Environmental Engineering Post-Graduation Program, University of Blumenau, Blumenau, SC, Brazil.
Department of Natural Science, University of Blumenau, Blumenau, SC, Brazil.
Sci Total Environ. 2021 Jun 1;771:144971. doi: 10.1016/j.scitotenv.2021.144971. Epub 2021 Jan 23.
Tebuthiuron (TBU) is a phenylurea herbicide that is extensively used in sugarcane fields. Owing to the low degradation rate, high water solubility, and leaching potential, TBU is believed to have harmful effects on aquatic organisms, such as anuran tadpoles. Contaminant effects can be influenced by temperature since increases in temperature are often associated with increased metabolic reactions. In this study, we evaluated the influence of temperature on the negative effects of TBU in bullfrog tadpoles (Lithobates catesbeianus) through a multi-biomarker approach. Tadpoles were exposed to 0 (control) 10, 50, and 200 ng L of TBU for 16 days at 25 and 32 °C. TBU increased the transcript levels of genes involved in biotransformation (glutathione S-transferase, GST, and sulfotransferase, SULT) and antioxidant (superoxide dismutase, SOD, and catalase, CAT) enzymes. TBU exposure also increased CAT and glutathione peroxidase (GPx) activities, whereas SOD and carboxylesterase activities were decreased. The highest temperature caused a decrease in the activities of ethoxyresorufin-O-deethylase and SOD but increased the activities of GST, GPx, glucose 6-phosphate dehydrogenase, and acetylcholinesterase. No effects of temperature or TBU exposure were observed in genotoxic markers (frequencies of micronucleous and nuclear abnormalities) or in lipid peroxidation levels. Tadpoles exposed to TBU at all tested concentrations presented a higher index of biomarker responses than that of the control groups. Higher values of severity scores from histological analyses were found in the liver of tadpoles exposed to 50 and 200 ng L of TBU at 32 °C compared with those of the control group at the same temperature. These results indicate that TBU and temperature increases are able to disturb the metabolic homeostasis of L. catesbeianus tadpoles after 16 days of exposure, causing substantial alterations in biomarker responses and liver morphology.
特丁净（TBU）是一种广泛应用于甘蔗田的苯脲类除草剂。由于其降解率低、水溶性高和淋溶潜力大，TBU 被认为对水生生物，如蛙类蝌蚪，具有有害影响。由于温度升高通常与代谢反应增加有关，因此温度会影响污染物的影响。在这项研究中，我们通过多生物标志物方法评估了温度对牛蛙蝌蚪（Lithobates catesbeianus）中 TBU 负面效应的影响。蝌蚪在 25 和 32°C 下分别暴露于 0（对照）、10、50 和 200ng/L 的 TBU 中 16 天。TBU 增加了参与生物转化（谷胱甘肽 S-转移酶，GST 和磺基转移酶，SULT）和抗氧化（超氧化物歧化酶，SOD 和过氧化氢酶，CAT）酶的基因的转录水平。TBU 暴露还增加了 CAT 和谷胱甘肽过氧化物酶（GPx）的活性，而 SOD 和羧酸酯酶的活性则降低。较高的温度导致乙氧基 RES 比色法-O-脱乙基酶和 SOD 的活性降低，但增加了 GST、GPx、葡萄糖 6-磷酸脱氢酶和乙酰胆碱酯酶的活性。在遗传毒性标志物（微核和核异常的频率）或脂质过氧化水平方面，未观察到温度或 TBU 暴露的影响。在所有测试浓度下暴露于 TBU 的蝌蚪的生物标志物反应指数均高于对照组。与同一温度下的对照组相比，在 32°C 下暴露于 50 和 200ng/L TBU 的蝌蚪肝脏中的组织学分析严重程度评分值更高。这些结果表明，在 16 天的暴露后，TBU 和温度升高能够扰乱 L. catesbeianus 蝌蚪的代谢稳态，导致生物标志物反应和肝脏形态发生重大变化。
