Molecular cloning and expression analysis of cDNAs encoding androgenic gland hormone precursors from two porcellionidae species, Porcellio scaber and P. dilatatus

Abstract

Male sexual characteristics in Crustacea are induced by androgenic gland hormone (AGH), which is produced by the male-specific androgenic gland. Recently, AGH in the terrestrial isopod Armadillidium vulgare was characterized and its cDNA cloned, the first example in which the structure of AGH was elucidated. We report here the molecular cloning of cDNAs encoding AGH precursors from two additional terrestrial isopods, Porcellio scaber and P. dilatatus, cDNA fragments encoding Porcellio scaber AGH (Pos-AGH) and P. dilatatus AGH (Pod-AGH) were amplified by RT-PCR using degenerate oligonucleotide primers designed based on the amino acid sequence of A. vulgare AGH (Arv-AGH). Subsequently, full length cDNAs were obtained by 5′- and 3′-RACE. Both AGH precursors consisted of a signal peptide, B chain, C peptide and A chain, and exhibited the same organization as that of Arv-AGH. The amino acid sequences of the A and B chains, which comprise mature AGH peptide, were highly conserved among the three species, while that of the C peptide showed only low sequence similarity. In Northern blot analysis, each cDNA fragment used as a probe specifically hybridized with a single band (0.75 kb) in mRNA extracted from whole male reproductive organs. In analysis of the tissue-specific gene expression of these two AGHs by RT-PCR, it was revealed that both AGH transcripts were detected only in cDNA synthesized using total RNA from the testis carrying the androgenic glands, but not in that from testis only, seminal vesicle, vas deferens, or hepatopancreas.