SiRNA knockdown of MrIR induces sex reversal in Macrobrachium rosenbergii

Abstract

In decapod crustaceans, the insulin-like peptides such as insulin-like receptor (IR) are involved in the key regulatory processes in sexual differentiation and sexual characteristic maintenance. Here, we studied the localization of MrIR (M. rosenbergii insulin-like receptor) in Macrobrachium rosenbergii and found that MrIR was mainly expressed in the spermatocytes, androgenic gland cells, and secretory epithelial cells of terminal ampullae. The co-localization between MrIR and MrIAG (M. rosenbergii insulin-like androgenic gland gene) confirmed that MrIR functions as a receptor for MrIAG. This is the first time the siRNA method was used to knock-down MrIR in M. rosenbergii. The optimal injection dose of siRNA-MrIR knockdown was 0.5 μg/g body weight and long-term knockdown experiment yielded neofemales. Through histological observations, we inferred that the injection dose of 0.5 μg/g body weight can efficiently retard the spermatogenesis in testes. The seminiferous lobules were loosely arranged, and only spermatocytes could be observed. Morphologically, neofemales developed as female prawns that contained brood chamber (sperm-receiving pouch), setal buds, ovipositing setae and ovigerous setae. However, the second pereiopod was longer than in female control, but shorter than in male control. The current study provides insight into the MrIR knockdown-induced sex reversal in M. rosenbergii.