Temporal silencing of an androgenic gland-specific insulinlike gene affecting phenotypical gender differences and spermatogenesis

Androgenic glands (AGs) of the freshwater prawnMacrobrachium rosenbergiiwere subjected to endocrinemanipulation, causing them to hypertrophy. Transcripts from these glandswere used in the constructionof anAGcDNAsubtractive library. Screeningof the library revealedanAG-specific gene, termed the M. rosenbergii insulin-like AG (Mr-IAG) gene. The cDNA of this gene was then clonedand fully sequenced. The cysteinebackboneof thepredictedmatureMr-IAGpeptide (B and Achains) showedhigh similarity to thatofother crustaceanAG-specific insulin-likepeptides. In vivo silencing of the gene, by injecting the prawns with Mr-IAG double-stranded RNA, temporarily prevented the regenerationofmale secondary sexual characteristics, accompaniedby a lag inmolt and a reduction in growth parameters, which are typically higher in males of the species. In terms of reproductive parameters, silencingofMr-IAG led to the arrest of testicular spermatogenesis and of spermatophore development in the terminal ampullae of the sperm duct, accompanied by hypertrophy and hyperplasia of the AGs. This study constitutes the first report of the silencing of a gene expressed specifically in the AG, which caused a transient adverse effect on male pheno-typical gender differences and spermatogenesis. (Endocrinology 150: 1278–1286, 2009) Ever since it was first proposed as the source of a hypotheticalmasculinizing hormone in crustaceans, the androgenic glan