Abstract
Russian sturgeon (Acipenser gueldenstaedtii) is a primitive freshwater fish and a source of black caviar. The genes involved in sexual determination and differentiation are still unknown and there are no molecular markers for sex identification in this species. Studying the variation of the sex-based differences in genomic sequences and in gene expression in the sturgeon may lead to markers of sex in early stages of development and advances in aquaculture, as well as provide novel insights about the evolution of reproduction, sex determination, and sexual differentiation mechanisms in vertebrates. Previous studies by our and other groups have identified differentially expressed genes in the gonads of adult female and male sturgeon. The current study aimed to test whether these genes were also differentially expressed in non-gonadal tissue, namely fins. We measured by qRT-PCR the mRNA levels of 29 known and novel sex-related genes in the gonads and fins of males (4 years old) and females (7 years old; sexual maturation is earlier in males than in females). Six genes (ATP6, IGFRM, LIA1A, S1A, NPL1A, GAPDH and SOX9) showed higher expression in female fins. However, only ATP6 mRNA levels differed in fins of males and females of the same age (4 years old). These findings underscore the impracticality of sex identification based on gene expression in non-gonadal tissue and the need for genetic sex markers in the Russian sturgeon.
Highlights
IntroductionAmong the various aspects of the adaptation of Russian sturgeon growth to aquaculture conditions and in producing caviar, of special note are the hormones that control oogenesis [2] [3] [6], growth [4] [7] and sex-related gonadal development, sex identification and differences in gene expression [8] [9] [10] [11] [12], and these have been studied extensively
The dramatic increase in the economic value of caviar
We measured by qRT-PCR the mRNA levels of 29 known and novel sex-related genes in the gonads and fins of males (4 years old) and females (7 years old; sexual maturation is earlier in males than in females)
Summary
Among the various aspects of the adaptation of Russian sturgeon growth to aquaculture conditions and in producing caviar, of special note are the hormones that control oogenesis [2] [3] [6], growth [4] [7] and sex-related gonadal development, sex identification and differences in gene expression [8] [9] [10] [11] [12], and these have been studied extensively. Some genes were shown to have higher expression in males, e.g., SOX9, and others in females, e.g., FOX12
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