Fisheries College of Huazhong Agricultural University; Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Wuhan 430070, People's Republic of China.
J Appl Toxicol. 2011 Aug;31(6):561-7. doi: 10.1002/jat.1597. Epub 2010 Nov 19.
It is well known that fish have stronger tolerance than mammals to microcystin (MC) exposure, and such a difference is attributed to their different core body temperatures. However, no in vivo study has been conducted to investigate the effects of temperature on MC-induced toxicity in fish, a typical poikilotherm. Tolerance and detoxification response of zebrafish treated with MC-LR were investigated under three temperatures. The LD50 values evidently increased with a decline of the temperature (547, 260 and 176 µg kg⁻¹ at 12, 22 and 32 °C, respectively), indicating stronger tolerance of the fish at lower temperatures. Changes in the transcription of glutathione S-transferase (GST) isoforms in the fish were observed, and their sensitivity of response in the transcription of GST mRNA was on the order of 12 > 32 > 22°C. We screened out several GST genes which were more delicate to solve the MC-LR exposure at different temperatures, i.e. GST rho1, al, p1 and theta1 in the 12 °C group, and GST zeta1 and p2 in the 22 and 32 °C groups. Our findings partly validate the hypothesis that high temperature enhances toxic effects of MCs on poikilotherms. Our studies also indicate that temperature-dependent toxic effects should be taken into account for field toxic assessment of microcystins in fish.
众所周知，鱼类对微囊藻毒素（MC）的耐受性强于哺乳动物，这种差异归因于它们的核心体温不同。然而，目前还没有体内研究来调查温度对鱼类（一种典型的变温动物）中 MC 诱导毒性的影响。在三种温度下，研究了 MC-LR 处理的斑马鱼的耐受性和解毒反应。LD50 值随温度下降而明显升高（分别为 12°C、22°C 和 32°C 时为 547、260 和 176μgkg⁻¹），表明鱼类在较低温度下具有更强的耐受性。观察到鱼类谷胱甘肽 S-转移酶（GST）同工型转录的变化，它们对 GST mRNA 转录的响应敏感性顺序为 12°C>32°C>22°C。我们筛选出了几个 GST 基因，这些基因在不同温度下对 MC-LR 暴露更为敏感，即 12°C 组中的 GST rho1、al、p1 和 theta1，以及 22°C 和 32°C 组中的 GST zeta1 和 p2。我们的发现部分验证了高温增强 MC 对变温动物毒性作用的假设。我们的研究还表明，在鱼类中进行微囊藻毒素的现场毒性评估时，应考虑温度依赖性的毒性效应。
