RESEARCH PROGRESS ON THE SEX DETERMINATION AND SEXUAL DIFFERENTIATION IN PENAEID SHRIMP

Understanding the mechanism of sex determination and differentiation in shrimp will facilitate the development of biotechnologies for the culture of monosex populations. In recent years, we have focused our studies on the sex determination and sexual differentiation of shrimp. The morphology of androgenic gland and its potential role in sex development of penaeid shrimp were first clarified. A high-density SNP genetic linkage map was constructed and a sex-linked QTL was identified. Sex-specific DNA markers were also developed based on the QTL or BSA analysis. In order to isolate genes important for sex determination and sexual differentiation, high throughput sequencing technologies were performed on the androgenic gland (AG) and shrimp of different genders and developmental stages. Based on the data, genes including sex lethal (Sxl), transformer 2 (Tra-2), doublesex (Dsx), crustacean hyperglycemic hormones (CHHs) and their receptor guanylate cyclase (GC), insulin-like androgenic gland hormone gene (IAG) and its receptor (IAGR) were identified and characterized. Sxl, Tra-2 and Dsx are homologs of genes in the sex determination cascade of Drosophila. They all show sex-biased expression patterns, indicating their involvement in sex determination or sexual differentiation. The expression of IAG, which controls sexual differentiation of crustacean, was regulated by Dsx, CHHs and GC in shrimp. An IAGR, which was mainly detected in AG and testis, could interact with IAG. The expression of IAGR was also regulated by CHHs and GC. The data suggest that IAG expression is not only regulated by sex determination gene Dsx, but also influenced by the endocrine system in the eyestalk. The results provide new clues to understand the molecular mechanism of sex determination and sexual differentiation of crustacean and present possible targets for developing sex control technology.