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

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.

Cross‐species conservation of a transposase‐linked element enables genetic sexing of commercial populations of Russian sturgeon (Acipenser gueldenstaedtii)

“…As sexual maturation is earlier in males than in females, the gonad and fin transcription profiles of 29 known and sex‐related genes of males (4 years old) and females (7 years old) have been compared. In non‐gonadal tissues of Russian sturgeon, the expression of these genes is similar among the sexes at 4 years old (Degani et al, 2021). Nevertheless, by analyzing the genome variation of five female and five male Russian sturgeon, it has been shown that 536 and 339 short segments are unique to females and males respectively (Hajouj, 2020).…”

Sturgeon (<i>Acipenser gueldenstaedtii</i>) Acclimatization to Optimal Growth Conditions—A Case Study of Adaptation, Nutrition, Reproduction, and Sex Determination

“…In the fins of 4-year-old males and 7-year-old females, 22 of 32 genes could be reliably quantified by qRT-PCR. Of these, six genes (ATP6, IGFRM, LIS1A, GAPDH, NPL1A, and SOX9) had significantly higher mRNA levels in females than in males [17] (Figure 14). However, when comparing male fin samples with fins from females of similar age (4 years old), the only significant difference in expression was observed for ATP6, which showed approximately 5-fold higher expression in female samples (Figure 15).…”

“…Male dissociation curve temperatures differed significantly from those of females (Figure 18 and Figure 19). Males had a melting point of 82.5˚C, while females had a melting point of 74˚C [17].…”

“…The overall coverage for all species was 99.65%, with Figure 17. DNA expression of the 100-bp gene fragments showing significant differences between sexes (mean + SE) (see Table 2) [17].…”

Whole-Genome Inter-Sex Variation in Russian Sturgeon (Acipenser gueldenstaedtii)

“…The genetic variability of seven sturgeon species was studied using mitochondrial DNA cytochrome oxidase subunit I (COI) and nine microsatellite markers [ 11 ]. Other studies measured transcriptomic differences between the gonads of males and females [ 9 , 10 , 12 , 13 ]. Recently, a conserved female-specific region was identified in six species of sturgeon, and a PCR-based genotyping method (AllWSex2) was developed [ 14 ].…”