Papers - MIYANISHI Hiroshi
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Konno N., Togashi A., Miyanishi H., Azuma M., Nakamachi T., Matsuda K.
Journal of Experimental Zoology Part A: Ecological and Integrative Physiology in press 2024.12
Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Experimental Zoology Part A: Ecological and Integrative Physiology
In euryhaline teleosts, the cystic fibrosis transmembrane conductance regulator (CFTR) in seawater (SW)-type chloride cells facilitates apical Cl− secretion for SW adaptation, while alternative Cl− excretion pathways remain understudied. This study investigates the role of the calcium-activated chloride channel, Anoctamin 1 (ANO1), in the gills of the euryhaline Japanese medaka (Oryzias latipes) under hyperosmolality and cortisol (CORT) influence. Acclimation to artificial SW, NaCl, mannitol, or glucose significantly upregulated ANO1 and CFTR mRNA expression in gills, unlike urea treatment. In situ hybridization revealed ANO1 mRNA in chloride cells co-expressing CFTR and Na+, K+-ATPase under hyperosmotic conditions. ANO1 inhibition elevated plasma Cl− concentration, indicating impaired Cl− excretion. CORT or dexamethasone administration in freshwater (FW) fish significantly increased branchial ANO1 and CFTR mRNA expression, an effect attenuated by the glucocorticoid receptor (GR) antagonist RU486. Hyperosmotic treatment of isolated gill tissues rapidly induced ANO1 mRNA expression independent of CFTR mRNA changes, and this induction was unaffected by RU486. These findings highlight the dual regulation of ANO1 expression via hyperosmolality-induced cellular response and the CORT–GR system. Thus, branchial ANO1 may likely complement CFTR in Cl⁻ excretion, playing a key role in the hyperosmotic adaptation of euryhaline teleosts.
DOI： 10.1002/jez.2894
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Yamamoto J, Deguchi H, Sumiyoshi T, Nakagami K, Saito A, Miyanishi H, Kondo M, Kono T, Sakai M, Kinoshita M, Hikima JI
Marine biotechnology (New York, N.Y.) 26 ( 4 ) 658 - 671 2024.6
Language：English Publishing type：Research paper (scientific journal) Publisher：Marine Biotechnology
Intracellular bacteria such as those belonging to the genus Edwardsiella can survive and proliferate within macrophages. However, the detailed mechanisms underlying the host macrophage immune response and pathogen evasion strategies remain unknown. To advance the field of host macrophage research, we successfully established transgenic (Tg) Japanese medaka Oryzias latipes that possesses fluorescently visualized macrophages. As a macrophage marker, the macrophage-expressed gene 1.1 (mpeg1.1) was selected because of its predominant expression across various tissues in medaka. To validate the macrophage characteristics of the fluorescently labeled cells, May-Grünwald Giemsa staining and peroxidase staining were conducted. The labeled cells exhibited morphological features consistent with those of monocyte/macrophage-like cells and tested negative for peroxidase activity. Through co-localization studies, the fluorescently labeled cells co-localized with E. piscicida in the intestines and kidneys of infected medaka larvae, confirming the ingestion of bacteria through phagocytosis. In addition, the labeled cells expressed macrophage markers but lacked a neutrophil marker. These results suggested that the fluorescently labeled cells of Tg[mpeg1.1:mCherry/mAG] medaka were monocytes/macrophages, which will be useful for future studies aimed at understanding the mechanisms of macrophage-mediated bacterial infections.
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Fujishiro K., Miyanishi H.
Zoological Science 40 ( 5 ) 404 - 413 2023.7
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Zoological Science
High stocking densities have negative effects on fish. However, the mechanism mediating density perception and growth inhibition is still unknown. This study was conducted to confirm the occurrence of growth inhibition and evaluate changes in growth-related factors in fish reared under high-stocking-density conditions and to determine the role of vision in density perception of medaka. In the graduated-stocking experiment, growth inhibition was clearly observed in fish reared at higher densities, although environmental factors, such as water quality, dissolved oxygen, and feeding conditions, were the same in each experimental group. Differences in growth were observed between the 6-fish and 8-fish groups, indicating that medaka have a superior sense that allows them to accurately perceive the number of individuals in their surroundings. In the pseudo-high stocking experiment, the inner 2-L tank in both groups contained six fish; however, the outer 3-L tank in the pseudo group contained several fish, while that of the control group contained only water. Growth inhibition was observed among the fish in the inner tank of the pseudo group despite having similar spatial density with the control group. These findings suggest that vision is important for density perception. The gene expression of growth-related and metabolic-regulatory hormones decreased in the high-density group. Furthermore, neuropeptide Y expression increased, while pro-opiomelanocortin expression decreased in the high-density group. This study is the first to report that fish can visually perceive density and the resulting growth inhibition, and concluded that medaka is a suitable model for studying density effects and perception in fish. .
