Local genetic adaptation to grazing pressure of the green alga Desmodesmus armatus in a strongly connected pond system

Dispersal potentially homogenizes genetic variation among populations and thus may prevent local genetic adaptation. If selection gradients are strong and the selection response efficient, however, local genetic adaptation may persist in the face of high dispersal rates. We compared grazing-resistance traits among populations of the green microalga Desmodesmus armatus, which inhabit ponds that are ecologically different but part of a strongly interconnected pond system. Desmodesmus clones were isolated from a clear-water and a turbid pond. For 16 clones from an internal transcribed spacer 2 clade with low sequence variation (1.3%) corresponding morphologically to D. armatus, coenobial dimensions and the average number of cells per coenobium, in both the absence and the presence of water conditioned by their main grazer, the waterflea Daphnia, were determined. Clones from the clear-water pond had four-celled coenobia with a higher greatest axial linear dimension and an increased average number of cells per coenobium in response to Daphnia kairomone, contrary to clones from the turbid pond. Unexpectedly, they were also characterized by a lower average number of cells per coenobium. No differences among populations were detected for cell length. Genetic variation was present in both populations for all traits, except for the response to kairomone. Continuous dispersal through overflows and rivulets in this pond system is thus incapable of preventing strong among-population genetic differentiation for ecological relevant traits, testifying both to the capacity of phytoplankton populations to adapt to local conditions and to the importance of grazing as a structuring factor in natural phytoplankton populations

Effect of the INTER-ACT lifestyle intervention on maternal mental health during the first year after childbirth:A randomized controlled trial

We assess whether the INTER-ACT postpartum lifestyle intervention influences symptoms of depression and anxiety, sense of coherence and quality of life during the first year after childbirth. A total of 1047 women of the INTER-ACT RCT were randomized into the intervention (n = 542) or control arm (n = 505). The lifestyle intervention consisted of 4 face-to-face coaching sessions, supported by an e-health app. Anthropometric and mental health data were collected at baseline, end of intervention and 6-months follow-up. We applied mixed models to assess whether the evolution over time of depressive symptoms, anxiety, sense of coherence and quality of life differed between the intervention and control arm, taking into account the women's pre-pregnancy BMI. There was no statistical evidence for a difference in evolution in anxiety or quality of life between intervention and control arm. But an improvement in symptoms of depression and sense of coherence was observed in women who received the intervention, depending on the mother's pre-pregnancy BMI. Women with normal/overweight pre-pregnancy BMI, reported a decrease in EPDS between baseline and end of intervention, and the decrease was larger in the intervention arm (control arm: -0.42 (95% CI, -0.76 to -0.08); intervention arm: -0.71 (95% CI, -1.07 to -0.35)). Women with pre-pregnancy obesity showed an increase in EPDS between baseline and end of intervention, but the increase was less pronounced in the intervention arm (control arm: +0.71 (95% CI, -0.12 to 1.54); intervention arm: +0.42 (95% CI -0.42 to 1.25)). Women with a normal or obese pre-pregnancy BMI in the intervention arm showed a decrease in sense of coherence between baseline and end of intervention (-0.36) (95% CI, -1.60 to 0.88), while women with overweight pre-pregnancy showed an increase in sense of coherence (+1.53) (95% CI, -0.08 to 3.15) between baseline and end of intervention. Receiving the INTER-ACT postpartum lifestyle intervention showed improvement in depressive symptoms, in normal weight or overweight women on the short run, as well as improvement in sense of coherence in women with pre-pregnancy overweight only

The impact of mindfulness on functional brain connectivity and peripheral inflammation in breast cancer survivors with cognitive complaints

