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Affiliation |
Faculty of Agriculture Region of Marine Life Science |
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Title |
Associate Professor |
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External Link |
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Related SDGs |
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MIYANISHI Hiroshi
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Degree 【 display / non-display 】
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博士（理学） ( 2011.10 東京大学 )
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修士（教育学） ( 2007.3 横浜国立大学 )
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学士（教育） ( 2005.3 横浜国立大学 )
Research Areas 【 display / non-display 】
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Life Science / Aquatic life science / 魚類生理学：メダカ、サケ、ウナギ、チョウザメ、浸透圧調節、生殖、成長
Papers 【 display / non-display 】
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Hata T., Tsuda K., Hirayoshi M., Miyanishi H., Hikima J.i., Kono T.
Fish and Shellfish Immunology 176 111416 2026.9
Language：English Publishing type：Research paper (scientific journal) Publisher：Fish and Shellfish Immunology
The circadian clock regulates diverse physiological and immune processes through transcriptional feedback loops, with Bmal1 (Brain and Muscle Arnt-like protein 1) as a core component. Although well studied in mammals, its immunological role in teleosts remains unclear. In this study, we examined the effects of Bmal1 deficiency on the fish immune system, by generating a Bmal1 knockout (Bmal1 KO) Japanese medaka (Oryzias latipes) using CRISPR-Cas9, introducing a 16-bp insertion in exon 4, which disrupted the bHLH and PAS domains. Unlike wild-type (WT) fish, Bmal1 KO individuals remained active during ZT21, suggesting altered time-of-day–dependent activity patterns. Exploratory RNA-seq analysis of the head kidneys under phosphate buffered saline and lipopolysaccharide stimulation revealed broad transcriptional changes, with 481 and 767 genes showing altered expression patterns in Bmal1 KO fish under control and LPS-stimulated conditions, respectively. Gene Ontology analysis suggested that among the top-ranked functional groups in Bmal1 KO fish, immune-related categories were less prominent whereas reproductive and vitellogenin-associated processes were more prominent, suggesting alteration of functional profiles rather than direct suppression of immune pathways. Infection assays at ZT2 demonstrated induction of ifng, tnfa, tlr1, tlr5m, tlr9, and tlr21 after bacterial challenge in WT medaka. In contrast, Bmal1 KO fish exhibited an altered response pattern —elevated expression in controls but reduced inducibility after infection. Bmal1 may thus contribute to time-of-day-dependent coordination of circadian and immune signaling, including potential involvement of NF-κB–related pathways. Loss of Bmal1 alters immune gene expression patterns and pathogen responsiveness in a time-of-day–dependent manner. Overall, Bmal1 deficiency was associated with altered clock-gene expression patterns and immune responses at specific Zeitgeber times. Therefore, Bmal1 may contribute to the time-of-day-dependent regulation of innate immune gene expression in medaka; however, circadian rhythmicity of immune responses remains to be directly demonstrated.
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Miyanishi H., Maeda S., Ohtani-Kaneko R., Kaneko T.
