Glutathione

Iron (Fe) deficiency is a common agricultural problem that affects both the productivity and nutritional quality of plants. Thus, identifying the key factors involved in the tolerance of Fe deficiency is important. In the present study, the zir1 mutant, which is glutathione deficient, was found to be more sensitive to Fe deficiency than the wild type, and grew poorly in alkaline soil. Other glutathione-deficient mutants also showed various degrees of sensitivity to Fe-limited conditions. Interestingly, we found that the glutathione level was increased under Fe deficiency in the wild type. By contrast, blocking glutathione biosynthesis led to increased physiological sensitivity to Fe deficiency. On the other hand, overexpressing glutathione enhanced the tolerance to Fe deficiency. Under Fe-limited conditions, glutathione-deficient mutants, zir1, pad2 and cad2 accumulated lower levels of Fe than the wild type. The key genes involved in Fe uptake, including IRT1, FRO2 and FIT, are expressed at low levels in zir1; however, a split-root experiment suggested that the systemic signals that govern the expression of Fe uptake-related genes are still active in zir1. Furthermore, we found that zir1 had a lower accumulation of nitric oxide (NO) and NO reservoir S-nitrosoglutathione (GSNO).

The present study investigates the effect of aspartate and glutamate on mitochondrial function during myocardial infarction (MI) in wistar rats. Male albino wistar rats were pretreated with aspartate [100 mg(kgbody weight)(-1) day(-1)] or glutamate [100 mg(kg body weight)(-1) day(-1)] intraperitoneally for a period of 7 days. Following amino acid treatment, MI was induced in rats by subcutaneous injection of isoproterenol [200 mg(kg body weight)(-1) day(-1)] for 2 days at an interval of 24 h. Isoproterenol (ISO) induction resulting in significant (P<0.05) increase in the levels of cardiac mitochondrial lipid peroxidation with a decrease in reduced glutathione level. The activities of glutathione peroxidase and glutathione reductase were significantly (P<0.05) decreased by ISO. ISO-induction also caused significant (P<0.05) decrease in the activities of mitochondrial tricarboxylic acid cycle enzymes (malate dehydrogenase, isocitrate dehydrogenase, succinate dehydrogenase, alpha-ketoglutarate dehydrogenase) and respiratory chain enzymes (NADH dehydrogenase and cytochrome-c-oxidase). ISO significantly (P<0.05) reduced the cytochrome contents, ATP production, ADP/O ratio and oxidation of succinate in state 3/state 4 whereas significantly (P<0.

Buthionine sulfoximine (BSO) is a specific inhibitor of γ-glutamylcysteine synthetase, thus blocking the synthesis of glutathione (GSH). It is known that this makes that BSO affects melanin synthesis because of the role of thiols in melanogenesis. However, BSO may also react with the intermediate oxidation products of melanogenesis, a possibility that has not been investigated from the initial steps of the pathway. We created in vitro conditions simulating eumelanogenesis (oxidation of L-DOPA in the absence of GSH) and pheomelanogenesis (oxidation of L-DOPA in the presence of GSH) under presence or absence of BSO. BSO made that eumelanogenesis results in pigments more soluble and less resistant to degradation by hydrogen peroxide than pigments obtained without BSO. A similar but less marked effect was observed for pheomelanogenesis only at subsaturating concentrations of GSH. These results suggest that BSO diverts the melanogenesis pathway toward the production of more soluble and degradable pigments.