Comparative biochemical, transcriptome and metabolome investigation on reproductive maturation of wild and captive female Monopterus albus

The main purpose of this study is to systematically elucidate mechanisms underlying ovarian development in wild and captive female Monopterus albus at the biochemical, transcriptomic, and metabolomic levels. Wild and captive female M. albus in Shanghai were continually collected over 1 year, and their ovarian development was analyzed statistically. We determined serum lipid metabolism and hormone contents of the fish during the study period, along with the largest differences in gonadosomatic indices (GSIs), and performed then transcriptome and metabolome detection analysis on their ovaries. The results demonstrated that wild group had approximately 1 month longer reproductive period than the captive group. Moreover, during the reproductive period, the wild group had higher GSIs than the captive group. Compared with the captive group, the wild group demonstrated significantly higher serum triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, 17β-estradiol, and progesterone contents in serum. Transcriptome and metabolome analyses revealed that 2318 genes and 172 metabolites were upregulated in the wild group, whereas 662 genes and 223 metabolites were downregulated. Furthermore, integrated transcriptome and metabolome analyses revealed that cholesterol metabolism was significantly affected, indicating that it was the main pathway affecting ovarian development in both wild and captive female M. albus. In this pathway, 17 genes (including apolipoprotein A, lipoprotein lipase and sortilin) and 2 metabolites (taurocholic acid and taurochenodesoxycholic acid) were significantly upregulated. In general, ovarian development was better in wild female M. albus than farmed ones.