Antioxidant supplementation slows telomere shortening in free-living white stork chicks.

Telomere length (TL) and shortening is increasingly shown to predict variation in survival and lifespan, raising the question of what causes variation in these traits. Oxidative stress is well known to accelerate telomere attrition in vitro, but its importance in vivo is largely hypothetical. We tested this hypothesis experimentally by supplementing white stork (Ciconia ciconia) chicks with antioxidants. Individuals received either a control treatment, or a supply of tocopherol (vitamin E) and selenium, which both have antioxidant properties. The antioxidant treatment increased the concentration of tocopherol for up to two weeks after treatment but did not affect growth. Using the telomere restriction fragment technique, we evaluated erythrocyte TL and its dynamics. Telomeres shortened significantly over the 21 days between the baseline and final sample, independent of sex, mass, size and hatching order. The antioxidant treatment significantly mitigated shortening rate of average TL (-31% in shorter telomeres; percentiles 10th, 20th and 30th). Thus, our results support the hypothesis that oxidative stress shortens telomeres in vivo.

Influence of climatic conditions on the link between oxidative stress balance and landfill utilisation as a food resource by white storks.

Landfills have played a significant role in the recovery of white storks (Ciconia ciconia) populations across various European countries. While there is ample information about the populational-level effects, there is a lack of knowledge regarding the individual effects of using this food resource for feeding nestlings. This study aims to assess the nutritional status and oxidative stress balance of nestlings with varying degrees of exposure to landfill-provided food This study aims to assess the nutritional status and oxidative stress balance of nestlings with different use of landfill-provided food. Nestlings fed with food foraged by breeding pairs from landfills exhibited better nutritional status compared to individuals located farther from landfills. This can be attributed to a higher ingestion rate, resulting in increased plasmatic values of cholesterol, triglycerides, and HDL in plasma. However, the oxidative stress balance varied across different years, with individuals raised in 2014 showing higher values of Vitamin E and lower values of LDH compared to those raised in 2013. Furthermore, the impact of landfills on certain oxidative stress parameters also depended on the year of study. In 2013, the Total Antioxidant Capacity (TAC) of plasma showed a positive correlation with the distance to landfills, while the concentration of Malondialdehyde (MDA), an indicator of lipid peroxidation, exhibited a negative correlation. These findings suggest that the use of landfills as a food resource has a consistently positive effect on the nutritional status of white stork nestling. However, the relationship with oxidative stress is highly dependent on the climatic conditions of each year, emphasizing the importance of considering these factors when evaluating the use of landfills as a food resource.

A multidisciplinary approach to the evaluation of the effects of foraging on landfills on white stork nestlings.

The use of landfills as foraging areas by white storks (Ciconia ciconia) is a recent well-known behaviour. While several studies have highlighted positive effects at a populational level others suggest that the presence of pollutants, pathogens and the lower presence of antioxidants in the food could pose a health risk for individuals. The objective of this study was to evaluate potential effects of the use of landfills as a food resource on the physiology and health of white stork nestlings, by a multidisciplinary approach based on the analysis of nutritional status, body condition, blood parameters, oxidative stress balance and the presence of pathogens. Results showed better body condition in individuals associated with landfills compared to the ones feeding on natural resources, as well as better nutritional status, as indicated by higher levels of albumin, cholesterol, and triglycerides in plasma. As many pollutants have a pro-oxidant effect, we evaluated oxidative stress balance, with no differences in the indicators of damage except for methaemoglobin (metHb), significantly higher in nestlings associated with landfill-origin food. Regarding antioxidants, GSH was higher in nestlings associated with landfills, which may suggest a hormetic response induced potentially by the presence of pollutants in waste. Nestlings fed food from landfills also had a higher presence of Escherichia coli with a multiresistant phenotype to antibiotics. In conclusion, our results show that nestlings fed with a higher proportion of food from landfills present a better nutritional status and body condition than those fed with a higher proportion of natural diet, being the only indicators of negative effects of the use of this food resource the higher percentage of metHb in the peripheral blood and the presence of antibiotic-resistant E. coli.

Oxidative stress in birds along a NOx and urbanisation gradient: An interspecific approach.

Urbanisation is regarded as one of the most threatening global issues for wildlife, however, measuring its impact is not always straight forward. Oxidative stress physiology has been suggested to be a useful biomarker of health and therefore, a potentially important indicator of the impact that urban environmental stressors, especially air pollution, can have on wildlife. For example, nitrogen oxides (NOx), released during incomplete combustion of fossil fuels, are highly potent pro-oxidants, thus predicted to affect either the protective antioxidants and/or cause oxidative damage to bio-molecules. To date, epidemiological modelling of the predicted association between oxidative stress and NOx exposure has not been performed in wild animals. Here, we address this short-coming, by investigating multiple oxidative stress markers in four common passerine bird species, the blue tit (Cyanistes caeruleus), great tit (Parus major), house sparrow (Passer domesticus) and tree sparrow (Passer montanus), living along a gradient of NOx and urbanisation levels in southern Sweden. First of all, the results revealed that long- and medium-term (one month and one week, respectively) NOx levels were highly correlated with the level of urbanisation. This confirms that the commonly used urbanisation index is a reliable proxy for urban air pollution. Furthermore, in accordance to our prediction, individuals exposed to higher long- and medium-term NOx levels/urbanisation had higher plasma antioxidant capacity. However, only tree sparrows showed higher oxidative damage (protein carbonyls) in relation to NOx levels and this association was absent with urbanisation. Lipid peroxidation, glutathione and superoxide dismutase levels did not co-vary with NOx/urbanisation. Given that most oxidative stress biomarkers showed strong species-specificity, independent of variation in NOx/urbanisation, the present study highlights the need to study variation in oxidative stress across contexts, seasons and life-stages in order to understand how the ecology and phylogeny of species interact to affect species resilience to urban environmental stress.

