Identification of key genes affecting development and nutrient metabolism in the early seedling stage of Dongting catfish (Silurus asotus)

As a carnivorous fish, the cannibalism are prone to happen in the early seedling stage in Dongting catfish ( Silurus asotus ), especailly when there is not enough food, which resulting in the low survival rate of Dongting catfish. To find clues to improve the survival rate of Dongting catfish offspring, the comparative transcriptomics analysis were conducted between normal and malformed larval fish, as well as normal larval fish before and after first food intake. In normal and malformed larval fish groups, a total of 881 differential genes were identified, including 634 up-regulated genes and 247 down-regulated genes. From these genes related to growth hormone synthesis and secretion were screened out as SLA isoform X1 , SOCS3 , STAT1b , JUNB , respectively. In the group of larval fish before and after the first food intake, 4901 up-regulated genes and 3660 down-regulated genes were found, from which the differential genes related to protein digestion and absorption pathway and pancreatic secretion pathway were screened out as cathepsin D precursor , elastase 2 like precursor , elastase 2 precursor , LPL isoform X1 , CTRB1 precursor , CTRL precursor , CPA precursor , FABP , SLC15A1 , CEL tandem duplicate 2 precursor . The differential genes screened for association with amino acid metabolism were ASAOC precursor , PLD3 , NDPKs , trehalase , UMP-CMP kinase , L-amino-acid oxidase , PLB1 , FALDH isoform X2 , PLA2 precursor , glucokinase . Meanwhile, nine differential genes were selected for qPCR verification. The results confirmed that the relative expression trends of these genes were consistent with those found in the transcriptome. These findings provide an important reference for developing strategies to enhance the survival rate of Dongting catfish at early seedling stage.