Interactive effects of dietary zinc and water temperature on growth performance, Zn transport, heat shock response and lipid metabolism in the livers of juvenile yellow catfish Pelteobagrus fulvidraco

A better understanding of metabolic responses is necessary to elucidate interactive effects between water temperature and Zn. This study is performed to investigate the interactive influences of dietary Zn and water temperature on Zn transport, heat stress and lipid metabolism in the livers of freshwater teleost yellow catfish Pelteobagrus fulvidraco. A 2 x 2 factorial design is used in this study, which includes two levels of Zn at 38.5 and 131.2 mg Zn /kg diet for adequate- and high-Zn diets, and two levels of water temperature (28 and 32 degrees C). The feeding experiment continues for 7 weeks. Water temperature of 32 degrees C alleviates dietary Zn-induced reduction of growth performance and mRNA expression of znt2, znt10, zip11 and zip13, and abrogates dietary Zn-induced increment of mRNA expression of znt5 and znt8 of yellow catfish. Compared to dietary Zn addition, dietary Zn addition and water temperature of 32 degrees C increase hepatic Zn content and up-regulated mV-1 mRNA expression. Compared to single dietary Zn addition, water temperature of 32 degrees C + dietary Zn addition increase mRNA expression of hsp70 and hsf1. Moreover, water temperature of 32 degrees C alleviates dietary Zn-induced reduction of TG content and acca mRNA expression, and abolishes the increment of mRNA expression of hsl and ppar alpha induced by dietary Zn. Mechanistically, Zn regulates hsp90 by the MTF-1 binding to the hsp90 promoter. Thus, there is a significant interaction between dietary Zn and water temperature in affecting growth performance, Zn transport, heat shock responses and lipid metabolism. Our results also provide the innovative insights into the mechanism for the interaction between mineral elements and heat stress in fish. Statement of relevance: The frequent heat waves and global warming influences the freshwater ecosystem, which in turn affects the growth performance, heat stress response, nutrient utilization and metabolism in fish. Our results provided the innovative insights into the interaction between mineral elements and heat stress in fish.