A blood-based multi-biomarker approach reveals different physiological responses of common kestrels to contrasting environments.

The increase of urbanization and agricultural activities is causing a dramatic reduction of natural environments. As a consequence, animals need to physiologically adjust to these novel environments, in order to exploit them for foraging and breeding. The aim of this work was to compare the physiological status among nestling common kestrels (Falco tinnunculus) that were raised in nest-boxes located in more natural, rural, or urban areas in a landscape with a mosaic of land uses around Rome in Central Italy. A blood-based multi-biomarker approach was applied to evaluate physiological responses at multiple levels, including antioxidant concentrations, immunological functions, genotoxicity, and neurotoxicity. We found lower concentrations of glutathione and GSH:GSSG ratio values and higher proportions of monocytes in urban birds compared to the other areas. We also found higher DNA damage in rural compared to urban and natural krestels and inhibition of butyrylcholinesterase activity in urban and natural birds compared to rural area. Finally, we found similar values among study areas for respiratory burst, complement system, bactericidal capacity, and plasma non-enzymatic antioxidant capacity. These results suggest that (i) city life does not necessarily cause physiological alterations in kestrels compared to life in other habitats, and (ii) environmental pressures are likely to differ in typology and intensity across habitats requiring specific responses that a multi-biomarker approach can help to detect. Further studies are needed to assess which factors are responsible for the physiological differences among city, rural, and natural birds, and whether these differences are consistent across time and space.

Contrasted Antibiotics and Pesticides Occurrence in Fish Exposed In Situ to Urban Effluents: A 20-Day Caging Experiment.

Urban freshwater ecosystems receive a wide array of organic pollutants through wastewater-treatment plant (WWTP) discharges and agricultural runoff. Evaluating the fate and effects of antibiotics and pesticides can be a challenging task, especially the effects on freshwater vertebrates because of their abilities to metabolize and excrete these chemicals and because of their high mobility and escape behavior when exposed to stressful environmental conditions. In the present study, 37 wild gudgeons (Gobio gobio) were caged for a period of up to 20 days, upstream and downstream of a WWTP effluent discharge in the Orge River (a tributary of the Seine River, France). Levels of pesticides and antibiotics in fish muscles were monitored weekly and compared with environmental contamination (water and sediments). Our results highlighted a slight bioaccumulation of pesticides in the gudgeon muscles at the downstream site after 20 days of exposure. Concerning antibiotics, ofloxacin was the most detected compound in fish muscles (85% of occurrence) and ranged from undetectable to 8 ng g-1 dry weight. Antibiotic levels in fish muscle were not higher at the downstream site and did not increase with exposure duration, despite high levels in the water (up to 29 times greater than upstream). Potential ecotoxicological effects were also evaluated: Body condition did not differ between the caging location and exposure time. Three oxidative status markers in the fish livers showed significant shifts after 14 days of caging. Our results suggest a high clearance rate of antibiotics and, to a lesser extent, of pesticides in wild gudgeons, which could be explained by changes in xenobiotic metabolism with pollutant exposure. Environ Toxicol Chem 2024;43:701-711. © 2023 SETAC.

Applied ecoimmunology: using immunological tools to improve conservation efforts in a changing world.

Ecoimmunology is a rapidly developing field that explores how the environment shapes immune function, which in turn influences host-parasite relationships and disease outcomes. Host immune defence is a key fitness determinant because it underlies the capacity of animals to resist or tolerate potential infections. Importantly, immune function can be suppressed, depressed, reconfigured or stimulated by exposure to rapidly changing environmental drivers like temperature, pollutants and food availability. Thus, hosts may experience trade-offs resulting from altered investment in immune function under environmental stressors. As such, approaches in ecoimmunology can provide powerful tools to assist in the conservation of wildlife. Here, we provide case studies that explore the diverse ways that ecoimmunology can inform and advance conservation efforts, from understanding how Galapagos finches will fare with introduced parasites, to using methods from human oncology to design vaccines against a transmissible cancer in Tasmanian devils. In addition, we discuss the future of ecoimmunology and present 10 questions that can help guide this emerging field to better inform conservation decisions and biodiversity protection. From better linking changes in immune function to disease outcomes under different environmental conditions, to understanding how individual variation contributes to disease dynamics in wild populations, there is immense potential for ecoimmunology to inform the conservation of imperilled hosts in the face of new and re-emerging pathogens, in addition to improving the detection and management of emerging potential zoonoses.

Mind the food: rapid changes in antioxidant content of diet affect oxidative status of chimpanzees.

