Crustacean Female Sex Hormone From the Mud Crab Scylla paramamosain Is Highly Expressed in Prepubertal Males and Inhibits the Development of Androgenic Gland

Recently, the crustacean female sex hormone (CFSH), which is considered a female-specific hormone, has been shown to play a crucial role in female phenotypes in crustaceans. In this study, two transcripts ( and ) encoding the same CFSH precursor were cloned from the mud crab . Homology and phylogenetic analysis showed that CFSHs were homologous to interleukin-17 and highly conserved among brachyuran crabs. PCR analysis revealed that was expressed exclusively in the eyestalk ganglion of both prepubertal males and females, and surprisingly, the abundance of transcripts detected in the males were not significantly different from that of the females ( > 0.05). In addition, mRNA hybridization showed that was localized in the X-organ of the male eyestalk ganglion. During the development of the androgenic gland (AG), the level of mRNA in AG remained at low levels from stages I to II (early stage) but had a significant increase at stage III (mature stage). In contrast, the level of transcripts in the eyestalk ganglion was high in the early stage but extremely low in the mature stage. To investigate the potential function of CFSH in male , the recombinant protein (∼20 kDa) was expressed in and was subsequently added to AG explants . It was demonstrated that recombinant protein significantly reduced the expression of in the AG explants at a concentration of 10 M ( 0.05). In conclusion, our study provides the first piece of evidence that shows CFSH from the eyestalk ganglion acts as a negative regulator inhibiting the development of AG in crustaceans.