| 1. |
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| 2. |
- Abbafati, Cristiana, et al.
(författare)
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- 2020
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 4. |
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| 5. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 6. |
- Brodin, Anders, et al.
(författare)
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Feather corticosterone reveals that urban great tits experience lower corticosterone exposure than forest individuals during dominance-rank establishment
- 2023
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Ingår i: Conservation Physiology. - 2051-1434. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Although the consequences of urbanization for the physiological health of animals are the focus of much active research, an overlooked aspect is how physiology could be indirectly modulated by the urban environment via changes in intraspecific behavioural interactions, particularly among gregarious species. Both urbanization and the establishment, as well as maintenance, of hierarchical rank position are processes that could incur physiological stress. Measurements of glucocorticoids (GCs) in relation to urbanization, however, have yielded inconsistent results. In most cases, GCs have been measured in blood, offering only a 'snapshot' of an animal's current physiological state. Because circulating GCs are incorporated into growing feathers or hair, measurements of feather/hair GCs offer a longer term measure of stress exposure reflecting the whole period of feather/hair growth. During two calendar years, we collected tail feathers from 188 urban and forest great tits (P. major) across multiple sampling sites and analysed corticosterone (CORT - the main GC in birds) levels, reflecting CORT exposure during the extended period in late summer and early autumn when great tits moult and winter flocks are formed. Urban individuals exhibited consistently lower feather CORT (fCORT) levels than forest birds indicating lower overall exposure to CORT during this period. The lower fCORT levels in urban individuals could represent an adaptation to cope with the more challenging urban environment, physiological constraints on stress axis function or a trade-off between the ability to respond to stressors and predation risk during moult. Despite the expectation that CORT responses to urbanization are highly context-dependent, the spatial consistency of our results and agreement with a multi-population study of fCORT in European blackbirds (Turdus merula) suggests a generalization of the effect of urbanization on CORT exposure during post-breeding moult (i.e. not site- or species-specific).
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| 7. |
- Broggi, Juli, et al.
(författare)
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Carry-over effects on reproduction in food-supplemented wintering great tits
- 2022
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 2022:8
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Tidskriftsartikel (refereegranskat)abstract
- Bird winter-feeding has become a popular backyard activity around the world, particularly in northern regions of Europe and America with cold winters. However, the short- and long-term ecological consequences of such artificial feeding remain inconclusive. In seasonal environments, timing of breeding is a crucial aspect that can strongly influence reproductive output and ultimately fitness. Individual condition at the start of the breeding season is especially important in determining breeding success, by influencing the onset of and investment in breeding. However, empirical evidence on the effects of winter feeding on avian breeding performance remain equivocal. We studied onset of reproduction (laying date) and breeding investment (clutch size) over seven consecutive seasons in a population of wild great tits Parus major in southern Sweden. During the first three years of study, no experimental manipulation was undertaken, while over the last four years the study area was exposed to either supplemented or unmanipulated winter feeding conditions. Breeding was positively affected by supplementary feeding during winter, as birds breeding in the supplemented area increased their clutch size compared to birds from the control area, although laying date remained unaffected by winter feeding. Since differences in clutch size were absent during the three years prior to the experimental manipulation, the results suggest that winter supplementary feeding, and not inherent differences between the two areas, was the reason for the observed effect. Both breeding parameters varied over the years of study, although the effects of the experimental manipulation on clutch size remained consistent, which suggests a carry-over effect of winter feeding on subsequent breeding performance.
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| 8. |
- Culina, Antica, et al.
(författare)
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Connecting the data landscape of long-term ecological studies : The SPI-Birds data hub
- 2021
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656. ; 90:9, s. 2147-2160
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Tidskriftsartikel (refereegranskat)abstract
- The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long-term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and ecological processes in the wild. Furthermore, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad-scale global issues (e.g. climate change). To solve data integration issues and enable a new scale of ecological and evolutionary research based on long-term studies of birds, we have created the SPI-Birds Network and Database ()-a large-scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within year and a half since the establishment, SPI-Birds has recruited over 120 members, and currently hosts data on almost 1.5 million individual birds collected in 80 populations over 2,000 cumulative years, and counting. SPI-Birds acts as a data hub and a catalogue of studied populations. It prevents data loss, secures easy data finding, use and integration and thus facilitates collaboration and synthesis. We provide community-derived data and meta-data standards and improve data integrity guided by the principles of Findable, Accessible, Interoperable and Reusable (FAIR), and aligned with the existing metadata languages (e.g. ecological meta-data language). The encouraging community involvement stems from SPI-Bird's decentralized approach: research groups retain full control over data use and their way of data management, while SPI-Birds creates tailored pipelines to convert each unique data format into a standard format. We outline the lessons learned, so that other communities (e.g. those working on other taxa) can adapt our successful model. Creating community-specific hubs (such as ours, COMADRE for animal demography, etc.) will aid much-needed large-scale ecological data integration.
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| 9. |
- Di Simplicio, Martina, et al.
(författare)
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An investigation of mental imagery in bipolar disorder : Exploring "the mind's eye"
- 2016
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Ingår i: Bipolar Disorders. - : WILEY-BLACKWELL. - 1398-5647 .- 1399-5618. ; 18:8, s. 669-683
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Mental imagery abnormalities occur across psychopathologies and are hypothesized to drive emotional difficulties in bipolar disorder (BD). A comprehensive assessment of mental imagery in BD is lacking. We aimed to test whether (i) mental imagery abnormalities (abnormalities in cognitive stages and subjective domains) occur in BD relative to non-clinical controls; and (ii) to determine the specificity of any abnormalities in BD relative to depression and anxiety disorders. Methods: Participants included 54 subjects in the BD group (depressed/euthymic; n=27 in each subgroup), subjects with unipolar depression (n=26), subjects with anxiety disorders (n=25), and non-clinical controls (n=27) matched for age, gender, ethnicity, education, and premorbid IQ. Experimental tasks assessed cognitive (non-emotional) measures of mental imagery (cognitive stages). Questionnaires, experimental tasks, and a phenomenological interview assessed subjective domains including spontaneous imagery use, interpretation bias, and emotional mental imagery. Results: (i) Compared to non-clinical controls, the BD combined group reported a greater impact of intrusive prospective imagery in daily life, more vivid and "real" negative images (prospective imagery task), and higher self-involvement (picture-word task). The BD combined group showed no clear abnormalities in cognitive stages of mental imagery. (ii) When depressed individuals with BD were compared to the depressed or anxious clinical control groups, no significant differences remained-across all groups, imagery differences were associated with affective lability and anxiety. Conclusions: Compared to non-clinical controls, BD is characterized by abnormalities in aspects of emotional mental imagery within the context of otherwise normal cognitive aspects. When matched for depression and anxiety, these abnormalities are not specific to BD-rather, imagery may reflect a transdiagnostic marker of emotional psychopathology.