DOI： 10.2108/zs230018
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キャビアサイクルの短縮化
宮西 弘
調査月報 361 2 - 6 2023
Publishing type：Research paper (scientific journal)
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Takeuchi T., Hata T., Miyanishi H., Yuasa T., Setoguchi S., Takeda A., Morimoto N., Hikima J.i., Sakai M., Kono T.
Fish and Shellfish Immunology 127 238 - 246 2022.8
Language：English Publishing type：Research paper (scientific journal) Publisher：Fish and Shellfish Immunology
In recent years, studies on circadian control in immunity have been actively conducted in mammals, but little is known about circadian rhythms in the field of fish immunology. In this study, we aimed to analyse the regulation of the diel oscillation of inflammatory cytokine interleukin-1β (il1b) gene expression by core components of the circadian clock in Japanese medaka (Oryzias latipes). The expression of il1b and clock genes (bmal1 and clock1) in medaka acclimated to a 12:12 light (L): dark (D) cycle showed diel rhythm. Additionally, higher expression of il1b was detected in medaka embryo cells (OLHdrR-e3) overexpressing bmal1 and clock1. A significant decrease in il1b expression was observed in OLHdrR-e3 cells after bmal1 knockdown using morpholino oligos. These changes may be mediated by transcriptional regulation via clock proteins, which target the E-box sequence in the cis-element of il1b as identified using luciferase reporter assays. Moreover, LPS stimulation and pathogenic bacterial infection at different zeitgeber time (ZT) under LD12:12 conditions affected the degree of il1b expression, which showed high and low responsiveness to both immuno-stimulations at ZT2 and ZT14, respectively. These results suggested that fish IL-1β exhibited diel oscillation regulated by clock proteins, and its responsiveness to immune-stimulation depends on the time of day.
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Reproductive farming technology in Japanese eel and chub mackerel Invited Reviewed
Hiroshi Miyanishi, Naoki Nagano
Aquaculture and Fisheries 7 ( 5 ) 595 - 600 2022.4
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
Japanese eel (Anguilla japonica) and chub mackerel (Scomber japonicus) are commercially valuable species in Asian aquaculture. The reduction in eel and chub mackerel resources has been a serious problem in recent years that should be addressed by reducing the catch of their natural populations to halt their decline and reach the Sustainable Development Goals. Furthermore, securing sufficient food supply by aquaculture is an important step in addressing the increasing demand for fish products in recent years. Traditionally, juveniles of the Japanese eel and chub mackerel have been captured to be raised in aquaculture. Owing to the extensive research on these species, new technologies have been developed for full-lifecycle aquaculture of Japanese eel in 2011 and chub mackerel in 2014. These technologies are expected to stop the decline of natural resources and provide a stable food supply. Recently, seed production of these species has increased owing to the development of successful broodstock management and larval rearing techniques. Fundamental information on oocyte maturation and ovulation and its application for artificial induction of sexual maturation is needed to produce good quality seeds of the Japanese eel and chub mackerel. Here, hormonal mechanisms and previously and newly developed methods for artificial seed production have been described.
