasma GH levels in GH secretogoge-treated and brackish water-adapted catfish resulted in reductions of the 44- and 47-kDa IGFBPs as well as a reduction in presence of a 35-kDa IGFBP that was not detected in the Norris or USDA-103 strains. Reduced levels of the 35, 44, and 47 kDa IGFBPs, seen in the plasma of the GH secretogogue-treated and brackish water-adapted animals, suggests that the atypical response of channel catfish to GH treatment is not attributed to the use of heterologous (bovine) GH. This negative response of the 35-47 kDa IGFBPs to GH has not been reported in any teleost or vertebrate (healthy) and may be partly responsible for the atypical physiological responses of channel catfish to GH treatment. (C) 2003 Elsevier Inc. All rights reserved.
  • Development of an RIA for salmon 41 kDa IGF-binding protein
    M Shimizu, A Hara, WW Dickhoff
    JOURNAL OF ENDOCRINOLOGY 178 (2) 275 - 283 0022-0795 2003/08 [Refereed][Not invited]
    Salmon plasma contains at least three IGF-binding proteins (IGFBPs) with molecular masses of 41, 28 and 22 kDa. The 41 kDa IGFBP is similar to mammalian IGFBP-3 in size, type of glycosylation and physiological responses. In this study, we developed an RIA for the 41 kDa IGFBP. The 41 kDa IGFBP purified from serum was used for antibody production and as an assay standard. Binding of three different preparations of tracer were examined: I-125-41 kDa IGFBP, I-125-41 kDa IGFBP cross-linked with IGF-I and 41 kDa IGFBP cross-linked with I-125- IGF-I (41 kDa IGFBP/I-125-IGF-I). Only binding of 41 kDa IGFBP/I-125-IGF-I was not affected by added IGFs, and therefore it was chosen for the tracer in the RIA. Plasma 41 kDa IGFBP levels measured by RIA were increased by GH treatment (178.9 +/- 4.9 ng/m) and decreased after fasting (95.0 +/- 7.0 ng/ml). The molarities of plasma 41 kDa IGFBP and total IGF-I were comparable, and they were positively correlated, suggesting that salmon 41 kDa IGFBP is a main carrier of circulating IGF-I in salmon, as is mammalian IGFBP-3 in mammals. During the parr-smolt transformation (smoltification) of coho salmon, plasma 41 kDa IGFBP levels showed a transient peak (182.5 +/- 10.3 ng/ml) in March and stayed relatively constant thereafter, whereas IGF-I showed peak levels in March and April. Differences in the molar ratio between 41 kDa IGFBP and IGF-I possibly influence availability of IGF-I in the circulation during smoltification.
  • M Shimizu, P Swanson, A Hara, WW Dickhoff
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 132 (1) 103 - 111 0016-6480 2003/06 [Refereed][Not invited]
    In salmon, at least three insulin-like growth factor binding proteins (IGFBPs) with molecular masses of 41, 28, and 22 kDa exist in serum. The 41-kDa IGFBP is up-regulated by growth hormone treatment and down-regulated by fasting, suggesting that it is a homolog of IGFBP-3. We purified the 41-kDa IGFBP from chinook salmon serum by IGF-I affinity chromatography followed by reversed-phase high pressure liquid chromatography. Purified IGFBP appeared as doublet bands on electrophoresis and was N-glycosylated. Analysis of partial N-terminal amino acid sequence revealed that salmon 41-kDa IGFBP has the cysteine rich domain conserved among IGFBP family. In a binding assay using I-125-salmon IGF-I, purified 41-kDa IGFBP specifically bound salmon IGF-I, human IGF-I and human IGF-II, but neither Long R 3 IGF-I nor salmon insulin, showing that binding characteristics of the salmon IGFBP are similar to those of mammalian IGFBPs. Although the partial amino acid sequence of 41-kDa IGFBP showed highest homologies with zebrafish and seabream IGFBP-2, the highly conserved nature of the N-terminus makes it impossible to identify the type of IGFBP from partial sequence data. However, based on physiological responses, molecular weight and type of glycosylation, the 41-kDa IGFBP is most similar to mammalian IGFBP-3. (C) 2003 Elsevier Science (USA). All rights reserved.
