Hepatic effects of the clomazone herbicide in both its free form and associated with chitosan-alginate nanoparticles in bullfrog tadpoles

Abstract

The use of agrochemicals in agriculture is intense and most of them could be carried out to aquatic environment. Nevertheless, there are only few studies that assess the effects of these xenobiotics on amphibians. Clomazone is an herbicide widely used in rice fields, where amphibian species live. Thus, those species may be threatened by non-target exposure. However, nanoparticles are being developed to be used as a carrier system for the agrochemicals. Such nanoparticles release the herbicide in a modified way, and are considered to be more efficient and less harmful to the environment. The aim of this study was to comparatively evaluate the effect of clomazone in its free form and associated with nanoparticles, in the liver of bullfrog tadpoles (Lithobates catesbeianus) when submitted to acute exposure for 96 h. According to semi-quantitative analysis, there was an increase in the frequency of melanomacrophage centres, in the accumulation of eosinophils and in lipidosis in the liver of experimental groups exposed to clomazone - in its free form and associated with nanoparticles - in comparison with the control group, and the nanotoxicity of chitosan-alginate nanoparticles. The increase of melanomacrophage centres in all exposed groups was significant (P < 0.0001) in comparison to control group. Therefore, the results of this research have shown that exposure to sublethal doses of the herbicide and nanoparticles triggered hepatic responses. Moreover, these results provided important data about the effect of the clomazone herbicide and organic nanoparticles, which act as carriers of agrochemicals, on the bullfrog tadpole liver.

Effects of both cold and heat stresses on the liver of giant spiny frog Quasipaa spinosa: stress response and histological changes

“…The MMCs, which are Kupffer cells in the liver, are focal accumulations of pigmented macrophages involved in the phagocytosis of apoptotic cells of poikilothermic vertebrates (Arciuli et al, 2012;van Wilpe and Groenewald, 2014;Purrello et al, 2001;Steinel and Bolnick, 2017). Several environmental stresses can affect the number and size of MMCs, leading to the disruption of physiological function (Ben Ameur et al, 2012;Ben Hamed et al, 2017;Chai et al, 2017;de Oliveira et al, 2016;Wu et al, 2017). MMCs in the liver were further analysed to detect whether thermal stress can cause physiological damage in Q. spinosa.…”

Melanomacrophage functions in the liver of the caecilian Siphonops annulatus

“…Published data lack information about quantification of melanomacrophages in healthy adult amphibians. An interesting research made by De Oliveira et al (2016) evaluated the adverse effects of the clomazone herbicide on amphibian tadpoles. The frequency of melanomacrophage centers in the exposed groups was increased in relation to control groups.…”

Evaluation of Ecotoxicology Assessment Methods of Nanomaterials and Their Effects

“…In all exposed groups (clomazone, BNMs and clomazone-BNMs) there was a significant increase of melanomacrophage centers, triggering a hepatic response in the tadpoles. Both groups exposed to BNMs presented hepatic sinusoids full of erythrocytes and abundant melanomacrophage centers which reflect that the BNMs might be recognized as toxin by the tadpole organism [101].…”