Key Laboratory of Ecology and Environment Science in Guangdong Higher Education & Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, China.
Aquat Toxicol. 2010 Nov 1;100(3):271-81. doi: 10.1016/j.aquatox.2010.07.025. Epub 2010 Aug 3.
Acid rain and inputs of acidic effluent can result in increased acidity in aquatic ecosystems, where it is known to have a significant impact and possibly, to cause the decline of some populations of aquatic organisms. In previous studies, intracellular acid-induced oxidative stress has been shown to cause DNA damage, and cooperatively activate the expression of the p53 gene. The acute effects of acidic environments on shrimp and fish have been widely studied. However, the molecular mechanism of acid-induced injury remains largely unknown. In this study, we examined the cellular responses of tilapia to acidic exposure-induced oxidative stress and antioxidant enzyme gene expression. Furthermore, we determined how acute acid stress activates the ATM-p53 signal pathway. We measured the upregulation of reactive oxygen species (ROS) production, the intracellular Ca(2)(+) concentration (Ca(2)(+)), the tail DNA values, the malondialdehyde (MDA) level in the blood cells and the percentage of dead and damaged blood cells. Our results suggest that oxidative stress and DNA damage occurred in tilapia in conditions where the pH was 5.3. Apoptosis was detected by Hoechst staining, which was mainly associated with changes in cell viability. The parameters that we measured were related to acid-induced DNA damage, and all parameters changed in the blood cells through time. The effects of acute acid exposure (pH 5.3) on the expression of ATM, p53, p21, Bax, manganese superoxide dismutase (MnSOD), glutathione peroxidase (GPx) were investigated in tilapia blood cells. The results showed that acute acid stress induced upregulation of ATM, p53 and p21, associated with increasing of DNA damage and apoptosis in blood cells. Additionally, the expression of Bax was slightly increased. Moreover, consensus p53-binding sequences were identified in tilapia MnSOD and GPx gene promoter regions and increased levels of ROS in the blood cells coincided with increased mRNA expression of p53, MnSOD and GPx. Therefore, it suggests that acid exposure-induced oxidative stress may cause DNA damage or apoptosis, and cooperatively activate ATM-p53 pathway, which may lead to the activation of p21 and regulate transcription of MnSOD and GPx.
酸雨和酸性废水的输入会导致水生生态系统酸化，这被认为对水生生物的某些种群有重大影响，并可能导致其减少。在以前的研究中，细胞内酸诱导的氧化应激已被证明会导致 DNA 损伤，并协同激活 p53 基因的表达。酸性环境对虾和鱼类的急性影响已得到广泛研究。然而，酸诱导损伤的分子机制在很大程度上仍然未知。在这项研究中，我们研究了罗非鱼对酸性暴露诱导的氧化应激和抗氧化酶基因表达的细胞反应。此外，我们还确定了急性酸胁迫如何激活 ATM-p53 信号通路。我们测量了活性氧（ROS）产生、细胞内 Ca(2)(+)浓度 (Ca(2)(+))、尾 DNA 值、血细胞中的丙二醛（MDA）水平和死亡及受损血细胞的百分比。我们的结果表明，在 pH 值为 5.3 的条件下，罗非鱼体内发生了氧化应激和 DNA 损伤。通过 Hoechst 染色检测到细胞凋亡，这主要与细胞活力的变化有关。我们测量的参数与酸诱导的 DNA 损伤有关，并且所有参数都随时间在血细胞中发生变化。急性酸暴露（pH 5.3）对 ATM、p53、p21、Bax、锰超氧化物歧化酶（MnSOD）、谷胱甘肽过氧化物酶（GPx）在罗非鱼血细胞中的表达的影响进行了研究。结果表明，急性酸应激诱导 ATM、p53 和 p21 的上调，与血细胞中 DNA 损伤和凋亡的增加有关。此外，Bax 的表达略有增加。此外，在罗非鱼 MnSOD 和 GPx 基因启动子区域中鉴定出与 p53 结合的共有序列，并且 ROS 水平的增加与 p53、MnSOD 和 GPx 的 mRNA 表达增加相吻合。因此，这表明酸暴露诱导的氧化应激可能导致 DNA 损伤或凋亡，并协同激活 ATM-p53 通路，这可能导致 p21 的激活，并调节 MnSOD 和 GPx 的转录。
