Mining of key genes related to growth of Chinese longsnout catfish (Leiocassis longirostris) based on transcriptome analysis

The Chinese longsnout catfish (Leiocassis longirostris) is a rare and valuable freshwater fish, and wildly distributed in fresh water systems throughout China. Fish growth is one of the most economically important traits in fish farming. The cultured fish with high growth performance can often bring direct economic benefits while meeting human food needs. The hypothalamus is an important regulation organ in fish metabolic processes and endocrine activities, which could regulate the growth of fish directly or indirectly. Although a lot of research on L. longirostris has been reported, the molecular mechanisms and key genes of its growth are still unclear. Therefore, we performed comparative transcriptomics analysis using Illumina high throughput sequencing technology, and analyzed transcript profiles of the brains from fast-growth (FG) and slow-growth (SG) L. longirostris individuals. A total of 267 404 674 clean reads were generated, and 1 019 differentially expressed genes of which 711 genes were up-regulated and 308 genes were down-regulated in fast-growth fishes were identified in this study. Then, we subjected all these differentially expressed genes to GO term enrichment and KEGG pathway analysis to find the underlying function annotation. Based on Gene Ontology analysis, plenty of differentially expressed genes were enriched in growth, growth factor activity and hormone-mediated signaling pathway. KEGG enrichment analysis indicated that some differentially expressed genes involved in MAPK signaling pathway, TGF-beta signaling pathway, calcium signaling pathway and neuroactive ligand-receptor interaction were enriched. With the differentially expressed genes subject to GO and KEGG enrichment analysis, several key genes related to growth of L. longirostris were screened, such as gnrh, thr, egr 1, fgf, sst, gipr, cart and crf were identified. The results of this study enriched the gene resources and provided the valuable references for further study on the regulation mechanism of growth of L. longirostris.