論文 - 内田 勝久
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Effect of seasons and fishing ban period on umami-related and functional components of greeneye (Chlorophthalmus albatrossis) from Japanese coast 査読あり
Horie Ryohei, Imagawa Takumi, Uchida Katsuhisa, Taoka Yousuke, Tanaka Ryusuke
Journal of Food Composition and Analysis 139 107163 2025年3月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Gluconeogenesis in the extraembryonic yolk syncytial layer of the zebrafish embryo. 査読あり
Furukawa F, Aoyagi A, Sano K, Sameshima K, Goto M, Tseng YC, Ikeda D, Lin CC, Uchida K, Okumura SI, Yasumoto K, Jimbo M, Hwang PP
PNAS nexus 3 ( 4 ) pgae125 2024年4月
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Ishimaru M., Uchida K., Taoka Y., Matsumoto T., Tanaka R.
Journal of Aquatic Food Product Technology 33 ( 1 ) 33 - 48 2023年11月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Aquatic Food Product Technology
The chemical composition of muscles from Japanese eels cultured in hot-spring water was determined and compared with that of eels cultured in well water. The proximate composition did not differ significantly between the culture conditions, but the hepatosomatic indices of the hot-spring water eels were significantly higher than those of the well water eels. Amino acid levels were higher in the hot-spring water eels, and the carnosine content of the hot-spring eels was lower than that of the controls. Our results suggest that hot-spring water is a promising medium for eel culture, and its use may bring energy cost savings.
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Yasaka Y., Binh P.T., Hayami Y., Tanaka R., Uchida K., Taoka Y.
Fisheries Science 89 ( 1 ) 41 - 51 2023年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Fisheries Science
We focused on developing an epidemic prevention method for circulating masu salmon aquaculture using the probiotic Lactococcus lactis strain K-C2. This study aimed to evaluate the antibacterial activities of strain K-C2 against pathogens isolated from dead Yamame and masu salmon. First, we identified pathogenic bacteria that were isolated from dead masu salmon based on phylogenetic analysis of the 16S rRNA gene sequence and biological and biochemical characterization. The antibacterial activity of strain K-C2 against seven pathogenic strains isolated from dead masu salmon in this study and two strains of Aeromonas salmonicida previously isolated from dead Yamame was tested using a double agar plate method. The results of a BLAST search using 16S rRNA partial sequence data (1200–1300 bp) revealed that six of the former strains and one of the latter strains showed high similarity to Vibrio anguillarum and Tenacibaculum maritimum, respectively. Strain K-C2 showed antibacterial activity against all pathogenic bacteria. In this study, pathogenic bacteria were newly isolated from dead seawater-acclimated masu salmon, and strain K-C2 was found to have antibacterial effects against these pathogens.
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Miyanishi H., Uchida K.
Fishes 6 ( 2 ) 2021年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Fishes
In fishes, it is necessary to select a salinity environment suitable for survival. However, little is known about the mechanisms regarding detection and selection of salinity environments in fish. This study involved the establishment of a simple aquarium system in which fish can swim between freshwater (FW) and seawater (SW) in a single tank. In this tank, the lower level contained SW, the upper level contained FW, and the FW and SW levels were clearly separated as different salinity areas. Behavioral experiments of salinity environment selection using this simplified system to evaluate salinity preference showed that FW-acclimated medakas preferred FW to SW. In contrast, SW-acclimated medakas preferred SW to FW. These results indicate that euryhaline medakas prefer the saline habitats to which they are acclimated, when able to select the salinity environment. We identified the taste receptor type-2 and polycystic kidney disease 2-like 1 genes as possibly related to high-salinity taste in medaka. The expression of these genes increased at certain time points after SW challenges. In this study, we established an aquarium system to facilitate a simple experiment for salinity preference. Our results suggest that the medaka is good model for research related to seawater environment selection in fish.
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Irachi S, Hall DJ, Fleming MS, Maugars G, Björnsson BT, Dufour S, Uchida K, McCormick SD.
Molecular and Cellular Endocrinology. 519 111056 2021年1月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Molecular and Cellular Endocrinology
Seasonal timing is important for many critical life history events of vertebrates, and photoperiod is often used as a reliable seasonal cue. In mammals and birds, it has been established that a photoperiod-driven seasonal clock resides in the brain and pituitary, and is driven by increased levels of pituitary thyroid stimulating hormone (TSH) and brain type 2 iodothyronine deiodinase (DIO2), which leads to local increases in triiodothyronine (T3). In order to determine if a similar mechanism occurs in fish, we conducted photoperiod manipulations in anadromous (migratory) Atlantic salmon (Salmo salar) that use photoperiod to time the preparatory development of salinity tolerance which accompanies downstream migration in spring. Changing daylength from short days (light:dark (LD) 10:14) to long days (LD 16:8) for 20 days increased gill Na+/K+-ATPase (NKA) activity, gill NKAα1b abundance and plasma growth hormone (GH) levels that normally accompany increased salinity tolerance of salmon in spring. Long-day exposure resulted in five-fold increases in pituitary tshβb mRNA levels after 10 days and were sustained for at least 20 days. tshβb mRNA levels in the saccus vasculosus were low and not influenced by photoperiod. Increased daylength resulted in significant increases in dio2b mRNA levels in the hypothalamus and midbrain/optic tectum regions of the brain. The results are consistent with the presence of a photoperiod-driven seasonal clock in fish which involves pituitary TSH, brain DIO2 and the subsequent production of T3, supporting the hypothesis that this is a common feature of photoperiodic regulation of seasonality in vertebrates.
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宮崎県沿岸域における循環型サクラマス養殖体制の確立と地域水産業の活性化．
内田勝久
調査月報（一般財団法人みやぎん経済研究所） 325 2 - 8 2020年5月
記述言語：日本語 掲載種別：研究論文（大学，研究機関等紀要）
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Taoka Y., Nakamura M., Nagai S., Nagasaka N., Tanaka R., Uchida K.
Fermentation 5 ( 2 ) 2019年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Fermentation
© 2019 by the authors. Previously, we developed a novel production technique for giant masu salmon (GMS). This study aimed to develop a fish sauce from GMS to explore ways to efficiently utilize the salmon and to enrich the fish sauce with γ-aminobutyric acid (GABA) by microbial fermentation. The minced bodies of GMS were autolyzed by endogenous protease at 55 °C and 60 °C. During autolysis, the changes in total free amino acids and protein size was monitored by LC-MS and SDS-PAGE analysis, respectively. After 96 h, fish sauce was prepared by heating, and the amino acid composition was analyzed by LC-MS. To enrich the fish sauce with GABA, Lactobacillus plantarum strain N10 was added and incubated at 28 °C for 48 h. The total free amino acids content significantly increased for 96 h. SDS-PAGE analysis showed that major bands at 200 kDa and 48 kDa detected at 0 h gradually disappeared over time. The ratio of anserine to total amino acids in the fish sauce was approximately 36%. The concentration of GABA in the fish sauce significantly increased through the addition of strain N10. Thus, anserine-rich fish sauce could be quickly produced from GMS, and the fish sauce was enriched with GABA by microbial fermentation.
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日本比較内分泌学会主催シンポジウム「Bridge to a new generation: 時代をつなぐ研究を未来へ」を開催して
内田 勝久
比較内分泌学 45 ( 167 ) 85_1 - 85_1 2019年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：日本比較内分泌学会
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Changes in glycogen concentration and gene expression levels of glycogen-metabolizing enzymes in muscle and liver of developing masu salmon. 査読あり
Fumiya Furukawa,Shotaro Irachi, Mugen Koyama, Otto Baba, Hajime Akimoto,Sei-ichi Okumura, Hirohiko Kagawa, Katsuhisa Uchida
Comp Biochem Physiol A Mol Integr Physiol 225 74 - 82 2018年11月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Assessment of the timing and degree of smolt development in southern populations of masu salmon Oncorhynchus masou 査読あり
INATANI Y, INENO T, SONE S, MATSUMOTO N, UCHIDA K, SHIMIZU M
Journal of Fish Biology 2018年4月
記述言語：英語 掲載種別：研究論文（学術雑誌）
DOI： 10.1111/jfb.13647
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Tanaka R., Uchida K., Ishimaru M., Ito M., Matsumoto N., Taoka Y., Hatate H.
