SHECHTER , A*; AFLALO , D.E; DAVIS , C; WEIL , S; SAGI , A; Ben-Gurion University ; Ben-Gurion University ; Ben-Gurion University ; Ben-Gurion University ; Ben-Gurion University : The expression and regulation of the vitellogenin gene in male Cherax quadricarinatus
In female decapod crustaceans, vitellogenin (Vg) synthesis is a process related to reproduction and regulated by inhibitory neuropeptides secreted by the X-organ sinus gland complex (XO-SG). We demonstrate that the expression of the Vg gene (CqVg) could be induced in adult male crayfish C. quadricarinatus through bilateral removal of the XO-SG. CqVg differentially expressed during the induced molt cycle. In contrast, CqVg expression was never detected in intact males. RT-PCR using cDNA template from induced molting males and CqVg specific primers showed 100% homology with the corresponding regions of CqVg expressed in females. Quantitative real-time RT-PCR showed that CqVg expression in induced molting males was an order of magnitude lower than in vitellogenic females, this was confirmed by in situ hybridization. The lower expression in males could be explained by the absence of an ovarian stimulatory factor. Intersex individuals are functional males with a permanently arrested ovary serving as a model to investigate a possible stimulatory effect of the ovary. XO-SG removal in intersex leaded to a higher CqVg expression than in induced males, comparable to vitellogenic females. Translation of the Vg transcript was detected using a high density lipoprotein profile of the hemolymph. Induced molting males showed no resemblance to the vitellogenic female profile, suggesting that although the Vg gene was transcribed, translation or export were not executed, as it normally is during vitellogenesis. Induced intersex, on the other hand, showed a profile similar to the vitellogenic female. The expression of a female-specific gene in manipulated males and intersex animals provides an inducible model for investigating the endocrine regulation of Vg expression in crustaceans.
