The effects of crustacean hyperglycemic hormone-family peptides on vitellogenin gene expression in the kuruma prawn, Marsupenaeus japonicus

In crustaceans, eyestalk ablation induces gonadal maturation of which vitellogenin gene expression is an essential step. However, the molecular mechanisms by which the hormones produced by the X-organ/sinus gland complex in the eyestalk regulate vitellogenesis remain poorly understood. We therefore investigated the effects of sinus gland extracts and certain sinus gland peptides belonging to the crustacean hyperglycemic hormone peptide family on vitellogenin gene expression in ovarian fragments of immature kuruma prawn, Marsupenaeus japonicus. Vitellogenin mRNA levels in incubated ovarian fragments were significantly higher than those in unincubated ovarian fragments prepared from the same animal. Sinus gland extracts and sinus gland peptide-III (type I peptide) both reduced vitellogenin mRNA levels in a dose-dependent manner. In contrast, neither molt-inhibiting hormone (sinus gland peptide-IV) nor molt-inhibiting hormone B, both of which are type II peptides, exerted significant effects on vitellogenin mRNA levels. These results suggest that, in the immature ovary, sinus gland peptide-III is involved in the suppression of vitellogenin gene expression. The existence of such a peptide in the X-organ/sinus gland complex provides a rationale for the significant increase in vitellogenin mRNA levels in the ovaries of eyestalk-ablated prawns.