  • M Shimizu, Y Fujiwara, H Fukada, A Hara
    JOURNAL OF EXPERIMENTAL ZOOLOGY 293 (7) 726 - 735 0022-104X 2002/12 [Refereed][Not invited]
    Estrogen treatment of medaka leads to accumulation of ascites, in which vitellogenin (Vg) and choriogenins (precursors to vitelline envelope) are abundant. Besides those female-specific proteins, we detected a new component in ascites that cross-reacts with antiserum against egg yolk proteins. We tentatively named it egg yolk-related protein (YRP). YRP was purified from ascites by hydroxylapatite chromatography followed by gel filtration. Purified YRP had a molecular mass of 460 kDa in intact state while 570 kDa for Vg. The molecular weight of purified YRP on SDS-PAGE under both reducing and nonreducing conditions was 130 kDa. YRP was confirmed to be a lipoglycophosphoprotein by staining with Sudan black, periodic acid-Schiff (PAS) and methyl green. Amino acid composition of YRP resembled that of Vg except for a relatively low content of serine. A specific antiserum against YRP was raised in a rabbit. Antiserum against YRP specifically immunostained its antigen but not Vg or choriogenins. YRP was detected as a female-specific protein in serum of breeding medaka. The antiserum also cross-reacted with a band at 29 kDa in egg extracts, which is not immunoreactive to antiserum against Vg. These data show that YRP is a precursor to some egg yolk proteins with differing antigenicity from Vg (Hamazaki et al. '87). We thus conclude that YRP is a second form of medaka Vg and rename YRP as Vg 2 while formerly reported Vg as Vg 1. (C) 2002 Wiley-Liss, Inc.
  • T Fujita, M Shimizu, N Hiramatsu, H Fukada, A Hara
    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY 132 (3) 599 - 610 1096-4959 2002/07 [Refereed][Not invited]
    Three vitelline envelope-related proteins (VERPs), very-high-molecular-weight VERP (vhVERP), high-molecular-weight VERP (hVERP) and low-molecular-weight VERP (IVERP) were purified from female masu salmon serum. The apparent molecular weights of vhVERP, hVERP and IVERP, in their native state, were 520, 88 and 54 kDa, respectively, by gel-filtration chromatography Very-high-molecular-weight VERP comprises two subunits, corresponding to 175 and 126 kDa. On SDS-PAGE, hVERP and IVERP migrate at 53 and 47 kDa, respectively. Amino acid analysis of vhVERP and hVERP showed that they share a high content of glutamic acid and proline. By contrast, IVERP is rich in glutamic acid and asparatic acid. These features are in good agreement with the amino acid composition of the vitelline envelope. Immuno-biochemical analysis suggested that vhVERP is derived from hVERP by polymerization and/or aggregation. Antibodies against hVERP and IVERP specifically immunostained the vitelline envelope and liver of female masu salmon. In addition, both hVERP and IVERP were induced in the serum of estrogen-treated male fish. Taken together, it is suggested that hVERP and IVERP are homologous molecules with choriogenin H and choriogenin L in medaka, respectively. These results indicate that hVERP and IVERP are precursor proteins to the vitelline envelope (choriogenins) in masu salmon. (C) 2002 Elsevier Science Inc. All rights reserved.
