Molecular cloning of a cDNA encoding insulin-like androgenic gland factor from the kuruma prawn Marsupenaeus japonicus and analysis of its expression

Androgenic gland hormone (AGH), which is produced in the male-specific androgenic gland (AG) and controls sex differentiation in crustaceans, has been characterized only from isopod species. To date, complementary DNA (cDNA) encoding an androgenic gland-specific polypeptide, which was designated as an insulin-like androgenic gland factor (IAG), has been cloned from three decapod species. IAG has been thought to be a candidate for AGH in decapod crustaceans; however, there has been no clear evidence. To accumulate sequence information of additional IAGs, we cloned cDNA encoding an IAG precursor from the kuruma prawn Marsupenaeus japonicus by reverse-transcription polymerase chain reaction (RT-PCR) coupled with 5'- and 3'-rapid amplification of cDNA ends (RACE). The Mar. japonicus IAG precursor consisted of a signal peptide, a B chain, a C peptide, and an A chain. This organization is the same as those of the known isopod AGH and decapod IAG precursors. In RT-PCR analysis of tissue-specific gene expression of Mar. japonicus IAG, transcript was detected in the distal part of medial vas deferens, distal vas deferens, proximal part of terminal ampoule, and terminal ampoule. This result indicates that AG cells of Mar. japonicus are probably distributed widely in the distal part of the male reproductive organ.