Freitas Juliane Silberschmidt, Teresa Fabrício Barreto, de Almeida Eduardo Alves
Graduate Program in Animal Biology, Department of Chemistry and Environmental Sciences, Universidade Estadual Paulista "Júlio de Mesquita Filho", Cristóvão Colombo, 2265, 15054-000 São José do Rio Preto, SP, Brazil.
Universidade Estadual de Goiás, Campus de Ciências Exatas e Tecnológicas, BR 153 n° 3105 - Fazenda Barreiro do Meio, CEP: 75132-903 Anápolis, GO, Brazil.
Comp Biochem Physiol C Toxicol Pharmacol. 2017 Jul;197:32-44. doi: 10.1016/j.cbpc.2017.04.005. Epub 2017 Apr 27.
Amphibians can experience large temperature fluctuations in their habitats, especially during the larval stage, when tadpoles are restricted to small and ephemeral ponds. Changes in water temperature can alter development, metabolism and behaviour of cold-blooded animals but also the toxicokinetics of chemicals in the environment. In Brazil, pesticides application is intensified during the rainy season, which is the period of reproduction for many amphibian species. We evaluated here the influence of temperature (28, 32, and 36°C) on the toxicity of the herbicide sulfentrazone (Boral®SC) in tadpoles of Physalaemus nattereri and Rhinella schneideri, by analysis of oxidative stress biomarkers. Exposure of tadpoles to sulfentrazone altered the antioxidant enzymes activities and induced lipid peroxidation with temperature-associated responses. Catalase, superoxide dismutase and glucose-6-phosphate dehydrogenase (G6PDH) were impaired by combined effect of temperature and sulfentrazone in both species. G6PDH was increased in most groups exposed to 36°C. Biotransformation enzyme glutathione-S-transferase had more evident alterations in P. nattereri at higher temperatures and changes in tGSH contents presented different patterns between the species. Lipid peroxidation was particularly induced in tadpoles of P. nattereri. Integrated biomarker response (IBR) index indicated a synergic effect of temperature and sulfentrazone for tadpoles of P. nattereri, while the IBR was mainly influenced by temperature in R. schneideri. Our study showed that temperature modulates biochemical responses in tadpoles exposed to sulfentrazone with a species-specific pattern. These findings imply that the effects of abiotic factors should be taken into account to evaluate the real risks of exposure of amphibians to commonly used pesticides.
两栖动物在其栖息地可能会经历大幅度的温度波动，尤其是在幼体阶段，此时蝌蚪被限制在小而短暂的池塘中。水温的变化不仅会改变冷血动物的发育、新陈代谢和行为，还会改变环境中化学物质的毒代动力学。在巴西，雨季期间农药的使用会增加，而雨季正是许多两栖动物物种的繁殖期。我们通过分析氧化应激生物标志物，评估了温度（28、32和36°C）对除草剂乙磺隆（Boral®SC）对纳氏细趾蟾和施氏蟾蜍蝌蚪毒性的影响。蝌蚪暴露于乙磺隆会改变抗氧化酶活性，并诱导脂质过氧化，且呈现出与温度相关的反应。在这两个物种中，过氧化氢酶、超氧化物歧化酶和葡萄糖-6-磷酸脱氢酶（G6PDH）都受到温度和乙磺隆联合作用的损害。在大多数暴露于36°C的组中，G6PDH增加。生物转化酶谷胱甘肽-S-转移酶在较高温度下，在纳氏细趾蟾中表现出更明显的变化，并且总谷胱甘肽含量的变化在两个物种之间呈现出不同的模式。脂质过氧化在纳氏细趾蟾蝌蚪中尤为明显。综合生物标志物反应（IBR）指数表明，温度和乙磺隆对纳氏细趾蟾蝌蚪有协同作用，而IBR在施氏蟾蜍中主要受温度影响。我们的研究表明，温度以物种特异性模式调节暴露于乙磺隆的蝌蚪的生化反应。这些发现意味着，在评估两栖动物接触常用农药的实际风险时，应考虑非生物因素的影响。
