Tissue expression of lipid metabolism related genes PPARs and their responses to heat stress in turbot (Scophthalmus maximus)

Scophthalmus maximus is a commercially valuable flatfish and one of most promising aquaculture species in Europe. Since S. maximus was introduced into China in 1990s, it has been a major maricultured fish in northern coastal areas of China. As a kind of cold-water fish, S. maximus has strict requirements for breeding temperature, which greatly limits the breeding range of this important marine fish. Therefore, it is of great research significance to explore the mechanism of heat-resistance in turbot. In this paper, tissue distribution of PPARs and the expression of PPARs in kidney at different temperature were analyzed by qPCR.The results showed that there are significant differences in the tissue distribution of the three subtypes of S. maximus PPARs. PPARα1 and PPARα2 were markedly expressed in the heart, PPARβ was widely distributed in various tissues of S. maximus, while PPARγ was significantly expressed in the gill of S. maximus. What's more, the transcript abundance of PPARs in S. maximus kidney showed different response patterns to the elevated temperature. At 20 ℃, the expression level of PPARα diminished dramatically and then increased with the elevated temperature. The expression of PPARβ was not significantly different at 14, 20, 23 and 25 ℃, however, its transcript abundance increased significantly when the temperature was increased to the lethal temperature of S. maximus at 28 ℃. The expression level of PPARγ showed a tendency to increase with increasing temperature. In summary, our results revealed that there are three subtypes PPARα, PPARβ and PPARγ in S. maximus, which may be involved in the regulation of lipid metabolism in a tissue-specific manner, and more importantly, the expression of three subtypes of PPARs under thermal stress was pointed out for the first time. Collectively, these studies will shed light on the regulation mechanism of PPARs on lipid metabolism in the kidney of S. maximus during heat stress, which will promote the further study of fish lipid metabolism.