Temperature regulates fatty acid desaturase and elongase at the transcriptional level and modulates the fatty acid profile in the early stage of the common carp (Cyprinus carpio)

This study explored the regulatory effect of temperature stress on fatty acid biosynthesis in the early stage of common carp (Cyprinus carpio) based on Δ6-fatty acids desaturase (Δ6FAD) and elongase-5 (ELOVL5) gene expression and fatty acid composition. One-day-old carp larvae were selected, and after seven days of acclimatisation at 25 °C, the larvae were subjected to temperature stress for 96 h in water at 32 °C or 10 °C. In the post-larval stage, 30-day-old carp juveniles were selected and, after seven days of acclimatisation at 25 °C, were subjected to temperature stress for seven days in water at 32 °C or 10 °C. The results showed that common carp larvae could rapidly and highly express Δ6FAD and ELOVL5 genes within 48 h at high temperature (32 °C) compared with the 0 h group (P < 0.05), while gene expression began to gradually increase after 48 h at low temperature (10 °C). There was a significant improvement in C22:6n-3 and C20:5n-3 after 96 h at low temperature compared with the 0 h group (P < 0.05). In common carp juveniles, the Δ6FAD gene in the intestine, brain and liver was sensitive to low temperature, but the ELOVL5 gene in the intestine, brain and liver of common carp was sensitive to high temperature. The low temperature increased the amount of highly unsaturated fatty acids (HUFA) in the common carp juveniles. The results indicated that temperature could regulate the expression of the Δ6FAD and ELOVL5 genes for HUFA production, as well as for participation in the biosynthesis of fatty acids in the body during the early development of common carp. The results of this study help clarify the regulatory effects of temperature on fatty acid biosynthesis during the early development of common carp.