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| 10. |
- Dobson, Hannah, et al.
(författare)
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Elevated plasma neurofilament light and glial fibrillary acidic protein in epilepsy versus nonepileptic seizures and nonepileptic disorders
- 2024
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Ingår i: Epilepsia. - 0013-9580.
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Research suggests that recurrent seizures may lead to neuronal injury. Neurofilament light chain protein (NfL) and glial fibrillary acidic protein (GFAP) levels increase in cerebrospinal fluid and blood in response to neuroaxonal damage, and they have been hypothesized as potential biomarkers for epilepsy. We examined plasma NfL and GFAP levels and their diagnostic utility in differentiating patients with epilepsy from those with psychogenic nonepileptic seizures (PNES) and other nonepileptic disorders. Methods: We recruited consecutive adults admitted for video-electroencephalographic monitoring and formal neuropsychiatric assessment. NfL and GFAP levels were quantified and compared between different patient groups and an age-matched reference cohort (n = 1926) and correlated with clinical variables in patients with epilepsy. Results: A total of 138 patients were included, of whom 104 were diagnosed with epilepsy, 22 with PNES, and 12 with other conditions. Plasma NfL and GFAP levels were elevated in patients with epilepsy compared to PNES, adjusted for age and sex (NfL p =.04, GFAP p =.04). A high proportion of patients with epilepsy (20%) had NfL levels above the 95th age-matched percentile compared to the reference cohort (5%). NfL levels above the 95th percentile of the reference cohort had a 95% positive predictive value for epilepsy. Patients with epilepsy who had NfL levels above the 95th percentile were younger than those with lower levels (37.5 vs. 43.8 years, p =.03). Significance: An elevated NfL or GFAP level in an individual patient may support an underlying epilepsy diagnosis, particularly in younger adults, and cautions against a diagnosis of PNES alone. Further examination of the association between NfL and GFAP levels and specific epilepsy subtypes or seizure characteristics may provide valuable insights into disease heterogeneity and contribute to the refinement of diagnosis, understanding pathophysiological mechanisms, and formulating treatment approaches.
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| 11. |
- Evans, Tom J., et al.
(författare)
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Effects of back-mounted biologgers on condition, diving and flight performance in a breeding seabird
- 2020
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 51:11
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Tidskriftsartikel (refereegranskat)abstract
- Biologging devices are providing detailed insights into the behaviour and movement of animals in their natural environments. It is usually assumed that this method of gathering data does not impact on the behaviour observed. However, potential negative effects on birds have rarely been investigated before field-based studies are initiated. Seabirds which both fly and use pursuit diving may be particularly sensitive to increases in drag and load resulting from carrying biologging devices. We studied chick-rearing adult common guillemots Uria aalge equipped with and without back-mounted GPS tags over short deployments of a few days. Concurrently guillemots carried small leg-mounted TDR devices (time-depth recorders) providing activity data throughout. Changes in body mass and breeding success were followed for device equipped and control guillemots. At the colony level guillemots lost body mass throughout the chick-rearing period. When-equipped with the additional GPS tag, the guillemots lost mass at close to twice the rate they did when equipped with only the smaller leg-mounted TDR device. The elevated mass loss suggests an impact on energy expenditure or foraging performance. When equipped with GPS tags diving performance, time-activity budgets and daily patterns of activity were unchanged, yet dive depth distributions differed. We review studies of tag-effects in guillemots Uria sp. finding elevated mass loss and reduced chick-provisioning to be the most commonly observed effects. Less information is available for behavioural measures, and results vary between studies. In general, small tags deployed over several days appear to have small or no measurable effect on the behavioural variables commonly observed in most guillemot tagging studies. However, there may still be impacts on fitness via physiological effects and/or reduced chick-provisioning, while more detailed measures of behaviour (e.g. using accelerometery) may reveal effects on diving and flight performance.
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| 12. |
- Giraudeau, Mathieu, et al.
(författare)
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Will urbanisation affect the expression level of genes related to cancer of wild great tits?
- 2020
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 714
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies suggest that oncogenic processes (from precancerous lesions to metastatic cancers) are widespread in wild animal species, but their importance for ecosystem functioning is still underestimated by evolutionary biologists and animal ecologists. Similar to what has been observed in humans, environmental modifications that often place wild organisms into an evolutionary trap and/or exposes them to a cocktail of mutagenic and carcinogenic pollutants might favor cancer emergence and progression, if animals do not up-regulate their defenses against these pathologies. Here, we compared, for the first time, the expression of 59 tumor-suppressor genes in blood and liver tissues of urban and rural great tits (Parus major); urban conditions being known to favor cancer progression due to, among other things, exposure to chemical or light pollution. Contrary to earlier indications, once we aligned the transcriptome to the great tit genome, we found negligible differences in the expression of anti-cancer defenses between urban and rural birds in blood and liver. Our results indicate the higher expression of a single caretaker gene (i.e. BRCA1) in livers of rural compared to urban birds. We conclude that, while urban birds might be exposed to an environment favoring the development of oncogenic processes, they seem to not upregulate their cancer defenses accordingly and future studies should confirm this result by assessing more markers of cancer defenses. This may result in a mismatch that might predispose urban birds to higher cancer risk and future studies in urban ecology should take into account this, so far completely ignored, hazard.
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| 13. |
- Guintivano, Jerry, et al.