  • HIRAMATSU Naoshi, FUKADA Haruhisa, KITAMURA Makiko, SHIMIZU Munetaka, FUDA Hirotoshi, KOBAYASHI Kunihiko, HARA Akihiko
    水産増殖 日本水産増殖学会 49 (3) 347 - 355 0371-4217 2001/09/20 [Refereed][Not invited]
  • Munetaka SHIMIZU, Penny SWANSON, Haruhisa FUKADA, Akihiko HARA, Walton W, DICKHOFF
    Gen. Comp. Endocrinol. 119 26 - 36 2000 [Refereed][Not invited]
  • Free and protein-bound insulin-like growth factor-I (IGF-I) and IGF-binding proteins in plasma of coho salmon, Oncorhynchus kisutch
    M Shimizu, P Swanson, WW Dickhoff
    GENERAL AND COMPARATIVE ENDOCRINOLOGY 115 (3) 398 - 405 0016-6480 1999/09 [Refereed][Not invited]
    Total and free insulin-like growth factor-I (IGF-I) levels were quantified in plasma from growth hormone (GH)-treated and fasted coho salmon. Total IGF-I was measured by radioimmunoassay after acid-ethanol extraction and free IGF-I was separated from protein-bound IGF-I using ultrafiltration by centrifugation. Total and free TGF-I increased in plasma after GH treatment and decreased after fasting. The level of free IGF-I, however, was maintained at approximately 0.3% in both experiments. Unsaturated binding activity in plasma for IGF-I was assessed by incubation with I-125-recombinant salmon IGF-I (I-125-sIGF-I). Although there was no difference in binding activity between GH-treated and control fish, fasted fish showed higher binding activity than did fed fish, suggesting induction of unsaturated binding protein by fasting. IGF-binding protein (IGFBP) bands were observed in plasma of coho salmon by Western ligand blotting using I-125-sIGF-I. A low-molecular-weight (22 kDa) band was clear in fasted fish but not detectable in fed fish. The IGFBP band, which has molecular weight similar to that of human IGFBP-3 (41 kDa), was more intense in GH-treated fish than in controls. The molecular distribution of IGF-1 in plasma was examined by gel filtration under neutral conditions. Most IGF-I was eluted around 40 kDa. This result suggests that the major form of bound IGF-I in the circulation of coho salmon may be in a 40-kDa binary complex rather than in a 150-kDa ternary complex, as in mammals.
  • Changes in serum choriogenin and vitellogenin levels in masu salmon (Oncorhynchus masou) during sexual maturation and after estrogen treatment.
    Fujita T, Hiramatsu N, Shimizu M, Sullivan CV, Hara A
    Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish 314  1999 [Refereed][Not invited]
  • Changes of serum growth hormone and vitellogenin levels in chtthroat trout during sexual maturation.
    Fukada H, Hiramatsu N, Shimizu M, Sullivan CV, Hara A
    Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish 314  1999 [Refereed][Not invited]
  • Shimizu M, Fujita T, Hara A
    JOURNAL OF EXPERIMENTAL ZOOLOGY 282 (3) 385 - 395 0022-104X 1998/10/15 [Refereed][Not invited]
  • Munetaka Shimizu, Toshiaki Fujita, Naoshi Hiramatsu, Akihiko Hara
    Fisheries Science 64 (4) 600 - 605 0919-9268 1998 [Refereed][Not invited]
  • Transition of serum vitellogenin cycle in Sakhalin taimen (Hucho perryi)
    N Hiramatsu, M Shimizu, H Fukada, M Kitamura, K Ura, H Fuda, A Hara
    A specific and sensitive enzyme linked immunosorbent assay (ELISA) and a single radial immunodiffusion (SRID) were developed for measurement of serum vitellogenin (Vg) levels in Sakhalin taimen (Hucho perryi). Regarding specificity for serum Vg, an antiserum raised against lipovitellin of taimen (a-Lv) was adequate for both assays. ELISA and SRID could detect Vg in serum at concentrations as low as 10 ng/ml and 25 mu g/ml, respectively. In estrogen administration experiments, the level of serum Vg began clearly increasing within 12 to 24 hr after injection of immature females with estradiol-17 beta (E-2) The appearance and levels of Vg in males treated with E-2 were delayed and smaller, respectively, than for females. Vg levels varied throughout natural vitellogenesis from 0-4 mu g/ml (3 years old) to approximately 30 mg/ml (5-6 years old). We observed an early transitory peak of serum Vg levels (primary reaction) at the time of early vitellogenesis and chronic high Vg levels (for 6-7 months) in winter period before ovulation. Changes of serum E-2 levels were correlated with Vg levels. However, E-2 levels decreased a month earlier than Vg levels near ovulation. It appears that the duration of vitellogenesis in taimen is considerably longer than that in other salmonids, lasting more than 2 years. (C) 1997 Elsevier Science Inc.