Oxidative Challenges of Avian Migration: A Comparative Field Study on a Partial Migrant.

Most avian migrants alternate flight bouts, characterized by high metabolic rates, with stopovers, periods of fuel replenishment through hyperphagia. High-energy metabolism and excessive calorie intake shift the balance between damaging prooxidants and antioxidants toward the former. Hence, migration likely affects the oxidative balance of birds. Migratory flight indeed appears to cause oxidative damage; however, whether migration affects the oxidative state of birds at stopover is unclear. Therefore, we compared total nonenzymatic antioxidant capacity (AOX) and malondialdehyde concentration (MDA; a measure of lipid peroxidation) in the plasma of migrant and resident common blackbirds. We also determined plasmatic uric acid (UA) and fatty acid (FA) concentrations and calculated a FA peroxidation index. Birds were sampled during autumn migration at a stopover site that also supports a sedentary blackbird population. Migrants had higher AOX than residents, also after correcting for UA concentration. Migrants tended to have higher FA peroxidation indexes than residents, indicating that the energy source of migrants contains higher concentrations of peroxidizable FAs. However, the two groups did not differ in MDA concentration, also not after correcting for peroxidation index. Peroxidation-corrected MDA concentration was negatively correlated with UA-corrected AOX. In other words, individuals with low nonenzymatic AOX suffered more from lipid peroxidation than individuals with high nonenzymatic AOX. These results together indicate that migrant blackbirds invest in antioxidant defenses to reduce oxidative damage to lipids, likely representing an adaptation to diminish the physiological costs of migration.

Prevalence and Genetic Diversity of Avipoxvirus in House Sparrows in Spain.

Avipoxvirus (APV) is a fairly common virus affecting birds that causes morbidity and mortality in wild and captive birds. We studied the prevalence of pox-like lesions and genetic diversity of APV in house sparrows (Passer domesticus) in natural, agricultural and urban areas in southern Spain in 2013 and 2014 and in central Spain for 8 months (2012-2013). Overall, 3.2% of 2,341 house sparrows visually examined in southern Spain had cutaneous lesions consistent with avian pox. A similar prevalence (3%) was found in 338 birds from central Spain. Prevalence was higher in hatch-year birds than in adults. We did not detect any clear spatial or temporal patterns of APV distribution. Molecular analyses of poxvirus-like lesions revealed that 63% of the samples were positive. Molecular and phylogenetic analyses of 29 DNA sequences from the fpv167 gene, detected two strains belonging to the canarypox clade (subclades B1 and B2) previously found in Spain. One of them appears predominant in Iberia and North Africa and shares 70% similarity to fowlpox and canarypox virus. This APV strain has been identified in a limited number of species in the Iberian Peninsula, Morocco and Hungary. The second one has a global distribution and has been found in numerous wild bird species around the world. To our knowledge, this represents the largest study of avian poxvirus disease in the broadly distributed house sparrow and strongly supports the findings that Avipox prevalence in this species in South and central Spain is moderate and the genetic diversity low.

Hematological effects of arsenic in rats after subchronical exposure during pregnancy and lactation: the protective role of antioxidants.

Free radicals production is involved in the toxicity of arsenic. The aim of this study was to determine whether biochemical changes occurred in the blood of arsenic-exposed pups during gestation and lactation, and additionally to investigate the potential beneficial role of the administration of certain antioxidants against arsenic exposure damage. Pregnant wistar rats received the following treatments as drinking water: (1) distilled water; (2) arsenic (50 mg/L); (3) antioxidants: zinc (20 mg/L)+vitamin C (2 g/L)+vitamin E (500 mg/L); (4) arsenic (50 mg/L)+antioxidants: zinc (20 mg/L)+vitamin C (2 g/L)+vitamin E (500 mg/L). We found a normocytic and normochromic anemia as well as a significant increase in hemolysis, TBARS production and catalase activity in the blood of arsenic intoxicated pups. Moreover, this metalloid produced a significant increase of serum cholesterol, triglicerids and urea levels whereas the proteins diminished. These effects were palliated in some extent by the coadministration of vitamins and zinc. Our findings suggest that administration of antioxidants during gestation and lactation could prevent some of the negative effects of arsenic.