(författare)
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Meta-Analyses of Genome-Wide Association Studies for Postpartum Depression
- 2023
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Ingår i: American Journal of Psychiatry. - : American Psychiatric Association Publishing. - 0002-953X .- 1535-7228. ; 180:12, s. 884-895
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Postpartum depression (PPD) is a common subtype of major depressive disorder (MDD) that is more heritable, yet is understudied in psychiatric genetics. The authors conducted meta-analyses of genome-wide association studies (GWASs) to investigate the genetic architecture of PPD.METHOD: Meta-analyses were conducted on 18 cohorts of European ancestry (17,339 PPD cases and 53,426 controls), one cohort of East Asian ancestry (975 cases and 3,780 controls), and one cohort of African ancestry (456 cases and 1,255 controls), totaling 18,770 PPD cases and 58,461 controls. Post-GWAS analyses included 1) single-nucleotide polymorphism (SNP)-based heritability ([Formula: see text]), 2) genetic correlations between PPD and other phenotypes, and 3) enrichment of the PPD GWAS findings in 27 human tissues and 265 cell types from the mouse central and peripheral nervous system.RESULTS: No SNP achieved genome-wide significance in the European or the trans-ancestry meta-analyses. The [Formula: see text] of PPD was 0.14 (SE=0.02). Significant genetic correlations were estimated for PPD with MDD, bipolar disorder, anxiety disorders, posttraumatic stress disorder, insomnia, age at menarche, and polycystic ovary syndrome. Cell-type enrichment analyses implicate inhibitory neurons in the thalamus and cholinergic neurons within septal nuclei of the hypothalamus, a pattern that differs from MDD.CONCLUSIONS: While more samples are needed to reach genome-wide levels of significance, the results presented confirm PPD as a polygenic and heritable phenotype. There is also evidence that despite a high correlation with MDD, PPD may have unique genetic components. Cell enrichment results suggest GABAergic neurons, which converge on a common mechanism with the only medication approved by the U.S. Food and Drug Administration for PPD (brexanolone).
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| 14. |
- Jensen, Johan Kjellberg, et al.
(författare)
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Urban tree composition is associated with breeding success of a passerine bird, but effects vary within and between years
- 2023
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 201:3, s. 585-597
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Tidskriftsartikel (refereegranskat)abstract
- Birds breeding in urban environments have lower reproductive output compared to rural conspecifics, most likely because of food limitation. However, which characteristics of urban environments may cause this deficiency is not clear. Here, we investigated how tree composition within urban territories of passerine birds is associated with breeding probability and reproductive success. We used 7 years of data of breeding occupancy for blue and great tits (Cyanistes caeruleus; Parus major) and several reproductive traits for great tits, from 400 urban nest boxes located in 5 parks within the city of Malmö, Sweden. We found that tits, overall, were less likely to breed in territories dominated by either non-native trees or beech trees. Great tit chicks reared in territories dominated by non-native trees weighed significantly less, compared to territories with fewer non-native trees. An earlier onset of breeding correlated with increased chick weight in great tits. Increasing number of common oak trees (Quercus robur) was associated with delayed onset of breeding in great tits. Notably, as offspring survival probability generally increased by breeding earlier, in particular in oak-dominated territories, our results suggest that delayed onset of breeding induced by oak trees may be maladaptive and indicate a mismatch to this food source. Our results demonstrate that tree composition may have important consequences on breeding success of urban birds, but some of these effects are not consistent between years, highlighting the need to account for temporal effects to understand determinants of breeding success and inform optimal management in urban green spaces.
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| 15. |
- Khatri, C, et al.
(författare)
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Outcomes after perioperative SARS-CoV-2 infection in patients with proximal femoral fractures: an international cohort study
- 2021
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 11:11, s. e050830-
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Tidskriftsartikel (refereegranskat)abstract
- Studies have demonstrated high rates of mortality in people with proximal femoral fracture and SARS-CoV-2, but there is limited published data on the factors that influence mortality for clinicians to make informed treatment decisions. This study aims to report the 30-day mortality associated with perioperative infection of patients undergoing surgery for proximal femoral fractures and to examine the factors that influence mortality in a multivariate analysis.SettingProspective, international, multicentre, observational cohort study.ParticipantsPatients undergoing any operation for a proximal femoral fracture from 1 February to 30 April 2020 and with perioperative SARS-CoV-2 infection (either 7 days prior or 30-day postoperative).Primary outcome30-day mortality. Multivariate modelling was performed to identify factors associated with 30-day mortality.ResultsThis study reports included 1063 patients from 174 hospitals in 19 countries. Overall 30-day mortality was 29.4% (313/1063). In an adjusted model, 30-day mortality was associated with male gender (OR 2.29, 95% CI 1.68 to 3.13, p<0.001), age >80 years (OR 1.60, 95% CI 1.1 to 2.31, p=0.013), preoperative diagnosis of dementia (OR 1.57, 95% CI 1.15 to 2.16, p=0.005), kidney disease (OR 1.73, 95% CI 1.18 to 2.55, p=0.005) and congestive heart failure (OR 1.62, 95% CI 1.06 to 2.48, p=0.025). Mortality at 30 days was lower in patients with a preoperative diagnosis of SARS-CoV-2 (OR 0.6, 95% CI 0.6 (0.42 to 0.85), p=0.004). There was no difference in mortality in patients with an increase to delay in surgery (p=0.220) or type of anaesthetic given (p=0.787).ConclusionsPatients undergoing surgery for a proximal femoral fracture with a perioperative infection of SARS-CoV-2 have a high rate of mortality. This study would support the need for providing these patients with individualised medical and anaesthetic care, including medical optimisation before theatre. Careful preoperative counselling is needed for those with a proximal femoral fracture and SARS-CoV-2, especially those in the highest risk groups.Trial registration numberNCT04323644
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| 16. |
- Kothari, Radha, et al.
(författare)
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A randomised controlled trial of guided internet-based cognitive behavioural therapy for perfectionism : Effects on psychopathology and transdiagnostic processes
- 2019
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Ingår i: Journal of Behavior Therapy and Experimental Psychiatry. - : Pergamon Press. - 0005-7916 .- 1873-7943. ; 64, s. 113-122
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Tidskriftsartikel (refereegranskat)abstract
- Background and objectivesPerfectionism is a transdiagnostic process that has been associated with a range of psychopathology and also with other transdiagnostic processes. We have previously shown that guided internet-based cognitive behavioural therapy (ICBT) can reduce symptoms of dysfunctional perfectionism, however, no impact was observed on symptoms of depression and anxiety. Here we explore the impact of guided ICBT for perfectionism on symptoms of other associated psychopathology, specifically obsessive-compulsive disorder (OCD) and eating disorders, and also on other associated transdiagnostic processes (self-esteem, intolerance of uncertainty, and self-compassion).MethodsParticipants who presented with clinical levels of perfectionism were randomised to an experimental group that received the intervention (n = 62), or a wait list control group (n = 58). Questionnaires assessing symptoms of OCD, eating disorders, self-esteem, intolerance of uncertainty, and fear of self-compassion were completed pre-intervention, post-intervention (12 weeks), and at follow-up (24 weeks). Between group effect sizes are reported.ResultsThe intervention led to significant decreases in symptoms of OCD (d = −0.9; CI: -1.4, −0.4) and eating disorders (d = −0.6; CI: -1.0, −0.1), and had an impact on other transdiagnostic processes resulting in increased self-esteem (d = 0.7; CI: 0.2, 1.2), decreases in intolerance of uncertainty (d = −0.9; CI: -1.4, −0.4), and fear of self-compassion (d = −0.8; CI: -1.3, −0.3). At follow-up changes were maintained in symptoms of OCD (d = −1.3; CI: -1.8, −0.8), disordered eating (d = −0.7; CI: -1.2, −0.2), intolerance of uncertainty (d = −0.8; CI: -1.2, −0.3), and fear of self-compassion (d = −1.0; CI: -1.5, −0.5).ConclusionsGuided ICBT for perfectionism improves associated psychopathology and transdiagnostic processes. ClinicalTrials.gov registration no. NCT02756871.
