Sex-Based Variation of Gene Expression in the Gonads and Fins of Russian Sturgeon (Acipenser gueldenstaedtii)

Abstract

Russian sturgeon (Acipenser \ngueldenstaedtii) \nis a primitive freshwater fish and a source of black caviar. The genes involved in sexual \ndetermination and differentiation are still unknown and there are no molecular \nmarkers for sex identification in this species. Studying the variation of the \nsex-based differences in genomic sequences and in gene expression in the \nsturgeon may lead to markers of sex in early stages of development and advances \nin aquaculture, as well as provide novel insights about the evolution of \nreproduction, sex determination, and sexual differentiation mechanisms in \nvertebrates. Previous studies by our and other groups have identified \ndifferentially expressed genes in the gonads of adult female and male sturgeon. \nThe current study aimed to test whether these genes were also differentially expressed in non-gonadal tissue, namely \nfins. We measured by qRT-PCR the mRNA levels of 29 known and novel sex-related \ngenes in the gonads and fins of males (4 years old) and females (7 years old; \nsexual maturation is earlier in males than in females). Six genes (ATP6, IGFRM, \nLIA1A, S1A, NPL1A, GAPDH and SOX9) showed higher expression in female fins. However, only ATP6 mRNA levels differed in fins \nof males and females of the same age (4 years old). These findings underscore \nthe impracticality of sex identification based on gene expression in \nnon-gonadal tissue and the need for genetic sex markers in the Russian \nsturgeon.