The PvdRT-OpmQ efflux pump controls the metal selectivity of the iron uptake pathway mediated by the siderophore pyoverdine in Pseudomonas aeruginosa

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The mitochondrial consequences of uncoupling intact cells depend on the nature of the exogenous substrate.

International audienceIn isolated mitochondria the consequences of oxidative phosphorylation uncoupling are well defined, whereas in intact cells various effects have been described. Uncoupling liver cells with 2,4-dinitrophenol (DNP) in the presence of dihydroxyacetone (DHA) and ethanol results in a marked decrease in mitochondrial transmembrane electrical potential (DeltaPsi), ATP/ADP ratios and gluconeogenesis (as an ATP-utilizing process), whereas the increased oxidation rate is limited and transient. Conversely, when DHA is associated with octanoate or proline, DNP addition results in a very large and sustained increase in oxidation rate, whereas the decreases in DeltaPsi, ATP/ADP ratios and gluconeogenesis are significantly less when compared with DHA and ethanol. Hence significant energy wastage (high oxidation rate) by uncoupling is achieved only with substrates that are directly oxidized in the mitochondrial matrix. Conversely in the presence of substrates that are first oxidized in the cytosol, uncoupling results in a profound decrease in mitochondrial DeltaPsi and ATP synthesis, whereas energy wastage is very limited

Consequences of trace metal cocktail exposure in zebra finch (Taeniopygia guttata) and effect of calcium supplementation

International audienceTrace metal elements are significant stressors in urban areas. Their harmful effects on physiological parameters are demonstrated, but current laboratory studies are not representative of wild chronic exposure to a trace metal cocktail. Calcium can reduce the accumulation and toxicity of several metals, but soil acidification in cities leads to a decrease in bioavailability of this mineral. The objective of this study was to investigate the accumulation and toxicity of a trace metal cocktail representative of urban exposure on passerine birds, and test the importance of calcium availability on these toxic effects. We exposed zebra finches (Taeniopygia guttata) to a cocktail of seven metals and one metalloid in drinking water, with or without calcium supplementation. We monitored the concentration of metals in the blood and feathers, and their effects on oxidative status and telomere length. The metal cocktail led to higher concentration of all elements in the feathers, and of arsenic and lead in the blood. Birds with a higher concentration of cadmium, arsenic and lead in the feathers had shorter telomeres, but no impact of the cocktail was detected on oxidative status. Birds of the 'calcium' group and the 'calcium and metal' group accumulated higher concentrations of zinc, chromium and nickel in feathers. The 'calcium and metal' group also accumulated lower concentrations of arsenic and lead in feathers compared to the 'metal' group. Our results suggest that chronic exposure to a cocktail of metals at low concentrations has deleterious effects on birds, which can be limited through calcium intake

Hydrophobic gold catalysts: From synthesis on passivated silica to synthesis on few-layer graphene

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Oral Supplementation Effect of Iron and its Complex Form With Quercetin on Oxidant Status and on Redistribution of Essential Metals in Organs of Streptozotocin Diabetic Rats

Background and aims: Quercetin, is a polyphenolic antioxidant compound. It is able to form complex with metal ions such as iron and exerts a broad range of biological activities like improving metabolic disorders. This research aims at investigating the effect of oral supplementation of iron (2.5mg Fe/Kg/day) and its complex form (molar ratio 1:5; 2.5mg/25mg/Kg/day) with quercetin (25mg/Kg/day) on lipid metabolism, oxidant status and trace elements contents in organs of Wistar diabetic rats (45 mg/kg/rat.ip of streptozotocin) during eight weeks of experimentation

Oral Supplementation Effect of Iron and its Complex Form With Quercetin on Oxidant Status and on Redistribution of Essential Metals in Organs of Streptozotocin Diabetic Rats

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Sodium arsenite effect on Vitis vinifera L. Physiology

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Reproductive differences between urban and forest birds across the years: importance of environmental and weather parameters

International audienceUrban environments pose many challenges to wildlife, not least for insectivorous passerines. Numerous studies have reported on the negative effects of urbanization on reproduction in these species. However, depending on the taxa and cities studied, no particular or positive effects have been reported. This may be related to the different levels of urban environmental stressors. As unfavorable weather can have deleterious effects on birds (e.g. lower prey availability and higher costs of pollutants), annual variations in the differences observed between sites could be related to synergetic effects between the urban environment and weather conditions. In this context, we studied the reproduction of great tit (Parus major) at two sites (urban and forest) over four years. First, we quantified pollution, prey availability, and vegetal cover at each site to characterize each environment. Second, we measured the effects of site and weather conditions on tit reproductive success to determine if the influence of weather is higher in the city. Except for the fledging rate, reproductive parameters were lower in the city than in the forest whatever the year probably because of poorer food availability and a predominance of non-vegetated areas in cities. The fledging rate and the nestling number in the urban environment were positively correlated to temperatures during rearing whereas there was no significant correlations in the forest. These results support the hypothesis of additive effects of urban constraints and weather that limit bird productivity in cities