Identification of differentially expressed genes associated with differential body size in mandarin fish (Siniperca chuatsi).

Body size is an obvious and important characteristic of fish. Mandarin fish Siniperca chuatsi (Basilewsky) is one of the most valuable perciform species widely cultured in China. Individual differences in body size are common in mandarin fish and significantly influence the aquaculture production. However, little is currently known about its genetic control. In this study, digital gene expression profiling and transcriptome sequencing were performed in mandarin fish with differential body size at 30 and 180 days post-hatch (dph), respectively. Body weight, total length and body length of fish with big-size were significantly higher than those with small-size at both 30 and 180 dph (P < 0.05). 2171 and 2014 differentially expressed genes were identified between small-size and big-size fish at 30 and 180 dph, respectively. RT quantitative PCR (qPCR) analysis showed that the differential expression of 10 selected genes in mandarin fish that went through the same training procedure. The genes were involved in the growth hormone-insulin-like growth factor axis, cell proliferation and differentiation, appetite control, glucose metabolism, reproduction and sexual size dimorphism pathways. This study will help toward a comprehensive understanding of the complexity of regulation of body size in mandarin fish individuals and provide valuable information for future research.