Effects of manganese on fat snook Centropomus parallelus (Carangaria: Centropomidae) exposed to different temperatures

ABSTRACT This study evaluates the effects of exposure to manganese (Mn2+) for 96 hours at two different temperatures (24 and 27°C) on juveniles of Centropomus parallelus through the activities of glutathione S-transferase (GST) and catalase (CAT), micronuclei test (MN) and comet assay. The GST activity did not show any significant difference between the groups exposed to Mn2+ and the respective control groups; in contrast, a major increase in the CAT activity was observed at 27°C in the group exposed to Mn2+ compared to the control group. The genotoxic analyses showed that in all animals exposed to Mn2+, the number of red cells with micronuclei increased significantly compared to the respective control groups. There was also a significant increase in the incidence of DNA damage in the groups exposed to Mn2+. At a temperature of 24ºC, animals exposed to Mn2+ had more DNA damage than those at 27°C. It is likely that the increase in temperature can also induce oxidative stress. Thus, we conclude that manganese is toxic to the fat snook juveniles, causing genotoxic damage, and when associated with an increase in temperature, manganese can also provoke an increase in oxidative stress.

摘要 本研究以平行锯盖鱼（Centropomus parallelus，俗称肥军曹鱼）幼鱼为实验对象，设置24℃与27℃两个温度梯度，将其暴露于锰离子（Mn²+）环境中96小时，通过检测谷胱甘肽S-转移酶（GST）、过氧化氢酶（CAT）活性，结合微核试验（MN）与彗星试验，评估锰离子暴露对实验对象的影响。谷胱甘肽S-转移酶活性在锰离子暴露组与对应对照组间未呈现显著差异；与之相反，27℃条件下的锰离子暴露组过氧化氢酶活性较对照组显著升高。遗传毒性分析结果显示，所有锰离子暴露组的红细胞微核数量均显著高于对应对照组。锰离子暴露组的DNA损伤发生率同样显著升高。在24℃条件下，锰离子暴露组幼鱼的DNA损伤程度高于27℃组。研究推测温度升高同样可诱导氧化应激。综上，本研究认为锰离子对平行锯盖鱼幼鱼具有毒性作用，可引发遗传毒性损伤；当锰离子暴露与温度升高协同作用时，还可加剧氧化应激反应。