| 1. |
- Åberg, Anna, et al.
(author)
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Helicobacter pylori adapts to chronic infection and gastric disease via ph-responsive baba-mediated adherence
- 2017
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In: Cell Host and Microbe. - : Elsevier BV. - 1931-3128 .- 1934-6069. ; 21:3, s. 376-389
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Journal article (peer-reviewed)abstract
- The BabA adhesin mediates high-affinity binding of Helicobacter pylori to the ABO blood group antigen-glycosylated gastric mucosa. Here we show that BabA is acid responsive-binding is reduced at low pH and restored by acid neutralization. Acid responsiveness differs among strains; often correlates with different intragastric regions and evolves during chronic infection and disease progression; and depends on pH sensor sequences in BabA and on pH reversible formation of high-affinity binding BabA multimers. We propose that BabA's extraordinary reversible acid responsiveness enables tight mucosal bacterial adherence while also allowing an effective escape from epithelial cells and mucus that are shed into the acidic bactericidal lumen and that bio-selection and changes in BabA binding properties through mutation and recombination with babA-related genes are selected by differences among individuals and by changes in gastric acidity over time. These processes generate diverse H. pylori subpopulations, in which BabA's adaptive evolution contributes to H. pylori persistence and overt gastric disease.
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| 2. |
- Arnqvist, Göran, et al.
(author)
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Negative frequency dependent selection on sympatric mtDNA haplotypes in Drosophila subobscura
- 2016
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In: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 153
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Journal article (peer-reviewed)abstract
- Background: Recent experimental evidence for selection on mitochondrial DNA (mtDNA) has prompted the question as to what processes act to maintain within-population variation in mtDNA. Balancing selection though negative frequency dependent selection (NFDS) among sympatric haplotypes is a possibility, but direct empirical evidence for this is very scarce. Findings: We extend the previous findings of a multi-generation replicated cage experiment in Drosophila subobscura, where mtDNA polymorphism was maintained in a laboratory setting. First, we use a set of Monte Carlo simulations to show that the haplotype frequency dynamics observed are inconsistent with genetic drift alone and most closely match those expected under NFDS. Second, we show that haplotype frequency changes over time were significantly different from those expected under either genetic drift or positive selection but were consistent with those expected under NFSD. Conclusions: Collectively, our analyses provide novel support for NFDS on mtDNA haplotypes, suggesting that mtDNA polymorphism may at least in part be maintained by balancing selection also in natural populations. We very briefly discuss the possible mechanisms that might be involved.
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| 3. |
- Avila, M., et al.
(author)
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Daily cycle simulations of thermally stratified flows over forests
- 2019
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In: Wake Conference 2019 22–24 May 2019, Visby, Sweden. - : IOP PUBLISHING LTD.
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Conference paper (peer-reviewed)abstract
- The aim of the present work is to obtain a better understanding of how to model the thermally stratified wind field over a forest during full diurnal cycles. The setup of the study assumes a horizontally homogeneous forest, with the objective of finding a simple and efficient way to model the canopy flow using time-dependent input data, obtained from measurements and mesoscale simulations. With this, new insights can be gained for future microscale modelling of complex forested terrains using mesoscale input data. In terrain without forest a diurnal cycle is commonly simulated by imposing time-dependent ground temperature. However, the presence of forests partially isolates the temperature at ground level from the flow above the canopy, making this common approach ineffective. This work proposes imposing the time-dependent net radiation at the forest canopy top to drive the thermal stratification changes along the diurnal cycle. To this end, several full days of simulation are driven by prescribing the net radiative heat flux balance measured on top of the canopy, together with a geostrophic pressure gradient. The advantage of the method is its simplicity and that the input data can be easily obtained from mesoscale modelling. When compared to the observations at the Swedish site Ryningsnas, the new method dramatically improves estimations of wind speed, wind direction and turbulent kinetic energy compared to simulations that only assume neutral stratification. Out of the variables studied, temperature and turbulent heat flux profiles were the ones that qualitatively followed the measurements the best, while wind speed and turbulent kinetic energy showed a larger disagreement.
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| 4. |
- Berger, David, et al.