Zoological Science 43 ( 2 ) 162 - 171 2026.2
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Zoological Science
Na<sup>+</sup>/K<sup>+</sup>-ATPase (Nka) is essential for maintaining body fluid homeostasis in teleost osmoregulatory epithelia. In the present study, we identified six Nka α-subunit isoforms, including those previously reported in Mozambique tilapia. Among the Nka α-subunit isoforms, nkaa1a, nkaa1b, nkaa1c, and nkaa3b were highly expressed in the gills. In the gills of freshwater (FW)-acclimated fish, the expression levels of nkaa1c, were the highest, and those of nkaa1a and nkaa1b were moderately expressed, whereas in the gills of seawater (SW)-acclimated fish, nkaa1b expression was the highest, followed by nkaa3b. We also investigated the expressions of the four Nka α-subunit isoforms in the four types of ionocytes by means of triple fluorescence staining with whole-mount in situ hybridization and immunocytochemistry. The Nka α-subunit isoforms showed differential expression in functionally distinct types of ionocytes in Mozambique tilapia. Only nkaa1c was expressed in type I ionocytes, which are considered to be in the immature or resting phase. Nkaa1a is the major isoform in type II ionocytes that absorb Na<sup>+</sup> and Cl<sup>–</sup> through apically-located Na<sup>+</sup>/Cl<sup>–</sup> cotransporter 2 (Ncc2) in FW. Type III ionocytes, which absorb Na<sup>+</sup> in exchange for H<sup>+</sup> through apical Na<sup>+</sup>/H<sup>+</sup> exchanger 3 (Nhe3) in FW, mainly expressed nkaa1b, with moderate expression of nkaa1a and nkaa1c. Type IV ionocytes that secrete Na<sup>+</sup> and Cl– in SW expressed mainly nkaa1b and, secondarily nkaa3b. It should be noted that nkaa1b is the major Nka α-subunit isoform in both type III and type IV ionocytes, which are substantially the same cell type with functional plasticity.
DOI： 10.2108/zs250088
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Fujishiro Kouyou, Nishikawa Sotaro, Miyanishi Hiroshi
Fisheries Science 2025.11
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science + Business Media, LLC
High stocking densities negatively affect fish production, even if the water quality is managed correctly. However, the mechanisms underlying the growth inhibition at high stocking densities remain unknown. This study aimed to reveal changes in gene expression in the brain that processes sensory information and to predict neuronal response changes under high stocking densities. Juvenile rainbow trout were reared at five different densities (22–180 fish/tank) for 60 days. The 180 fish group showed lower body weights than that of the 22 fish group on the28th day, even though environmental factors such as water quality, dissolved oxygen, and feeding conditions were the same. Final fork length and condition factor results revealed growth inhibition in the high-density group. In addition, the brain transcriptomics of the 22 and 180 fish groups were analyzed. Gene set enrichment analysis based on the Kyoto Encyclopedia of Genes and Genomes was used to detect alterations in the five pathways. Steroid biosynthesis and extracellular matrix–receptor interaction pathways were downregulated in the 180 fish group, suggesting the stagnation of myelination in a high-density environment. These results offer insights into growth inhibition mechanisms and brain responses in environments where many individuals of the same fish species are present.
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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 ( 3 ) 356 - 372 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.
MISC 【 display / non-display 】
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サケ・マス類における海水経験法による成長促進 Invited
宮西 弘
月刊養殖ビジネス 61 ( 3 ) 42 - 46 2024.3
Authorship：Lead author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)
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キャビア生産サイクルの短縮化 Invited
宮西 弘
調査月報 361 2 - 6 2023.5
Authorship：Lead author Language：Japanese Publishing type：Internal/External technical report, pre-print, etc.