  • Changes in serum levels of two choriogenins in Sakhalin taimen treated with estrogen
    Shimizu M, Fujita T, Hara A
    ADVANCES IN COMPARATIVE ENDOCRINOLOGY, TOMES 1 AND 2 1493 - 1496 1997 [Refereed][Not invited]
  • Electrophoretic changes in olfactory system proteins in masu salmon during parr-smolt transformation
    M Shimizu, H Ueda, H Kawamura, K Shimazaki, K Yamauchi
    JOURNAL OF FISH BIOLOGY 47 (6) 1044 - 1054 0022-1112 1995/12 [Refereed][Not invited]
    Changes in cytosolic proteins of the olfactory system (olfactory epithelium, olfactory nerve and olfactory bulb) and the telencephalon of masu salmon Oncorhynchus masou were analysed by two-dimensional polyacrylamide gel electrophoresis during parr-smelt transformation; parr, pre-smelt and full-smelt stages. In the olfactory system, several protein spots appeared and disappeared in the course of smelting. One protein spot in particular with an estimated molecular weight of 27 kDa and isoelectric point of 5.6 (M27) disappeared in common with the olfactory system during smelting. The disappearance of M27 was also observed in the telencephalon. These proteins, which appeared and disappeared, may reflect the changes in olfactory function during smelting. Simultaneously, the present study confirmed a salmonid olfactory specific protein of 24 kDa (N24), which existed in the olfactory system but not in the telencephalon, as a single neutral protein spot in masu salmon. (C) 1995 The Fisheries Society of the British Isles
    Fisheries Science 60 (2) 239 - 240 0919-9268 1994 [Refereed][Not invited]
    ZOOLOGICAL SCIENCE 10 (4) 685 - 690 0289-0003 1993/08 [Refereed][Not invited]
    An olfactory system-specific protein (N24; molecular weight 24 kDa) was examined for immunological similarity to proteins from various organs (heart, intestine, kidney, muscle, ovary and testis) of mature kokanee salmon (Oncorhynchus nerka) by means of Western blotting analysis using a polyclonal antibody to N24. The antibody recognized one 24 kDa protein in the testis but none in the other organs examined. Immunoelectron microscopic analysis revealed that immunoreactive gold particles were mainly concentrated on the nuclei of spermatids and spermatozoa, while no specific gold particles were observed on the nuclei and the cytoplasm of spermatogonia, spermatocytes, Sertoli, Leydig and peritubular cells in maturing and mature testes of kokanee salmon. This is the first description of an antigenic similarity between an olfactory system-specific protein and a testicular germ cell protein in the animal kingdom. This corresponding protein may prove to be a useful molecular marker for studying the mechanism of sperm chemotaxis during fertilization.
