Toxicidade aguda e efeito subletal do Roundup Transorb® nos testículos de mato grosso Hyphessobrycon eques (Steindachner, 1882) (Teleostei: Characidae)

• Autor(a) principal: Nunes, Leandro Rodrigues
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5076
• topic: Hyphessobrycon eques; Roundup Transorb® HC liquid; Hyphessobrycon eques; Roundup Transorb® HC liquid; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA

The toxicity of several environmental pollutants has been investigated in humans and other species. Substances contained in agrochemicals, such as herbicides, can affect the reproductive systems of male and female animals. This study aimed to determine the LC50 and sublethal effects of Roundup Transorb® on the testicular morphology of mature male Hyphessobrycon eques. Acute toxicity of Roundup Transorb® was determined in the static system according to the Brazilian standard (NBR 15088, ABNT, 2005). Adult male Hyphessobrycon eques of approximately 30mm length were selected for the experiments, conducted after a ten day acclimation period. Seven concentrations (0.5, 1.0, 2.0, 4.0, 8.0, 16.0 and 32.0mg.L-1), based on glyphosate, the active ingredient in Roundup Transorb® were tested and the LC50 estimated using the Probit 1.5 program. The sublethal effects of Roundup Transorb® were evaluated after 96 hours of exposure at three concentrations defined as approximately 1/2, 1/4 and 1/8 of the LC50. After exposure, 10 animals from each treatment were anesthetized, euthanized, weighed, measured and their testes removed. Tissue samples were fixed, embedded in historesin, sectioned with a rotating microtome and stained with toluidine blue and hematoxylineosin. Ten fields per animal were observed to collect histological and morphometric data. The LC50 calculated at an average temperature 22.0 ± 0.71°C was 2.64 mg.L-1, with a 95% confidence interval of 2.09 to 3.33 mg.L-1. At an average temperature of 24.0 ± 0.20°C the LC50 was 2.18 mg L-1 with a 95% confidence interval of 1.75 to 2.72 mg.L-1. Morphometric and histopathological changes observed at sublethal exposure concentrations included reduced tubule diameters, reduced numbers of spermatogenic cells lines (A and B spermatogonia, primary and secondary spermatocytes), spermatocyte and spermatid cysts, increased numbers of ruptured cysts and alterations related to necrosis (cytoplasmic vacuolization and nuclear pyknosis). Indices of ruptured cysts cytoplasmic vacuolization increased with increasing exposure concentration. Roundup Transorb® was found to be moderately toxic to Hiphessobrycon eques and promoted morphological alterations harmful to spermatogenesis in this species at glyphosphate exposure concentrations reported to exist in the environment and permitted by Brazilian law.