(author)
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Intralocus Sexual Conflict and the Tragedy of the Commons in Seed Beetles
- 2016
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In: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 188:4, s. E98-E112
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Journal article (peer-reviewed)abstract
- The evolution of male traits that inflict direct harm on females during mating interactions can result in a so-called tragedy of the commons, where selfish male strategies depress population viability. This tragedy of the commons can be magnified by intralocus sexual conflict (IaSC) whenever alleles that reduce fecundity when expressed in females spread in the population because of their benefits in males. We evaluated this prediction by detailed phenotyping of 73 isofemale lines of the seed beetle Callosobruchus maculatus. We quantified genetic variation in life history andmorphology, as well as associated covariance in male and female adult reproductive success. In parallel, we created replicated artificial populations of each line and measured their productivity. Genetic constraints limited independent trait expression in the sexes, and we identified several instances of sexually antagonistic covariance between traits and fitness, signifying IaSC. Population productivity was strongly positively correlated to female adult reproductive success but uncorrelated with male reproductive success. Moreover, male (female) phenotypic optima for several traits under sexually antagonistic selection were exhibited by the genotypes with the lowest (highest) population productivity. Our study forms a direct link between individuallevel sex-specific selection and population demography and places lifehistory traits at the epicenter of these dynamics.
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| 5. |
- Berger, David, et al.
(author)
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Sexually antagonistic selection on genetic variation underlying both male and female same-sex sexual behavior
- 2016
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In: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 16
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Journal article (peer-reviewed)abstract
- Intralocus sexual conflict, arising from selection for different alleles at the same locus in males and females, imposes a constraint on sex-specific adaptation. Intralocus sexual conflict can be alleviated by the evolution of sex-limited genetic architectures and phenotypic expression, but pleiotropic constraints may hinder this process. Here, we explored putative intralocus sexual conflict and genetic (co)variance in a poorly understood behavior with near male-limited expression. Same-sex sexual behaviors (SSBs) generally do not conform to classic evolutionary models of adaptation but are common in male animals and have been hypothesized to result from perception errors and selection for high male mating rates. However, perspectives incorporating sex-specific selection on genes shared by males and females to explain the expression and evolution of SSBs have largely been neglected.
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| 6. |
- Dougherty, Liam R., et al.
(author)
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Sexual conflict and correlated evolution between male persistence and female resistance traits in the seed beetle Callosobruchus maculatus
- 2017
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In: Proceedings of the Royal Society of London. Biological Sciences. - : ROYAL SOC. - 0962-8452 .- 1471-2954. ; 284:1855
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Journal article (peer-reviewed)abstract
- Traumatic mating (or copulatory wounding) is an extreme form of sexual conflict whereby male genitalia physically harm females during mating. In such species females are expected to evolve counter-adaptations to reduce male-induced harm. Importantly, female counter-adaptations may include both genital and non-genital traits. in this study, we examine evolutionary associations between harmful male genital morphology and female reproductive tract morphology and immune function across 13 populations of the seed beetle Callosobruchus maculatus. We detected positive correlated evolution between the injuriousness of male genitalia and putative female resistance adaptations across populations. Moreover, we found evidence for a negative relationship between female immunity and population productivity, which suggests that investment in female resistance may be costly due to the resource trade-offs that are predicted between immunity and reproduction. Finally, the degree of female tract scarring (harm to females) was greater in those populations with both longer aedeagal spines and a thinner female tract lining. Our results are thus consistent with a sexual arms race, which is only apparent when both male and female traits are taken into account. Importantly, our study provides rare evidence for sexually antagonistic coevolution of male and female traits at the within-species level.
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| 7. |
- Gutefeldt, Kerstin, et al.