Journal of Food Measurement and Characterization 12 ( 1 ) 200 - 208 2018年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Food Measurement and Characterization
© 2017, Springer Science+Business Media, LLC. A new system of aquaculture for landlocked masu salmon (Oncorhynchus masou masou) has recently been developed in the southern Kyushu Island, Miyazaki, Japan. In this system, moderately silvering fish (smolt salmon) are artificially transported from the freshwater aquaculture ponds to floating seawater fish preserve, and they are then aquacultured during winter season, starting from December to the following April. As a result, their growth and body mass were greatly increased (total length: 21.25 ± 1.04–37.80 ± 3.71 cm; body weight: 81.75 ± 19.91–632.00 ± 172.42 g; condition factor: 8.45 ± 1.44–11.4 ± 0.74). In addition, There was a marked increase in chemical components such as the lipid contents (35.0 ± 9.4–79.2 ± 6.7 mg/g muscle), α-tocopherol (29.0 ± 17.0–178.6 ± 15.0 μg/g muscle), astaxanthin (0.1 ± 0.1–15.2 ± 8.8 μg/g muscle), and anserine (4.75 ± 0.59–10.32 ± 2.68 mg/g muscle) in the seawater-reared landlocked masu salmon. Furthermore, the antioxidant activity of the water soluble extract from the seawater-reared landlocked masu salmon increased from 480.96 ± 79.295–848.99 ± 182.79 μmol Trolox equivalent/g tissue. This new system that involves a short period of aquaculture in seawater not only promotes the growth of landlocked masu salmon, but may also improve its nutritional components and antioxidant activity.
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Variation in the ontogeny of sex steroid levels between latitudinal populations of the medaka. 査読あり
Kawajiri M, Uchida K, Chiba H, Moriyama S, Yamahira K
Zoological Letters 2015年11月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Induction of Phosphoenolpyruvate Carboxykinase (PEPCK) during Acute Acidosis and Its Role in Acid Secretion by V-ATPase-Expressing Ionocytes. 査読あり
Fumiya Furukawa, Yung-Che Tseng, Sian-Tai Liu, Yi-Ling Chou, Ching-Chun Lin1, Po-Hsuan Sung, Katsuhisa Uchida, Li-Yih Lin, Pung-Pung Hwang
International Journal of Biological Sciences 11 ( 6 ) 712 - 725 2015年5月
記述言語：英語 掲載種別：研究論文（学術雑誌）
DOI： 10.7150/ijbs.11827
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Nishiyama M., Uchida K., Abe N., Nozaki M.
General and Comparative Endocrinology 212 1 - 9 2015年2月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
© 2015 Elsevier Inc. Since hagfishes are considered the most primitive vertebrate known, extant or extinct, studies on their reproduction are indispensable for understanding phylogenetic aspects of vertebrate reproduction. However, little information is available on the endocrine regulation of the gonadal function in the hagfish. Based on EST analysis of the testis of the brown hagfish (Paramyxine atami), P450 side chain cleavage (CYP11A), which is the first and essential enzyme for steroidogenesis in jawed vertebrates, was cloned. The deduced amino acid sequence of hagfish CYP11A shows high identity to other animal forms especially in two functional domains, adrenodoxin binding domain and heme-binding domain. In the phylogenetic analysis, hagfish CYP11A forms a clade with the vertebrate CYP11A. Following the real-time PCR analysis, CYP11A mRNA expression levels were clearly correlated to the developmental stages of gonads in both sexes of the brown hagfish. By in situ hybridization, CYP11A mRNA signals were found in the theca cells of the ovarian follicles and Leydig cells and the tubule-boundary cells of the testis. These molecular and histological evidences are suggesting that CYP11A plays functional roles as a steroidogenic enzyme in gonadal development. Moreover, native GTH purified from hagfish pituitary stimulated the transcriptional levels of CYP11A in the organ-cultured testis in vitro, clearly suggesting that the steroidogenic activity of the hagfish is under the control of the pituitary GTH. It is suggested that vertebrates, during their early evolution, have established the pituitary-gonadal reproductive system.
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Scoliorhapis dianthus, a new species of sea cucumber (Apodida: Chiridotidae) from the Sea of Japan 査読あり
Solis-Marin F, Komatsu M, Soliman T, Uchida K, Shimotani T, Nozaki M
The Proceedings of the Biological Society of Washington 2014年8月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Relationships between plasma concentrations of sex steroid hormones and gonadal development in the brown hagfish, Paramyxine atami. 査読あり
Nishiyama M., Chiba H., Uchida K., Shimotani T., Nozaki M.
Zoollogical Science 2013年12月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Nozaki M., Uchida K., Honda K., Shimotani T., Nishiyama M.
General and Comparative Endocrinology 189 111 - 118 2013年8月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
A single functional gonadotropin (GTH) comprising two subunits, α and β, was recently identified in the pituitary of brown hagfish (Paramyxine atami). Little is known about the feedback mechanisms that regulate these GTH subunits by sex steroids in the hagfish. The present study was designed to examine feedback effects of estradiol and testosterone on mRNA expression and protein expression of both GTHα and GTHβ subunits in the pituitary of the juvenile P. atami. Intraperitoneal administration of estradiol over the course of 27. days resulted in substantial accumulation of immunoreactive (ir)-GTHα and ir-GTHβ in the adenohypophysis, but testosterone treatments over 27. days had no effects on ir-GTHα or ir-GTHβ. Estradiol treatment for 1, 2, 4 or 14. days had no effect on GTHα mRNA levels. In contrast, after 2. days of estradiol treatment, GTHβ mRNA levels had increased significantly from baseline, while these levels were not affected after treatment over 1, 4, or 14. days. After 14. days of testosterone treatment, both GTHα and GTHβ mRNA levels had decreased significantly from baseline levels. These results indicate that estradiol acted primarily to suppress the secretion of GTH, and hence resulted in the accumulations of ir-GTHα and ir-GTHβ in the pituitary. On the other hand, testosterone appeared to suppress both the synthesis and the secretion of GTH. Thus, estradiol and testosterone probably differ in their effects on the regulation of pituitary GTH syn thesis and secretion in juvenile hagfish. © 2013 Elsevier Inc.
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Effects of estradiol or testosterone treatment on expression of gonadotropin subunit mRNAs and proteins in the pituitary of juvenile brown hagfish, Paramyxine atami. 査読あり
Nozaki M., Uchida K., Honda K., Shimotani T., Nishiyama M.
General and Comparative Endocrinology 189 111 - 118 2013年5月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Glycoprotein hormone in the pituitary of hagfish and its evolutionary implications. 招待あり 査読あり
Uchida K, Moriyama S, Sower SA, Nozaki M.
Fish Physiology Biochemistry. 39 75 - 83 2013年2月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Nagashima H., Kuraku S., Uchida K., Kawashima-Ohya Y., Narita Y., Kuratani S.
Vertebrate Paleobiology and Paleoanthropology ( 9789400743083 ) 37 - 50 2013年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Vertebrate Paleobiology and Paleoanthropology
© Springer Science+Business Media Dordrecht 2013. The turtle shell is comprised of a dorsal carapace and a ventral plastron, and is an autapomorphy of this group. The carapace consists of the vertebral column and ribs as well as a specialized dermis. The formation of the shell is accompanied by a change in the spatial relationship of the ribs and the pectoral girdle. Because of this rearrangement, the turtle shell has been regarded as an example of an evolutionary novelty. Understanding the changes behind this developmental repatterning will help us elucidate the evolutionary history of turtles. The change has been attributed to a deflected pattern of development of the ribs, which in normal tetrapods grow ventrally into the lateral body wall. In turtles, they grow laterally toward the primordium of the carapacial margin, called the carapacial ridge (CR), while remaining in the axial part of the embryonic body. Based on a similarity in histological configuration, the CR has been thought to possess inductive activity for rib growth, as seen in the apical ectodermal ridge of the amniote limb bud. The CR does not function as a guidance cue for rib progenitor cells but rather functions in the marginal growth of the carapacial primordium, resulting in fanned-out growth of the ribs. This peripheral and concentric expansion of the axial domain makes the lateral body wall fold inward, while the ribs cover the pectoral girdle. The turtle ribs develop along the muscle plate as in other amniotes, and do not take a different trajectory from that in other amniotes, unlike the scenario hypothesized previously. This folding enables turtles to change the apparent spatial relationships between the ribs and the pectoral girdle without altering their topological alignment and body plan as amniotes. This developmental sequence of the modern turtles aligns with a stepwise evolutionary process in the group, which is supported by the anatomy of a recently discovered fossil species, Odontochelys.