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川が好きなメダカと海が好きな？メダカ２ Invited
宮西 弘
月刊アクアライフ 9月号増刊 270 - 271 2022.9
Authorship：Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media) Publisher：エムビージェー
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川が好きなメダカと海が好きな？メダカ Invited
宮西 弘
月刊アクアライフ 43 ( 5 ) 80 - 81 2021.4
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media) Publisher：エムビージェー
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総論 : 海洋生物の適応戦略－新規技術・現象からの新展開－ Invited
御輿 真穂, 宮西弘, 兵藤 晋
月刊海洋 49 183 - 186 2017.3
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)
Presentations 【 display / non-display 】
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魚類の浸透圧調節を担う塩類細胞の特殊性と機能 Invited
宮西 弘
第168回日本獣医学会学術集会 2025.9.3
Event date： 2025.9.3 - 2025.9.6
Language：Japanese Presentation type：Oral presentation (general)
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Loss of salinity tolerance in central Sulawesi ricefishes: are ancient lakes an evolutionary trap? International coauthorship International conference
Ilham V. Utama, Ryo Kakioka, Hiroshi Miyanishi, Kazunori Yamahira
8th International conference on fisheries and marine sciences 2025.9
Event date： 2025.9
Language：English Presentation type：Oral presentation (general)
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時計遺伝子Bmal1変異メダカにおける免疫応答
羽田崇彦 ・平吉美優・津田和忠・宮西弘・引間順一・河野智哉
令和6年度日本水産学会 秋季大会
Event date： 2024.9.24 - 2024.9.27
Presentation type：Oral presentation (general)
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チョウザメにおける海水経験法による成長促進
宮西弘・濵嵜菜々子・松島悠一郎
令和６年度日本水産学会 秋季大会
Event date： 2024.9.24 - 2024.9.27
Presentation type：Oral presentation (general)
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ニジマスの高密度飼育による成長および脳内遺伝子発現への影響
藤城耕陽・西川颯太朗・宮西弘
令和６年度日本水産学会 秋季大会
Event date： 2024.9.24 - 2024.9.27
Presentation type：Oral presentation (general)
Awards 【 display / non-display 】
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地域貢献表彰 最優秀賞
2024.12 宮崎大学農学部 チョウザメにおけるキャビア生産効率向上に資する産学官連携研究
宮西弘
Award type：International academic award (Japan or overseas)
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学生優秀発表賞
2023.12 日本水産学会九州支部 高密度飼育および認識によるメダカ脳内遺伝子発現変化とfos遺伝子の解析
藤城耕陽・宮西弘
Award type：Award from Japanese society, conference, symposium, etc.
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最優秀発表賞
2023.8 日本下垂体研究会 メダカにおける密度認識と高密度飼育下での成長阻害および内分泌学的解析
藤城耕陽・宮西弘
Award type：International academic award (Japan or overseas)
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学生優秀発表賞
2023.1 日本水産学会九州支部 単一細胞レベルトランスクリプトーム解析による魚類の鰓塩類細胞分化因子の探索
谷口雄真・宮西弘
Award type：Award from Japanese society, conference, symposium, etc.
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第24回バゾプレシン研究会 研究奨励賞
2014.1 バゾプレシン研究会
宮西弘
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
Grant-in-Aid for Scientific Research 【 display / non-display 】
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海水経験技術による回遊性水産有用魚種の成長・成熟促進機構の解明と応用
Grant number：23K26989 2023.04 - 2027.03
日本学術振興会 科学研究費基金 基盤研究(B)
宮西 弘
Authorship：Principal investigator
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海水経験技術による回遊性水産有用魚種の成長・成熟促進機構の解明と応用
Grant number：23H02296 2023.04 - 2027.03
日本学術振興会 科学研究費補助金 基盤研究(B)
宮西 弘
Authorship：Principal investigator
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魚類の高密度飼育による成長阻害因子の同定および高密度耐性魚の作出
Grant number：22K19216 2022.06 - 2025.03
日本学術振興会 科学研究費基金 挑戦的研究(萌芽)
宮西 弘
Authorship：Principal investigator
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魚類塩類細胞分化誘導シグナリングの解明から迫る広塩性決定因子の同定と応用
Grant number：19K15912 2019.04 - 2022.03
科学研究費補助金 若手研究
Authorship：Principal investigator
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新規海水適応遺伝子の探索および海水型塩類細胞分化誘導因子の同定
Grant number：26850130 2014.04 - 2017.03
科学研究費補助金 若手研究(B)
Authorship：Principal investigator
Available Technology 【 display / non-display 】
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魚の水環境における適応機構と飼育密度の研究
海水経験技術による成長の促進と海水への適応能力の向上
光環境操作によるウナギの成熟促進技術の開発Home Page： 海洋生物環境学科・教員紹介（宮西弘）
Related fields where technical consultation is available：・魚に適した環境を整え、健康に飼う方法
・魚を大きくする方法Message：・魚を健康に大きく育てたいなど、様々な相談があればご連絡下さい。
・遺伝子操作などの先端的な研究手法から飼育まで幅広く研究を行っていますので、何でもご相談下さい。