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Thyroid and endostyle development in cyclostomes provides new insights into the evolutionary history of vertebrates Reviewed International coauthorship
Wataru Takagi, Fumiaki Sugahara, Shinnosuke Higuchi, Rie Kusakabe, Juan Pascual-Anaya, Iori Sato, Yasuhiro Oisi, Nobuhiro Ogawa, Hiroshi Miyanishi, Noritaka Adachi, Susumu Hyodo, Shigeru Kuratani
BMC Biology 20 ( 1 ) 76 2022.4
Language：English Publishing type：Research paper (scientific journal)
Background: The endostyle is an epithelial exocrine gland found in non-vertebrate chordates (amphioxi and tunicates) and the larvae of modern lampreys. It is generally considered to be an evolutionary precursor of the thyroid gland of vertebrates. Transformation of the endostyle into the thyroid gland during the metamorphosis of lampreys is thus deemed to be a recapitulation of a past event in vertebrate evolution. In 1906, Stockard reported that the thyroid gland in hagfish, the sister cyclostome group of lampreys, develops through an endostyle-like primordium, strongly supporting the plesiomorphy of the lamprey endostyle. However, the findings in hagfish thyroid development were solely based on this single study, and these have not been confirmed by modern molecular, genetic, and morphological data pertaining to hagfish thyroid development over the last century. Results: Here, we showed that the thyroid gland of hagfish undergoes direct development from the ventrorostral pharyngeal endoderm, where the previously described endostyle-like primordium was not found. The developmental pattern of the hagfish thyroid, including histological features and regulatory gene expression profiles, closely resembles that found in modern jawed vertebrates (gnathostomes). Meanwhile, as opposed to gnathostomes but similar to non-vertebrate chordates, lamprey and hagfish share a broad expression domain of Nkx2-1/2-4, a key regulatory gene, in the pharyngeal epithelium during early developmental stages. Conclusions: Based on the direct development of the thyroid gland both in hagfish and gnathostomes, and the shared expression profile of thyroid-related transcription factors in the cyclostomes, we challenge the plesiomorphic status of the lamprey endostyle and propose an alternative hypothesis where the lamprey endostyle could be obtained secondarily in crown lampreys.
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Yoshie Takahashi, Yo Okamura, Nanaki Harada, Mika Watanabe, Hiroshi Miyanishi, Tomoya Kono, Masahiro Sakai, Jun Ichi Hikima
Frontiers in Immunology 12 688036 2021.10
Language：English Publishing type：Research paper (scientific journal)
Mucosal tissue forms the first line of defense against pathogenic microorganisms. Cellular damage in the mucosal epithelium may induce the interleukin (IL)-22-related activation of many immune cells, which are essential for maintaining the mucosal epithelial barrier. A previous study on mucosal immunity elucidated that mammalian IL-22 contributes to mucus and antimicrobial peptides (AMPs) production and anti-apoptotic function. IL-22 has been identified in several teleost species and is also induced in response to bacterial infections. However, the roles of IL-22 in teleost immunity and mucus homeostasis are poorly understood. In this study, Japanese medaka (Oryzias latipes) was used as a model fish. The medaka il22, il22 receptor A1 (il22ra1), and il22 binding protein (il22bp) were cloned and characterized. The expression of medaka il22, il22ra1, and il22bp in various tissues was measured using qPCR. These genes were expressed at high levels in the mucosal tissues of the intestines, gills, and skin. The localization of il22 and il22bp mRNA in the gills and intestines was confirmed by in situ hybridizations. Herein, we established IL-22-knockout (KO) medaka using the CRISPR/Cas9 system. In the IL-22-KO medaka, a 4-bp deletion caused a frameshift in il22. To investigate the genes subject to IL-22-dependent regulation, we compared the transcripts of larval medaka between wild-type (WT) and IL-22-KO medaka using RNA-seq and qPCR analyses. The comparison was performed not only in the naïve state but also in the dextran sulfate sodium (DSS)-exposed state. At the transcriptional level, 368 genes, including immune genes, such as those encoding AMPs and cytokines, were significantly downregulated in IL-22-KO medaka compared that in WT medaka in naïve states. Gene ontology analysis revealed that upon DSS stimulation, genes associated with cell death, acute inflammatory response, cell proliferation, and others were upregulated in WT medaka. Furthermore, in DSS-stimulated IL-22-KO medaka, wound healing was delayed, the number of apoptotic cells increased, and the number of goblet cells in the intestinal epithelium decreased. These results suggested that in medaka, IL-22 is important for maintaining intestinal homeostasis, and the disruption of the IL-22 pathway is associated with the exacerbation of inflammatory pathology, as observed for mammalian IL-22.