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Regulation of growth hormone (GH) receptor (GHR1 and GHR2) mRNA level by GH and metabolic hormones in primary cultured tilapia hepatocytes. 査読あり
Pierce AL, Breves JP, Moriyama S, Uchida K, Grau EG.
General and Comparative Endocrinology 179 ( 1 ) 22 - 29 2012年10月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Induction of sexual maturation of the female honeycomb grouper, Epinephelus merra, in the non-breeding season by modulating environmental factors with GnRH analogue implantation 査読あり
Kanemaru T, Nakamura M, Murata R, Kuroki K, Horie H, Uchida K, Senthilkumaran B, Kagawa H
Aquaculture 358-359 85 - 91 2012年7月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Body plan of turtles: an anatomical, developmental and evolutionary perspective. 招待あり 査読あり
Nagashima H, Kuraku S, Uchida K, Kawashima-Ohya Y, Narita Y, Kuratani S
Anatomical Science International 87 ( 1 ) 1 - 13 2011年12月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Characterization of novel RFamide peptides in the central nervous system of the brown hagfish: isolation, localization, and functional analysis. 査読あり
Osugi T, Uchida K, Nozaki M, Tsutsui K
Endocrinology 152 ( 11 ) 4252 - 4264 2011年8月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Evolutionary origin of a functional gonadotropin in the pituitary of the hagfish 招待あり
Uchida K, Moriyama S, Sower S.A, Nozaki M.
Internal Symposium on Reproductive Physiology of Fish 4 ( S8 ) 4 - 5 2011年8月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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最も原始的な脊椎動物・ヌタウナギの下垂体から単離された生殖腺刺激ホルモンとその進化的起源
内田 勝久
比較内分泌学 = Comparative endocrinology 37 ( 140 ) 32 - 36 2011年2月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Japan Society for Comparative Endocrinology
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Uchida K., Moriyama S., Chiba H., Shimotani T., Honda K., Miki M., Takahashi A., Sower S., Nozaki M.
Proceedings of the National Academy of Sciences of the United States of America 107 ( 36 ) 15832 - 15837 2010年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Proceedings of the National Academy of Sciences of the United States of America
Hagfish, which lack both jaws and vertebrae, are considered the most primitive vertebrate known, living or extinct. Hagfish have long been the enigma of vertebrate evolution not only because of their evolutionary position, but also because of our lack of knowledge on fundamental processes. Key elements of the reproductive endocrine system in hagfish have yet to be elucidated. Here, the presence and identity of a functional glycoprotein hormone (GPH) have been elucidated from the brown hagfish Paramyxine atami. The hagfish GPH consists of two subunits, α and β, which are synthesized and colocalized in the same cells of the adenohypophysis. The cellular and transcriptional activities of hagfish GPHα and -β were significantly correlated with the developmental stages of the gonad. The purified native GPH induced the release of gonadal sex steroids in vitro. From our phylogenetic analysis, we propose that ancestral glycoprotein α-subunit 2 (GPA2) and β-subunit 5 (GPB5) gave rise to GPHα and GPHβ of the vertebrate glycoprotein hormone family, respectively. The identified hagfish GPHα and -β subunits appear to be the typical gnathostome GPHα and -β subunits based on the sequence and phylogenetic analyses. We hypothesize that the identity of a single functional GPH of the hagfish, hagfish GTH, provides critical evidence for the existence of a pituitary-gonadal system in the earliest divergent vertebrate that likely evolved from an ancestral, prevertebrate exclusively neuroendocrine mechanism by gradual emergence of a previously undescribed control level, the pituitary, which is not found in the Protochordates.
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Evolutionary origin of a functional gonadotropin in the pituitary of the most primitive vertebrate, hagfish. 査読あり
Uchida K., Moriyama S., Chiba H., Simotani T., Honda K., Miki M., Takahashi A., Sower S.A., Nozaki M.
Proceedings of the National Academy of Sciences of the United State of America 107 ( 36 ) 15832 - 15837 2010年8月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Furukawa F., Watanabe S., Kaneko T., Uchida K.
General and Comparative Endocrinology 166 ( 3 ) 549 - 555 2010年5月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
Mozambique tilapia, Oreochromis mossambicus, is easily acclimated to highly acidic water, and thus presents a useful model to unravel endocrine regulation of adaptation to acidic water in fish. We analyzed gene expression of somatolactin (sl), growth hormone (gh) and prolactin (prl), in the pituitary gland and size distribution of mitochondria-rich (MR) cells in the gills after transfer from normal freshwater (FW, pH 7.2) to acidified freshwater (AW, pH 3.5). Plasma osmolality drastically decreased until 2. days after transfer to AW, but had restored to normal after 1. week of acclimation, and this confirmed the excellent acid tolerance of tilapia. Expression levels of sl, gh and prl were all up-regulated during short-term exposure to AW. The expression of sl remained elevated up to 7. days after transfer; the expression of gh and prl was back to initial levels at that time. These findings point to an important and specific role of SL in adaptation to acid water in this tilapia, although temporal contribution of GH and PRL cannot be ruled out. The size distribution of branchial MR cells changed drastically during acclimation to AW. The mean MR cell size was 1.5-fold larger in the fish exposed to AW for 7. da ys compared to controls in FW. The gills and their MR cells are a likely site of important acid-base regulation, and SL may change ion-transport functions of MR cells to correct plasma osmotic balance disturbed by acid exposure. © 2010 Elsevier Inc.
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Uchida K., Moriyama S., Breves J., Fox B., Pierce A., Borski R., Hirano T., Gordon Grau E.
General and Comparative Endocrinology 161 ( 2 ) 162 - 170 2009年4月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
Somatolactin (SL) is a member of the growth hormone (GH)/prolactin (PRL) family of pituitary hormones, and is found in a variety of teleost species. Somatolactin is thought to be involved in a wide range of physiological actions, including reproduction, stress response, the regulation of Ca 2+ and acid-base balance, growth, metabolism, and immune response. We report here on the cDNA structure of SL from the pituitary of Mozambique tilapia, Oreochromis mossambicus, and its gene expression in response to seawater acclimation, stress, and fasting. Tilapia SL cDNA (1573 bp long) encoded a prehormone of 230 amino acids. Sequence analysis of purified SL revealed that the prehormone is composed of a signal peptide of 23 amino acids and a mature protein of 207 amino acids, which has a possible N-glycosylation site at position 121 and seven Cys residues. Tilapia SL shows over 80% amino acid identity with SLα of advanced teleosts such as medaka and flounder, and around 50% identity with SLβ of carp and goldfish. Acclimation to seawater had no effect on pituitary expression of SL or on hepatic expression of the putative tilapia SL receptor (GHR1). By contrast, seawater acclimation resulted in significant increases in pituitary GH expression and in hepatic expression of tilapia GH receptor (GHR2). Confinement stress had no effect on pituitary expression of either SL or GH, or on hepatic expression of GHR1, whereas a significant increase was seen in GHR2 expression in the liver. Fasting for 4 weeks resulted in significant reductions in SL transcripts both in fresh water and seawater. It is highly likely that SL is involved in metabolic processes in tilapia along with the GH/IGF-I axis. © 2009 Elsevier Inc. All rights reserved.
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Radiolarian faunal characteristics in surface-subsurface waters of the Japan Sea off Tassha, Sado Island, central Japan in June 2007: inflowing radiolarians on the Tsushima Warm Current.
Kurihara T., Uchida K., Shimotani T., Matsuoka A.
Science Reports of Niigata University (Geology) 23 65 - 74 2008年3月
記述言語：英語 掲載種別：研究論文（大学，研究機関等紀要）
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Magdeldin S., Uchida K., Hirano T., Grau E., Abdelfattah A., Nozaki M.
Fisheries Science 73 ( 5 ) 1025 - 1034 2007年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Fisheries Science
Hormonal control of growth was examined in juvenile Mozambique tilapia Oreochromis mossambicus under different environmental salinities. When juvenile tilapia were acclimated to fresh water (FW) or to full-strength sea water (SW) for 3 weeks, growth rate of the SW-acclimated fish doubled compared to FW fish. Pituitary mRNA levels of growth hormone (GH) were significantly higher in SW-adapted tilapia compared with FW fish, while the gene expression of prolactin (PRL 188 and PRL 177 ) in SW fish was lower than in the FW group. The release and synthesis of insulin-like growth factor-I (IGF-I) were significantly elevated in the SW fish. This indicates that the GH/IGF-I axis is up-regulated in juvenile tilapia in SW and likely leads to the observed elevation in growth. Transfer of the juveniles from FW to 70% SW or vice versa for 2 weeks had no effect on growth rate. On the other hand, GH transcripts as well as hepatic IGF-I mRNA levels increased significantly after transfer of the FW-acclimated fish to 70% SW, while PRL 188 mRNA levels were significantly elevated after transfer of the 70% SW fish to FW. Our findings indicate that the GH/IGF-I axis plays important roles both in growth and in osmoregulation in juvenile tilapia in SW. © 2007 Japanese Society of Fisheries Science.