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| 17. |
- Nilsson, Johan F., et al.
(författare)
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Predictability of food supply modulates nocturnal hypothermia in a small passerine : Food supply and nocturnal hypothermia
- 2020
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Ingår i: Biology letters. - 1744-9561. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- The combination of short days and long cold winter nights, in temperate regions, presents a major challenge for small diurnal birds. Small birds regularly employ heterothermy and enter rest-phase hypothermia during winter nights to conserve energy. However, we know little about how environmental conditions, such as food availability, shape these strategies. We experimentally manipulated food availability in winter to free-living great tits Parus major. A 'predictable' and constant food supply was provided to birds in one area of a forest, while birds in another area did not have access to a reliable supplementary food source. We found that predictability of food affected the extent of nocturnal hypothermia, but the response differed between the sexes. Whereas male nocturnal body temperature was similar regardless of food availability, females exposed to a naturally 'unpredictable' food supply entered deeper hypothermia at night, compared with females that had access to predictable food and compared with males in both treatment groups. We suggest that this response is likely a consequence of dominance, and subdominant females subject to unpredictable food resources cannot maintain sufficient energy intake, resulting in a higher demand for energy conservation at night.
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| 18. |
- Nilsson, Johan, et al.
(författare)
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Predictability of food supply modulates nocturnal hypothermia in a small passerine
- 2020
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Ingår i: Biology letters. - : The Royal Society. - 1744-957X .- 1744-9561. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- The combination of short days and long cold winter nights, in temperate regions, presents a major challenge for small diurnal birds. Small birds regularly employ heterothermy and enter rest-phase hypothermia during winter nights to conserve energy. However, we know little about how environmental conditions, such as food availability, shape these strategies. We experimentally manipulated food availability in winter to free-living great titsParus major. A ‘predictable' and constant food supply was provided to birds in one area of a forest, while birds in another area did not have access to a reliable supplementary food source. We found that predictability of food affected the extent of nocturnal hypothermia, but the response differed between the sexes. Whereas male nocturnal body temperature was similar regardless of food availability, females exposed to a naturally ‘unpredictable' food supply entered deeper hypothermia at night, compared with females that had access to predictable food and compared with males in both treatment groups. We suggest that this response is likely a consequence of dominance, and subdominant females subject to unpredictable food resources cannot maintain sufficient energy intake, resulting in a higher demand for energy conservation at night.
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| 19. |
- Parsons, Bryony N., et al.
(författare)
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Dietary Supplementation with Soluble Plantain Non-Starch Polysaccharides Inhibits Intestinal Invasion of Salmonella Typhimurium in the Chicken
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:2, s. 87658-
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Tidskriftsartikel (refereegranskat)abstract
- Soluble fibres (non-starch polysaccharides, NSP) from edible plants but particularly plantain banana (Musa spp.), have been shown in vitro and ex vivo to prevent various enteric pathogens from adhering to, or translocating across, the human intestinal epithelium, a property that we have termed contrabiotic. Here we report that dietary plantain fibre prevents invasion of the chicken intestinal mucosa by Salmonella. In vivo experiments were performed with chicks fed from hatch on a pellet diet containing soluble plantain NSP (0 to 200 mg/d) and orally infected with S. Typhimurium 4/74 at 8 d of age. Birds were sacrificed 3, 6 and 10 d post-infection. Bacteria were enumerated from liver, spleen and caecal contents. In vitro studies were performed using chicken caecal crypts and porcine intestinal epithelial cells infected with Salmonella enterica serovars following pre-treatment separately with soluble plantain NSP and acidic or neutral polysaccharide fractions of plantain NSP, each compared with saline vehicle. Bacterial adherence and invasion were assessed by gentamicin protection assay. In vivo dietary supplementation with plantain NSP 50 mg/d reduced invasion by S. Typhimurium, as reflected by viable bacterial counts from splenic tissue, by 98.9% (95% CI, 98.1-99.7; Pless than0.0001). In vitro studies confirmed that plantain NSP (5-10 mg/ml) inhibited adhesion of S. Typhimurium 4/74 to a porcine epithelial cell-line (73% mean inhibition (95% CI, 64-81); Pless than0.001) and to primary chick caecal crypts (82% mean inhibition (95% CI, 75-90); Pless than0.001). Adherence inhibition was shown to be mediated via an effect on the epithelial cells and Ussing chamber experiments with ex-vivo human ileal mucosa showed that this effect was associated with increased short circuit current but no change in electrical resistance. The inhibitory activity of plantain NSP lay mainly within the acidic/pectic (homogalacturonan-rich) component. Supplementation of chick feed with plantain NSP was well tolerated and shows promise as a simple approach for reducing invasive salmonellosis.
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| 20. |
- Rodseth, Edmund, et al.
(författare)
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Pleiotropic effects of melanin pigmentation : haemoparasite infection intensity but not telomere length is associated with plumage morph in black sparrowhawks
- 2024
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Ingår i: Royal Society Open Science. - 2054-5703. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- There is increasing recognition of the potential pleiotropic effects of melanin pigmentation, particularly on immunity, with reports of variation in haemoparasite infection intensity and immune responses between the morphs of colour-polymorphic bird species. In a population of the black sparrowhawk (Accipiter melanoleucus) in western South Africa, light morphs have a higher haemoparasite infection intensity, but no physiological effects of this are apparent. Here, we investigate the possible effects of haemoparasite infection on telomere length in this species and explore whether relative telomere length is associated with either plumage morph or sex. Using quantitative polymerase chain reaction analysis, we confirmed that dark morphs had a lower haemoparasite infection intensity than light morphs. However, we found no differences in telomere length associated with either the haemoparasite infection status or morph in adults, although males have longer telomeres than females. While differences in haemoparasite intensity between morphs are consistent with pleiotropic effects of melanin pigmentation in the black sparrowhawk, we found no evidence that telomere length was associated with haemoparasite infection. Further work is needed to investigate the implications of possible pleiotropic effects of plumage morph and their potential role in the maintenance of colour polymorphism in this species.