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Identification and expression of phospholipase A2 genes related to transcriptional control in the interleukin-17A/F1 pathway in the intestines of Japanese medaka Oryzias latipes Reviewed
Okamura Y, Miyanishi H, Kono T, Sakai M, Hikima J.
Fish and Shellfish Immunology Reports 2 100028 2021.9
Language：English Publishing type：Research paper (scientific journal)
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Hiroshi Miyanishi, Katsuhisa Uchida
Fishes 6 ( 2 ) 2021.6
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
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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Yo Okamura, Hiroshi Miyanishi, Masato Kinoshita, Tomoya Kono, Masahiro Sakai, Jun ichi Hikima
Scientific Reports 11 ( 1 ) 12099 2021.6
Language：English Publishing type：Research paper (scientific journal)
In the intestine, the host must be able to control the gut microbiota and efficiently absorb transiently supplied metabolites, at the risk of enormous infection. In mammals, the inflammatory cytokine interleukin (IL)-17A/F is one of the key mediators in the intestinal immune system. However, many functions of IL-17 in vertebrate intestines remain unclarified. In this study, we established a gene-knockout (KO) model of IL-17 receptor A1 (IL-17RA1, an IL-17A/F receptor) in Japanese medaka (Oryzias latipes) using genome editing technique, and the phenotypes were compared to wild type (WT) based on transcriptome analyses. Upon hatching, homozygous IL-17RA1-KO medaka mutants showed no significant morphological abnormality. However, after 4 months, significant weight decreases and reduced survival rates were observed in IL-17RA1-KO medaka. Comparison of gene-expression patterns in WT and IL-17RA1-KO medaka revealed that various metabolism- and immune-related genes were significantly down-regulated in IL-17RA1-KO medaka intestine, particularly genes related to mevalonate metabolism (mvda, acat2, hmgcs1, and hmgcra) and genes related to IL-17 signaling (such as il17c, il17a/f1, and rorc) were found to be decreased. Conversely, expression of genes related to cardiovascular system development, including fli1a, sox7, and notch1b in the anterior intestine, and that of genes related to oxidation–reduction processes including ugp2a, aoc1, and nos1 in posterior intestine was up-regulated in IL-17RA1-KO medaka. These findings show that IL-17RA regulated immune- and various metabolism-related genes in the intestine for maintaining the health of Japanese medaka.
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Yo Okamura, Natsuki Morimoto, Daisuke Ikeda, Nanami Mizusawa, Shugo Watabe, Hiroshi Miyanishi, Yuichi Saeki, Haruko Takeyama, Takashi Aoki, Masato Kinoshita, Tomoya Kono, Masahiro Sakai, Jun Ichi Hikima
Frontiers in Immunology 11 425 2020.3
Language：English Publishing type：Research paper (scientific journal)
In mammals, interleukin (IL)-17A and F are hallmark inflammatory cytokines that play key roles in protection against infection and intestinal mucosal immunity. In the gastrointestinal tract (GI), the induction of antimicrobial peptide (AMP) production via Paneth cells is a fundamental role of IL-17A and F in maintaining homeostasis of the GI microbiome and health. Although mammalian IL-17A and F homologs (referred to as IL-17A/F1-3) have been identified in several fish species, their function in the intestine is poorly understood. Additionally, the fish intestine lacks Paneth cells, and its GI structure is very different from that of mammals. Therefore, the GI microbiome modulatory mechanism via IL-17A/F genes has not been fully elucidated. In this study, Japanese medaka (Oryzias latipes) were used as a teleost model, and IL-17A/F1-knockout (IL-17A/F1-KO) medaka were established using the CRISPR/Cas9 genome editing technique. Furthermore, two IL-17A/F1-deficient medaka strains were generated, including one strain containing a 7-bp deletion (-7) and another with an 11-bp addition (+11). After establishing F2 homozygous KO medaka, transcriptome analysis (RNA-seq) was conducted to elucidate IL-17A/F1-dependent gene induction in the intestine. Results of RNA-seq and real-time PCR (qPCR) demonstrated down-regulation of immune-related genes, including interleukin-1β (IL-1β), complement 1q subunit C (C1qc), transferrin a (Tfa), and G-type lysozyme (LyzG), in IL-17A/F1-KO medaka. Interestingly, protein and lipid digestive enzyme genes, including phospholipase A2, group IB (pla2g1b), and elastase-1-like (CELA1), were also downregulated in the intestines of IL-17A/F1-KO medaka. Furthermore, to reveal the influence of these downregulated genes on the gut microbiome in IL-17A/F1-KO, 16S rRNA-based metagenomic sequencing analysis was conducted to analyze the microbiome constitution. Under a non-exposed state, the intestinal microbiome of IL-17A/F1-KO medaka differed at the phylum level from wild-type, with significantly higher levels of Verrucomicrobia and Planctomycetes. Additionally, at the operational taxonomic unit (OTU) level of the human and fish pathogens, the Enterobacteriaceae Plesiomonas shigelloides was the dominant species in IL-17A/F1-KO medaka. These findings suggest that IL-17A/F1 is involved in the maintenance of a healthy gut microbiome.
