A gonad-stimulating peptide of the crown-of-thorns starfish, Acanthaster planci

Abstract

The crown-of thorns starfish, Acanthaster planci, has been blamed for coral mortality in a large number of coral reef systems in the Indo-Pacific region. Because population outbreaks of A. planci are closely related to reproduction, it is important to examine the mechanism of reproductive control in this starfish. Previously, a relaxin-like gonad-stimulating peptide (RGP) in starfish Asterina pectinifera has been identified as the gonadotropin responsible for final gamete maturation. On the basis of homology research on RGP cDNAs from several species, this study was carried out to identify gonadotropin in A. planci. The cDNA sequence of RGP was determined using a RACE product of mRNA from the radial nerves of A. planci. The coding DNA sequence consisted of 351 base pairs with an open reading frame encoding a peptide of 116 amino acids (aa), including a signal peptide (29 aa), B-chain (19 aa), C-peptide (44 aa), and A-chain (24 aa). The chemical structure of A. planci RGP was exactly the same as that of A. pectinifera RGP. Furthermore, synthetic RGP could induce gamete spawning and oocyte maturation in the ovarian fragments of A. planci. This strongly suggested that the RGP is a gonadotropin in A. planci.

Keywords:

• crown-of-thorns starfish (Acanthaster planci)
• gonadotropin
• radial nerves
• relaxin-like gonad-stimulating peptide

Acknowledgements

The authors are grateful to Dr M. Kiyomoto and Mr M. Yamaguchi of the Marine Coastal Research Center, Ochanomizu University, Dr K. Kyozuka and Mr M. Washio of the Research Center for Asamushi Marine Biology, Tohoku University, and Dr T. Sakamoto and Mr W. Godou of the Ushimado Marine Laboratory, Okayama University for their kind help in collecting starfish. This work was supported by JSPS KAKENHI under Grant number 25440151 to M. Mita; and Okinawa Churashima Foundation Award. This is a contribution from the Sesoko Station Tropical Biosphere Center, University of the Ryukyus.

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].