Relaxin-like gonad-stimulating peptide is highly conserved in starfish Asterina pectinifera

Abstract

Relaxin-like gonad-stimulating peptide (RGP) in starfish is the only known invertebrate peptide hormone responsible for final gamete maturation, rendering it functionally analogous to gonadotropins in vertebrates. Recently, RGP was purified from the radial nerves of starfish Asterina pectinifera, which belongs to the Order Valvatida in the Class Asteroidea. A. pectinifera is an endemic Japanese species, inhabiting rocky shores from northern to southern Japanese waters. This study examined whether genetic variation or polymorphism is found in RGP. Comparing cDNA sequences of RGP in A. pectinifera from 10 local populations in Japanese waters, we found that the coding DNA sequences (CDSs) were exactly the same. This result indicated that RGP is a highly conserved peptide in A. pectinifera. Furthermore, the CDS of RGP identified in Certonardoa semiregularis, which also belongs to Order Valvatida, was completely consistent with that of A. pectinifera. Thus, this also suggested that the chemical structure of A. pectinifera RGP is conserved among starfish of the Order Valvatida beyond species.

Keywords:

• relaxin-like gonad-stimulating peptide
• coding DNA sequence
• species specificity
• Asterina pectinifera
• Order Valvatida

Acknowledgements

The authors are grateful to Dr M. Nakaoka and Mr S. Hamano (Akkeshi Marine Station, Field Science Center for Northern Biosphere Hokkaido University); to Dr K. Kyozuka and Mr M. Washio (Research Center for Asamushi Marine Biology, Graduate School of Life Sciences, Tohoku University); Dr H. Ando (Sado Marine Biological Station, Faculty of Science, Niigata University); Dr M. Kiyomoto and Mr M. Yamaguchi (Marine Coastal Research Center, Ochanomizu University); Dr N. Suzuki and Mr M. Matada (Institute of Nature and Environmental Technology, Noto Marine Laboratory, Kanazawa University); Dr H. Sawada, Mr M. Sunagawa and Mr M. Fukuoka (Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University); Dr T. Sakamoto and Mr W. Godo (Ushimado Marine Laboratory, Okayama University); Dr N. Hirohashi (Oki Marine Biological Station, Education and Research Center for Biological Resources, Faculty of Life and Environmental Science, Shimane University); Dr K. Miyawaki (Shikoku-Chuoh Medical & Welfare General College); Dr A. Murakami (Marine Site of Kobe University Research Center for Inland Seas); Dr K. Soyano (Institute for East China Sea Research, Graduate School of Fisheries Science and Environmental Studies, Nagasaki University); and Dr H. Tousuji (Kagoshima University) for their kind help in collecting starfish.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by JSPS KAKENHI [grant number 25440151] to M. Mita.