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Higuchi Ichiro

Faculty of Fisheries Sciences　Marine Life Science　Aquaculture BiologySpecially Appointed Assistant Professor

Researcher basic information

■ Degree
  • Master of Fisheries, Hokkaido University, Mar. 2019
■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Research Keywords and Fields
Research Keyword
  • 磯焼け
  • 藻場再生
  • ナマコ
  • ウニ
  • 人工飼料開発
  • 棘皮動物
  • 海洋施肥材
  • 配偶子形成
  • 卵黄タンパク質
  • 核内受容体

Research activity information

■ Papers
  • Potential role of COUP-TF in regulating major yolk protein gene expression in sea urchin.
    Ichiro Higuchi; Shiori Tsue; Yudai Kitano; Osamu Nishimiya; Masashi Hosokawa; Fumiaki Beppu; Kazuhiro Ura; Yasuaki Takagi
    General and comparative endocrinology, 376, 114867, 114867, Jan. 2026, [International Magazine]
    English, Scientific journal, Major yolk protein (MYP) serves as a critical nutrient reservoir for gonadal development in sea urchins, but the transcriptional regulation of its encoding gene remains largely uncharacterized. Here, we cloned and analyzed the MYP promoter from Mesocentrotus nudus and found two conserved elements with putative binding sites for the orphan nuclear receptor COUP-TF (chicken ovalbumin upstream promoter-transcription factor). We cloned the full-length cDNA encoding COUP-TF from M. nudus (MnCOUP-TF). The cDNA encoded a 472-amino acid protein highly homologous to other COUP-TF/SVP subfamily members. RT-PCR and qPCR analyses revealed that transcripts of both MnCOUP-TF and MYP were present in several tissues, including gonads, and their levels exhibited a significant positive correlation during gonadal maturation (R2 = 0.6764, p < 0.01). Electrophoretic mobility shift assays demonstrated specific binding of MnCOUP-TF to the MYP promoter, and transactivation assays showed that MnCOUP-TF activates transcription through these sites. Furthermore, total lipids extracted from gonadal tissue enhanced MnCOUP-TF-dependent reporter activity in a dose-dependent manner. This enhancement was comparable to the effect of 9-cis-retinoic acid, a compound known to activate COUP-TF at high concentrations, although it is not considered to be a physiological COUP-TF ligand. These results suggest that MnCOUP-TF regulates MYP expression in a ligand-dependent manner and that endogenous activators may be present in gonadal lipids. To our knowledge, this is the first molecular evidence implicating COUP-TF in yolk protein gene regulation in sea urchins, providing new insights into nuclear receptor-mediated control of reproduction in marine invertebrates.
  • Comparative Study of the Gel-Forming Ability of Type I Collagens Extracted from Different Organs and Fish Species.
    Abdul Ghani; Mantaro Okada; Beini Sun; Xi Zhang; Ichiro Higuchi; Yasuaki Takagi
    Gels (Basel, Switzerland), 11, 7, 09 Jul. 2025, [International Magazine]
    English, Scientific journal, The gel-forming ability of collagens is vital for their application in cell scaffolds, yet very few comparative studies on fish collagen sources are available. This study isolated and characterized type I collagens from carp skin (CSK), scales (CSC), and swim bladders (CSB) and sturgeon skin (SSK) and swim bladders (SSB). The carp collagens exhibited higher thermal stability (34.75-34.78 °C) and formed more transparent, stronger gels than the sturgeon collagens. Additionally, as demonstrated by scanning electron microscopy, the sturgeon collagens exhibited faster fibril formation, with visible fibrils after 3 h which grew thicker but did not form bundles. The carp collagens, in contrast, initially displayed fewer, thinner, and longer fibrils, with their formation accelerating over time and fibril bundles emerging after 24 h. All collagen solutions of 4% (w/v) exhibited shear-thinning flow behavior, with the carp-derived solutions showing higher viscosities (103-104 Pa·s) than those demonstrated by the sturgeon-derived solutions (102-103 Pa·s). The CSBs and SSBs demonstrated the highest storage (G') and loss (G″) moduli, with the former exhibiting the lowest loss tangent (tan δ), indicative of a stronger gel structure. The gels at 24 h showed slightly poorer mechanical properties than those at 3 h. The CSC and SSB gels had the highest thermal stability. These findings highlight the distinctiveness of the characteristics of collagens and their gels, emphasizing their potential in biomaterial applications. The present study also provides a foundational framework for assessing cellular responses in a comparative context that may help in identifying the most suitable collagen types for biomedical applications.
  • Identification and expression of nuclear receptor genes during nutritive phagocyte development in sea urchin Mesocentrotus nudus gonads.
    Kazuhiro Ura; Shiori Tsue; Takushi Sato; Seishi Hagihara; Mizuha Satoh; Ichiro Higuchi; Heng Wang; Osamu Nishimiya; Shigeho Ijiri; Yasuaki Takagi
    General and comparative endocrinology, 366, 114715, 114715, Apr. 2025, [International Magazine]
    English, Scientific journal, The role of the endocrine system during synthesis of the nutrients (e.g., proteins, lipids, polysaccharides) in the gonad in sea urchins is imperfectly understood. We identify genes encoding nuclear receptors (NRs) involved in the development of nutritive phagocytes of the sea urchin Mesocentrotus nudus, and investigate their gene expression patterns during this time. RNA-seq analysis was performed on immature gonads using a next-generation sequencer. A total of 7,651,421 quality-controlled reads obtained using an Ion PGM sequencer were assembled into 175,092 contigs. BLASTn analysis identified 20 NR genes potentially involved in the development of nutritive phagocytes. Expression analyses revealed levels of four NR genes to increase during the development of nutritive phagocytes. These results indicate that these 20 NR genes have physiological functions in gonadal growth, and that 4 NR genes mainly control the expression of genes involved in the synthesis and metabolism of proteins, lipids, and polysaccharides during cellular proliferation in sea urchin gonads.
  • Nuclear receptor gene expression during early gametogenesis in sea urchin Mesocentrotus nudus gonads
    Shuichiro Watanabe; Ken Matsuzaki; Utano Shimizu; Ichiro Higuchi; Takashi Todo; Yasuaki Takagi; Kazuhiro Ura
    Fisheries Science, 90, 6, 907, 924, Springer Science and Business Media LLC, 10 Jun. 2024
    Scientific journal
  • The reproductive cycle and transcription-level changes in the major yolk protein of wild northern sea urchin, Mesocentrotus nudus, in southern Hokkaido
    Kazuhiro URA, Heng WANG, Tetsuo HORI, Shunsuke AIZAW, Shiori TSUE, Mizuha SATOH, Narumi TAKEI, Kosuke HOSHINO, Ichiro HIGUCHI, Shun SANUKI, Tomoharu YUHI, Osamu NISHIMIYA and Yasuaki TAKAGI
    Aquaculture Science, 65, 3, 231, 237, Sep. 2017, [Peer-reviewed]
■ Other Activities and Achievements
■ Affiliated academic society
  • Sep. 2023 - Present
    日本水産学会