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Nozaki M., Shimotani T., Uchida K.
Cell and Tissue Research 328 ( 3 ) 563 - 572 2007年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Cell and Tissue Research
The pituitary system of the hagfish remains an enigma. The present study has aimed to detect possible adenohypophysial hormones in the pituitary gland of the brown hagfish, Paramyxine atami, by means of immunohistochemistry in combination with lectin histochemistry. Rabbit antisera raised against ovine luteinizing hormone (LH)β, proopiomelanocortin (POMC)-related peptides, and the growth hormone/prolactin family of tetrapod and fish species were used, and 25 kinds of lectins were tested. Three different types of adenohypophysial cells were revealed in the pituitary of brown hagfish. The first was stained with both anti-ovine LHβ and several D-mannose-binding lectins, such as Lens culinaris agglutinin and Pisum sativum agglutinin. This cell type predominated in the adenohypophysis in adults with developing gonads and thus appeared to be involved in the regulation of gonadal functions. The second was negative for anti-ovine LHβ but was stained with several N-acetylglucosamine-binding lectins, such as wheat germ agglutinin and Lycopersicon esculentum lectin. This cell type exhibited a weak positive reaction with anti-lamprey adrenocorticotropin (ACTH) and thus appeared to be related to POMC-like cells. The second cell type was found in the adenohypophysis regardless of the developmental state of the gonads. The third cell type was negative for both antisera and lectins. Since this cell type was numerous in juveniles and adults without developing gonads, most cells of this type were probably undifferentiated. These findings suggest that GTH and ACTH are major adenohypophysial hormones in the hagfish. © 2007 Springer-Verlag.
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Nagashima H., Kuraku S., Uchida K., Ohya Y., Narita Y., Kuratani S.
Development 134 ( 12 ) 2219 - 2226 2007年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Development
The chelonian carapace is composed of dorsolaterally expanded ribs; an evolutionary change in the rib-patterning program is assumed to be related to this novelty. Turtle embryos exhibit a longitudinal ridge called the carapacial ridge (CR) on the flank, and its histological resemblance to the apical ectodermal ridge of the limb bud implies its inductive activity in the unique patterning of the ribs. We studied the Chinese soft-shelled turtle, Pelodiscus sinensis, and confirmed by labeling with a lipophilic dye, Dil, that the CR contains the somite-derived dermis and that it is a unique structure among amniotes. Using electroporation of a dominant-negative form of LEF-1, the CR-specific gene, we showed that CR-specific genes function in the growth and maintenance of the CR. Microcauterization or implantation of the CR did not change the dorsoventral pattern of the ribs, and only their fan-shaped pattern was arrested by CR removal. We conclude that the CR is a true embryonic novelty among amniotes and, because of the specific expression of regulatory genes, it functions in the marginal growth of the carapacial primordium, thereby inducing the fan-shaped arrangement of the ribs.
DOI： 10.1242/dev.002618
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Gonadotropin-like and adrenocorticotropin-like cells in the pituitary gland of hagfish, Paramyxine atami: immunohistochemistry in combination with lectin histochemistry. 査読あり
Nozaki M., Shimotani T., Uchida K.
Cell and Tissue Research 328 563 - 572 2007年3月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Radiolarian faunas and water properties in surface and subsurface waters of the Japan Sea in September 2005 off Tassha, Sado Island, central Japan.
Kurihara T., Uchida K., Shimotani S., Matsuoka A.
Science Reports of Niigata University (Geology) 22 35 - 42 2007年3月
記述言語：英語 掲載種別：研究論文（大学，研究機関等紀要）
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Identification of gonadotropin producing cells in the adenohypophysis of brown hagfish, Paramyxine atami.
Honda K., Uchida K., Shimotani S., Moriyama S., Nozaki M.
Proceedings of The Japan Society for Comparative Endocrinology 21 52 - 52 2006年12月
記述言語：英語 掲載種別：研究論文（その他学術会議資料等）
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Identification of sea lamprey GTHβ-like cDNA and its evolutionary implications
Sower S., Moriyama S., Kasahara M., Takahashi A., Nozaki M., Uchida K., Dahlstrom J., Kawauchi H.
General and Comparative Endocrinology 148 ( 1 ) 22 - 32 2006年8月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
We have identified the first and perhaps only gonadotropin β-like protein by cDNA cloning in sea lamprey, a member of the oldest lineage of vertebrates, the agnathans. Two pituitary gonadotropins (GTHs: follicle-stimulating hormone (FSH) and luteinizing hormone (LH)) have been identified in representative species of all classes of vertebrates except the agnathans. The present study was undertaken to identify GTH in sea lamprey, Petromyzon marinus, to gain a further understanding of the origin and evolution of reproductive pituitary hormones and their respective genes in vertebrates. Sea lamprey preGTHβ-like cDNA was cloned from a plasmid cDNA library using an expressed sequence tag analysis. The preGTHβ-like cDNA encoded 150 amino acids, in which the GTHβ-like protein consisted of 134 amino acid residues. Sea lamprey GTHβ-like protein contained 12 Cys residues and two N-glycosylation sites at homologous positions to those of FSHβ and LHβ. The region of the molecule that has been proposed to control receptor binding specificity (i.e., the region between the 10th and 12th Cys residues) suggests that the proposed heterodimer would be more like a FSH than a LH. Sea lamprey GTHβ-like protein-producing cells were identified immunocytochemically in the ventral part of the proximal pars distalis of pituitary using antiserum prepared against a synthetic peptide of preGTHβ-like protein (52-68). Intraperitoneal administration of sea lamprey GnRH-I and -III at 100 μg/g body weight (twice at a 24 h interval) increased expression of GTHβ-like protein in the pituitary of adult female sea lamprey during the final maturational period. Thus, these results are the first to demonstrate the presence of a single GTH-like system in lampreys. Because the sea lamprey GTHβ-like protein is a clear out-group compared to those of the LH and FSH family based on phylogenic analysis, we propose that an ancestral glycoprotein hormone gave rise to only one GTH in lampreys and to the glycoprotein hormone family that gave rise to LH, FSH, and TSH during the early evolution of gnathostomes. © 2005 Elsevier Inc. All rights reserved.
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Miki M., Shimotani T., Uchida K., Hirano S., Nozaki M.
General and Comparative Endocrinology 148 ( 1 ) 15 - 21 2006年8月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
Since hagfish are members of the most primitive group of living vertebrates, studies on their reproduction are indispensable for understanding phylogenetic aspects of vertebrate reproductive system. Nevertheless, our knowledge of the reproductive physiology of the hagfish, especially of the pituitary-gonadal axis, is almost completely lacking. In the present study, the relationship between the amount of immunoreactive gonadotropin (GTH)-like material in the pituitary gland and gonadal conditions was examined in the brown hagfish, Paramyxine atami. First, pituitary sections were stained immunohistochemically with anti-ovine LHβ, and the degrees of the accumulation of GTH-like material were compared among three different groups of gonadal conditions; juveniles and adults with and without developing gonads. Immunoreactive GTH-like material was heavily accumulated in adults with developing gonads, whereas it was not or only weakly accumulated in juveniles or adults without developing gonads. Thus, there was a strong positive correlation between the amount of GTH-like material and gonadal conditions. Second, effect of estradiol benzoate on GTH-like material was examined using three groups of juvenile hagfish: initial control, sham control, and experimental animals. Experimental animals received estradiol benzoate resolved in sesame oil intraperitoneally every third day for 1 month, whereas sham control animals received the same doses of sesame oil. GTH-like material was heavily or moderately accumulated in most estrogen-treated animals, whereas it was not or weakly accumulated in initial or sham control animals. Thus, estrogen treatment in juvenile hagfish resulted in the large increase in the amount of GTH-like material. From these results, it is suggested the presence of not only GTH but also the hypophysial-gonadal feedback system in the hagfish. © 2006 Elsevier Inc. All rights reserved.
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Evolution of the brain developmental plan: Insights from agnathans
Murakami Y., Uchida K., Rijli F., Kuratani S.
