Study: https://repositorio.ufsc.br/handle/123456789/215808
Author(s): Melo, M.S.D.
Article Type: Study
Abstract:
Glyphosate-based herbicides (GBH), including Roundup ® formulations, are the most widely used herbicides in the world. Although they are mostly used in agriculture and urban gardening, glyphosate residues are being more and more detected in aquatic ecosystems, food and human fluids. Thus, the study of the toxic effects of these formulations on different organisms has grown in the last 30 years. However, the toxicity of GBH is mainly focused on vertebrates, in which different GBH caused oxidative stress, genotoxicity, cytotoxicity, teratogenicity, as well as, being considered as an endocrine disrupting compound (EDC). Although representing over 90% of the fauna, studies on the GBH effects on invertebrates, particularly native crustacean species of the Brazilian fauna are scarce. Thus, the aim of this thesis was to identify the acute toxicity of Roundup WG ® , as well as to investigate the cytotoxic effects on the hepatopancreas, the detoxification organ and the potential endocrine disruptor of environmentally relevant Roundup WG ® concentrations in the freshwater prawn Macrobrachium potiuna. Males and females were collected at Cachoeira do Poção, Florianópolis, transported to the Laboratório de Reprodução e Desenvolvimento Animal, acclimated for seven days and used for acute toxicity bioassays (determination of Lethal Concentration 50% in 96h) and subacute toxicity of low concentrations (0.0065, 0.065 and 0.28 mg L -1 ) in animals exposed for seven and 14 days. Subacute bioassays were divided into two sets; Set 1 evaluated the cytotoxicity effect of low concentrations in hepatopancreas morphology and morphometry, R cells subcellular compartments integrity, DNA fragmentation, and hepatopancreas lipid peroxidation. Set 2 consisted of evaluating the transcript levels (molt-inhibiting hormone – MIH, ecdysteroid receptor – EcR and vitelogenin – Vg), hormonal (20-hydroxyecdsone – 20-HE) and enzymatic (chitobiase) of molecules involved in ecdysis, growth and reproduction processes of crustaceans, and to identify the biomarkers that best responded to the herbicide exposure. Prawns exposed in Set 1 showed histopathological alterations such as hepatopancreatic cell vacuolation, hemocyte aggregation, cell death, hyperplasia and hypertrophy as well as alterations in R cell subcellular compartments (vacuolization, perinuclear space dilatation, rough endoplasmic reticulum and Golgi bodies dilation, mitochondrial membrane loss and concentric membrane formation) in animals exposed for seven and 14 days and hepatopancreas DNA fragmentation in animals exposed for 14 days. In addition, alterations in EcR, MIH and Vg transcript levels were observed in Set 2, mainly for male prawns. On the other hand, males and females showed a decrease in 20-HE concentration and chitobiase activity. Our results indicated that the concentrations studied were cytotoxic to M. potiuna. In addition, the Roundup WG ® herbicide acted as an EDC. Hepatopancreas morphological and ultrastructural alterations, as well as DNA fragmentation for 14-day exposed animals, were the most responsive biomarkers after exposure to Roundup WG ® , in contrast, the best biomarkers in Set 2 were dependent on prawn gender and time of exposure. This study also contributed to the standardization of histopathological and ultrastructural alteration indices for evaluations of GBH effects on crustaceans or other species with hepatopancreas. Our results suggest a decrease in the molecules used for the ecdysis in exposed prawns, and indicate that concentrations considered safe by regulatory agencies should be reviewed in order to minimized adverse effects on non-target organisms.
Keywords: glyphosate, herbicide, Roundup, Macrobrachium potiuna
Citation:
Melo, M.S.D., 2020. Toxicidade do herbicida à base de glifosato (Roundup WG) no hepatopâncreas e sistema endócrino do camarão de água doce Macrobrachium potiuna.