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| 21. |
- Salmon, Pablo, et al.
(författare)
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Effects of the Urban Environment on Oxidative Stress in Early Life : Insights from a Cross-fostering Experiment
- 2018
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Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1557-7023 .- 1540-7063. ; , s. 986-994
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Tidskriftsartikel (refereegranskat)abstract
- As urban areas expand rapidly worldwide, wildlife is exposed to a wide range of novel environmental stressors, such as increased air pollution and artificial light at night. Birds in highly polluted and/or urbanized habitats have been found to have increased antioxidant protection, which is likely important to avoid accumulation of oxidative damage, which can have negative fitness consequences. Yet, the current knowledge about the ontogeny of antioxidant protection in urban areas is limited; i.e., is the capacity to up-regulate the antioxidant defences already established during pre-natal development, or does it manifest itself during post-natal development? We cross-fostered great tit (Parus major) nestlings within and between urban and rural habitats, to determine if oxidative stress (measured as non-enzymatic total antioxidant capacity, superoxide dismutase (SOD), and plasma lipid peroxidation) is affected by habitat of origin and/or by habitat of rearing. The results demonstrate that being reared in the urban environment triggers an increase in SOD (an intracellular, enzymatic antioxidant) independent of natal habitat. Oxidative damage increased with hatching date in urban-reared nestlings, but there was little seasonal change in rural-reared nestlings. Total antioxidant capacity was neither affected by habitat of rearing or habitat of origin, but we observed a decline with hatching date in both rearing habitats. Taken together, our results support the growing evidence that the urban environment induces a direct plastic adjustment in antioxidant protection, but that up-regulation is not sufficient to avoid increased oxidative damage in late-hatched broods. Future studies should explore the underlying causes for this effect in late-hatched broods and whether it has any negative long-term implications, both at the individual- and the population level.
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| 22. |
- Salmón, Pablo, et al.
(författare)
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Selective disappearance of great tits with short telomeres in urban areas
- 2017
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 284:1862
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Tidskriftsartikel (refereegranskat)abstract
- Urban environments pose novel challenges, as well as opportunities, for urban-dwelling wildlife. Although differences have been reported in several phenotypic traits (e.g. morphology, physiology and behaviour) between urban and rural populations, it is poorly understood whether this affects individual fitness. Telomere dynamics are posited as one possible mechanism underlying senescence and mortality. It was recently shown that telomere shortening is accelerated when growing up in an urban, compared with a rural, environment. However, the implications of accelerated telomere attrition for fitness are still unclear. Here, we examine the relationship between telomere length (TL) and survival in a bird common to urban and rural environments, and during both early and later life. The results reveal that TL is a strong predictor of post-fledging survival and recruitment in both habitats but, crucially, selective disappearance of individuals with short telomeres early in life is more pronounced in the urban environment, resulting in a longer average TL among the adult population. However, following recruitment, we found no difference in the relationship between TL and survival between the urban and rural environments. This indicates that the urban environment has negative effects in early life, while during later life the benefits could potentially outweigh the costs.
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| 23. |
- Salmón, Pablo, et al.
(författare)
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Urbanisation impacts plumage colouration in a songbird across Europe : Evidence from a correlational, experimental and meta-analytical approach
- 2023
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Ingår i: Journal of Animal Ecology. - 0021-8790. ; 92:10, s. 1924-1936
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Tidskriftsartikel (refereegranskat)abstract
- Urbanisation is accelerating across the globe, transforming landscapes, presenting organisms with novel challenges, shaping phenotypes and impacting fitness. Urban individuals are claimed to have duller carotenoid-based colouration, compared to their non-urban counterparts, the so-called ‘urban dullness’ phenomenon. However, at the intraspecific level, this generalisation is surprisingly inconsistent and often based on comparisons of single urban/non-urban populations or studies from a limited geographical area. Here, we combine correlational, experimental and meta-analytical data on a common songbird, the great tit Parus major, to investigate carotenoid-based plumage colouration in urban and forest populations across Europe. We find that, as predicted, urban individuals are paler than forest individuals, although there are large population-specific differences in the magnitude of the urban-forest contrast in colouration. Using one focal region (Malmö, Sweden), we reveal population-specific processes behind plumage colouration differences, which are unlikely to be the result of genetic or early-life conditions, but instead a consequence of environmental factors acting after fledging. Finally, our meta-analysis indicates that the urban dullness phenomenon is well established in the literature, for great tits, with consistent changes in carotenoid-based plumage traits, particularly carotenoid chroma, in response to anthropogenic disturbances. Overall, our results provide evidence for uniformity in the ‘urban dullness’ phenomenon but also highlight that the magnitude of the effect on colouration depends on local urban characteristics. Future long-term replicated studies, covering a wider range of species and feeding guilds, will be essential to further our understanding of the eco-evolutionary implications of this phenomenon.
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| 24. |
- Shafran, Roz, et al.
(författare)
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Is the devil in the detail? : A randomised controlled trial of guided internet-based CBT for perfectionism
- 2017
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Ingår i: Behaviour Research and Therapy. - : Elsevier BV. - 0005-7967 .- 1873-622X. ; 95, s. 99-106, s. 127-127
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Tidskriftsartikel (refereegranskat)abstract
- An internet guided self-help cognitive-behavioural treatment (ICBT) for perfectionism was recently found to be effective (see this issue). Such studies stand in need of replication. The aim of this study was to report the outcomes and predictors of change when the treatment is delivered in a UK setting. A total of 120 people (Mean = 28.9 years; 79% female) were randomised to receive ICBT or wait-list control over 12 weeks (trial registration: NCT02756871). While there were strong similarities between the current study and its Swedish counterpart, there were also important differences in procedural details. There was a significant impact of the intervention on the primary outcome measure (Frost Multidimensional Perfectionism Scale, Concern over Mistakes subscale) and also on the Clinical Perfectionism Questionnaire (between group effect sizes d = 0.98 (95% CI: 0.60–1.36) and d = 1.04 (95% CI: 0.66–1.43) respectively using intent-to-treat analyses). Unlike the Swedish study, there was significant non-engagement and non-completion of modules with 71% of participants completing fewer than half the modules. The number of modules completed moderated the rate of change in clinical perfectionism over time. In conclusion, the study indicates the intervention is effective in a UK setting but highlighted the importance of procedural details to optimise retention.
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| 25. |
- Sumasgutner, Petra, et al.