Developmental Biology 280 ( 2 ) 249 - 259 2005年4月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Developmental Biology
In vertebrate evolution, the brain exhibits both conserved and unique morphological features in each animal group. Thus, the molecular program of nervous system development is expected to have experienced various changes through evolution. In this review, we discuss recent data from the agnathan lamprey (jawless vertebrate) together with available information from amphioxus and speculate the sequence of changes during chordate evolution that have been brought into the brain developmental plan to yield the current variety of the gnathostome (jawed vertebrate) brains. © 2005 Elsevier Inc. All rights reserved.
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Nagashima H., Uchida K., Yamamoto K., Kuraku S., Usuda R., Kuratani S.
Developmental Dynamics 232 ( 1 ) 149 - 161 2005年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Developmental Dynamics
Turtles have a body plan unique among vertebrates in that their ribs have shifted topographically to a superficial layer of the body and the trunk muscles are greatly reduced. Identifying the developmental factors that cause this pattern would further our understanding of the evolutionary origin of the turtles. As the first step in addressing this question, we replaced newly developed epithelial somites of the chicken at the thoracic level with those of the Chinese soft-shelled turtle Pelodiscus sinensis (P. sinensis somites into a chicken host) and observed the developmental patterning of the grafted somites in the chimera. The P. sinensis somites differentiated normally in the chicken embryonic environment into sclerotomes and dermomyotomes, and the myotomes differentiated further into the epaxial and hypaxial muscles with histological morphology similar to that of normal P. sinensis embryos and not to that of the chicken. Epaxial dermis also arose from the graft. Skeletal components, however, did not differentiate from the P. sinensis sclerotome, except for small fragments of cartilage associated with the host centrum and neural arches. We conclude that chicken and P. sinensis share the developmental programs necessary for the early differentiation of somites and that turtle-specific traits in muscle patterning arise mainly through a cell-autonomous developmental process in the somites per se. However, the mechanism for turtle-specific cartilage patterning, including that of the ribs, is not supported by the chicken embryonic environment. 149-161 © 2004 Wiley-Liss, Inc.
DOI： 10.1002/dvdy.20235
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Novel RFamide-like peptide in amphioxus.
Kubokawa K., Uchida K., Kuratani S., Agata K.
Integral Comparative Biology 44 716 - 717 2004年12月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Development of the pituitary gland in the lamprey: evolution of epigenetic patterning program in organogenesis.
Uchida K., Murakami Y., Kuraku S., Kuratani Y.
Journal of Morphology 260 335 - 336 2004年8月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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In vitro effects of cortisol on release and gene expression of prolactin and growth hormone in the tilapia, Oreochromis mossambicus. 査読あり
Uchida K., Yoshikawa-Ebesu J.S.M., Kajimura S., Yada T., Hirano T., Grau E.G.
General and Comparative Endocrinology 135 116 - 125 2004年2月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Uchida K., Yoshikawa-Ebesu J., Kajimura S., Yada T., Hirano T., Grau E.
General and Comparative Endocrinology 135 ( 1 ) 116 - 125 2004年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
Exposure to cortisol inhibits prolactin (PRL) release from the tilapia pituitary within 10-20min through a plasma membrane-associated, non-genomic pathway. In the present study, in vitro effects of cortisol on the release and mRNA levels of two PRLs (PRL 188 and PRL 177 ) and growth hormone (GH) were examined in the organ-cultured pituitary of the Mozambique tilapia, Oreochromis mossambicus. The PRL release was significantly greater in hyposmotic (300mOsmolal) than in hyperosmotic (350mOsmolal) medium during the 2-8h of incubation. The mRNA levels of two PRLs, as estimated by RNase protection assay, were increased after 8h in hyposmotic medium. Cortisol (200nM) inhibited the release of two PRLs under hyposmotic conditions within 1h, and the inhibitory effects lasted for 24h. Cortisol also reduced the gene transcription of both PRLs during 2-8h of incubation but not after 24h. No effect of cortisol was observed on PRL release or on its mRNA levels under hyperosmotic condition. There was no significant effect of medium osmolality on the release or mRNA levels of GH during 8h of incubation. However, GH release was significantly stimulated by cortisol after 4h, and the effect lasted for 24h under both hyposmotic and hyperosmotic conditions. Cortisol also caused a significant increase in GH mRNA levels at 8 and 24h. These results suggest that cortisol inhibits PRL release from the tilapia pituitary through non-genomic and also through transcriptional pathways, while stimulating GH release through classical genomically mediated glucocorticoid actions. © 2003 Elsevier Inc. All rights reserved.
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Uchida K., Murakami Y., Kuraku S., Hirano S., Kuratani S.
Journal of Experimental Zoology Part B: Molecular and Developmental Evolution 300 ( 1 ) 32 - 47 2003年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
In gnathostomes, the adenohypophysis, a component of the hypothalamohypophysial complex, is believed to develop through hierarchically organized epigenetic interactions based primarily on the topographical relationships between tissues. From a comparison of developmental processes and gene expression patterns of pituitary-related genes between the agnathan species, lampreys and gnathostomes, we speculate on the evolutionary pathway of the vertebrate adenohypophysis. In the lamprey, this is derived from the nasohypophysial placode (NHP) that develops anterior to the oral ectoderm. The NHP can be identified by the expression of LjPitxA, before actual histogenesis, but it is initially distant from the future hypothalamic region. Subsequently, the NHP expresses both LjFgf8/17 and LjBmp2/4a gene transcripts, and grows caudally to establish a de novo contact with the hypothalamic region by the mid-pharyngula stage. Later, the NHP gives rise to both the adenohypophysis and an unpaired nasal organ. Thus, the topographical relationship between the NHP and the hypothalamic region is established secondarily in the lamprey, unlike gnathostomes in which the equivalent relationship appears early in development. Comparing the developmental pattern of the amphioxus homologue of the adenohypophysis, we hypothesize that a modification of the regulation of the growth factor encoding gene lies behind the evolutionary changes recognized as heterochrony and heterotopy, which leads to the gnathostome hypophysial developmental pattern. © 2003, Wiley-Liss, Inc.
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Uchida K., Kajimura S., Riley L., Hirano T., Aida K., Grau E.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology 134 ( 2 ) 429 - 439 2003年2月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Effects of fasting on the growth hormone (GH)-insulin-like growth factor I (IGF-I) axis were examined in the tilapia (Oreochromis mossambicus) acclimated to fresh water. Fasting for 2 weeks resulted in significant reductions in body weight, specific growth rate and hepatosomatic index in both males and females. Significant reductions in specific growth rates were observed after 1 and 2 weeks in both sexes, although the decrease in body weight was not significant in the female. A significant reduction was also seen in the condition factor of females after 2 weeks. No change was seen in the gonadosomatic index in either sex. Two weeks of fasting also produced a significant reduction in plasma IGF-I but not in plasma GH, prolactin (PRL 188 ) or cortisol. Significant reductions in the hepatic IGF-I mRNA were seen in both sexes. On the other hand, a significant increase was observed in cortisol receptor mRNA in the female liver. Plasma IGF-I levels were correlated significantly with specific growth rate, condition factor and hepatosomatic index, indicating that plasma IGF-I is a good indicator of growth in the tilapia. No change was seen in plasma glucose or osmolality after 2 weeks of fasting. During fasting, tilapia appears to convert metabolic energy from growth to basal metabolism including maintenance of ion and water balance. © 2002 Elsevier Science Inc. All rights reserved.
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Development of the adenohypophysis in the lamprey: evolution of epigenetic patterning programs in organogenesis. 査読あり
Uchida K., Murakami Y., Kuraku S., Hirano S., Kuratani S.
Journal of Experimental Zoology B 300 32 - 47 2003年1月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Stimulation of insulin-like growth factor-I production by recombinant bovine growth hormone in euryhaline tilapia, Oreochromis mossambicus. 査読あり
Kajimura S., Uchida K., Yada T., Riley L.G., Byatt J.C., Collier R.J., Hirano T., Aida K., Grau E.G.
Fish Physiology and Biochemistry 25 221 - 230 2002年11月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Recombinant bovine growth hormone treatment of tilapia: growth response, metabolic clearance, receptor binding and immunoglobulin production. 査読あり
Leedom T.A., Uchida K., Yada T., Richman III N.H, Byatt J.C., Collier R.J., Hirano T., Grau E.G.