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Jun Hwan Byun, Ji Yeon Hyeon, Eun Su Kim, Byeong Hoon Kim, Hiroshi Miyanishi, Hirohiko Kagawa, Yuki Takeuchi, Se Jae Kim, Akihiro Takemura, Sung Pyo Hur
PeerJ 8 ( 2 ) e8326 2020
Language：English Publishing type：Research paper (scientific journal)
This study was carried out to identify and estimate physiological function of a new type of opsin subfamily present in the retina and whole brain tissues of Japanese eel using RNA-Seq transcriptome method. A total of 18 opsin subfamilies were identified through RNA-seq. The visual opsin family included Rh2, SWS2, FWO, DSO, and Exo-Rhod. The non-visual opsin family included four types of melanopsin subfamily (Opn4x1, Opn4x2, Opn4m1, and Opn4m2), peropsin, two types of neuropsin sub-family (Opn5-like, Opn5), Opn3, three types of TMT opsin subfamily (TMT1, 2, 3), VA-opsin, and parapinopsin. In terms of changes in photoreceptor gene expression in the retina of sexually mature and immature male eels, DSO mRNA increased in the maturation group. Analysis of expression of opsin family gene in male eel brain before and after maturation revealed that DSO and SWS2 expression in terms of visual opsin mRNA increased in the sexually mature group. In terms of non-visual opsin mRNA, parapinopsin mRNA increased whereas that of TMT2 decreased in the fore-brain of the sexually mature group. The mRNA for parapinopsin increased in the mid-brain of the sexually mature group, whereas those of TMT1 and TMT3 increased in the hind-brain of the sexually mature group. DSO mRNA also increased in the retina after sexual maturation, and DSO and SWS2 mRNA increased in whole brain part, suggesting that DSO and SWS2 are closely related to sexual maturation.
DOI： 10.7717/peerj.8326
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Kaneko T., Suzuki R., Watanabe S., Miyanishi H., Matsuzawa S., Furihata M., Ishida N.
Fisheries Science 85 ( 6 ) 925 - 930 2019.11
Language：English Publishing type：Research paper (scientific journal) Publisher：Fisheries Science
© 2019, Japanese Society of Fisheries Science. In the present study, we attempted to investigate the effects of temporal seawater experience on subsequent growth and later seawater acclimability in rainbow trout. To elucidate seawater acclimability of small juveniles (3–4 g), fish were transferred to seawater diluted to 25 ppt (25-ppt seawater) and the change in blood osmolality was examined. All the juveniles survived transfer to 25-ppt seawater for 7 days with blood osmolality remaining within a physiological range, indicating successful acclimation to 25-ppt seawater. For the preparation of seawater-experienced fish, young adults of rainbow trout (about 40 g) were exposed to 25-ppt seawater for 7 days without feeding, transferred back to fresh water, and reared with feeding for another 76 days. The daily growth rate was higher in seawater-experienced fish (1.86%/day) than in control fish (1.66%/day). The seawater-experienced and control fishes were then transferred directly to full-strength seawater. The blood osmolality stayed within a normal range with a transient increase just after transfer in seawater-experienced fish, but kept increasing without a declining trend in control fish. Our findings showed that temporal seawater exposure in the past enhances subsequent growth and seawater acclimability in the later life stage in rainbow trout.