    ZOOLOGICAL SCIENCE 10 (2) 287 - 294 0289-0003 1993/04 [Refereed][Not invited]
    An olfactory system-specific protein of 24 kDa (N24) was identified in kokanee salmon (Oncorhynchus nerka) by the comparison of proteins restricted to the olfactory system (olfactory epithelium, olfactory nerve and olfactory bulb) with those found in other parts of the brain (telencephalon, optic tectum, cerebellum, hypothalamus) and hypophysis. A polyclonal antibody to N24 was raised in a rabbit, and the specificity of the antiserum was examined by Western blotting analysis; the antiserum recognized only one 24 kDa band in the olfactory system but not in other parts of the brain in kokanee salmon, sockeye salmon (O. nerka), masu salmon (O. masou) and chum salmon (O. keta). Immunocytochemical analysis revealed that positive immunoreactivity occurred exclusively in the olfactory nerve and in some olfactory neuroepithelial cells. Both at the time of imprinting of maternal stream odorants and at the time of homing to the maternal stream, the immunoreactivity of N24 in fish in the maternal stream was stronger than that in seawater fish. The present study indicates that an olfactory system-specific protein may be importantly related to both imprinting and homing mechanisms in salmonids.


  • 清水宗敬  日本水産学会大会講演要旨集  2018-  249  2018/03/26  [Not refereed][Not invited]
  • 金子信人, 虎尾充, 藤原真, 越野陽介, 宮腰靖之, 清水宗敬  日本水産学会大会講演要旨集  2018-  16  2018/03/26  [Not refereed][Not invited]
  • 中村周, 金子信人, 宮腰靖之, 清水宗敬  日本水産学会大会講演要旨集  2017-  133  2017/03/26  [Not refereed][Not invited]
  • 棟方有宗, 新房由紀子, 佐藤大介, 清水宗敬  日本水産学会大会講演要旨集  2017-  13  2017/03/26  [Not refereed][Not invited]
  • 金子信人, 虎尾充, 藤原真, 越野陽介, 宮腰靖之, 清水宗敬  日本水産学会大会講演要旨集  2017-  15  2017/03/26  [Not refereed][Not invited]
  • 田中英絵, 中野裕介, 水田紘子, 平松尚志, 清水宗敬  日本水産学会大会講演要旨集  2017-  170  2017/03/26  [Not refereed][Not invited]
  • 金子信人, 谷山奈津美, 宮腰靖之, 清水宗敬  日本水産学会大会講演要旨集  2016-  162  2016/03/26  [Not refereed][Not invited]
  • 實吉隼人, 大森始, 飯嶋亜内, 小山達也, 春日井潔, 宮腰靖之, 金子信人, 清水宗敬  日本水産学会大会講演要旨集  2016-  134  2016/03/26  [Not refereed][Not invited]
  • 志村遥夏, 中嶋拓郎, 浦和寛, 清水宗敬  日本水産学会大会講演要旨集  2015-  214  2015/03/27  [Not refereed][Not invited]
  • 金子信人, 谷山奈津美, 藤原真, 虎尾充, 宮腰靖之, 清水宗敬  日本水産学会大会講演要旨集  2015-  16  2015/03/27  [Not refereed][Not invited]
  • Endocrine control of growth in coho salmon: validation of a multiplex gene expression assay and quantification of relations between messenger RNA levels and proteins during feeding and fasting
    Brian R. Beckman, J. Adam Luckenbach, David C. Metzger, Munetaka Shimizu, Jon T. Dickey  INTEGRATIVE AND COMPARATIVE BIOLOGY  50-  E9  -E9  2010/07  [Not refereed][Not invited]
  • Munetaka SHIMIZU, Haruhisa FUKADA, Akihiko HARA, Walton W, DICKHOFF  Aquaculture  273-  320  -328  2007  [Not refereed][Not invited]
  • Measuring salmon insulin-like growth factor (IGF)-I and IGF-binding proteins by radioimmunoassay
    M Shimizu, A Hara, WW Dickhoff  JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-COMPARATIVE EXPERIMENTAL BIOLOGY  305A-  (2)  176  -176  2006/02  [Not refereed][Not invited]
  • Y Tokushima, Y Ito, M Shimizu, N Omoto, A Hara  FISH PHYSIOLOGY AND BIOCHEMISTRY  30-  (2)  179  -188  2004/06  [Not refereed][Not invited]
    Fish has a unique, non-respiratory vascular system called secondary circulation, which forms capillary networks to the internal and external body surfaces. We compared protein composition in serum from the secondary circulation with that from the primary (blood) circulation. Chromatographic and electrophoretic patterns of sera from the two circulations were essentially same. Immunochemical analysis using specific antibodies against albumin-like protein (alpha 1-protein), immunoglobulin M (IgM), transferrin, vitellogenin and choriogenin (precursor to eggshell protein) revealed that these major blood serum proteins in the primary circulation are present in the secondary circulation. Total protein concentrations in the secondary circulation were lower than those in the primary circulation. alpha 1-Protein levels in the secondary circulation relative to the primary circulation were similar to those of total protein. IgM, however, had significantly lower relative levels in the secondary circulation than total protein. Despite some differences in the protein composition between the primary and secondary circulations, the presence of major blood serum proteins in the secondary circulation suggests that the secondary circulation plays a role in transporting them from the primary circulation to the body surfaces.
