Histopathological and ultrastructural indices for the assessment of glyphosate-based herbicide cytotoxicity in decapod crustacean hepatopancreas.

Glyphosate-based herbicides (GBH), including Roundup, are the most widely used pesticides in the world. Glyphosate residues have been detected in surface and groundwater, in food, and in human blood and urine. The effects of this herbicide on different levels of biological organization are an important concern that needs to be investigated. In general, the toxicity of GBH in invertebrates is poorly understood, and it is the motivation of this study. Thus, the aim of this study was to evaluate cellular responses of the hepatopancreas, an organ involved in the detoxification process in invertebrates, after exposure to environmentally relevant concentrations of GBH, using prawn Macrobrachium potiuna as a model. Prawns were exposed to three concentrations of GBH (0.0065, 0.065 and 0.28 mg L-1) for 7 or 14 days. Alterations in the morphology of the hepatopancreas and in subcellular components of R cells, which are responsible for the detoxification process, were analyzed, and an index for subcellular alterations was standardized. GBH exposure induced tissue commitments on the hepatopancreas, as well as important impairments of R cells that could compromise the normal functioning of the cells, especially in the detoxification processes. The major cellular impairments were intense vacuolization, dilatation of the cisterns of the rough endoplasmic reticulum and Golgi bodies, increase of perinuclear space, necrosis, concentric membrane formation and mitochondria crest loss. Our data contribute to the knowledge of the cytotoxic effects of low GBH concentrations on aquatic invertebrates, specifically their effects on the hepatopancreas, an important organ for the metabolism of crustaceans. These results also indicate that concentrations considered safe by regulatory agencies should be reviewed to minimize the effects on non-target organisms. This study also contributes to the standardization of an ultrastructure index for the assessment of GBH in palaemonids, which could be used for the assessment of contaminants in crustaceans and other species with hepatopancreas.

New insights on the olfactory lobe of decapod crustaceans.

Studies on the crustacean nervous system have been responsible for advances in neuroscience and continue to play an important role in comparative neurobiology. The organization of crustacean brains provides clues about their phylogeny and might also offer some hints regarding their lifestyles. In this study, we compared the organization of specific brain regions of three species of marine shrimp with two species of freshwater prawns, making possible the identification of a pathway issuing from the periphery and cluster 9, which was not previously identified in freshwater prawns and shrimp. Although the brains of the species studied show the same general organization of other crustaceans, variations in the structural organization of the olfactory lobe, evidenced by different immuno-markers, were observed between shrimp species and prawns. In contrast to shrimp, the more well-defined organization of the olfactory lobe in freshwater prawns might reflect greater integration in the processing of olfactory information. Also, in freshwater prawns we described fibers organized as a tract similar to the deutocerebral commissure.

Protective effects of diphenyl diselenide in a mouse model of brain toxicity.

Interest in organoselenide chemistry and biochemistry has increased in the past three decades, mainly due to their chemical and biological activities. Here, we investigated the protective effect of the organic selenium compound diphenyl diselenide (PhSe)2 (5 µmol/kg), in a mouse model of methylmercury (MeHg)-induced brain toxicity. Our group has previously demonstrated that the oral and repeated administration (21 days) of MeHg (40 mg/L) induced MeHg brain accumulation at toxic concentrations, and a pattern of severe cortical and cerebellar biochemical and behavioral. In order to assess neurotoxicity, the neurochemical parameters, namely, mitochondrial complexes I, II, II-III and IV, glutathione peroxidase (GPx) and glutathione reductase (GR) activities, the content of thiobarbituric acid-reactive substances (TBA-RS), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and brain-derived neurotrophic factor (BDNF), as well as, metal deposition were investigated in mouse cerebral cortex. Cortical neurotoxicity induced by brain MeHg deposition was characterized by the reduction of complexes I, II, and IV activities, reduction of GPx and increased GR activities, increased TBA-RS and 8-OHdG content, and reduced BDNF levels. The daily treatment with (PhSe)2 was able to counteract the inhibitory effect of MeHg on mitochondrial activities, the increased oxidative stress parameters, TBA-RS and 8-OHdG levels, and the reduction of BDNF content. The observed protective (PhSe)2 effect could be linked to its antioxidant properties and/or its ability to reduce MeHg deposition in brain, which was here histochemically corroborated. Altogether, these data indicate that (PhSe)2 could be consider as a neuroprotectant compound to be tested under neurotoxicity.