Pb-induced phytotoxicity in para grass (Brachiaria mutica) and Castorbean (Ricinus communis L.): Antioxidant and ultrastructural studies.

Hydroponics experiment was conducted to investigate the effects of different levels of Pb on Para Grass (Brachiaria mutica) and Castorbean (Ricinus communis L). Generally, Para Grass exhibited higher tolerance to excessive concentrations of Pb in nutrient solution, whereas a consistent decline was observed in growth of Castorbean plants exposed to similar Pb levels. Malondialdehyde (MDA) and H2O2 contents exhibited contrasting results with a general decrease in Para Grass and a linear increase in case of Castorbean. In both species a decrease was noticed in the activities of superoxide dismutase (SOD) and guaiacol peroxidase (G-POD) while catalase (CAT) activity was significantly increased. Ultrastructural studies revealed increased starch grains and adversely affected thylakoid membranes in chloroplasts of leaf cells of plants treated with 500 µM Pb. Photosynthetic parameters such as CO2 assimilation rate, stomatal conductance (gs) and transpiration rate (E) decreased in both plant species under different levels of Pb. Maximum concentrations of Pb in shoots of Para Grass and Castorbean were 1.29 and 0.352 g kg-1, respectively while in roots maximum values were 8.88 and 49.86 g kg-1, respectively. The high concentrations of Pb (about 5%) in the roots of Castorbean plants suggest its possible role in the phytoremediation/rhizofiltration of Pb contaminated water.

Applications in environmental bioinorganic: Nutritional and ultrastructural evaluation and calculus of thermodynamic and structural properties of metal-oxalate complexes.

Lead (Pb) is known by its toxicity both for animals and plants. In order to evaluate its toxicity, plants of Brachiaria brizantha were cultivated on nutritive solution of Hoagland during 90 days and submitted to different concentrations of Pb. The content of macro and micronutrients was evaluated and there was a reduction on root content of Ca, besides the lowest dosages of Pb had induced an increase of N, S, Mn, Cu, Zn and Fe. The cell ultrastructure of leaves and roots were analyzed by transmission electronic microscopy (TEM). Among the main alterations occurred there were invaginations on cell walls, the presence of crystals on the root cells, accumulation of material on the interior of cells and vacuolar compartmentalization. On the leaves the degradation of chloroplasts was observed, as well as the increase of vacuoles. Structures for the formation of oxalate crystals were proposed through molecular modeling and thermodynamic stability. Calculi suggest the formation of highly stable metal-oxalate complexes.

Intoxicação espontânea e experimental por Brachiaria radicans (tanner-grass) em bovinos / Natural and experimental poisoning by Brachiaria radicans (tanner grass) in cattle

Brachiaria radicans (tanner-grass,) cresce bem em solos úmidos. Em Santa Catarina é encontrada principalmente nas regiões dos vales dos rios Tubarão e Itajaí. Quando ingerida em grandes quantidades pelos bovinos induz anemia hemolítica, hemoglobinúria, diarreia e pode evoluir para a morte. O objetivo deste trabalho foi avaliar os dados epidemiológicos e clínico-patológicos causados por B. radicans em bovinos. A planta foi administrada a 12 bovinos em doses de 50-100 por cento da dieta. Os animais que receberam uma dieta que consistia de 100 por cento da planta, originária de solos turfosos, mostraram hemoglobinúria, diarreia, mucosas vermelho-escuras e recuperação após suspensão da ingestão da planta. Exames de sangue e urina revelaram anemia, hemoglobinúria e proteinúria. A histopatologia de material coletado de bovinos que morreram pela doença espontânea, revelou necrose hepática coagulativa e paracentral e nefrose hemoglobinúrica. B. radicans mostrou ser tóxica para bovinos somente quando cresce em solos férteis e se consistir de 100 por cento da dieta.

Brachiaria radicans is a grass that grows well on humid soils. In Santa Catarina, it is found mainly in the valleys of the Tubarão and Itajaí rivers. When eaten by cattle in large amounts induces hemolytic anemia, hemoglobinuria, diarrhea and even death. The objective of this study was to evaluate epidemiologic, clinical and pathological data of the intoxication caused by B. radicans in cattle. The plant was administered to 12 cattle in doses of 50-100 percent of the diet. The animals that received 100 percent of B. radicans, grown on peaty soils, showed hemoglobinuria, diarrhea and dark red mucous membranes; they recovered when ingestion of the grass was discontinued. Blood and urine tests revealed anemia, hemoglobinuria and proteinuria. Histopathology of organs collected from cattle that died from spontaneous poisoning revealed hepatic centrolobular and paracentralr coagulative necrosis and hemoglobinuric nephrosis. B. radicans proved toxic for cattle only when it grows on fertile soils and is ingested as 100 percent of the diet.