  • Cloning of salmon insulin-like growth factor binding proteins
    M Shimizu, JT Dickey, H Fukada, WW Dickhoff  INTEGRATIVE AND COMPARATIVE BIOLOGY  43-  (6)  1047  -1047  2003/12  [Not refereed][Not invited]
  • In vivo effects of testosterone and 11-ketotestosterone on the GH-IGF-1 axis (plasma GH, IGF-1, and putative IGFBP-3) in coho salmon, Oncorhynchus kisutch.
    DA Larsen, KA Cooper, M Shimizu  INTEGRATIVE AND COMPARATIVE BIOLOGY  42-  (6)  1262  -1262  2002/12  [Not refereed][Not invited]
  • Development of a radioimmunoassay for salmon 41-kDa insulin-like growth factor binding protein.
    M Shimizu, A Hara, WW Dickhoff  INTEGRATIVE AND COMPARATIVE BIOLOGY  42-  (6)  1312  -1312  2002/12  [Not refereed][Not invited]
  • Cloning of cDNA for choriogenin H and choriogenin L of masu salmon.
    Fujita T, Fukada H, Shimizu M, Hiramatsu N, Hara A  Fisheries Science  68-  1273  -1274  2002  [Not refereed][Not invited]
  • Purification of a serum insulin-like growth factor binding protein from chinook salmon, Oncorhynchus tshawytscha.
    M Shimizu, P Swanson, A Hara, WW Dickoff  AMERICAN ZOOLOGIST  41-  (6)  1587  -1587  2001/12  [Not refereed][Not invited]
  • Fukada H, Hiramatsu N, Kiramura M, Shimizu M, Hara A  Fisheries Science  66-  (4)  789  -791  2000  [Not refereed][Not invited]
  • Munetaka Shimizu, Haruhisa Fukada, Toshiaki Fujita, Naoshi Hiramatsu, Akihiko Hara  Journal of Fish Biology  57-  170  -181  2000  [Not refereed][Not invited]
  • Validation of radioimmunoassay for salmon insulin-like growth factor-1 using commercially available assay components.
    M Shimizu, P Swanson, WW Dickhoff  AMERICAN ZOOLOGIST  39-  (5)  29A  -29A  1999  [Not refereed][Not invited]
  • Immunochemical detection of vitelline envelope-related proteins in masu salmon
    T Fujita, M Shimizu, A Hara  ADVANCES IN COMPARATIVE ENDOCRINOLOGY, TOMES 1 AND 2  1487  -1491  1997  [Not refereed][Not invited]
    Two vitelline envelope-related proteins (VERPs) of masu salmon were detected in serum and liver extract of mature females using rabbit antiserum against vitelline envelope protein., Their antigenicity was identical with that of the vitelline envelope of oocytes. These results suggest that VERPs are synthesized by the liver and secreted into the female serum. Probably, they represent precursors of vitelline envelope proteins in masu salmon.
