Oxidative status of blue tit nestlings varies with habitat and nestling size.

Oxidative status has been proposed as an important ecological and evolutionary force given that pro-oxidant metabolites damage molecules, cells and tissues, with fitness consequences for organisms. Consequently, organisms usually face a trade-off between regulating their oxidative status and other physiological traits. However, environmental stressors and the availability of dietary-derived antioxidants vary according to local conditions and, thus, organisms inhabiting different habitats face different oxidative pressures. Still, there is little information on how different environmental conditions influence the oxidative status of animals inhabiting terrestrial environments. In this work, we examined the variation in oxidative status in the blue tit (Cyanistes caeruleus), a bird species with hatching asynchrony. Specifically, we examined the oxidative status of the largest and the smallest nestlings in the brood, inhabiting four forests differing in food availability and ectoparasite prevalence. We measured lipid peroxidation (malondialdehyde; MDA) as a marker of oxidative damage, total antioxidant capacity (Trolox-equivalent antioxidant capacity; TEAC) and antioxidant enzymatic activity (catalase, glutathione S-transferase, glutathione peroxidase) in blood samples. The glutathione peroxidase (GPX) activity differed among the forests, being the highest in the pine forest and the lowest in a mixed oak (Quercus) forest in the most humid area. Lipid peroxidation was higher in larger nestlings, suggesting higher oxidative damage with an increasing growth rate. Neither brood size, laying date, nor ectoparasites were related to the oxidative status of nestlings. These results suggest that nest rearing conditions might shape the oxidative status of birds, having consequences for habitat-dependent variation in regulation of oxidative status.

Ultraviolet radiation does not increase oxidative stress in the lizard Psammodromus algirus along an elevational gradient.

Lizards, as ectotherms, spend much time basking for thermoregulating exposed to solar radiation. Consequently, they are subjected to ultraviolet radiation (UVR), which is the most harmful component of solar radiation spectrum. UVR can provoke damages, from the molecular to tissue level, even cause death. Photooxidation triggered by UVR produces reactive oxidative species (ROS). When antioxidant machinery cannot combat the ROS concentration, oxidative stress occurs in the organisms. Given that UVR increases with elevation, we hypothesised that lizards from high elevations should be better adapted against UVR than lizards from lower elevations. In this work, we test this hypothesis in Psammodromus algirus along an elevation gradient (three elevational belts, from 300 to 2500 m above sea level). We ran an experiment in which lizards from each elevation belt were exposed to 5-hour doses of UVR (UV-light bulb, experimental group) or photosynthetically active radiation (white-light bulb, control group) and, 24 h after the exposure, we took tissue samples from the tail. We measured oxidative damage (lipid and protein peroxidation) and antioxidant capacity as oxidative-stress biomarkers. We found no differences in oxidative stress between treatments. However, consistent with a previous work, less oxidative damage appeared in lizards from the highlands. We conclude that UVR is not a stressor agent for P. algirus; however, our findings suggest that the lowland environment is more oxidative for lizards. Therefore, P. algirus is well adapted to inhabit a large elevation range, and this would favour the lizard in case it ascends in response to global climate change.

Oxidative stress decreases with elevation in the lizard Psammodromus algirus.

Oxidative stress is considered one of the main ecological and evolutionary forces. Several environmental stressors vary geographically and thus organisms inhabiting different sites face different oxidant environments. Nevertheless, there is scarce information about how oxidative damage and antioxidant defences vary geographically in animals. Here we study how oxidative stress varies from lowlands (300-700 m asl) to highlands (2200-2500 m asl) in the lizard Psammodromus algirus. To accomplish this, antioxidant enzymatic activity (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione transferase, DT-diaphorase) and lipid peroxidation were assayed in tissue samples from the lizards' tail. Lipid peroxidation was higher in individuals from lowlands than from highlands, indicating higher oxidative stress in lowland lizards. These results suggest that environmental conditions are less oxidant at high elevations with respect to low ones. Therefore, our study shows that oxidative stress varies geographically, which should have important consequences for our understanding of geographic variation in physiology and life-history of organisms.

Changes in iron metabolism and oxidative status in STZ-induced diabetic rats treated with bis(maltolato) oxovanadium (IV) as an antidiabetic agent.

