| 1. |
- Giraudeau, Mathieu, et al.
(författare)
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In ovo yolk carotenoid and testosterone levels interactively influence female transfer of yolk antioxidants to her eggs
- 2018
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Ingår i: Biology letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 14:6
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Tidskriftsartikel (refereegranskat)abstract
- Mothers can influence prenatal conditions by varying the amount of nutrients, hormones or antioxidants they provide to their developing young. Some of these substances even affect the transfer of these compounds in the next generation, but it is less clear how different maternally transmitted compounds interact with each other to shape reproductive resource allocation in their offspring. Here, we found that female Japanese quails (Coturnix japonica) that were exposed to high carotenoid levels during embryonic development transferred lower concentrations of yolk antioxidants to their own eggs later in life. This effect disappeared when both testosterone and carotenoid concentrations were manipulated simultaneously, showing long-term and interactive effects of these maternally derived egg components on a female’s own egg composition. Given that exposure to high levels of testosterone during embryo development stimulates the production of reactive oxygen species (ROS) and impairs antioxidant defenses, we propose that carotenoids act as in ovo antioxidants in an oxidatively stressful environment (i.e. when levels of testosterone are high) but might have prooxidant properties in an environment where they are not used to counteract an increased production of ROS. In line with this hypothesis, we previously showed that prenatal exposure to increased concentrations of yolk carotenoids leads to a rise of oxidative damage at adulthood, but only when yolk testosterone concentrations were not experimentally increased as well. As a consequence, antioxidants in the body may be used to limit oxidative damage in females exposed to high levels of carotenoids during development (but not in females exposed to increased levels of both carotenoids and testosterone), resulting in lower amounts of antioxidants being available for deposition into eggs. Since prenatal antioxidant exposure is known to influence fitness-related traits, the effect detected in this study might have transgenerational consequences.
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| 2. |
- Kjellberg Jensen, Johan, et al.
(författare)
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Quantifying the influence of urban biotic and abiotic environmental factors on great tit nestling physiology
- 2023
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Ingår i: Science of the Total Environment. - : Elsevier B.V.. - 0048-9697 .- 1879-1026. ; 859
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Tidskriftsartikel (refereegranskat)abstract
- There is a long history of avian studies investigating the impacts of urbanization. While differences in several life-history traits have been documented, either between urban and rural populations or across generalized urbanization gradients, a detailed understanding of which specific environmental variables cause these phenotypic differences is still lacking. Here, we quantified several local environmental variables coupled to urbanization (air pollution, tree composition, ambient temperature, and artificial light at night [ALAN]) within territories of breeding great tits (Parus major). We linked the environmental variables to physiological measures of the nestlings (circulating fatty acid composition [FA], antioxidant capacity and an oxidative damage marker [malondialdehyde; MDA]), to garner a mechanistic understanding of the impact of urbanization. We found that the antioxidant capacity of nestlings decreased with higher numbers of oak trees and levels of PM2.5 (airborne particulate matter with a diameter < 2.5 μm). Furthermore, the ratio of ω6:ω3 polyunsaturated FAs, important for immune function, was positively correlated with PM2.5 concentration, while being negatively associated with ambient temperature and number of non-native trees in the territory. Body mass and wing length both increased with the number of local oak trees. We also show, through a principal component analysis, that while the environmental variables fall into an urbanization gradient, this gradient is insufficient to explain the observed physiological responses. Therefore, accounting for individual environmental variables in parallel, and thus allowing for interactions between these, is crucial to fully understand of the urban ecosystem. © 2022 The Authors
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| 3. |
- Ziegler, Ann Kathrin, et al.
(författare)
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Dietary fatty acids modulate oxidative stress response to air pollution but not to infection
- 2024
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic changes to the environment expose wildlife to many pollutants. Among these, tropospheric ozone is of global concern and a highly potent pro-oxidant. In addition, human activities include several other implications for wildlife, e.g., changed food availability and changed distribution of pathogens in cities. These co-occurring habitat changes may interact, thereby modulating the physiological responses and costs related to anthropogenic change. For instance, many food items associated with humans (e.g., food waste and feeders for wild birds) contain relatively more ω6-than ω3-polyunsaturated fatty acids (PUFAs). Metabolites derived from ω6-PUFAs can enhance inflammation and oxidative stress towards a stimulus, whereas the opposite response is linked to ω3-derived metabolites. Hence, we hypothesized that differential intake of ω6-and ω3-PUFAs modulates the oxidative stress state of birds and thereby affects the responses towards pro-oxidants. To test this, we manipulated dietary ω6:ω3 ratios and ozone levels in a full-factorial experiment using captive zebra finches (Taeniopygia guttata). Additionally, we simulated an infection, thereby also triggering the immune system’s adaptive pro-oxidant release (i.e., oxidative burst), by injecting lipopolysaccharide. Under normal air conditions, the ω3-diet birds had a lower antioxidant ratio (GSH/GSSG ratio) compared to the ω6-diet birds. When exposed to ozone, however, the diet effect disappeared. Instead, ozone exposure overall reduced the total concentration of the key antioxidant glutathione (tGSH). Moreover, the birds on the ω6-rich diet had an overall higher antioxidant capacity (OXY) compared to birds fed a ω3-rich diet. Interestingly, only the immune challenge increased oxidative damage, suggesting the oxidative burst of the immune system overrides the other pro-oxidative processes, including diet. Taken together, our results show that ozone, dietary PUFAs, and infection all affect the redox-system, but in different ways, suggesting that the underlying responses are decoupled despite that they all increase pro-oxidant exposure or generation. Despite lack of apparent cumulative effect in the independent biomarkers, the combined single effects could together reduce overall cellular functioning and efficiency over time in wild birds exposed to pathogens, ozone, and anthropogenic food sources.