(author)
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Upper extremity impairments in type 1 diabetes with long duration : common problems with great impact on daily life
- 2019
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In: Disability and Rehabilitation. - : Taylor & Francis. - 0963-8288 .- 1464-5165. ; 41:6, s. 633-640
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Journal article (peer-reviewed)abstract
- PURPOSE: To investigate the prevalence, activity limitations and potential risk factors of upper extremity impairments in type 1 diabetes in comparison to controls.METHODS: In a cross-sectional population-based study in the southeast of Sweden, patients with type 1 diabetes <35 years at onset, duration ≥20 years, <67 years old and matched controls were invited to answer a questionnaire on upper extremity impairments and activity limitations and to take blood samples.RESULTS: Seven hundred and seventy-three patients (ages 50 ± 10 years, diabetes duration 35 ± 10 years) and 708 controls (ages 54 ± 9 years) were included. Shoulder pain and stiffness, hand paraesthesia and finger impairments were common in patients with a prevalence of 28-48%, which was 2-4-folds higher than in controls. Compared to controls, the patients had more bilateral impairments, often had coexistence of several upper extremity impairments, and in the presence of impairments, reported more pronounced activity limitations. Female gender (1.72 (1.066-2.272), p = 0.014), longer duration (1.046 (1.015-1.077), p = 0.003), higher body mass index (1.08 (1.017-1.147), p = 0.013) and HbA1c (1.029 (1.008-1.05), p = 0.007) were associated with upper extremity impairments.CONCLUSIONS: Compared to controls, patients with type 1 diabetes have a high prevalence of upper extremity impairments, often bilateral, which are strongly associated with activity limitations. Recognising these in clinical practise is crucial, and improved preventative, therapeutic and rehabilitative interventions are needed. Implications for rehabilitation Upper extremity impairments affecting the shoulder, hand and fingers are common in patients with type 1 diabetes, the prevalence being 2-4-fold higher compared to non-diabetic persons. Patients with diabetes type 1 with upper extremity impairments have more pronounced limitations in daily activities compared to controls with similar impairments. Recognising upper extremity impairments and activity limitations are important and improved preventive, therapeutic and rehabilitation methods are needed.
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| 8. |
- Mann, J., et al.
(author)
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Complex terrain experiments in the New European Wind Atlas
- 2017
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In: Philosophical Transactions. Series A. - : The Royal Society. - 1364-503X .- 1471-2962. ; 375:2091, s. 1-23
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Journal article (peer-reviewed)abstract
- The New European Wind Atlas project will create a freely accessible wind atlas covering Europe and Turkey, develop the model chain to create the atlas and perform a series of experiments on flow in many different kinds of complex terrain to validate the models. This paper describes the experiments of which some are nearly completed while others are in the planning stage. All experiments focus on the flow properties that are relevant for wind turbines, so the main focus is the mean flow and the turbulence at heights between 40 and 300 m. Also extreme winds, wind shear and veer, and diurnal and seasonal variations of the wind are of interest. Common to all the experiments is the use of Doppler lidar systems to supplement and in some cases replace completely meteorological towers. Many of the lidars will be equipped with scan heads that will allow for arbitrary scan patterns by several synchronized systems. Two pilot experiments, one in Portugal and one in Germany, show the value of using multiple synchronized, scanning lidar, both in terms of the accuracy of the measurements and the atmospheric physical processes that can be studied. The experimental data will be used for validation of atmospheric flow models and will by the end of the project be freely available. This article is part of the themed issue 'Wind energy in complex terrains'.
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| 9. |
- Van dijk, Peter R, et al.
(author)
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After 6years of intraperitoneal insulin administration IGF-I concentrations in T1DM patients are at low-normal level.
- 2015
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In: Growth Hormone & IGF Research. - : Elsevier BV. - 1096-6374 .- 1532-2238. ; 25:6, s. 316-319
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Low concentrations of insulin-like growth factor-I (IGFI) have been reported in type 1 diabetes mellitus (T1DM), suggested to be due to low insulin concentrations in the portal vein. The aim was to describe the long-term course of IGFI concentrations among T1DM subjects treated with continuous intraperitoneal (IP) insulin infusion (CIPII).DESIGN: Nineteen patients that participated in a randomized cross-over trial comparing CIPII and subcutaneous (SC) insulin therapy in 2006 were followed until 2012. IGF-I measurements were performed at the start of the 2006 study, after the 6month SC- and CIPII treatment phase in 2006 and during CIPII therapy in 2012. Z-scores were calculated to compare the IGF-I concentrations with age-specific normative range values of a non-DM reference population.RESULTS: In 2012, IGF-I Z-scores (-0.7; 95% confidence interval -1.3, -0.2) were significantly higher than at the start of the 2006 study (-2.5; -3.3, -1.8), the end of the SC (-2.0; -2.6, -1.5) and CIPII (-1.6; -2.1, -1.0) treatment phase with a mean difference of: 1.8 (0.9, 2.7), 1.3 (0.5, 2.1) and 0.8 (0.1, 1.6), respectively.CONCLUSION: After 6years of treatment with CIPII, IGF-I concentrations among T1DM patients increased to a level that is higher than during prior SC insulin treatment and is in the lower normal range compared to a non-DM reference population. The results of this study suggest that long-term IP insulin administration influences the IGF system in T1DM.
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