Characterization and localization of relaxin-like gonad-stimulating peptide in the crown-of-thorns starfish, Acanthaster cf. solaris.

Gen Comp Endocrinol

Department of Global Environmental Studies, Faculty of Environmental Studies, Hiroshima Institute of Technology, Miyake 2-1-1, Saeki-ku, Hiroshima 731-5193, Japan.

Published: November 2022

AI Article Synopsis

  • The relaxin-like gonad-stimulating peptide (RGP) in starfish is crucial for final gamete maturation, comprising two peptide chains with notable disulfide bonds.
  • Recent studies identified the sequence of RGP in the Pacific crown-of-thorns starfish, Acanthaster cf. solaris, revealing it shares 74% and 60% amino acid identity with RGPs from other starfish species.
  • Aso-RGP induces spawning in A. cf. solaris, and its presence was confirmed in the radial nerve cords, suggesting it is synthesized in the epithelium and transferred to nerve fibers.

Article Abstract

In starfish, a relaxin-like gonad-stimulating peptide (RGP) is the gonadotropin responsible for final gamete maturation. RGP comprises two different peptides, A- and B-chains with two interchain and one intrachain disulfide bonds. The existence of two isomers of RGP in the crown-of-thorns starfish, Acanthaster planci, has been reported previously, but it was recently shown that A. planci represents a species complex with four different species. Here we elucidated the authentic sequence of the Pacific species, Acanthaster cf. solaris, RGP (Aso-RGP). The Aso-RGP precursor encoded by a 354 base pair open reading frame was composed of 117 amino acids (aa). The amino acid identity of Aso-RGP to Patiria pectinifera RGP (Ppe-RGP) and Asterias amurensis RGP (Aam-RGP) was 74% and 60%, respectively. Synthetic Aso-RGP induced spawning of ovarian fragments from A. cf. solaris. Ppe-RGP and Aam-RGP also induced spawning by A. cf. solaris ovaries. In contrast, Ppe-RGP and Aso-RGP induced spawning by P. pectinifera ovaries, but Aam-RGP was inactive. Notably, anti-Ppe-RGP antibodies recognized Aso-RGP as well as Ppe-RGP. Localization of Aso-RGP was observed immunohistochemically using anti-Ppe-RGP antibodies, showing that Aso-RGP was mainly present in the radial nerve cords of A. cf. solaris. Aso-RGP was distributed not only in the epithelium of the ectoneural region but also in the neuropile of the ectoneural region. These results suggest that Aso-RGP is synthesized in the epithelium of the ectoneural region, then transferred to fibers in the neuropile of the ectoneural region in radial nerve cords.

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http://dx.doi.org/10.1016/j.ygcen.2022.114107DOI Listing

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Characterization and localization of relaxin-like gonad-stimulating peptide in the crown-of-thorns starfish, Acanthaster cf. solaris.

Gen Comp Endocrinol

November 2022

Department of Global Environmental Studies, Faculty of Environmental Studies, Hiroshima Institute of Technology, Miyake 2-1-1, Saeki-ku, Hiroshima 731-5193, Japan.

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  • The relaxin-like gonad-stimulating peptide (RGP) in starfish is crucial for final gamete maturation, comprising two peptide chains with notable disulfide bonds.
  • Recent studies identified the sequence of RGP in the Pacific crown-of-thorns starfish, Acanthaster cf. solaris, revealing it shares 74% and 60% amino acid identity with RGPs from other starfish species.
  • Aso-RGP induces spawning in A. cf. solaris, and its presence was confirmed in the radial nerve cords, suggesting it is synthesized in the epithelium and transferred to nerve fibers.
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