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| 4. |
- Ziegler, Ann-Kathrin, et al.
(författare)
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Exposure to artificial light at night alters innate immune response in wild great tit nestlings
- 2021
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 224:10
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Tidskriftsartikel (refereegranskat)abstract
- The large-scale impact of urbanization on wildlife is rather well documented; however, the mechanisms underlying the effects of urban environments on animal physiology and behaviour are still poorly understood. Here, we focused on one major urban pollutant – artificial light at night (ALAN) – and its effects on the capacity to mount an innate immune response in wild great tit (Parus major) nestlings. Exposure to ALAN alters circadian rhythms of physiological processes, by disrupting the nocturnal production of the hormone melatonin. Nestlings were exposed to a light source emitting 3 lx for seven consecutive nights. Subsequently, nestlings were immune challenged with a lipopolysaccharide injection, and we measured haptoglobin and nitric oxide levels pre- and post-injection. Both haptoglobin and nitric oxide are important markers for innate immune function. We found that ALAN exposure altered the innate immune response, with nestlings exposed to ALAN having lower haptoglobin and higher nitric oxide levels after the immune challenge compared with dark-night nestlings. Unexpectedly, nitric oxide levels were overall lower after the immune challenge than before. These effects were probably mediated by melatonin, as ALAN-treated birds had on average 49% lower melatonin levels than the dark-night birds. ALAN exposure did not have any clear effects on nestling growth. This study provides a potential physiological mechanism underlying the documented differences in immune function between urban and rural birds observed in other studies. Moreover, it gives evidence that ALAN exposure affects nestling physiology, potentially causing long-term effects on physiology and behaviour, which ultimately can affect their fitness.
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| 5. |
- Ziegler, Ann-Kathrin
(författare)
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Impacts of urbanisation on birds : Disentangling the effects of multiple pollutants on avian behaviour and physiology
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Anthropogenic pollution is a pervasive feature of urbanisation, reaching into ecosystems worldwide and posing novel challenges to wildlife. Not surprisingly, differences in behaviour, and physiology, have been found between urban and rural populations. Most studies on anthropogenic impacts have so far either used a dichotomous approach, comparing urban-rural sites, or investigated impacts of just one stressor. However, urban environments create a complex matrix of co-occuring pollutants, leading to potentially complex interactive effects between stressors. We currently lack a deeper knowledge of the combined and single effects and the underlying mechanisms creating urban-rural phenotypic variation. In this thesis, I investigated the single and combined effects of urban pollutants of avian behaviour and physiology. Specifically, I used the oxidative stress system, immune system, and plasma fatty acid composition, as the key physiological traits responding to human-induced environmental change. Urban pollutants of interest were artificial light at night (ALAN), anthropogenic noise, ozone and soot, and as human-influenced additional factors I looked at impacts of differential diets, and vegetation structure. I utilised full-factorial experimental exposure experiments in the wild and in the laboratory, and a correlative study in the wild, using wild and captive birds.I found that ALAN exposure alone decreases activity and noise exposure alone decreases the proportion of birds found feeding. The combined exposure to these two pollutants led to a non-additive effect on the proportion of birds resting, with ALAN as the driving stressor. ALAN-exposed nestlings mounted a less strong immune response, with a reduction of melatonin levels being the likely mechanistic link to an impaired immune functioning. Simultaneous exposure to ALAN and noise increased levels of an important antioxidant, total glutathione, more than the additive effect from single pollutant effects would have estimated (positive synergistic effect). Furthermore, I found that ozone is a potent pro-oxidant, negatively affecting antioxidant capacity, but we found no increased levels of oxidative damage due to ozone exposure. Soot exposure, on the other hand, did not affect avian oxidative stress status. Dietary ω6- and ω3-polyunsaturated fatty acids (PUFAs) modulated oxidative stress response to ozone exposure, but also act alone, with ω3-PUFAs decreasing non-enzymatic antioxidant capacity. Likewise, ω6:ω3 ratios of circulating PUFAs of wild nestlings are changed by human-influenced environmental factors, as well as their antioxidant capacity is negatively affected by air pollution and number of oak trees around their nest box. We also showed in this latter study, that using multi-stressor approach gives a more profound mechanistic understanding of phenotypic effects, then using a dichotomous comparison, which might obscure certain effects. Overall, I show that pollutants affect behaviour and key fitness related physiological traits and that the combined exposure to multiple stressors can lead to unexpected non-additive effects. This highlights the need of a more thorough mechanistic understanding of multi-stressor effects. A deeper understanding of single and combinatory effects of anthropogenic stressors will help gaining crucial insight into populations and species resilience to environmental change, thereby targeted actions can be proposed to maintain biodiversity in cities and have a future development of sustainable cities.
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