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Shinji J., Gotoh H., Miyanishi H., Lavine M., Lavine L.
Evolution and Development 21 ( 1 ) 44 - 55 2019.1
Language：English Publishing type：Research paper (scientific journal) Publisher：Evolution and Development
© 2018 Wiley Periodicals, Inc. Members of the phylum Arthropoda, comprising over 80% of total animal species, have evolved regenerative abilities, but little is known about the molecular mechanisms mediating this process. Transforming growth factor β (TGF-β) signaling mediates a diverse set of essential processes in animals and is a good candidate pathway for regulation of regeneration in arthropods. In this study we investigated the role of activin signaling, a TGF-β superfamily pathway, in limb regeneration in the crayfish. We identified and cloned a downstream transcription factor in the activin pathway, Smox, and characterized its function with regard to other elements of the activin signaling pathway. Gene knockdown of Smox by RNAi induced regeneration of complete but smaller pereopods after autotomy. This indicates that activin signaling via Smox functions in regulation of pereopod growth and size. The expression levels of both Smox and the activin receptor babo were closely correlated with molting. The expression level of Smox increased when babo was knocked down by RNAi, indicating that Smox and babo transcription are linked. Our study suggests that the Babo-Smox system in activin signaling is conserved in decapods, and supports an evolutionary conservation of this aspect of molecular signaling during regeneration between protostomes and deuterostomes.
DOI： 10.1111/ede.12277
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Inokuchi M., Nakamura M., Miyanishi H., Hiroi J., Kaneko T.
Journal of Experimental Biology 220 ( 24 ) 4720 - 4732 2017.12
Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Experimental Biology
© 2017. Published by The Company of Biologists Ltd . Spatiotemporal changes in branchial ionocyte distribution were investigated following transfer from seawater (SW) to freshwater (FW) in Japanese seabass. The mRNA expression levels of cystic fibrosis transmembrane conductance regulator (CFTR) and Na+//K+// 2Cl- cotransporter 1a (NKCC1a) in the gills rapidly decreased after transfer to FW, whereas Na+/H+ exchanger 3 (NHE3) and Na+/Cl- cotransporter 2 (NCC2) expression were upregulated following the transfer. Using quadruple-color whole-mount immunofluorescence staining with anti-Na+/K+/-ATPase, anti-NHE3, anti-CFTR and T4 (anti-NKCC1a/NCC2) antibodies, we classified ionocytes into one SW type and two FW types: NHE3 cell and NCC2 cell. Time course observation after transfer revealed an intermediate type between SWtype and FW-Type NHE3 ionocytes, suggesting functional plasticity of ionocytes. Finally, on the basis of the ionocyte classification of Japanese seabass, we observed the location of ionocyte subtypes on frozen sections of the gill filaments stained by triple-color immunofluorescence staining. Our observation indicated that SWtype ionocytes transformed into FW-Type NHE3 ionocytes and at the same time shifted their distribution from filaments to lamellae. However, FW-specific NCC2 ionocytes appeared mainly in the filaments. Taken together, these findings indicate that ionocytes originated from undifferentiated cells in the filaments and expanded their distribution to the lamellae during FW acclimation.
DOI： 10.1242/jeb.167320
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Shinji J., Miyanishi H., Gotoh H., Kaneko T.
Journal of Crustacean Biology 36 ( 5 ) 649 - 657 2016
Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Crustacean Biology
© 2016 Copyright 2016 by The Crustacean Society. Published by Brill NV, Leiden.Autotomy is an adaptive response in which animals escape from predators by shedding their own appendages. It is made possible by the presence of an efficient mechanism for regeneration. Decapod crustaceans frequently exhibit excellent abilities to regenerate complete pereopods in just a few molts following autotomy. The molecular basis of regeneration pereopods in decapods remains unclear. We identified the primary structure of Baboon (Babo), a type I TGF-β superfamily receptor involved in the activin pathway, in the crayfish, Procambarus fallax f. virginalis Martin, Dorn, Kawai, Heiden and Scholtz, 2010. Molecular cloning revealed that babo possesses three splice variants. The expression levels of the functional babo transcript did not show increases during regeneration. RNA interference (RNAi) targeting a common region of the babo sequence, however, caused a reduction in regenerated pereopod lengths. No loss or reduction in a specific article was observed. Instead, the regenerated legs were smaller but retained the morphology and proportions of regenerated legs from control animals. Babo thus appears to control the growth, but not the pattern, of legs during the regeneration process in decapod crustaceans.