(författare)
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Interactive effects of rising temperatures and urbanisation on birds across different climate zones : A mechanistic perspective
- 2023
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 29:9, s. 2399-2420
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Forskningsöversikt (refereegranskat)abstract
- Climate change and urbanisation are among the most pervasive and rapidly growing threats to biodiversity worldwide. However, their impacts are usually considered in isolation, and interactions are rarely examined. Predicting species' responses to the combined effects of climate change and urbanisation, therefore, represents a pressing challenge in global change biology. Birds are important model taxa for exploring the impacts of both climate change and urbanisation, and their behaviour and physiology have been well studied in urban and non-urban systems. This understanding should allow interactive effects of rising temperatures and urbanisation to be inferred, yet considerations of these interactions are almost entirely lacking from empirical research. Here, we synthesise our current understanding of the potential mechanisms that could affect how species respond to the combined effects of rising temperatures and urbanisation, with a focus on avian taxa. We discuss potential interactive effects to motivate future in-depth research on this critically important, yet overlooked, aspect of global change biology. Increased temperatures are a pronounced consequence of both urbanisation (through the urban heat island effect) and climate change. The biological impact of this warming in urban and non-urban systems will likely differ in magnitude and direction when interacting with other factors that typically vary between these habitats, such as resource availability (e.g. water, food and microsites) and pollution levels. Furthermore, the nature of such interactions may differ for cities situated in different climate types, for example, tropical, arid, temperate, continental and polar. Within this article, we highlight the potential for interactive effects of climate and urban drivers on the mechanistic responses of birds, identify knowledge gaps and propose promising future research avenues. A deeper understanding of the behavioural and physiological mechanisms mediating species' responses to urbanisation and rising temperatures will provide novel insights into ecology and evolution under global change and may help better predict future population responses.
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| 26. |
- Toledo, Alejandra, et al.
(författare)
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Fatty acid profiles of great tit (Parus major) eggs differ between urban and rural habitats, but not between coniferous and deciduous forests
- 2016
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Ingår i: Naturwissenschaften. - : Springer Science and Business Media LLC. - 0028-1042. ; 103:7-8
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Tidskriftsartikel (refereegranskat)abstract
- Early-life nutrition is an important determinant of both short- and long-term performance and fitness. The avian embryo develops within an enclosed package of nutrients, of which fatty acids (FA) are essential for many aspects of development. The FA composition of yolk depends on maternal nutrition and condition prior to egg formation, which may be affected by the external environment. To test if maternal environment affects yolk FA composition, we investigated whether the FA composition of great tit (Parus major) egg yolks differed between urban and rural habitats, and between deciduous and coniferous habitats. The results reveal differences in FA composition between eggs laid in urban and rural habitats, but not between eggs from the coniferous and deciduous habitats. To a large extent, this difference likely reflects dietary differences associated with urban habitats rather than dominating vegetation type. Specifically, urban yolks contained lower proportions of both ω-3 and ω-6 polyunsaturated FAs (PUFA), which are important for chick development. We also found a positive association between the proportion of saturated fatty acids and laying date, and a negative association between the proportion of ω-6 PUFA and clutch size. Given that urbanization is expanding rapidly, future studies should investigate whether factors such as anthropogenic food in the urban environment underlie these differences and whether they impair chick development.
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| 27. |
- Watson, Hannah, et al.
(författare)
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A theoretical model of the evolution of actuarial senescence under environmental stress.
- 2015
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Ingår i: Experimental Gerontology. - : Elsevier BV. - 1873-6815 .- 0531-5565. ; 71:Online 31 August 2015, s. 80-88
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Tidskriftsartikel (refereegranskat)abstract
- Free-living organisms are exposed to a wide range of stressors, all of which can disrupt components of stress-related and detoxification physiology. The subsequent accumulation of somatic damage is widely believed to play a major role in the evolution of senescence. Organisms have evolved sophisticated physiological regulatory mechanisms to maintain homeostasis in response to environmental perturbations, but these systems are likely to be constrained in their ability to optimise robustness to multiple stressors due to functional correlations among related traits. While evolutionary change can accelerate due to human ecological impacts, it remains to be understood how exposure to multiple environmental stressors could affect senescence rates and subsequently population dynamics and fitness. We used a theoretical evolutionary framework to quantify the potential consequences for the evolution of actuarial senescence in response to exposure to simultaneous physiological stressors - one versus multiple and additive versus synergistic - in a hypothetical population of avian "urban adapters". In a model in which multiple stressors have additive effects on physiology, species may retain greater capacity to recover, or respond adaptively, to environmental challenges. However, in the presence of high synergy, physiological dysregulation suddenly occurs, leading to a rapid increase in age-dependent mortality and subsequent population collapse. Our results suggest that, if the synergistic model is correct, population crashes in environmentally-stressed species could happen quickly and with little warning, as physiological thresholds of stress resistance are overcome.
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| 28. |
- Watson, Hannah, et al.
(författare)
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Assessing the effects of repeated handling on the physiology and condition of semi-precocial nestlings
- 2016
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Ingår i: Ibis. - : Wiley. - 0019-1019 .- 1474-919X. ; 158:4, s. 834-843
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Tidskriftsartikel (refereegranskat)abstract
- Repeated exposure to elevated levels of glucocorticoids during development can have long-term detrimental effects on survival and fitness, potentially associated with increased telomere attrition. Nestling birds are regularly handled for ecological research, yet few authors have considered the potential for handling-induced stress to influence hormonally mediated phenotypic development or bias interpretations of subsequent focal measurements. We experimentally manipulated the handling experience of the semi-precocial nestlings of European Storm Petrel Hydrobates pelagicus to simulate handling in a typical field study and examined cumulative effects on physiology and condition in late postnatal development. Neither baseline corticosterone (the primary glucocorticoid in birds), telomere length nor body condition varied with the number of handling episodes. The absence of a response could be explained if Storm Petrels did not perceive handling to be stressful or if there is dissociation of the hypothalamic–pituitary–adrenal axis from stressful stimuli in early life. Eliciting a response to a stressor may be maladaptive for cavity-dwelling young that are unable to escape or defend themselves. Furthermore, avoiding elevated overall glucocorticoid exposure may be particularly important in a long-lived species, in which accelerated early-life telomere erosion could impact negatively upon longevity. We propose that the level of colony-wide disturbance induced by investigator handling of young could be important in underlining species-specific responses. Storm Petrel nestlings appear unresponsive to investigator handling within the limits of handling in a typical field study and handling at this level should not bias physiological and morphological measurements.
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| 29. |
- Watson, Hannah, et al.