The link between dietary antioxidants and oxidative status has been studied extensively in humans. Surprisingly, comparative data are not available from closely related species, such as chimpanzees, which evolved in environments characterized by strong fluctuations in the availability and quality of vegetable food sources. We tested the hypothesis that an abrupt decrease in dietary antioxidants would increase oxidative damages in captive chimpanzees (Pan troglodytes), while a rapid increase in antioxidant intake would decrease oxidative damages accrued while on the low-antioxidant diet. An abrupt decline of dietary antioxidants increased urinary levels of lipid peroxides and of oxidative DNA damage but not of 8-isoprostanes. In contrast, an increased intake of dietary antioxidants did not affect the oxidative status. Chimpanzees that were both older and with a higher dominance rank had lower urinary levels of lipid peroxides and of DNA damage as compared with younger chimpanzees. Neither individual sex nor proportion of time being groomed explained any variation in all three markers of oxidative status. Finally, we found significant within-individual repeatability of all markers of oxidative status over the course of the experiment, suggesting a significant contribution of individual history to molding oxidative status. Our results show that antioxidant intake plays a nonnegligible role in the regulation of oxidative status homeostasis in our closest relatives, the chimpanzees. Our work also suggests that rapid short-term increases in antioxidant intake might not have the desired immediate impact on oxidative status, such as in the case of clinical interventions or training programs.

Dietary antioxidants, food deprivation and growth affect differently oxidative status of blood and brain in juvenile European seabass (Dicentrarchus labrax).

Compensatory growth may increase molecular oxidative damage, which may be mitigated through the intake of dietary antioxidants. However, dietary antioxidants may also reduce concentration of antioxidant enzymes, which have a key role in regulating the oxidative status. Here we investigated whether feeding on a diet rich in antioxidants (vitamin E) enables juvenile European seabass (Dicentrarchus labrax) to catch up after a period of food deprivation with negligible effects on the oxidative stress to blood and brain as compared to fish feeding on a normal diet (i.e., not enriched in antioxidants). The results show that a higher intake in antioxidants favoured compensatory growth, but this came at a cost in terms of increased oxidative damage. Increased intake of antioxidants also resulted in changes in the activity of enzymatic antioxidant defences and increased protein oxidative damage in both brain and blood. In addition, food deprivation caused increased protein oxidative damage in brain. Our findings show that the beneficial effects of dietary antioxidants on growth may be offset by hidden detrimental effects and that different early life events affect different components of oxidative status of a given tissue.

Neither artificial light at night, anthropogenic noise nor distance from roads are associated with oxidative status of nestlings in an urban population of songbirds.

Increasing urbanization is responsible for road-related pollutants and causes an unprecedented increase in light and noise pollution, with potential detrimental effects for individual animals, communities and ecosystems. These stressors rarely act in isolation but studies dissecting the effects of these multiple stressors are lacking. Moreover, studies on urban stressors have mainly focused on adults, while exposure in early-life may be detrimental but is largely ignored. To fill this important knowledge gap, we studied if artificial light at night, anthropogenic noise and road-related pollution (using distance from roads as a proxy) explain variation in oxidative status in great tit nestlings (Parus major) in an urban population. Artificial light at night, anthropogenic noise and distance from roads were not associated with variation of the nine studied metrics of oxidative status (superoxide dismutase-SOD-, glutathione peroxidase-GPX, catalase-CAT-, non-enzymatic total antioxidant capacity-TAC-, reduced glutathione-GSH-, oxidized glutathione-GSSG-, ratio GSH/GSSG, protein carbonyls and thiobarbituric acid reactive substances-TBARS). Interestingly, for all oxidative status metrics, we found that there was more variation in oxidative status among individuals of the same nest compared to between different nests. We also showed an increase in protein carbonyls and a decrease of the ratio GSH/GSSG as the day advanced, and an increase of GPX when weather conditions deteriorated. Our study suggests that anthropogenic noise, artificial light at night and road-related pollution are not the most important sources of variation in oxidative status in great tit nestlings. It also highlights the importance of considering bleeding time and weather conditions in studies with free-living animals.

Interaction between sexual steroids and immune response in affecting oxidative status of birds.

One hypothesis explaining the honesty of secondary sexual traits regulated by testosterone (T) is that T can impair the balance between pro-oxidant compounds and antioxidant defences, favouring a status of oxidative stress that only good quality individuals can sustain (oxidative handicap hypothesis). In the present study, we evaluated for the first time the effects of sexual steroids, T and its metabolites 5-α-dihydrotestosterone (DHT) and estradiol (E2) on oxidative damage and plasma non-enzymatic antioxidant capacity, while birds are faced by an oxidative challenge induced by an immune stimulation with sheep red blood cells. We used male and female diamond doves Geopelia cuneata, a species that shows an orange-red periorbital ring, whose size and color are strongly affected by androgens, but not by estrogens. Immunization increased oxidative damage in all groups, regardless of hormone treatment. It also decreased anti-oxidant capacity in all groups, except for testosterone treated birds. The ratio of oxidative damage over anti-oxidant capacity (oxidative stress) was increased in both immunological challenged controls and E2 birds, while challenged birds treated with androgens did not differ from non-challenged birds. The response of males and females to our treatments never differed. Our results undermine the idea that T can induce honest signalling through a pro-oxidant activity.

