Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Russia.
Fish Physiol Biochem. 2022 Feb;48(1):1-13. doi: 10.1007/s10695-021-01034-4. Epub 2021 Nov 24.
Humic substances, a major component of natural organic matter in surface waters, can induce biotransformation enzyme activities and influence antioxidant defense in fish. The study aimed to provide a molecular basis for the stress responses, the synthesis of biotransformation, and antioxidant enzymes in particular. Adult medaka fish (Hd-rR strain) were exposed to environmentally relevant concentrations of humic acid for 96 h. The actual humic acid concentrations in water were determined photometrically and expressed as organic carbon concentrations. Liquid chromatography with tandem mass spectrometry was used for protein profile analysis of medaka liver samples. The relative amount of isozymes was determined using the label-free quantification approach. Hepatic biotransformation enzyme activities were measured as well. Thus, ethoxyresorufin-O-deethylase activity showed a pronounced induction at the highest tested concentration (9.4 mg C/L). Various biotransformation and antioxidant isozymes responded to humic acid differently, reflecting a balanced interplay of proteins that ensures the metabolism of humic acid in fish liver. Some isozymes were not affected by humic acid. The study provides new insight into the molecular mechanisms of the fish stress response to the humic acid-related challenge.
腐殖质是地表水天然有机物的主要成分，能诱导生物转化酶的活性，并影响鱼类的抗氧化防御能力。本研究旨在为鱼类的应激反应、生物转化和抗氧化酶的合成提供分子基础。研究人员用环境相关浓度的腐殖酸处理成年稻斑纹鱼（Hd-rR 品系）96 小时。采用分光光度法测定水中实际腐殖酸浓度，并以有机碳浓度表示。采用液相色谱-串联质谱法分析鱼肝样品的蛋白质图谱。采用无标记定量方法测定同工酶的相对含量。同时还测定了肝生物转化酶的活性。结果表明，在最高测试浓度（9.4mg C/L）下，乙氧基试卤灵-O-去乙基酶活性明显诱导。不同的生物转化和抗氧化同工酶对腐殖酸的反应不同，反映了蛋白质的平衡相互作用，以确保鱼类肝脏中腐殖酸的代谢。一些同工酶不受腐殖酸的影响。该研究为鱼类对腐殖酸相关挑战的应激反应的分子机制提供了新的见解。