(författare)
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Dynamic changes in DNA methylation during embryonic and postnatal development of an altricial wild bird
- 2019
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9:17, s. 9580-9585
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Tidskriftsartikel (refereegranskat)abstract
- DNA methylation could shape phenotypic responses to environmental cues and underlie developmental plasticity. Environmentally induced changes in DNA methylation during development can give rise to stable phenotypic traits and thus affect fitness. In the laboratory, it has been shown that the vertebrate methylome undergoes dynamic reprogramming during development, creating a critical window for environmentally induced epigenetic modifications. Studies of DNA methylation in the wild are lacking, yet are essential for understanding how genes and the environment interact to affect phenotypic development and ultimately fitness. Furthermore, our knowledge of the establishment of methylation patterns during development in birds is limited. We quantified genome-wide DNA methylation at various stages of embryonic and postnatal development in an altricial passerine bird, the great tit Parus major. While, there was no change in global DNA methylation in embryonic tissue during the second half of embryonic development, a twofold increase in DNA methylation in blood occurred between 6 and 15 days posthatch. Though not directly comparable, DNA methylation levels were higher in the blood of nestlings compared with embryonic tissue at any stage of prenatal development. This provides the first evidence that DNA methylation undergoes global change during development in a wild bird, supporting the hypothesis that methylation mediates phenotypic development. Furthermore, the plasticity of DNA methylation demonstrated during late postnatal development, in the present study, suggests a wide window during which DNA methylation could be sensitive to environmental influences. This is particularly important for our understanding of the mechanisms by which early-life conditions influence later-life performance. While, we found no evidence for differences in genome-wide methylation in relation to habitat of origin, environmental variation is likely to be an important driver of variation in methylation at specific loci.
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| 30. |
- Watson, Hannah, et al.
(författare)
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Effects of human disturbance on postnatal growth and baseline corticosterone in a long-lived bird
- 2021
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Ingår i: Conservation Physiology. - : Oxford University Press (OUP). - 2051-1434. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Prolonged or repeated episodes of environmental stress could be especially detrimental for developing young, via impaired growth or development. Despite this, most studies investigating the effects of human recreational and tourism activities have focused on adults. An increasing demand for nature-based tourism in remote locations means that many seabirds, which have evolved largely in the absence of predators and humans, are being exposed to novel pressures. The slow-growing semi-precocial nestlings of the European storm petrel Hydrobates pelagicus experience higher mortality rates in nests exposed to human recreational disturbance. Here, we examine whether surviving nestlings reared in disturbed areas are also affected via changes in growth trajectories and baseline circulating glucocorticoids. Nestlings reared in high-disturbance areas displayed delayed mass growth, and we found weak evidence for slower rates of mass gain and tarsus growth, compared with nestlings reared in undisturbed areas. There were no differences in wing growth, consistent with prioritization of long wings, important for post-fledging survival. A tendency for a less marked age-related decline in corticosterone (CORT) in disturbed nestlings offers limited evidence that changes in growth trajectories were mediated by baseline CORT. However, disturbed nestlings could have experienced overall higher GC exposure if the acute GC response was elevated. ‘Catch-up’ growth enabled high-disturbance nestlings to overcome early constraints and achieve a similar, or even larger, asymptotic body size and mass as low-disturbance nestlings. While catch-up growth has been shown to carry costs for parents and offspring, the effects of disturbance were slight and considerably smaller than growth alterations driven by variation in environmental conditions between years. Nonetheless, effects of human recreational activities could be exacerbated under higher levels of human disturbance or in the presence of multiple pressures, as imposed by present rapid rates of environmental change.
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| 31. |
- Watson, Hannah
(författare)
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How bird feeders help small species fight infection
- 2023
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Ingår i: The Conversation. - 2201-5639.
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Every day, throughout the world, people put huge quantities of food out at feeding stations for birds and other wild animals.Although we know that connecting with nature benefits human health and wellbeing, scientists still know relatively little about the consequences of providing food for wildlife. My team’s most recent research, however, has found that feeding garden birds in wintertime seems to make them more resilient to infection.Winter can be tough for small birds. During cold winter nights, small birds reduce their body temperature by several degrees. While this would be lethal for a human, it saves lots of energy, helping birds to survive particularly cold nights. However, reducing body temperature is risky, and hypothermic birds are slow to wake and respond to a predator.A reliable food supply at bird feeders can help small birds avoid starvation and survive the harsh winter. Our previous research showed that birds with access to feeders do not need to reduce their night-time body temperature as much as birds that did not have access to feeders. The extra energy birds get from human-provided food means they don’t have to take the risk of becoming severely hypothermic.
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| 32. |
- Watson, Hannah, et al.
(författare)
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Maternally derived yolk antioxidants buffer the developing avian embryo against oxidative stress induced by hyperoxia
- 2018
-
Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 221:13
-
Tidskriftsartikel (refereegranskat)abstract
- In oviparous animals, maternally transferred antioxidants protect the embryo from oxidative damage from high rates of reactive oxygen species (ROS) production incurred by rapid growth. Elevated ROS exposure, beyond that incurred by normal growth, can occur as a result of exposure to exogenous factors (e.g. pollutants, toxins, radiation), increasing the risk of oxidative damage, with potentially adverse consequences for embryonic development and long-term fitness. The capacity of the avian embryo’s antioxidant protection system to counter an increased exogenous oxidative threat is poorly understood. We induced an external oxidative challenge via experimental increase in ambient oxygen concentration throughout incubation of wild great tit Parus major eggs in the laboratory. At day 11 of incubation, brain tissue revealed no consistent differences in oxidative stress status [as measured by antioxidant levels (superoxide dismutase and total glutathione), lipid peroxidation and telomere length] between control (21% oxygen) and hyperoxic (40% oxygen) embryos. However, the level of vitamin E was significantly lower and lipid peroxidation was significantly higher in yolks of eggs reared under elevated oxygen concentrations. The results suggest that maternally derived yolk antioxidants successfully buffer developing embryonic tissues against an increased exogenous oxidative threat. Furthermore, vitamin E plays a more important role in protecting the embryo than carotenoids. However, the depletion of antioxidants and increased peroxidation of lipids in the yolk could have negative consequences for embryonic development, in particular for the brain and heart that require highly unsaturated fatty acids, and protection against the oxidative burst following hatching.
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| 33. |
- Watson, Hannah, et al.