Aquaculture 207 359 - 380 2002年9月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Immunomodulatory effects of prolactin and growth hormone in the tilapia, Oreochromis mossambicus
Yada T., Uchida K., Kajimura S., Azuma T., Hirano T., Grau E.
Journal of Endocrinology 173 ( 3 ) 483 - 492 2002年7月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Endocrinology
To clarify the roles of prolactin (PRL) and GH in the control of the immune system, the effects of environmental salinity, hypophysectomy, and PRL and GH administration on several immune functions were examined in tilapia (Oreochromis mossambicus). Transfer from fresh water (FW) to seawater (SW) did not alter plasma levels of immunoglobulin M (IgM) and lysozyme. The superoxide anion (O 2 - ) production in head kidney leucocytes accompanied by phagocytosis was elevated in SW-acclimated fish over the levels observed in FW fish. Hypophysectomy of the fish in FW resulted in a reduction in O 2 - production in leucocytes isolated from the head kidney, whereas there was no significant change in plasma levels of IgM or lysozyme. Treatment with tilapia GH and PRLs (PRL 177 and PRL 188 ) enhanced O 2 - production in vitro in head kidney leucocytes in a dose-related manner. Extrapituitary expression of two PRLs, GH and IGF-I mRNA was detected in lymphoid tissues and cells such as head kidney, spleen, intestine and leucocytes from peripheral blood and head kidney. PRL-receptor mRNA was detected in head kidney leucocytes, and the level of expression was higher in SW-acclimated fish than that in FW fish. Treatment with PRL 177 caused higher production of O 2 - in the head kidney leucocytes isolated from SW tilapia than that from FW fish. In view of the fact that PRL acts antagonistically to osmoregulation in SW, its immunomodulatory actions in this euryhaline fish would appear to be independent of its osmoregulatory action.
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Leedom T., Uchida K., Yada T., Richman N., Byatt J., Collier R., Hirano T., Grau E.
Aquaculture 207 ( 3-4 ) 359 - 380 2002年5月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Aquaculture
Experiments were performed to examine the growth-promoting effects of recombinant bovine growth hormone (rbGH) in the euryhaline tilapia (Oreochromis mossambicus). A radioreceptor assay using a crude membrane preparation of tilapia liver revealed that rbGH was about 100-fold less potent than native tilapia GH (tGH) in displacing 125 I-labeled tGH. Bovine prolactin (bPRL) was equipotent to bovine GH indicating that the GH receptor of tilapia does not distinguish mammalian GH from mammalian PRL. When juvenile tilapia, weighing 1 g, were maintained at 28°C and received intraperitoneal injection of rbGH at doses of 0.1, 1 or 10 μg/g weekly for 8 weeks, no significant effect on growth was observed. A second experiment examined weekly doses ranging from 1 to 50 μg/g for 16 weeks, using 1 g fish maintained at 23°C. rbGH (50 μg/g) significantly increased growth after 14 and 16 weeks, although the growth rate was significantly less than those held at 28°C. More pronounced growth-promoting effects were observed, however, when fish weighing 5 g and held at 29°C were injected with rbGH at doses of 100 and 1000 μg/g once a week for 4 weeks. A single injection of a sustained-release formulation of rbGH (Posilac®, 100 and 1000 μg/g) also elicited growth-promoting effects in fish weighing 4 g and kept at 29°C. Treatment with rbGH, Posilac® or bovine serum albumin (BSA) elicited significant increases in plasma levels of immunoglobulin (IgM) in a dose-dependent manner. By contrast, there was no change in plasma levels of lysozyme activity in rbGH- or Posilac®-injected fish compared with controls. An uptake and clearance study confirmed a slower decline in circulating levels of rbGH following Posilac® injection compared with rbGH in saline. There was no change in plasma concentration of tGH after rbGH treatment, indicating that GH secretion from the tilapia pituitary was unaffected by high plasma levels of rbGH. The relative refractoriness of juvenile tilapia to growth-promoting effects of rbGH compared with that of other species may be due to the specific nature of the tGH receptor in recognizing the homologous hormone. © 2002 Elsevier Science B.V. All rights reserved.
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Immunomodulatory effects of prolactin and growth hormone in immune system in the tilapia, Oreochromis mossambicus. 査読あり
Yada T., Uchida K., Kajimura S., Azuma T., Hirano T., Grau E.G.
Journal of Endocrinology 173 483 - 492 2002年2月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Uchida K., Hasegawa S., Kaneko T.
Canadian Journal of Zoology 80 ( 6 ) 1100 - 1108 2002年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Canadian Journal of Zoology
To clarify the involvement of branchial chloride cells in Ca 2+ uptake in fresh water (FW), chloride-cell morphology was compared in chum salmon (Oncorhynchus keta) fry acclimated to defined FWs with different Ca 2+ concentrations (0, 0.1, and 0.5 mM). Using immunocytochemical staining with an antiserum specific for Na + ,K + -ATPase, chloride cells were detected in both filament and lamellar epithelia. The numbers and sizes of chloride cells in the lamellar epithelia were greater in the low-Ca 2+ groups (0 and 0.1 mM Ca 2+ ) than in the normal-Ca 2+ groups (0.5 mM Ca 2+ and normal FW), whereas filament chloride cells were not affected in number or size by the environmental Ca 2+ concentration. Electron-microscope observations also revealed that enlarged lamellar chloride cells were more frequently observed in the 0 mM Ca 2+ group than in the 0.5 mM Ca 2+ group. To obtain morphological evidence for Ca 2+ uptake through the branchial epithelia, cellular localization of Ca 2+ -ATPase was examined with a monoclonal antibody specific for human erythrocyte Ca 2+ -ATPase. Ca 2+ -ATPase immunoreactivity was detected in Na + ,K + -ATPase-immunoreactive chloride cells in both filament and lamellar epithelia. Using electron-microscope immunocytochemistry, Ca 2+ -ATPase was found to be localized in the tubular system, which is continuous with the basolateral membrane of chloride cells. These findings indicate that chloride cells in the lamellar epithelia activated by a low Ca 2+ concentration may constitute the extra Ca 2+ and NaCl uptake capacity required to maintain homeostasis in soft water.
DOI： 10.1139/z02-090
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Kajimura S., Uchida K., Yada T., Hirano T., Aida K., Gordon Grau E.
General and Comparative Endocrinology 127 ( 3 ) 223 - 231 2002年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
We investigated in vitro effects of insulin-like growth factors (IGF-I and -II) on growth hormone (GH) and prolactin (PRL) release and gene expression in euryhaline tilapia, Oreochromis mossambicus. Pituitaries were removed from freshwater-acclimated adult males and incubated for 2-24 h in the presence of human IGF-I or -II at doses ranging from 1-1000 ng/ml (0.13-130 nM). IGF-I at concentrations higher than 10 ng/ml and IGF-II higher than 100 ng/ml significantly inhibited GH release after 8, 16, and 24 h. No effect of IGFs was seen during the first 4 h of incubation. IGFs at the same concentrations also significantly attenuated GH gene expression after 24 h, although no effect was seen at 2 h. By contrast, PRL 188 release was stimulated significantly and in a dose-related manner by IGF-I at concentrations higher than 10 ng/ml and by IGF-II at concentrations higher than 100 ng/ml within 2 h. No stimulation was observed after 4 h. Similarly, both IGFs at concentrations higher than 10 ng/ml increased PRL 177 release within 2 h. However, no significant effect of IGF-I or -II was observed on mRNA levels of both PRLs after 2 and 24 h at all concentrations examined. These results clearly indicate differential regulation of GH and PRL release and synthesis by IGFs in the tilapia pituitary, i.e., rapid-acting, stimulatory effects of IGFs on PRL release and slow-acting, inhibitory effects on GH release and synthesis. © 2002 Elsevier Science (USA). All rights reserved.
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Kajimura S., Uchida K., Yada T., Riley L., Byatt J., Collier R., Aida K., Hirano T., Grau E.
