論文 - 内田 勝久
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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）