(författare)
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Only rare classical MHC-I alleles are highly expressed in the European house sparrow
- 2024
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - 0962-8452. ; 291:2017
-
Tidskriftsartikel (refereegranskat)abstract
- The exceptional polymorphism observed within genes of the major histocompatibility complex (MHC), a core component of the vertebrate immune system, has long fascinated biologists. The highly polymorphic classical MHC class-I (MHC-I) genes are maintained by pathogen-mediated balancing selection (PMBS), as shown by many sites subject to positive selection, while the more monomorphic non-classical MHC-I genes show signatures of purifying selection. In line with PMBS, at any point in time, rare classical MHC alleles are more likely than common classical MHC alleles to confer a selective advantage in host–pathogen interactions. Combining genomic and expression data from the blood of wild house sparrows Passer domesticus, we found that only rare classical MHC-I alleles were highly expressed, while common classical MHC-I alleles were lowly expressed or not expressed. Moreover, highly expressed rare classical MHC-I alleles had more positively selected sites, indicating exposure to stronger PMBS, compared with lowly expressed classical alleles. As predicted, the level of expression was unrelated to allele frequency in the monomorphic non-classical MHC-I alleles. Going beyond previous studies, we offer a fine-scale view of selection on classical MHC-I genes in a wild population by revealing differences in the strength of PMBS according to allele frequency and expression level.
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| 34. |
- Watson, Hannah, et al.
(författare)
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Thermoregulatory costs of the innate immune response are modulated by winter food availability in a small passerine
- 2023
-
Ingår i: Journal of Animal Ecology. - 0021-8790. ; 92:5, s. 1065-1074
-
Tidskriftsartikel (refereegranskat)abstract
- In winter, a challenge to the immune system could pose a major energetic trade-off for small endotherms, whereby increasing body temperature (Tb; i.e. eliciting fever) may be beneficial to fight off invading pathogens yet incur a cost for vital energy-saving mechanisms. Having previously shown that the availability and acquisition of energy, through manipulation of food predictability, influences the depth of rest-phase hypothermia in a wild bird in winter, we expected that the nocturnal thermoregulatory component of the acute-phase immune response would also be modulated by food availability. By manipulating winter food availability in the wild for great tits Parus major, we created an area offering a “predictable” and constant supply of food at feeding stations, while an unmanipulated area was subject to naturally “unpredictable” food. Birds were subject to an immune challenge shortly after dusk, and the thermoregulatory response was quantified via continuous recording of nocturnal Tb, using subcutaneous thermo-sensitive transponders. In response to immune challenge, all birds increased Tb above the level maintained prior to immune challenge (i.e. baseline). However, birds experiencing a naturally unpredictable food supply elevated Tb more than birds subject to predictable food resources, during the period of expected peak response and for the duration of the night. Furthermore, “unpredictable-food” females took longer to return to their baseline Tb. Assuming baseline nocturnal Tb reflects an individual's optimum, based on their available energy budget, the metabolic cost of eliciting an acute-phase response for “unpredictable-food” birds was more than double that of “predictable-food” birds. The absence of differences in absolute Tb during the peak response could support the idea of an optimal Tb for immune system activation. Alternatively, “predictable-food” birds could have acquired tolerance to endotoxin as a result of using feeding stations, thus affording them reduced costs associated with a smaller Tb increase. These findings shed new light on the trade-offs associated with food acquisition, thermoregulation and immune function in small-bodied endotherms. This knowledge is of increasing importance, given the predicted elevated pathogen risks associated with changes in climate and anthropogenic activities.
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| 35. |
- Watson, Hannah, et al.
(författare)
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Transcriptome analysis of a wild bird reveals physiological responses to the urban environment
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7, s. 44180-44180
-
Tidskriftsartikel (refereegranskat)abstract
- Identifying the molecular basis of environmentally induced phenotypic variation presents exciting opportunities for furthering our understanding of how ecological processes and the environment can shape the phenotype. Urban and rural environments present free-living organisms with different challenges and opportunities, which have marked consequences for the phenotype, yet little is known about responses at the molecular level. We characterised transcriptomes from an urban and a rural population of great tits Parus major, demonstrating striking differences in gene expression profiles in both blood and liver tissues. Differentially expressed genes had functions related to immune and inflammatory responses, detoxification, protection against oxidative stress, lipid metabolism, and regulation of gene expression. Many genes linked to stress responses were expressed at higher levels in the urban birds, in accordance with our prediction that urban animals are exposed to greater environmental stress. This is one of the first studies to reveal transcriptional differences between urban- and rural-dwelling animals and suggests an important role for epigenetics in mediating environmentally induced physiological variation. The study provides valuable resources for developing further in-depth studies of the mechanisms driving phenotypic variation in the urban context at larger spatial and temporal scales.
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| 36. |
- Watson, Hannah, et al.
(författare)
-
Urbanization is associated with modifications in DNA methylation in a small passerine bird
- 2021
-
Ingår i: Evolutionary Applications. - : Wiley. - 1752-4563 .- 1752-4571. ; 14:1, s. 85-98
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Tidskriftsartikel (refereegranskat)abstract
- Urbanization represents a fierce driver of phenotypic change, yet the molecular mechanisms underlying observed phenotypic patterns are poorly understood. Epigenetic changes are expected to facilitate more rapid adaption to changing or novel environments, such as our towns and cities, compared with slow changes in gene sequence. A comparison of liver and blood tissue from great tits Parus major originating from an urban and a forest site demonstrated that urbanization is associated with variation in genome-wide patterns of DNA methylation. Combining reduced representation bisulphite sequencing with transcriptome data, we revealed habitat differences in DNA methylation patterns that suggest a regulated and coordinated response to the urban environment. In the liver, genomic sites that were differentially methylated between urban- and forest-dwelling birds were over-represented in regulatory regions of the genome and more likely to occur in expressed genes. DNA methylation levels were also inversely correlated with gene expression at transcription start sites. Furthermore, differentially methylated CpG sites, in liver, were over-represented in pathways involved in (i) steroid biosynthesis, (ii) superoxide metabolism, (iii) secondary alcohol metabolism, (iv) chylomicron remodelling, (v) cholesterol transport, (vi) reactive oxygen species (ROS) metabolic process and (vii) epithelial cell proliferation. This corresponds with earlier studies identifying diet and exposure to ROS as two of the main drivers of divergence between organisms in urban and nonurban environments. Conversely, in blood, sites that were differentially methylated between urban- and forest-dwelling birds were under-represented in regulatory regions, more likely to occur in nonexpressed genes and not over-represented in specific biological pathways. It remains to be determined whether diverging patterns of DNA methylation represent adaptive evolutionary responses and whether the conclusions can be more widely attributed to urbanization.
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| 37. |
- 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
-
Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 224:10
-
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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| 38. |
- Bravo, L, et al.
(författare)
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- 2021
-
swepub:Mat__t
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| 39. |
- Tabiri, S, et al.
(författare)
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- 2021
-
swepub:Mat__t
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