Toxidade aguda e cr?nica em girinos de Physalaemus gracilis (Anura : Leptodactylidae) expostos ? atrazina e tebuconazole

Pesticides, represented by chemical substances, also known as agrochemicals, have the objective of controlling agricultural pests. However, they may be harmful to the biological systems of various aquatic organisms, including anuran amphibians. It is important to evaluate effects through toxicological tests that provide information on the response to contaminants in an organism. This study evaluated the toxicological effects caused to species of anuran amphibian Physalaemus gracilis exposed to the herbicide atrazine and the fungicide tebuconazole. For this, the total direct nature spawnings with less than 24 hours of oviposition were collected and transported to the laboratory where they were kept under controlled conditions for their development. After that was performed the acute toxicity test for 96 hours to determine the LC50 and, subsequently, the chronic test, where mortality, morphological alterations and biochemical alterations of tadpoles exposed to sublethal concentrations were evaluated. To calculate the LC50 was employed the trimed spearman karber method. The LC50 for atrazine was 47.90 mg/L, meanwhile for tebuconazole was 1.64 mg/L. The exposure to sublethal doses caused changes in the oral morphology of tadpoles, such as absence of jaw, absence of one or more whole rows of denticles, rows of crooked teeth, missing or missing teeth, and edema of the intestine. In addition, atrazine and tebuconazole caused oxidative damage inducing effects on Physalaemus gracilis tadpoles. The occurrence of lipid peroxidation and carbonyl proteins suggest oxidative damage of the lipids and proteins.Os agrot?xicos, representados por subst?ncias qu?micas, tamb?m conhecidas por agroqu?micos tem objetivo de controlar as pragas agr?colas. Entretanto podem ser prejudiciais aos sistemas biol?gicos de diversos organismos aqu?ticos, incluindo os anf?bios anuros. Por isso ? importante avaliar efeitos atrav?s de teste toxicol?gicos que fornecem informa??es sobre a resposta a contaminantes em um organismo. Este estudo avaliou os efeitos toxicol?gicos causados a esp?cie de anf?bio anuro Physalaemus gracilis expostos ao herbicida atrazina e ao fungicida tebuconazole. Para tal, foram coletadas as desovas totais direto da natureza com menos de 24 horas de oviposi??o, transportadas at? o laborat?rio onde foram mantidas em condi??es controladas para seu desenvolvimento. Foi realizado teste de toxidade aguda de 96 horas para determina??o da CL50 96h e teste cr?nico, onde se avaliou a mortalidade, altera??es morfol?gicas e altera??es bioqu?micas dos girinos expostos a concentra??es subletais. Os c?lculos da CL50 96h seguiram o m?todo trimed spearman karber, para atrazina foi de 47,90 mg/L e 1,64 mg/L para tebuconazole. A exposi??o a doses subletais causou altera??es na morfologia oral dos girinos, como aus?ncia de mand?bula, aus?ncia de uma ou mais fileiras inteiras de dent?culos, fileiras de dent?culos tortas, dent?culos falhos ou ausentes, al?m de incha?o no intestino. Al?m disso, atrazina e tebuconazole causaram efeitos indutores de dano oxidativo em girinos de Physalaemus gracilis. O aumento da peroxida??o lip?dica e prote?na carbonil sugere que os danos oxidativos induzidos afetaram lip?deos e prote?nas podendo causar danos ? atividade enzim?tica devido ? oxida??o de prote?nas