Toxicidade do arsênio e mediação do óxido nítrico nas respostas celulares em alface (Lactuca sativa L.)

• Autor(a) principal: Silveira, Neidiquele Maria
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4333
• topic: Enzimas antioxidantes; Espécies reativas de oxigênio; Fluorescência; Sinalização celular; Antioxidant enzymes; Reactive oxygen species; Fluorescence; Cell Signaling; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETAL

Lettuce plants ((Lactuca sativa L. cv Hanson) Asteraceae) were exposed to different arsenic (As) toxic levels aiming to induce the oxidative stress and evaluate the role of nitric oxide (NO), given as SNP, as an attenuating agent of this kind of stress. Plants were treated with 50 μM As, with or without SNP at the concentration of 100 μM, added to the nutrient solution in 4, 12 and 24 hours. The concentration of H2O2, O2 - and MDA, the enzymatic activities pf catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione peroxidase (GPX) and the As and NO concentration were measured. Lettuce plants exposed to As showed elevated As concentration in leaves, in average 6,3 μg g-1 DW, in the short period of 24 hours with fast uptake and translocation to the leaves. The high As concentration detected in leaves were followed by a significant increase in H2O2 and MDA concentrations. SNP presence, however, acting as NO donator promoted reduction in the concentration of these oxidative agents. The enzymatic activities in the plants exposed to As were increased which indicates an active participation of these enzymes as part of the strategy to reduce the oxidative stress induced by the metalloid. In the plants exposed to As and SNP, theses activities were reduced, possibly related to the NO direct action in the scavenging of the generated toxic metabolites. In the plants exposed to As, there was higher production of NO observed through the high fluorescence intensity. When given as an exogenous form, No acted directly in the scavenging of the toxic metabolites generated in response to As exposure. Therefore, it was observed that NO, given as SNP, attenuate As-induced toxicity in lettuce leaves.