Fish Physiology and Biochemistry 25 ( 3 ) 221 - 230 2002年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Fish Physiology and Biochemistry
We have previously reported growth-promoting effects of recombinant bovine growth hormone (rbGH) in Mozambique tilapia, Oreochromis mossambicus, after 4 weekly injections or a single injection of slow-releasing formulation (Posilac®) (Leedom et al. 2002). In order to obtain further understanding of the role of the growth hormone (GH)-insulin-like growth factor-I (IGF-I) axis in growth in the tilapia, the effects of rbGH on plasma and mRNA levels of IGF-I were examined. Plasma IGF-I levels were significantly increased after rbGH and Posilac® injections, and a significant correlation was observed between plasma IGF-I levels, body length and mass in both treatments. IGF-I mRNA levels in the liver and in the skeletal muscle were also significantly increased after rbGH and Posilac® injections, indicating that IGF-I gene expression in these tissues is under control of circulating GH. IGF-I mRNA levels in the gill were not affected by treatment. Liver IGF-I mRNA levels were significantly correlated with body length and with body mass after rbGH and Posilac® injections. These results indicate that the growth-promoting effect of rbGH in this species is mediated to a significant extent via its stimulation of hepatic production of IGF-I and the resulting increase in plasma IGF-I, and also possibly through locally produced IGF-I in the skeletal muscle, acting in a paracrine or autocrine fashion.
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Sakamoto T., Uchida K., Yokota S.
Zoological Science 18 ( 9 ) 1163 - 1174 2001年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Zoological Science
The mitochondrion-rich cells (MRCs) in teleost gill and equivalent tissues are important osmo-regulatory sites in maintaining ionic balance. These cells express a variety of ion pumps, transporters, and channels, which play central roles in ionic regulation. Recently, two types of MRCs have been identified in euryhaline fishes: seawater (SW)-type MRCs extrude Na and Cl ions in SW conditions; freshwater (FW)-type MRCs take up at least Cl - . Long-term development/differentiation of the two types of MRCs during adaptation to different salinities appears to be regulated mainly by endocrine factors. Osmolality, Ca 2+ , neurotransmitters, and fast-acting hormones rapidly regulate the SW MRCs. Recent information is assembled in this review and suggests the functional plasticity of highly specialized MRCs.
DOI： 10.2108/zsj.18.1163
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Regulation of the ion-transporting mitochondrion-rich cell during adaptation of teleost fishes to different salinities. 招待あり 査読あり
Sakamoto T., Uchida K., Yokota S.
Zoological Science 18 1163 - 1174 2001年8月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Excellent salinity tolerance of Mozambique tilapia (Oreochromis mossambicus): elevated chloride cell activity in the branchial and opercular epithelia of the fish adapted to concentrated seawater. 査読あり
Uchida K., Kaneko T., Miyazaki H., Hasegawa S., Hirano T.
Zoological Science 17 149 - 160 2000年3月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Uchida K., Kaneko T., Miyazaki H., Hasegawa S., Hirano T.
Zoological Science 17 ( 2 ) 149 - 160 2000年3月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Zoological Science
Changes in morphology and cellular activity of the chloride cells in branchial and opercular epithelia were examined in tilapia, Oreochromis mossambicus, adapted to fresh water (FW), seawater (SW) and concentrated SW (180% SW). The tilapia are adaptable to a wide range of salinity, maintaining the plasma osmolality within physiological levels. Gill Na + , K + -ATPase activity was remarkably increased in response to elevated environmental salinity. Using immunocytochemical staining with an antiserum specific for α-subunit of Na + , K + -ATPase, chloride cells were detected on the afferent half of the filament epithelia. The size of immunoreactive chloride cells was twice larger in SW and four times larger in 180% SW than in FW. Confocal laser scanning microscopic observations revealed the frequent occurrence of chloride cell complexes under hypersaline conditions. By electron microscopy, a deeply invaginated apical crypt and well-developed tubular network were observed in chloride cells of SW- and 180% SW-adapted fish, indicating enhanced cellular activity. Chloride cells present in the opercular membrane were also developed in response to increased salinity. These findings suggest that highly activated chloride cells in branchial and opercular epithelia may be responsible for salt secretion in hyperosmotic environments. The excellent salinity tolerance of tilapia appears to be attributed to their ability to develop chloride cells in response to increased environmental salinity.
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Shift of chloride cell distribution during early life stages in seawater-adapted killifish, Fundulus heteroclitus. 査読あり
Katoh F., Shimizu A., Uchida K., Kanako T.
Zoological Science 17 11 - 18 2000年1月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Katoh F., Shimizu A., Uchida K., Kaneko T.
Zoological Science 17 ( 1-12 ) 11 - 18 2000年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Zoological Science
The shift of chloride cell distribution was investigated during early life stages of seawater-adapted killifish (Fundulus heteroclitus). Chloride cells were detected by immunocytochemistry with an antiserum specific for Na + , K + -ATPase in whole-mount preparations and paraffin sections. Chloride cells first appeared in the yolk-sac membrane in the early embryonic stage, followed by their appearance in the body skin in the late embryonic stage. Immunoreactive chloride cells in the yolk-sac membrane and body skin often formed multicellular complexes, as evidenced by the presence of more than one nucleus. The principal site for chloride cell distribution shifted from the yolk-sac membrane and body skin during embryonic stages to the gill and opercular membrane in larval and later developmental stages. Our observations suggest that killifish embryos and newly-hatched larvae could maintain their ion balance through chloride cells present in the yolk-sac membrane and body skin until branchial and opercular chloride cells become functional.
DOI： 10.2108/zsj.17.11
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Acid tolerance of Japanese dace (a cyprinid teleost) in Lake Osorezan, a remarkable acid lake. 査読あり
Kaneko T., Hasegawa S., Uchida K., Ogasawara T., Oyagi A., Hirano T.
Zoological Science 16 871 - 877 1999年12月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Acid tolerance of Japanese dace (a cyprinid teleost) in Lake Osorezan, a remarkable acid lake
Kaneko T., Hasegawa S., Uchida K., Ogasawara T., Oyagi A., Hirano T.
Zoological Science 16 ( 6 ) 871 - 877 1999年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Zoological Science
The Japanese dace (Tribolodon hakonensis) is the only teleost species that inhabits Lake Osorezan, a remarkable acid lake in Japan with the water pH of 3.4-3.8. In the present study, physiological changes following transfer of the dace acclimated to neutral stream water (pH 6.8-7.2) to acid lake water (pH 3.6-3.7) were examined with special reference to changes in gill chloride cell morphology. The dace survived direct transfer to acid lake water for 3 days. Plasma [Na + ] and [Cl - ] showed transient decreases at 1 hr after transfer; however, the decrease in [Na + ] was greater than that in [Cl - ]. The recovery of [Cl - ] was more evident than that of [Na + ]. The transient decreases of plasma [Na + ] and [Cl - ] were followed by acidosis. Blood pH was decreased by 0.13 unit at 6 hr, but partially restored by 24 hr. In the dace acclimated to neutral stream water, chloride cells were scattered in the gill filament. Following transfer to acid lake water, however, well-developed chloride cells were arranged in a radial fashion, forming follicular or gland-like structures in the gills. Each chloride cell was equipped with an apical pit, which faced a common lumen leading to the external environment. These findings provide morphological evidence for a significant role(s) of gill chloride cells in ion and acid-base regulation in the acid-tolerant dace.
DOI： 10.2108/zsj.16.871
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Hiroi J., Kaneko T., Uchida K., Hasegawa S., Tanaka M.
Zoological Science 15 ( 4 ) 447 - 453 1998年8月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Zoological Science
To investigate the involvement of the yolk-sac membrane in ion absorption, developmental changes in whole-body cation contents, cellular localization of vacuolar-type H + -ATPase (V-ATPase), and size and density of pavement and chloride cells in the yolk-sac membrane were examined in tilapia (Oreochromis mossambicus) larvae in fresh water (FW) and those transferred to seawater (SW) at 2 days before hatching (day-2). The whole-body content of Na + in embryos and larvae adapted to both FW and SW increased constantly from day-2 to day 10, although they were not fed through the experiment. The yolk-sac membrane of FW larvae at days 0 and 2 showed V-ATPase immunoreactivity in pavement cells, but not in chloride cells. No positive immunoreactivity was detected in SW larvae. Whole-mount immunocytochemistry showed that some pavement cells were intensively immunoreactive, whereas others were less or not immunoreactive. Electron-microscopic immunocytochemistry revealed that V-ATPase immunoreactivity was present in the apical regions of pavement cells in FW larvae, especially in their ridges. The pavement cells in FW larvae were significantly smaller in size but higher in density than those in SW. These results suggest that pavement cells are the site of active Na + uptake in exchange for H + secretion through V-ATPase in FW-adapted tilapia during early life stages.
DOI： 10.2108/zsj.15.447
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Immunolocalization of vacuolar-type H+-ATPase in the yolk-sac membrane of tilapia (Oreochromis mossambicus) larvae. 査読あり
Hiroi, J., Kaneko T., Uchida K., Hasegawa S., Tanaka M.
