Inhibition, recovery and field responses of Astyanax fasciatus (Cuvier, 1819) brain cholinesterases upon exposure to azinphos-methyl

Abstract

Pesticides used in agriculture are among the most important environmental pollutants. Organophosphate and carbamate insecticides, intensely used in deciduous fruit-trees, may be transported to aquatic ecosystems by runoff. Northwest rural Montevideo possesses zones of fruit-tree farms, where azinphos-methyl is currently the most used pesticide. Despite the well-known neurotoxic properties of this agrochemical, studies of its effects on aquatic organisms are scarce in Uruguay. The main goal of this study was to evaluate effects on brain cholinesterases and erythrocyte micronuclei in Astyanax fasciatus exposed to azinphos-methyl in laboratory and field conditions. Dose-response curves showed concentration-dependent brain cholinesterase inhibitions and a LC 50 (48-hour) of 2.31 mg L-1 for azinphos-methyl. Fishes exposed for 48 hours to toxicant and then transferred to clear water recovered 80% of brain cholinesterase activity in 10 days. Field study indicated that A. fasciatus from a watershed with low contamination showed a brain cholinesterase specific activity of 62.2±5.1 Units mg-1 protein (22ºC) 97.7 % of which was acetylcholinesterase. Specimens from a basin with intense fruticulture exhibited a spatial gradient, those collected downstream to the farms showed brain acetylcholinesterase activities 32% lower than fishes captured upstream. In conclusion, our data suggest that A. fasciatus is a suitable species for ecotoxicological biomonitoring.

Bell pepper (Capsicum annuum L. var. grossum Sendt.) under greenshade net: Nutraceutical traits

“…However, these transformations can also affect the natural resources (such as soil and freshwater) or ecosystem services that are required to support agricultural production systems [2,18,23]. For example, these transformations can be associated with soil erosion, fertility losses, water quality degradation, reductions in biodiversity [3,5,7,24,25], and lessened stream or aquifer recharge, among other effects. In this sense, the increased application of fertilizers is one of the most important causes of the eutrophication of surface water courses [6,22,27].…”

Morphological development of Corydoras aff. paleatus (Siluriformes, Callichthyidae) and correlation with the emergence of motor and social behaviors

“…Specimens were anesthetized and sacrificed as described (Pistone et al, 2012) or anaesthetized and gradually fixed by minute increases of fixative concentration in the water surrounding the fish. Fixatives used were either 2-4% paraformaldehyde in phosphate buffer (pH 7.4), 4% formaldehyde or decalcifying-fixative mixtures described by ramón y caJal & De castro (1972).…”

“…For examining particular sense organs in alive specimens, a Nikon Eclipse E-300 microscope equipped with a high resolution camera was used. When immobilization was needed, fishes were mildly anaesthetized by immersion in aquarium water containing either tricaine methanesulfonate (3-aminobenzoic acid ethyl ester) at a final concentration of 135-150 mg per liter (Pistone et al, 2012).…”