The role of vanadium as a micronutrient and hypoglycaemic agent has yet to be fully clarified. The present study was undertaken to investigate changes in the metabolism of iron and in antioxidant defences of diabetic STZ rats following treatment with vanadium. Four groups were examined: control; diabetic; diabetic treated with 1 mgV/day; and Diabetic treated with 3 mgV/day. The vanadium was supplied in drinking water as bis(maltolato) oxovanadium (IV) (BMOV). The experiment had a duration of five weeks. Iron was measured in food, faeces, urine, serum, muscle, kidney, liver, spleen, and femur. Superoxide dismutase, catalase, NAD(P)H: quinone-oxidoreductase-1 (NQO1) activity, and protein carbonyl group levels in the liver were determined. In the diabetic rats, higher levels of Fe absorbed, Fe content in kidney, muscle, and femur, and NQO1 activity were recorded, together with decreased catalase activity, in comparison with the control rats. In the rats treated with 3 mgV/day, there was a significant decrease in fasting glycaemia, Fe content in the liver, spleen, and heart, catalase activity, and levels of protein carbonyl groups in comparison with the diabetic group. In conclusion BMOV was a dose-dependent hypoglycaemic agent. Treatment with 3 mgV/day provoked increased Fe deposits in the tissues, which promoted a protein oxidative damage in the liver.

Oxidative stress mediates physiological costs of begging in magpie (Pica pica) nestlings.

BACKGROUND: Theoretical models predict that a cost is necessary to guarantee honesty in begging displays given by offspring to solicit food from their parents. There is evidence for begging costs in the form of a reduced growth rate and immunocompetence. Moreover, begging implies vigorous physical activity and attentiveness, which should increase metabolism and thus the releasing of pro-oxidant substances. Consequently, we predict that soliciting offspring incur a cost in terms of oxidative stress, and growth rate and immune response (processes that generate pro-oxidants substances) are reduced in order to maintain oxidative balance. METHODOLOGY/PRINCIPAL FINDINGS: We test whether magpie (Pica pica) nestlings incur a cost in terms of oxidative stress when experimentally forced to beg intensively, and whether oxidative balance is maintained by reducing growth rate and immune response. Our results show that begging provokes oxidative stress, and that nestlings begging for longer bouts reduce growth and immune response, thereby maintaining their oxidative status. CONCLUSIONS/SIGNIFICANCE: These findings help explaining the physiological link between begging and its associated growth and immunocompetence costs, which seems to be mediated by oxidative stress. Our study is a unique example of the complex relationships between the intensity of a communicative display (begging), oxidative stress, and life-history traits directly linked to viability.

Changes in the antioxidant defence and in selenium concentration in tissues of vanadium exposed rats.

Vanadium is an element whose role as a micronutrient for humans is not yet completely established, but which has been shown to possess hypoglycaemic properties in diabetes. In an earlier study, we showed that in STZ-diabetic rats, exposure to 1 mg V per day has no effect on glycaemia or on antioxidant status. When the exposure was raised to 3 mg V per day there was a hypoglycaemic effect, together with reduced Se in the tissues, which reduced antioxidant defences. The aim of the present study was to examine whether exposure to 1 mg V per day modifies Se nutritional status and/or antioxidant defences in healthy rats. Two groups of rats were examined: control and vanadium-treated. Vanadium, as bis(maltolato)oxovanadium(iv), was supplied in the drinking water. The experiment had a duration of five weeks. Selenium was measured in excreta, serum, skeletal muscle, kidneys, liver, heart, femur and adipose tissue. Number of red (RBC) and white (WBC) blood cells and haemoglobin (Hb) were determined in samples of whole blood. Glutathione peroxidase (GPx), glutathione transferase (GST), catalase (CAT) and NAD(P)H:quinine-oxidoreductase1 (NQO1) activity, and malondialdehyde (MDA) in the liver were evaluated. Treatment significantly reduced food intake, produced an anaemic state, and decreased Se absorption and Se content in serum, kidneys and the liver. GPx, GST and NQO1 activity were decreased in the liver, while MDA levels rose. We conclude that healthy rats are more sensitive than diabetic ones to the effects of V. This should be taken into account for populations that are particularly exposed to V for environmental reasons, and/or that consume V as a nutritional supplement.

The metabolic effects of prolonged starvation and refeeding in sturgeon and rainbow trout.

The present study examines the particular metabolic strategies of the sturgeon Acipenser naccarii in facing a period of prolonged starvation (72 days) and subsequent refeeding (60 days) compared to the trout Oncorhynchus mykiss response under similar conditions. Plasma metabolites, endogenous reserves, and the activity of intermediate enzymes in liver and white muscle were evaluated. This study shows the mobilization of tissue reserves during a starvation period in both species with an associated enzymatic response. The sturgeon displayed an early increase in hepatic glycolysis during starvation. The trout preferentially used lactate for gluconeogenesis in liver and white muscle. The sturgeon had higher lipid-degradation capacity and greater synthesis of hepatic ketone bodies than the trout, although this latter species also showed strong synthesis of ketone bodies during starvation. During refeeding, the metabolic activity present before starvation was recovered in both fish, with a reestablishment of tissue reserves, plasmatic parameters (glucemia and cholesterol), and enzymatic activities in the liver and muscle. A compensatory effect in enzymes regarding lipids, ketone bodies, and oxidative metabolism was displayed in the liver of both species. There are metabolic differences between sturgeon and trout that support the contention that the sturgeon has common characteristics with elasmobranchs and teleosts.

