Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Bunkyo 1-14, Nagasaki, 852-8521, Japan.
Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon, 16419, South Korea.
Chemosphere. 2021 Aug;277:130317. doi: 10.1016/j.chemosphere.2021.130317. Epub 2021 Mar 16.
Two euryhaline rotifers, the temperate species Brachionus plicatilis and tropical species Brachionus rotundiformis, were used to investigate the effects of iron (FeSO·7HO), an essential trace metal, on reproductive patterns and lifetables, including the metabolism of lipid and reactive oxygen species (ROS). B. plicatilis was more sensitive to iron with regard to sexual reproduction. While iron had no significant effect on the population growth at 0-48 μg/mL, it caused a decrease in the resting egg production. B. plicatilis exposed to 6 and 12 μg/mL of iron showed an increase in the intracellular ROS levels and a decrease in the neutral lipid content in sexual organs, accompanied by downregulation of antioxidant components CuZnSOD and two cytochromes (CYP clan 2&3). These patterns suggested that iron-induced oxidative stress was not neutralized by its antioxidant defense system, thus negatively affecting the fecundity of fertilized mictic females. However, B. rotundiformis showed a dose-dependent increase in population growth with extended lifespan and positive sexual reproduction in response to 0-24 μg/mL iron. Furthermore, compared to Fe-exposed B. plicatilis, B. rotundiformis showed better antioxidant mechanism, whereas genes involved in lipid synthesis (citrate lyase, mitochondrial CYP) and reproduction (vasa, sirtuin-2) were significantly upregulated compared to the control, implying that B. rotundiformis was likely to have higher resilience in response to iron-induced oxidative stress. These findings suggest that iron is likely to cause interspecific interactions in the B. plicatilis species complex, whereas the tropical species B. rotundiformis may have evolved an effective defense mechanism against iron-induced stress.
两种广盐轮虫，温带物种褶皱臂尾轮虫和热带物种圆尾轮虫，被用来研究铁（FeSO·7HO），一种必需的痕量金属，对生殖模式和生命表的影响，包括脂质和活性氧物质（ROS）的代谢。褶皱臂尾轮虫对铁的敏感性更强，表现在有性生殖方面。虽然铁对 0-48μg/mL 浓度范围内的种群增长没有显著影响，但它会导致休眠卵的产量减少。暴露于 6 和 12μg/mL 铁的褶皱臂尾轮虫表现出细胞内 ROS 水平升高，性器官中性脂质含量降低，同时抗氧化成分 CuZnSOD 和两种细胞色素（CYP 家族 2&3）下调。这些模式表明，铁诱导的氧化应激未被其抗氧化防御系统中和，从而对受精的有性雌体的繁殖力产生负面影响。然而，圆尾轮虫表现出种群增长的剂量依赖性增加，寿命延长，对 0-24μg/mL 铁的有性生殖呈正相关。此外，与暴露于铁的褶皱臂尾轮虫相比，圆尾轮虫表现出更好的抗氧化机制，而参与脂质合成（柠檬酸裂解酶、线粒体 CYP）和生殖（vasa、sirtuin-2）的基因则显著上调，与对照组相比，这表明圆尾轮虫可能对铁诱导的氧化应激有更高的适应能力。这些发现表明，铁可能会导致褶皱臂尾轮虫种复合体中的种间相互作用，而热带物种圆尾轮虫可能已经进化出了一种有效的防御机制来应对铁诱导的应激。
