Meeting Abstract
In crustaceans, male sexual differentiation and maintenance of masculine properties are governed by an endocrine gland located in proximity to the gonopores, termed the androgenic gland. This gland exerts its function through an insulin-like androgenic gland hormone (IAG). Insulin-like peptides mediate their signaling through a superfamily of tyrosine-kinase receptors. While IAGs were found in many decapods, including in the prawn Macrobracium rosenbergii, an IAG receptor is yet to be identified. Using comprehensive transcript libraries, generated by next generation sequencing, we have identified few putative sequences for tyrosine kinase receptors. Two of the above showed high sequence similarity in their deduced protein to insulin-related receptors from other taxa and thus named M. rosenbergii insulin receptors (Mr-IRs). The genes were found to be expressed in several tissues and developmental stages. Ligand blot and phosphorylation assays suggested possible in-vitro interactions between Mr-IAG and Mr-IRs. Therefore, the role of Mr-IRs was studied by loss of function experiments through RNAi during the time frame of sexual differentiation. In the case of one of the transcripts, Appendix masculinae, a secondary male characteristic, was observed earlier in the Mr-IR silenced group concomitantly with AG hypertrophy and elevated levels of Mr-IAG transcript. Additionally, substantial amount of immature spermatids was observed in the distal vas deference. In light of the above, the involvement of insulin receptors in the regulation of sexual development and reproduction processes in crustaceans will be discussed.
