Comparative transcriptomic analyses of two bighead carp (Hypophthalmichthys nobilis) groups with different growth rates

Growth is one of the most important and desired economic traits for aquaculture species, and identification of loci controlling growth is a difficult task without genomic sequences. In this study, the liver transcriptomes of two groups (F and S) of bighead carp (Hypophthalmichthys nobilis) within a full-sib family with significant differences in growth rate were sequenced. Following de novo assembly of the combined reads from the two groups, a total of 410 differentially expressed genes were identified. Functional annotation and analysis of these genes indicated that some of these were involved in regulation of glucose levels and lipid metabolism, particularly fatty acid oxidation and transport. In addition to the differences on expression levels between the two groups, we also identified many non-synonymous coding single-nucleotide polymorphisms (SNPs) that were specific to each group, including SNPs from 4 genes involved in the lipid metabolism process (GO: 0006629). These differences in gene expression and DNA sequences may in part comprise the genetic background for the regulation of early growth rate in bighead carp.