Zoological Science 15 447 - 453 1998年5月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Localization of cortisol receptor in branchial chloride cells in chum salmon fry. 査読あり
Uchida K., Kaneko T., Tagawa M., Hirano T.
General and Comparative Endocrinology 109 175 - 185 1998年2月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Localization of cortisol receptor in branchial chloride cells in chum salmon fry
Uchida K., Kaneko T., Tagawa M., Hirano T.
General and Comparative Endocrinology 109 ( 2 ) 175 - 185 1998年2月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：General and Comparative Endocrinology
To clarify the involvement of cortisol in functional differentiation of branchial chloride cells, cellular gene expression and localization of cortisol receptor were examined in chum salmon (Oncorhynchus keta) fry in freshwater (FW) and those adapted to seawater (SW) by in situ hybridization and immunocytochemical staining. Sodium-potassium adenosinetriphosphatase (Na + , K + -ATPase) activity in the whole gill homogenate was significantly higher in SW fish than in FW fish. There were no significant differences in plasma cortisol levels nor in the expression of cortisol receptor mRNA, examined by Northern blot analysis, between SW and FW fish. The receptor gene expression, examined by in situ hybridization with b iotin-labeled synthetic oligonucleotide probe, and specific immunostaining with anticortisol receptor serum were found in two types of chloride cells distributed in the gill filaments and lamellae, which were also labeled with anti-Na + ,K + -ATPase serum, indicating that cortisol may be one of the important factors regulating chloride cell functions. Gene expression of cortisol receptor in filament chloride cells, which were highly activated in SW-adapted fry, was significantly greater in the fry adapted to SW than in FW-adapted fry, reflecting their specific role in salt secretion in SW. Cortisol receptors were also present in undifferentiated cells in the interlamellar regions adjacent to the central venous sinus, also suggesting the involvement of cortisol in the functional differentiation of chloride cells.
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Functional differentiation of branchial chloride cells and its hormonal control in chum salmon.
Uchida K., Hirano T.
Marine Conservation and Resource Rehabilitation 35 - 39 1997年12月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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Localization of cortisol receptor in branchial chloride cells in chum salmon.
Uchida K. and Hirano T.
Advances in Comparative Endocrinology 1291 - 1295 1997年11月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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Uchida K., Kaneko T., Yamaguchi A., Ogasawara T., Hirano T.
Marine Biology 129 ( 2 ) 247 - 253 1997年8月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Marine Biology
Osmoregulatory ability of mature chum salmon (Oncorhynchus keta) during spawning migration was examined by following the changes in gill Na + , K + -ATPase activity and in the distribution and morphology of chloride cells. Mature chum salmon caught in Otsuchi Bay, northern Honshu Island, Japan, died within 5 d in seawater (SW) in association with a marked increase in plasma osmolality, whereas the fish transferred to fresh water (FW) maintained plasma osmolality efficiently. Gill Na + , K + -ATPase activity decreased in both SW-maintained and FW-transferred fish. Well-developed chloride cells, identified by immunocytochemical staining specific for Na + , K + -ATPase, were present mainly in the filament epithelium of immature fish caught in the ocean. In mature fish caught in the bay, however, additional chloride cells were also founding the lamellar epithelium. The number of filament chloride cells decreased markedly in the mature fish both in SW and in FW, whereas the number of lamellar chloride cells was maintained. These results suggest that the loss of hypo-osmoregulatory ability in mature chum salmon may be attributable to the decrease in filament chloride cells and associated decrease in gill Na + , K + -ATPase activity, and also that appearance of lamellar chloride cells may be preparatory to the forthcoming upstream migration.
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Reduced hypoosmoregulatory ability and alteration in gill chloride cell distribution in mature chum salmon (Oncorhynchus keta) migrating upstream for spawning. 査読あり
Uchida K., Kaneko T., Yamaguchi A., Ogasawara T., Hirano T.
Marine Biology 129 247 - 253 1997年5月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Uchida K., Kaneko T., Yamauchi K., Hirano T.
Journal of Experimental Zoology 276 ( 3 ) 193 - 200 1996年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Experimental Zoology
Changes in gill chloride cell morphology and Na + ,K + -ATPase activity were examined following transfer of chum salmon (Oncorhynchus keta) fry from fresh water (FW) to seawater (SW). The gill Na + ,K + -ATPase activity in chum salmon fry weighing 0.6-3 g had already been increased prior to SW entry, being twice as high as that in late alevin stages (0.3-0.4 g). The activity further increased gradually when the fry (2-3 g) were transferred to SW. Using immunocytochemicaI staining with an antiserum specific for the α- subunit of Na + ,K + -ATPase, chloride cells were detected in both filament and lamellar epithelia in FW fry. The number of chloride cells in the filament was not affected by SW transfer, whereas lamellar chloride cells were significantly decreased. The size of filament chloride cells was 1.8- fold larger than that of FW fish 21 days after SW transfer, whereas there was no change in the size of lamellar chloride cells throughout the experiment. The intensity of immunoreaction gradually increased after transfer to SW in filament chloride cells. Electron-microscopic observations revealed that mitochondria-rich chloride cells were moderately developed in both filaments and lamellae of FW fish. In the SW-adapted fish, well- developed chloride cells were detected only in the filament. These results suggest that chloride cells in the lamella may be the site of ion uptake in FW chum salmon fry and that the well-developed chloride cells in the filament are responsible for salt secretion in SW. The rich population of filament chloride cells, concomitant with enhanced gill Na + ,K + -ATPase activity, may explain the strong seawater adaptability in chum salmon fry prior to SW entry.
DOI： 10.1002/(SICI)1097-010X(19961015)276:3<193::AID-JEZ3>3.0.CO;2-I
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Enhanced chloride cell turnover in the gills of chum salmon fry in seawater
Uchida K., Kaneko T.
Zoological Science 13 ( 5 ) 655 - 660 1996年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Zoological Science
Cellular differentiation and renewal in the gill chloride cells were examined in freshwater (FW)- and seawater (SW)-adapted chum salmon (Oncorhynchus keta) fry and in fry during SW adaptation using 5-bromo-2′-deoxyuridine (BrdU) as a marker for newly-differentiated cells. Chloride cells and BrdU-labeled nuclei were immunocytochemically detected by using antisera specific for Na + ,K + -ATPase and BrdU, respectively. Although the number of chloride cells located at the base of the lamellae and in the interlamellar region (filament chloride cells) was constant in FW, SW and SW-transferred groups, chloride cells located in the lamellar epithelium (lamellar chloride cells) were fewer in SW than in FW, and decreased during SW adaptation. Newly-differentiated cells with BrdU-immunoreactive nuclei were detected mainly in the filaments, and rarely observed in the lamellae. The turnover rates of filament chloride cells for FW, SW and SW-transferred fish during the first 24 hr were 8%, 21% and 28%, respectively. These results indicate that chloride cells in the filament are replaced continuously by newly-differentiated cells in both FW and SW, and that the turnover was about 3 times greater in SW than in FW. More frequent turnover of filament chloride cells in SW suggests a specific role, presumably in salt excretion.
DOI： 10.2108/zsj.13.655
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Morphometrical analysis of chloride cell activity in the gill filament and lamellae and changes in gill Na+, K+-ATPase activity during seawater adaptation in chum salmon fry. 査読あり
Uchida K., Kaneko T., Yamauchi K., Hirano T.
Journal of Experimental Zoology 276 193 - 200 1996年6月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Enhanced chloride cell turn over in the gills of chum salmon fry. 査読あり
Uchida K. and Kaneko T.
Zoological Science 13 655 - 660 1996年5月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Levels of calcium in the skin of some amphibians and possible evolutionary implications
Uchida K., Ohtani Y., Sasayama Y., Nambu H., Yoshizawa H., Akabane S., Suzuki K., Suzuki N.
Zoological Science 10 ( 5 ) 819 - 826 1993年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Zoological Science
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Detection of calcitonin mRNA in the ultimobranchial gland of the Japanese char with in situ hybridization method.
Uchida K., Yamada H., Suzuki N., Sasayama Y., Nishizawa T.
Progress in Comparative Endocrinology 41 - 42 1993年9月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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Levels of calcium in the skin of some amphibians and possible evolutionary implication. 査読あり
Uchida K., Ohotani Y., Sasayama Y., Nambu H., Yoshizawa H., Akabane S., Suzuki K., Suzuki N.
Zoological Science 10 819 - 826 1993年4月
記述言語：英語 掲載種別：研究論文（学術雑誌）