Effect of bis(maltolato)oxovanadium (IV) (BMOV) on selenium nutritional status in diabetic streptozotocin rats.

The role of V as a micronutrient, and its hypoglycaemic and toxicological activity, have yet to be completely established. The present study focuses on changes in the bioavailability and tissue distribution of Se in diabetic streptozotocin rats following treatment with V. The following four study groups were examined: control; diabetic (DM); diabetic treated with 1 mg V/d (DMV); diabetic treated with 3 mg V/d (DMVH). V was supplied in the drinking water as bis(maltolato)oxovanadium (IV). The experiment had a duration of 5 weeks. Se was measured in food, faeces, urine, serum, muscle, kidney, liver and spleen. Glucose and insulin serum were studied, together with glutathione peroxidase (GSH-Px), glutathione reductase (GR), glutathione transferase (GST) activity and malondialdehyde (MDA) levels in the liver. In the DM group, we recorded higher levels of food intake, Se absorbed, Se retained, Se content in the kidney, liver and spleen, GSH-Px and GST activity, in comparison with the control rats. In the DMV group, there was a significant decrease in food intake, Se absorbed, Se retained and Se content in the liver and spleen, and in GSH-Px and GST activity, while fasting glycaemia and MDA remained unchanged, in comparison with the DM group. In the DMVH group, there was a significant decrease in food intake, glycaemia, Se absorbed, Se retained, Se content in the kidney, liver and spleen, and in GSH-Px and GST activity, and increased MDA, in comparison with the DM and DMV groups. We conclude that under the experimental conditions described, the treatment with 3 mg V/d caused a tissue depletion of Se that compromised Se nutritional status and antioxidant defences in the tissues.

Study of antioxidant defense in four species of Perloidea (Insecta, Plecoptera).

The aim of the present work is to conduct a comparative study of oxidative states in the nymphs of four species of Plecoptera belonging to the superfamily Perloidea: Perla marginata (Panzer, 1799) (family Perlidae), Guadalgenus franzi (Aubert, 1963), Isoperla curtate Navás, 1924, and lsoperla grammatica (Poda, 1761) (family Perlodidae) in relation to their ecological and biological characteristics. For this, the activity of the following antioxidant enzymes was determined: superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione transferase (GST), and DT-diaphorase (DTD), together with lipid peroxidation. Glucose 6-phosphate dehydrogenase (G6PDH) was also determined. The four species studied were selected based on significant ecological and biological differences. The results obtained when studying different indicative parameters of the oxidative state of the nymph of different species showed that each has an important enzymatic antioxidant potential, and that differences among species are conditioned by the duration of the nymphal development period more than by whether they come from permanent or temporary habitats. Thus, Plecoptera, although traditionally considered as typical inhabitants of permanent waters, seem to have sufficient variability in physiological mechanisms, together with behavioral and ecological adaptations, to cope with potentially unfavorable conditions that may occur in temporary waters.

Blood antioxidant defenses and hematological adjustments in crowded/uncrowded rainbow trout (Oncorhynchus mykiss) fed on diets with different levels of antioxidant vitamins and HUFA.

Rainbow trout maintained at crowding or noncrowding conditions were fed on five experimental diets that were formulated considering two levels of vitamin E (25.6 and 275.6 mg/kg diet), vitamin C (0 and 1000 mg/kg diet) and HUFA (12.5 and 30.5 g/kg diet): -E-HUFA, -E+HUFA, +E-HUFA, +E+HUFA, -C+E+HUFA. Hematological parameters, the activity of some antioxidant enzymes and lipid peroxidation from RBC were evaluated. The SOD isoenzyme pattern was analyzed by nondenaturing PAGE. Hematological response to crowding stress was manifested by increased hemoglobin and RBC count in most of the crowded groups. Antioxidant enzyme activity was clearly affected by dietary HUFA levels, with uncrowded fish fed on +HUFA diets showing a higher SOD activity compared to those fed on -HUFA diets. In uncrowded groups, only one CuZn-SOD isozyme was detected, whereas in the crowded fish a great variability was revealed with up to five isozymes. G6PDH activity was increased in uncrowded -E+HUFA fish compared to the remaining groups. Lipid peroxidation was significantly increased in -E+HUFA fish regardless of fish density. Data supported the negative correlation of lipid peroxidation and hematocrit or hemoglobin explained by decreased erythrocyte stability. Dietary imbalances in vitamin E and HUFA supplementation may promote oxidative stress which triggers hematological deterioration, which in turn would affect the whole hematological status and ultimately fish welfare.