Abstract
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 MCโinduced toxicity in fish, a typical poikilotherm. Tolerance and detoxification response of zebrafish treated with MCโLR were investigated under three temperatures. The LD~50~ values evidently increased with a decline of the temperature (547, 260 and 176โยตgโkg^โ1^ at 12, 22 and 32โยฐC, respectively), indicating stronger tolerance of the fish at lower temperatures. Changes in the transcription of glutathione Sโtransferase (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 > 22ยฐC. We screened out several GST genes which were more delicate to solve the MCโLR exposure at different temperatures, i.e. GST rho1, al, p1 and theta1 in the 12โยฐC group, and GST zeta1 and p2 in the 22 and 32โยฐC groups. Our findings partly validate the hypothesis that high temperature enhances toxic effects of MCs on poikilotherms. Our studies also indicate that temperatureโdependent toxic effects should be taken into account for field toxic assessment of microcystins in fish. Copyright ยฉ 2010 John Wiley & Sons, Ltd.