  • 卵黄蛋白前駆物質(ビテロジェニン)を指標にした成熟度判定手法の開発
    原彰彦, 平松尚志, 清水宗敬  平成6年度新品種作出基礎技術開発事業研究成果の概要  192  -203  1995  [Not refereed][Not invited]

Awards & Honors

  • 2017/03 日本水産学会 平成29年度日本水産学会論文賞
    受賞者: 桑田知宣;徳原哲也;清水宗敬;吉崎悟朗

Research Grants & Projects

  • サケ科魚類の成長調節メカニズムの理解に基づいた養殖魚診断法の実用化
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2019/04 -2023/03 
    Author : 清水 宗敬, 棟方 有宗, 森山 俊介, 内田 勝久
  • 海水移行時の低水温と栄養状態に着目したサケ稚魚の減耗機構に関する実験的検証
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2018/04 -2021/03 
    Author : 宮腰 靖之, 虎尾 充, 清水 宗敬
    異なる栄養状態と水温条件が海水移行時のサケ稚魚の初期減耗に与える影響を調べるため,2018年,水温条件と給餌・絶食の条件を変えた以下の試験群を設定してサケ稚魚の飼育試験を行った。給餌率をそれぞれ0%(絶食),1%,および3%で5日間飼育した後,それぞれの群を低水温区(4℃),中水温区(7℃),高水温区(10℃)の試験水槽に収容し,3日間の馴致期間を経て5日間の海水飼育を行った。 これらの試験群について,栄養状態の指標として筋肉中のトリグリセリド(TG)含量と肝臓中のグリコーゲン含量を測定した。成長率の指標として血中のインスリン様成長因子-I(IGF-I)量を測定した。海水飼育後のTG含量はいずれの水温区でも淡水飼育時の給餌率が高い群でTG量は高く,肝臓中グリコーゲン含量は高水温・絶食群で高い傾向がみられた。血中IGF-I量は淡水での絶食には差は無かったが,海水馴致時にはいずれの水温でも絶食群でIGF-I濃度が低かった。海水飼育後は絶食による違いはなく,高水温群でIGF-Iが高くなった。 遊泳力の指標として臨界遊泳速度(Ucrit)を測定した。海水飼育後には,低水温試験群の遊泳速度は高水温試験群より有意に低かった。サケ稚魚の海水移行後の遊泳速度は水温に大きく影響を受け,低水温では遊泳速度が低下することが示された。また,淡水生活期の絶食が海水移行後の遊泳速度低下につながることも示されたが,水温が高い場合はその影響が軽減される可能性がある。
  • サケ科魚類の新しい成長・ストレス診断法の開発と海面養殖への応用
    Date (from‐to) : 2016/04 -2020/03 
    Author : 清水宗敬
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2013/04 -2016/03 
    Author : MIYAKOSHI Yasuyuki, SHIMIZU Munetaka, TORAO Mitsuru
    To evaluate the growth rates of chum and pink salmon in their early marine life, we analyzed the otolith daily increments of juvenile chum and pink salmon and examined the effective physiological indicators for growth rates. By otolith increment analyses, the dates of ocean entry and daily growth rates can be estimated. From examining the physiological indicators, the serum insulin-like growth factor (IGF)-I can be used as a most useful indicator to evaluate the growth rates of juvenile salmon. Serum IGF-I levels in chum and pink salmon estuarine area were lower and fish in the coastal area were higher, indicating that growths of juvenile salmon was activated when they left the estuarine area and migrated to the offshore while fish of low growth stay in the estuary. Until May, IGF-I levels in pink salmon were lower than chum salmon but were higher in June, which likely reflects a higher growth rate of this species.
