The use of recombinant protein and RNA interference approaches to study the reproductive functions of a gonad‐stimulating hormone from the shrimp Metapenaeus ensis

Although the crustacean crustacean hyperglycemic hormone/molt‐inhibiting hormone/gonad‐inhibiting hormone neuropeptides have been studied extensively in the last two decades and several neuropeptides from the shrimp Metapenaeus ensis have been cloned, the functions of most of these neuropeptides remained putative. In this article, we describe the use of recombinant protein and an RNA interference approach to study the reproductive function of the previously reported molt‐inhibiting hormone (MeMIH‐B) in M. ensis. When hepatopancreas and ovary explants were cultured in medium containing recombinant MeMIH‐B, the vitellogenin gene (MeVg1) expression level was upregulated in a dose‐dependent manner, reaching a maximum in explants treated with 0.3 nm recombinant MeMIH‐B. Shrimp injected with recombinant MeMIH‐B showed an increase in vitellogenin gene expression in the hepatopancreas. Moreover, a corresponding increase in the vitellogenin‐like immunoreactive protein was detected in the hemolymph and ovary of these females. Injection of MeMIH‐B dsRNA into the female shrimp caused a decrease in MeMIH‐B transcript level in thoracic ganglion and eyestalk. These shrimp also showed reduction of vitellogenin gene expression in the hepatopancreas and ovary. Furthermore, the hemolymph vitellogenin level was also reduced in these animals. In summary, the results from recombinant protein and RNA interference experiments have demonstrated the gonad‐stimulatory function of MeMIH‐B in shrimp.