Effect of Relaxin-Like Gonad-Stimulating Peptide on Ovaries of the Sea Cucumber Holothuria leucospilota

Masatoshi Mita; Hidekazu Katayama; Paul A. Wright; Scott F. Cummins; Sumio Udagawa; Masato Kiyomoto

doi:10.2108/zs250095

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Effect of Relaxin-Like Gonad-Stimulating Peptide on Ovaries of the Sea Cucumber Holothuria leucospilota

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Effect of Relaxin-Like Gonad-Stimulating Peptide on Ovaries of the Sea Cucumber Holothuria leucospilota

Masatoshi Mita, Hidekazu Katayama, Paul A. Wright, Scott F. Cummins, Sumio Udagawa and Masato Kiyomoto

Zoological Science, Vol.43(2), pp.1-8

2026

DOI: https://doi.org/10.2108/zs250095

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Abstract

ex vivo spawning

maturation-inducing hormone

oocyte maturation

relaxin-like gonad-stimulating peptide

sea cucumbers

Relaxin-like gonad-stimulating peptide (RGP), identified in starfish as a gonadotropin-like active peptide, has been shown to have a similar effect in sea cucumbers. Chemically synthesized RGP of the black sea cucumber, Holothuria leucospilota, (Hle-RGP) induced oocyte maturation and ex vivo spawning in ovarian fragments of the same species in the reproductive season. Therefore, this study established ovarian fragments of H. leucospilota as a bioassay model to determine the RGP concentration (EC50) required for 50% ex vivo spawning. The EC50 for Hle-RGP was approximately 7 nM. However, Hle-RGP could not induce germinal vesicle breakdown (GVBD) in defolliculated immature oocytes isolated from ovaries, suggesting that follicle cells are essential for Hle-RGP-directed oocyte maturation. When the ovaries of H. leucospilota were incubated with Hle-RGP for 6 h at 18°C, activity of a maturation-inducing hormone (MIH) was found in the media. Because approximately 50 follicle cells surround an oocyte, it is probable that follicle cells stimulated by Hle-RGP produce the MIH. In contrast, neither 1-methyladenine (1-MeAde) nor RGP of the starfish Patiria pectinifera (Ppe-RGP) had any effect on oocyte maturation in H. leucospilota. These results strongly suggest that an MIH is involved in the process of oocyte maturation in sea cucumbers, similar to starfish, but the MIH in sea cucumbers is not 1-MeAde.

Details

Title: Effect of Relaxin-Like Gonad-Stimulating Peptide on Ovaries of the Sea Cucumber Holothuria leucospilota
Authors: Masatoshi Mita (Corresponding Author) - Ochanomizu University
Hidekazu Katayama - Teikyo University
Paul A. Wright - University of the Sunshine Coast
Scott F. Cummins - University of the Sunshine Coast
Sumio Udagawa - Ochanomizu University
Masato Kiyomoto - Ochanomizu University
Publication details: Zoological Science, Vol.43(2), pp.1-8
Publisher: Nihon Dobutsu Gakkai, Zoological Society of Japan
Date published: 2026
DOI: 10.2108/zs250095
ISSN: 2212-3830
Copyright note: This open-access article is distributed under the CC BY-NC-ND 4.0 license
Organisation Unit: School of Health - Biomedicine; School of Science, Technology and Engineering; Centre for Bioinnovation
Language: English
Record Identifier: 991217260002621
Output Type: Journal article

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