Gao Yiming, Xie Zhe, Qian Jin, Tu Zhihan, Yang Chuangye, Deng Yuewen, Xue Yucai, Shang Yueyong, Hu Menghong, Wang Youji
International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China.
Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China.
Mar Environ Res. 2023 Oct;191:106124. doi: 10.1016/j.marenvres.2023.106124. Epub 2023 Aug 9.
For marine animals living in estuarine, coastal, and intertidal areas, salinity changes and periodic hypoxia are typical stressors; however, how the varying salinity and dissolved oxygen affect the quality and nutrition of marine aquaculture species, such as oysters remains unknown. In this study, we evaluated the diel-cycling hypoxia under different salinities on fatty acid composition and lipid metabolism in oyster Crassostrea hongkongensis digestive glands. After 28 days of exposure, both hypoxia and elevated salinity caused a decrease in the saturated fatty acid (SFA)/polyunsaturated fatty acid (PUFA) ratio of C. hongkongensis, salinity mainly causes changes in C17:0, C17:1, C18:1n9, C20:1n9, C20:4n6, C21:5n3, C22:5n3, with high salinity being more damaging to the fatty acid fractions. Also, Hypoxia accelerates the synthesis of C18:1n9 and C20:4n6. Fatty acid synthase (FAS) synthesis is increased by reduced salinity or hypoxia, but Acetyl CoA carboxylase (ACC) only weakly promotes fatty acid synthesis. Under hypoxic conditions, the activity of both hepatic lipase (HL) and lipoprotein lipase activity (LPL) decreases, which is contrary to the results for dissolved oxygen. The increase in salinity under dissolved oxygen leads to a decrease in LPL activity and an increase in HL activity. Our findings highlighted that exposure to a combination of salinity and hypoxia stressors, can disrupt the protective mechanisms of the oyster and affect the function of its lipid metabolism. Therefore, long-term exposure to periodic hypoxia with salinity changes poses a risk to the nutritional quality of C. hongkongensis, affecting oyster aquaculture and the coastal ecosystem.
对于生活在河口、沿海和潮间带地区的海洋动物来说，盐度变化和周期性缺氧是典型的应激源；然而，盐度和溶解氧的变化如何影响牡蛎等海水养殖品种的品质和营养状况仍不清楚。在本研究中，我们评估了不同盐度下的昼夜循环缺氧对香港牡蛎消化腺中脂肪酸组成和脂质代谢的影响。暴露28天后，缺氧和盐度升高均导致香港牡蛎的饱和脂肪酸（SFA）/多不饱和脂肪酸（PUFA）比值下降，盐度主要引起C17:0、C17:1、C18:1n9、C20:1n9、C20:4n6、C21:5n3、C22:5n3的变化，高盐度对脂肪酸组分的损害更大。此外，缺氧加速了C18:1n9和C20:4n6的合成。盐度降低或缺氧会增加脂肪酸合酶（FAS）的合成，但乙酰辅酶A羧化酶（ACC）对脂肪酸合成的促进作用较弱。在缺氧条件下，肝脂酶（HL）和脂蛋白脂酶活性（LPL）均降低，这与溶解氧的结果相反。溶解氧条件下盐度升高会导致LPL活性降低和HL活性增加。我们的研究结果突出表明，暴露于盐度和缺氧应激源的组合会破坏牡蛎的保护机制，并影响其脂质代谢功能。因此，长期暴露于盐度变化的周期性缺氧对香港牡蛎的营养品质构成风险，影响牡蛎养殖和沿海生态系统。
