Fanny Zirulnik

Cadmium induces two waves of reactive oxygen species in Glycine max (L.) roots

Cadmium (Cd) is a non-essential heavy metal that may be toxic or even lethal to plants as it can be easily taken up by the roots and loaded into the xylem to the leaves. Using soybean roots (Glycine max L.) DM 4800, we have analysed various parameters related to reactive oxygen metabolism and nitric oxide (NO) during a 6 day Cd exposure. A rise in H(2)O(2) and NO, and to a lesser extent O(2)(·-) content was observed after 6 h exposure with a concomitant increase in lipid peroxidation and carbonyl group content. Both oxidative markers were significantly reduced after 24 h. A second, higher wave of O(2)(·-) production was also observed after 72 h of exposure followed by a reduction until the end of the treatment. NOX and glicolate oxidase activity might be involved in the initial Cd-induced reactive oxygen species (ROS) production and it appears that other sources may also participate. The analysis of antioxidative enzymes showed an increase in glutathione-S-transferase activity and in transcript levels and activity of enzymes involved in the ascorbate-glutathione cycle and the NADPH-generating enzymes. These results suggest that soybean is able to respond rapidly to oxidative stress imposed by Cd by improving the availability of NADPH necessary for the ascorbate-glutathione cycle.

Alterations in the Lipid Metabolism of Rat Aorta: Effects of Vitamin A Deficiency

Antioxidants are known to reduce cardiovascular disease by reducing the concentration of free radicals in the vessel wall and by preventing the oxidative modification of low-density lipoproteins. The prooxidative effect of a vitamin-A-deficient diet on the aorta has previously been demonstrated by us. In this study, the lipid metabolism in the aorta of rats fed on a vitamin-A-deficient diet was evaluated. Vitamin A deficiency induced a hypolipidemic effect (lower serum triglyceride and cholesterol levels) and a decreased serum paraoxonase 1/arylesterase activity. The concentrations of triglycerides, total cholesterol, free and esterified cholesterol, and phospholipids were increased in the aorta of vitamin-A-deficient rats. The phospholipid compositions showed an increase in phosphatidylcholine (PC), phosphatidylinositol plus phosphatidylserine and phosphatidylethanolamine, a decrease in sphingomyelin, and no change in phosphatidylglycerol. In the aorta, the increase in triglycerides was associated with an increased fatty acid synthesis and mRNA expression of diacylglycerol acyltransferase 1. The increased PC content was attributed to an increased synthesis, as measured by [methyl-14C]choline incorporation into PC and high CTP:phosphocholine cytidylyltransferase-α mRNA expression. The cholesterol synthesis, evaluated by [1-14C]acetate incorporated into cholesterol and mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase, did not change. The lipoprotein lipase and lectin-like oxidized low-density lipoprotein receptor 1 mRNA expression levels increased in the aorta of vitamin-A-deficient animals. The incorporation of vitamin A into the diet of vitamin-A-deficient rats reverted all the changes observed. These results indicate that a vitamin-A-deficient diet,in addition to having a prooxidative effect, alters the aorta lipid metabolism.

CHRONIC ZINC DEFICIENCY INDUCES AN ANTIOXIDANT ADAPTIVE RESPONSE IN RAT LUNG

Few studies are available about the role of dietary zinc (Zn) in respiratory diseases. Adult male rats were divided into 2 groups and fed respectively a moderate Zn-deficient diet and a Zn-adequate control diet. In lung tissue at 2 months, thiobarbituric acid-reactive species (TBARS), total glutathione, glutathione disulfide, protein carbonyls, metallothionein, and the activities of glutathione peroxidase (GPx), catalase, CuZn-superoxide dismutase (CuZnSOD) and glucose-6-phosphate dehydrogenase (G-6-PDH) were increased, but protein thiols decreased. In lung tissue at 4 months, TBARS, metallothionein, and the activities of CuZnSOD, Mn-superoxide dismutase (MnSOD) increased. The activities GPx, catalase, G-6-PDH were lower than control group. The changes were accompanied by histological alterations in Zn-deficient lung. The results provide evidence of the pro-oxidative effects of Zn-deficiency in lung, and suggest that the time of treatment play a key role in determining lung susceptibility to oxidative stress.

Dietary regulation of liver NADP-isocitrate dehydrogenase in the rat

Abstract The objective of this work is to study the dietary regulation of cytosolic NADP- linked isocitrate dehydrogenase (EC 1.1.1.4.2) in male rat liver. Seven different diets were prepared: 1- AIN-93 (control), 3501 kcal/g diet; 2- Soy, 3540 kcal/g diet; 3- Low protein, 3593 kcal/g diet; 4- Dextrin, 4056 kcal/g diet; 5- High- carbohydrate, 4101 kcal/g diet; 6- Fat, 4120 kcal/g diet and 7- High- fat, 6521 kcal/g diet. The enzymatic activities of isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase, as marker enzyme, were determined. The variation of some serum parameters as glucose, total cholesterol and triglycerides, was studied. The results showed that isocitrate dehydrogenase did not change significantly with different diets, while for glucose- 6- phosphate dehydrogenase, significant differences were observed for each diet respect to control. Glucose, cholesterol and triglycerides did not show any difference to diets 2 and 3, compared with diet 1. In hypercaloric diets, there was a significative increase (p

Cadmium-induced oxidative damage and antioxidant defense mechanisms in Glycine max L.

Fil: Felici, Emiliano. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico San Luis. Instituto de Quimica de San Luis; Argentina. Universidad Nacional de San Luis; Argentina