Molecular Cloning and Expression Analysis of cDNAs Encoding an Insulin-like Androgenic Gland Factor from Three Palaemonid Species, Macrobrachium lar, Palaemon paucidens and P. pacificus

Abstract

An androgenic gland hormone (AGH) is synthesized in the male-specific androgenic gland (AG) and is responsible for sex differentiation in crustaceans. To date, AGH cDNAs have been cloned from only three isopod species, but not decapod crustaceans. Recently, however, cDNAs encoding the AG specific polypeptide, which was designated as an insulin-like AG factor (IAG), have been cloned from two decapods, the red-claw crayfish Cherax quadricarinatus and the giant freshwater prawn Macrobrachium rosenbergii. These studies suggested that IAG may be involved in controlling sex differentiation in decapod crustaceans, but this point remains unclear. In order to accumulate knowledge on IAG, here we cloned IAG cDNAs from three palaemonid species (Crustacea, Decapoda), M. lar, Palaemon paucidens and P. pacificus. The three IAG precursors consisted of a signal peptide, a B chain, a C peptide and an A chain. This organization corresponds to that of the known isopod AGH and decapod IAG precursors. The three IAGs showed higher sequence identities to M. rosenbergii IAG (49∼72%) than to C. quadricarinatus IAG (29∼32%). These results are consistent with their phylogenetic relationship. In the analysis of the tissue-specific gene expression of the cloned three IAGs by RT-PCR, each IAG was detected only in the AG. Our data obtained in this study will facilitate further investigation of sex differentiation controlled by the AG in decapods.