Complex trade-offs in the pigeon (Columba livia): egg antioxidant capacity and female serum oxidative status in relation to diet quality.

Despite the great deal of ecological research interest in modulators of offspring quality and consequences of reproduction on female status, we still know little about the relationships among diet quality, antioxidant capacity of egg components (yolk and albumen) and oxidative status of female birds. In this study, I compared the egg quality (egg size, albumen and yolk antioxidant capacity) and serum oxidative status (oxidative damage, total serum antioxidant capacity, and serum thiols) of female pigeons (Columba livia) fed with foods of different quality (standard quality and decreased quality). I also analysed the patterns of covariation among egg and female traits. The study focussed on the first clutch laid by the female in the breeding season and on the short-term effects of a decrease in diet quality. The treatment did not affect the egg volume, the lipophilic and hydrophilic components of antioxidant capacity (lipOXY and hydrOXY, respectively) or the antioxidant capacity of the albumen (albumOXY). However, females fed a higher quality diet were fatter and had marginally higher values of serum hydroperoxides (oxidative damage) than females fed a lower quality diet. Moreover, females that showed an increase in yolk hydrOXY and serum hydroperoxides also showed a decrease in yolk lipOXY, albumOXY and serum antioxidant capacity. These results show that the female's oxidative status can be correlated with the antioxidant content of her eggs, but the nature of these correlations is complex, depending on the molecular component measured. The results also suggest that in the pigeon the deposition of hydrophilic and lipophilic antioxidants in the egg may trade off against each other.

Head morphology and degree of variation in lacerta bilineata: podarcis muralis and podarcis sicula / Morfología de la cabeza y el grado de variación en lacerta bilineata: podarcis muralis y podarcis sicula

The morphology of cephalic scales in Lacertids is organised in well defined geometrical structures. The variation of these elements is related to the underlying bone growth and morphogenesis, but it is also associated with the muscular system and the sutural dynamics. In this paper, the patterns of variation of the cephalic scales have been compared between three common Mediterranean species: Podarcis muralis, Podarcis sicula and Lacerta bilineata. The morphospace generated by the morphological relationships within the cephalic system in these three species is investigated in order to consider their degree of variation and their anatomical peculiarities. Generally, Lacerta is 64 percent larger than Podarcis, shows a relative reduction of the frontal scale, enlarged fronto-parietal structures, and stretched occipital area. L. bilineata shows the smaller degree of variation within the shape space, while P. muralis shows the highest values. The morphology of the two genera is definitely different mostly because of allometric variation. Non-allometric distinctions between the three species are subtle but detectable. The degree and pattern of variation are interpreted in terms of possible environmental pressures and of functional cranial dynamics associated with the fronto-parietal suture, respectively. In this sense, the structural relationships between bones and scales are of particular interest to further investigate ontogeny and phylogeny in reptiles.

La morfología de las escamas cefálicas en Lacértidos se organiza en estructuras geométricas bien definidas. La variación de estos elementos está relacionada con el crecimiento y la morfogénesis del hueso subyacente, pero está también es asociada con el sistema muscular y sutural dinámico. En este trabajo, son comparados los patrones de variación de las escamas cefálicas de tres especies mediterráneas comunes: Podarcis muralis, Podarcis sicula y Lacerta bilineata. El morfoespacio generado por las relaciones morfológicas con el sistema cefálico en estas tres especies se investigó con el fin de examinar su grado de variación y sus peculiaridades anatómicas. En general, Lacerta es 64 por ciento más grande que Podarcis, muestra una reducción relativa de la escama frontal, alargamiento de la estructura fronto-parietal, y estrechamiento del área occipital. L. bilineata muestra el menor grado de variación en la forma del espacio, mientras que P. muralis muestra los valores más altos. La morfología de los dos géneros es diferente principalmente debido a variaciones alométricas. Diferencias no alométricas entre las tres especies son sutiles pero detectables. El grado y el patrón de variación son interpretados en términos de las posibles presiones del medio ambiente y la dinámica funcional craneal asociada a la sutura fronto-parietal, respectivamente. En este sentido, las relaciones estructurales entre los huesos y las escamas son de particular interés para seguir investigando ontogenia y filogenia de los reptiles.