Laboratory of Conservation Physiology (LaFisC), Federal University of São Carlos, Brazil; Graduate Program of Biotechnology and Environmental Monitoring, Federal University of SãoCarlos, Brazil.
Laboratory of Structural and Functional Biology (LaBEF), Federal University of São Carlos, Brazil.
Ecotoxicol Environ Saf. 2021 Jan 1;207:111101. doi: 10.1016/j.ecoenv.2020.111101. Epub 2020 Sep 6.
To regulate the presence of contaminants in Brazilian water, the Brazilian Environmental Council (CONAMA) promulgates regulations regarding the concentrations of given compounds that are supposed to be safe for aquatic life. Considering these regulations, this study tested the effects of considered safe levels of lithium (2.5 mgL) and selenium (0.01 mgL), isolated and mixed, on the American bullfrog (Lithobates catesbeianus) tadpoles. The evaluation was done through the use of biomarkers of larval development as total wet weight (TWW), snout-vent-length (SVL), hind-limb-length (HLL), activity level (AL), histologic evaluation of the thyroid gland and the mortality rate. The tadpoles were allocated into four groups (n = 20 each): a control group (CT); a group exposed to lithium (LI), a group exposed to selenium (SE), and a group exposed to both lithium and selenium (SELI). The whole assay was carried out over 21 days, with two rounds of data collection (on 7th and 21st day) to evaluate the responses over time. A statistical reduction in the AL was observed in the tadpoles from the LI and SELI groups after 7 days of exposure, the same pattern was observed after 21 days. Histological analyses of the thyroid gland showed signs of up-regulation (i.e. statistic reduction in number and area of the follicles, as well a significant reduction in the area of the gland) in all exposed groups, which represents an endocrine response as an adaptative strategy to deal with polluted aquatic environment. The stress triggered by the polluted medium is discussed.
为了规范巴西水中污染物的存在，巴西环境理事会（CONAMA）颁布了有关特定化合物浓度的规定，这些化合物被认为对水生生物是安全的。考虑到这些规定，本研究测试了锂（2.5mg/L）和硒（0.01mg/L）在被认为安全的水平下，单独和混合对美洲牛蛙（Lithobates catesbeianus）蝌蚪的影响。评估是通过使用幼虫发育的生物标志物来完成的，包括总湿重（TWW）、吻肛长（SVL）、后肢长（HLL）、活动水平（AL）、甲状腺组织学评估和死亡率。将蝌蚪分配到四个组（每组 20 个）：对照组（CT）；锂暴露组（LI）、硒暴露组（SE）和锂和硒混合暴露组（SELI）。整个试验持续 21 天，进行了两轮数据收集（第 7 天和第 21 天），以评估随时间的反应。在暴露 7 天后，LI 和 SELI 组的蝌蚪的 AL 统计显著降低，21 天后也观察到了同样的模式。甲状腺组织学分析显示，所有暴露组的甲状腺都出现了上调迹象（即滤泡数量和面积减少，以及腺体面积显著减少），这代表了一种内分泌反应，是应对污染水生环境的一种适应策略。还讨论了污染介质引发的应激。