  • 文部科学省:科学研究費補助金(基盤研究(C))
    Date (from‐to) : 2012 -2012 
    Author : 清水 宗敬
  • 文部科学省:科学研究費補助金(基盤研究(C))
    Date (from‐to) : 2009 -2011 
    Author : 清水 宗敬
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2007 -2008 
    Author : Munetaka SHIMIZU
    魚類を含む脊椎動物の成長には、インスリン様成長因子(insulin-like growth factor, IGF)-Iが重要な役割を果たしている。しかし、IGF-Iの活性は6種類のIGF結合蛋白(IGF-binding protein, IGFBP)によって厳密に調節されている。これらのIGFBPの機能はタイプにより異なるが、大まかにIGF-Iを介した成長の「促進型」と「阻害型」に分けられる。サケ科魚類の血中には少なくとも3種類のIGFBPが検出されるが、それぞれがどのタイプに相当するのかは非常に混乱している。本研究はこれらのIGFBPの同定を行って上述の混乱を解決することを目的としている。まず、サケ科魚類の血中IGF-Iの主要な運搬役であり、成長の「促進型」と考えられている41 kDa IGFBP(41K BP)およびIGFBP-3のcDNAクローニングを行った。クローニングにより得られた配列を解析したところ、41K BPはIGFBP-2に最も高い相同性を示した。一方、IGFBP-3の配列は、41K BPのものとは異なっていた。このことから、41K BPはIGFBP-3ではなくIGFBP-2であることが明らかになった。さらにもう一種類のIGFBPをクローニングすると共に、これらの発現解析を行った。新たに得られたIGFBPの演繹アミノ酸配列はIGFBP-2に最も近かった。ま...
  • サケ科魚類の河川生活期における相分化機構に関する免疫生化学的研究
    日本学術振興会:科学研究費助成事業 特別研究員奨励費
    Date (from‐to) : 1999 -1999 
    Author : 清水 宗敬

Educational Activities

Teaching Experience

  • 海洋生態系保全学
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 水産学部
  • Fundamental Lecture in Marine Biological Processes
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 海洋学 Oceanography
  • 海洋生物学実験
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 水産学部
  • Advanced Course in Marine Ecological Modeling II
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 海洋生態系、気候変動、海洋環境、海洋生物資源、モニタリング、魚類と水圏動物、生活史、環境生理学 Marine ecosystem, Climate change, Marine environment, Marine bioresources, Monitoring, Fish and Aquatic animals, Life history, Environmental physiology
  • Environment and People
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : サケ、回遊、人工ふ化放流、分類、気候変化、資源変動、生活史、個体群密度効果、生物多様性、バイオロギング、母川回帰、嗅覚、物質循環、海水適応、ゲノム、性統御、始原生殖細胞、流通、ハサップ(HACCP)、先住民族、市民運動、魚病
  • Marine Biological Science Ⅰ
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 海洋生物,遺伝,分子生物学,機能,生理学,構造,細胞生物学,解剖組織学
  • English for Fisheries Sciences I
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 海洋生物学、資源生物学、海洋環境化学、海洋共生学
  • Comparative Physiology
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 繁殖,ホルモン,免疫系,生理機能,生体防御
  • Marine Science Biology II - Laboratory
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 海藻 サケ マス ベントス 貝類 甲殻類 魚類 頭足類 分類 成長曲線 資源量推定 生物測定 外部形態 稚魚 耳石 胃内容物
  • Functional Biology in the Northern Biosphere
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 水圏環境、水圏生物機能、水圏生物資源、養殖生産、生物改変手法
  • Environment and People
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 海洋環境,海洋生態系,環境変化,プランクトン,ベントス,魚類,イカ・タコ類,鯨類,海鳥類,海獣類,海藻,衛星海洋学,生態系モデル,人間活動,地球温暖化,海洋動物の保全・保護

Social Contribution

Social Contribution

Social Contribution

  • マリンラーニングセミナー
    Date (from-to) : 2018/08
    Role : Lecturer
    Sponser, Organizer, Publisher  : 日本財団・海と日本Project
  • マリンラーニングセミナー
    Date (from-to) : 2017/07
    Role : Lecturer
    Sponser, Organizer, Publisher  : 日本財団・海と日本Project

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