Meeting Abstract

81.2  Tuesday, Jan. 6  Insulin-like gene in prawn sexual differentiation VENTURA, T.*; MANOR, R.; AFLALO, E.D.; WEIL, S.; GLAZER, L.; SAGI, A.; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev sagia@bgu.ac.il

Androgenic glands (AGs) are unique endocrine glands regulating male sexual differentiation and growth in crustaceans. In the prawn Macrobrachium rosenbergii complete sex reversal was achieved by AG grafting or removal in females and males, respectively. In the prawn M. rosenbergii AG cDNA subtractive library was constructed. Screening of this library revealed an AG specifically expressed gene, termed M. rosenbergii insulin-like AG factor (Mr-IAG). The predicted mature Mr-IAG peptide (B and A chains) showed high similarity in its cysteine backbone to other crustacean AG specific insulin-like peptides with low sequence homology. Mr-IAG was found to have a prominent expression comprising 55% of the library sequences. Using real-time RT-PCR Mr-IAG transcript level was found to be higher in the sexually active morphotypes relative to its level in the sexually less active morphotype. In vivo, Mr-IAG dsRNA injections to young males temporally prevented the regeneration of male secondary sexual features accompanied by a delay in molt and growth parameters. Moreover, prominent histological changes were observed following Mr-IAG silencing: arrest of spermatogenesis in the testis, absence of spermatozoa in the sperm duct and a dramatic effect on the AG manifested by hypertrophy and hyperplasia. These results indicate that Mr-IAG might be an AG hormone responsible not only for male sexual differentiation but also for maintenance of male hood.