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Past seawater experience enhances seawater adaptability in medaka, Oryzias latipes. Reviewed
Miyanishi H, Inokuchi M, Nobata S, Kaneko T
Zoological letters 2 12 2016
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
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Teleocortin: A novel member of the CRH family in teleost fish Reviewed
Hosono K., Kikuchi Y., Miyanishi H., Hiraki-Kajiyama T., Takeuchi A., Nakasone K., Maehiro S., Okubo K.
Endocrinology 156 ( 8 ) 2949 - 2957 2015.8
Language：English Publishing type：Research paper (scientific journal) Publisher：Endocrinology
The CRH family of neuropeptides, including CRH and urocortins, plays pivotal roles in the regulation of physiological and behavioral stress responses in vertebrates. In this study, we identified a previously undescribed member of the CRH family of peptides in a teleost fish species (medaka; Oryzias latipes) and named this peptide teleocortin (Tcn). Medaka Tcn is a 41-amino acid polypeptide derived from the C terminus of a larger precursor protein that is encoded by a 2-exon gene, thus sharing common structural features with known CRH family peptides. tcn was found exclusively in teleost fish. Phylogenetic analysis suggested that tcn probably has an ancient origin but was lost from the tetrapod lineage shortly after the divergence of the teleost and tetrapod lineages. In the medaka brain, tcn was expressed in nuclei of the telencephalon, preoptic area, hypothalamus, tegmentum,andisthmic region. Becausenoneof these nuclei have been implicated in the control of ACTH secretion from the pituitary, Tcn may exert its effects centrally in the brain rather than via stimulation of the pituitary-adrenal/interrenal axis. Most, if not all, tcn-expressing neurons also expressed crh, suggesting that Tcn and Crh share common physiological functions. Moreover, Tcn activated Crh receptors 1 and 2 with equivalent or slightly higher potency than Crh, further suggesting that these peptides share common functions. Taken together, these data identified Tcn as a novel, teleost-specific member of the CRH family of peptides that may act centrally with Crh to regulate physiological and behavioral stress responses.
DOI： 10.1210/en.2015-1042
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Miyanishi H., Okubo K., Kaneko T., Takei Y.
American Journal of Physiology - Regulatory Integrative and Comparative Physiology 304 ( 6 ) R423 - 34 2013.6
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Journal of Physiology - Regulatory Integrative and Comparative Physiology
Cardiac natriuretic peptides (atrial natriuretic peptide, ANP; b-type natriuretic peptide, BNP; ventricular natriuretic peptide, VNP) and their direct ancestor C-type natriuretic peptide 3 (CNP3) exert potent osmoregulatory actions in fish. However, very little is known about their roles in embryonic osmoregulation. In this study, we performed loss-of-function analysis using euryhaline medaka (Oryzias latipes), which has lost ANP and VNP during evolution and thus possesses only BNP and CNP3. We found that the maintenance of whole-body osmolality in seawater embryos was impaired by the knockdown of BNPOLGC7 (BNP receptor) or CNP3 alone from 1 day postfertilization, and the CNP3 knockdown was accompanied by greater water loss. The impaired osmoregulation in the knockdown embryos was not due to the suppressed expression of major transporters for NaCl excretion via ionocytes or of key enzyme genes for metabolic water production, but to the impaired blood circulation to the yolk-sac membrane caused by abnormal heart development. We detected a strong positive correlation between impaired blood circulation and increased body fluid osmolality and pharmacological blockade of blood flow increased body fluid osmolality in seawater embryos. We also found that the exaggerated water loss in CNP3 knockdown embryos is related to the failure to suppress aquaporin (AQP3, AQP4, and AQP9) gene expression. These results show that CNP3 decrease water permeability of body surfaces and that both BNP and CNP3 ensure sufficient blood flow to the yolk-sac membrane for efficient salt excretion by ionocytes and sufficient water production by yolk metabolism to promote seawater adaptation during early development in medaka. © 2013 the American Physiological Society.