Effects of constant and diel cyclic temperatures on the liver and intestinal phospholipid fatty acid composition in rainbow trout Oncorhynchus mykiss during seawater acclimation

Jian Ge; Yangen Zhou; Ming Huang; Qinfeng Gao; Yunwei Dong; Shuanglin Dong

doi:10.1186/s40850-021-00086-6

Effects of constant and diel cyclic temperatures on the liver and intestinal phospholipid fatty acid composition in rainbow trout Oncorhynchus mykiss during seawater acclimation

BMC Zool. 2021 Jun 21;6(1):21. doi: 10.1186/s40850-021-00086-6.

Authors

Jian Ge¹, Yangen Zhou², Ming Huang¹, Qinfeng Gao^{1

3}, Yunwei Dong^{1

3}, Shuanglin Dong^{1

3}

Affiliations

¹ Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266100, Shandong Province, China.
² Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266100, Shandong Province, China. zhouyg@ouc.edu.cn.
³ Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, Shandong Province, China.

Abstract

Background: Rainbow trout is an economically important fish in aquaculture and is a model species in environmental physiology. Despite earlier research on the seawater adaptability of rainbow trout at different temperature regimes, the influence on the liver and intestine in this species is still unknown. Two trials were conducted to investigate the effects of constant and diel cyclic temperatures on phospholipid fatty acid (PLFA) composition in the liver and intestine of rainbow trout during seawater acclimation.

Results: At the end of growth trial 1, fish at 9 and 12.5 °C showed significantly higher ratios of unsaturated to saturated (U/S) and unsaturation index (UI) than those at 16 °C in liver and intestine phospholipids. After day 1 of seawater acclimation, the U/S, UI, and average chain length (ACL) of liver and intestinal phospholipids in fish at 16 °C significantly increased. Two weeks after seawater acclimation, the liver and intestinal PLFA composition adapted to salinity changes. In trial 2, significantly higher U/S, UI, and ACL were found in intestinal phospholipids at 13 ± 2 °C. On the first day after seawater acclimation, UI and ACL in liver phospholipids significantly increased at 13 °C, while fish at 13 ± 2 °C showed significantly decreased U/S, UI, and ACL in the intestine. At the end of growth trial 2, liver PLFA compositions were stable, whereas intestinal PLFA at 13 and 13 ± 1 °C showed significantly decreased U/S, UI, and ACL. A two-way analysis of variance and principal component analysis revealed significant effects of different constant temperatures, seawater acclimation, and their interaction on the liver and intestinal phospholipids, a significant effect of diel cyclic temperature on intestinal phospholipids, and the effects of seawater acclimation and its interaction with diel cyclic temperature on liver phospholipids.

Conclusion: Temperatures of 9 and 12.5 °C could elevate membrane fluidity and thickness in the liver and intestine of rainbow trout in freshwater, whereas no significant effects were found with diel temperature variations. After seawater acclimation, constant and diel cyclic temperatures significantly influenced the membrane fluidity and thickness of the liver and intestine. Compared with constant temperature, diel temperature variation (13 ± 2 °C) can enhance the adaptability of rainbow trout during seawater acclimation.

Keywords: Constant temperature; Diel cyclic temperature; Phospholipid fatty acid composition; Rainbow trout; Seawater acclimation.