Discovery and identification of candidate sex-related genes based on transcriptome sequencing of Russian sturgeon (Acipenser gueldenstaedtii) gonads.

As the Russian sturgeon (Acipenser gueldenstaedtii) is an important food and is the main source of caviar, it is necessary to discover the genes associated with its sex differentiation. However, the complicated life and maturity cycles of the Russian sturgeon restrict the accurate identification of sex in early development. To generate a first look at specific sex-related genes, we sequenced the transcriptome of gonads in different development stages (1, 2, and 5 yr old stages) with next-generation RNA sequencing. We generated >60 million raw reads, and the filtered reads were assembled into 263,341 contigs, which produced 38,505 unigenes. Genes involved in signal transduction mechanisms were the most abundant, suggesting that development of sturgeon gonads is under control of signal transduction mechanisms. Differentially expressed gene analysis suggests that more genes for protein synthesis, cytochrome c oxidase subunits, and ribosomal proteins were expressed in female gonads than in male. Meanwhile, male gonads expressed more transposable element transposase, reverse transcriptase, and transposase-related genes than female. In total, 342, 782, and 7,845 genes were detected in intersex, male, and female transcriptomes, respectively. The female gonad expressed more genes than the male gonad, and more genes were involved in female gonadal development. Genes (sox9, foxl2) are differentially expressed in different sexes and may be important sex-related genes in Russian sturgeon. Sox9 genes are responsible for the development of male gonads and foxl2 for female gonads.

[Effects of initial feeding on the growth, survival, and body biochemical composition of Siberian sturgeon (Acipenser baerii) larvae].

Siberian sturgeon (Acipenser baerii) larvae were raised with Limnodrilus sp., Artemia nauplii, Moina sp., and artificial commercial diet for 30 days to investigate the effects of different initial feeding diets on the growth, survival, and body biochemical composition of the larvae. The results showed that A. nauplii was the best initial feeding diet, with the survival rate of A. baerii larvae being significant higher (96.67%) than the others. Feeding with Limnodrilus sp. gave the highest growth rate of A. baerii larvae, while feeding with artificial commercial diet gave the lowest efficiency on the growth rate and survival rate of the larvae. The larvae raised with different diets had significantly different body biochemical composition. After fed with artificial commercial diet, the larvae had the highest moisture content but the lowest crude protein and crude ash contents. Taking A. nauplii as the initial feeding diet and then feeding with Limnodrilus sp. could gave the ideal growth and survival rates of A. baerii larvae.