Simple Summary Cognitive impairment is a common side effect of cancer treatment and impacts the quality of life of cancer survivors. As there is currently no golden standard for the treatment of cancer-related cognitive impairment (CRCI), we investigated the potential of a mindfulness-based intervention to impact the underlying mechanisms of CRCI. Breast cancer survivors with cognitive complaints (n = 117) were randomly assigned to a mindfulness, physical training, or waitlist control group. Resting state functional MRI data and serum blood samples were collected and compared before and after the intervention. We could not identify differences between the groups in resting state functional connectivity. However, the functional organization of attention-, salience- and executive functioning-related neural networks differed between both intervention groups and the waitlist control group. Additionally, physical training could alter therapy-induced immune deregulation. In conclusion, physical training had the most pronounced effects on functional network organization and biomarkers of inflammation, two mechanisms that might be involved in CRCI. Background: Cancer-related cognitive impairment (CRCI) has been linked to functional brain changes and inflammatory processes. Hence, interventions targeting these underlying mechanisms are needed. In this study, we investigated the effects of a mindfulness-based intervention on brain function and inflammatory profiles in breast cancer survivors with CRCI. Methods: Female breast cancer survivors reporting cognitive complaints (n = 117) were randomly assigned to a mindfulness-based intervention (n = 43), physical training (n = 36), or waitlist control condition (n = 38). Region-of-interest (ROI) and graph theory analyses of resting state functional MRI data were performed to study longitudinal group differences in functional connectivity and organization in the default mode, dorsal attention, salience, and frontoparietal network. Additionally, bead-based immunoassays were used to investigate the differences in inflammatory profiles on serum samples. Measures were collected before, immediately after and three months post-intervention. Results: No ROI-to-ROI functional connectivity changes were identified. Compared to no intervention, graph analysis showed a larger decrease in clustering coefficient after mindfulness and physical training. Additionally, a larger increase in global efficiency after physical training was identified. Furthermore, the physical training group showed a larger decrease in an inflammatory profile compared to no intervention (IL-12p70, IFN-& gamma;, IL-1 & beta;, and IL-8). Conclusion: Both mindfulness and physical training induced changes in the functional organization of networks related to attention, emotion processing, and executive functioning. While both interventions reduced functional segregation, only physical training increased functional integration of the neural network. In conclusion, physical training had the most pronounced effects on functional network organization and biomarkers of inflammation, two mechanisms that might be involved in CRCI

Body size and dispersal mode as key traits determining metacommunity structure of aquatic organisms

Relationships between traits of organisms and the structure of their metacommunities have so far mainly been explored with meta-analyses. We compared metacommunities of a wide variety of aquatic organism groups (12 groups, ranging from bacteria to fish) in the same set of 99 ponds to minimise biases inherent to meta-analyses. In the category of passive dispersers, large-bodied groups showed stronger spatial patterning than small-bodied groups suggesting an increasing impact of dispersal limitation with increasing body size. Metacommunities of organisms with the ability to fly (i.e. insect groups) showed a weaker imprint of dispersal limitation than passive dispersers with similar body size. In contrast, dispersal movements of vertebrate groups (fish and amphibians) seemed to be mainly confined to local connectivity patterns. Our results reveal that body size and dispersal mode are important drivers of metacommunity structure and these traits should therefore be considered when developing a predictive framework for metacommunity dynamics

Lack of Phylogeographic Structure in the Freshwater Cyanobacterium Microcystis aeruginosa Suggests Global Dispersal

Background : Free-living microorganisms have long been assumed to have ubiquitous distributions with little biogeographic signature because they typically exhibit high dispersal potential and large population sizes. However, molecular data provide contrasting results and it is far from clear to what extent dispersal limitation determines geographic structuring of microbial populations. We aimed to determine biogeographical patterns of the bloom-forming freshwater cyanobacterium Microcystis aeruginosa. Being widely distributed on a global scale but patchily on a regional scale, this prokaryote is an ideal model organism to study microbial dispersal and biogeography. Methodology/Principal Findings : The phylogeography of M. aeruginosa was studied based on a dataset of 311 rDNA internal transcribed spacer (ITS) sequences sampled from six continents. Richness of ITS sequences was high (239 ITS types were detected). Genetic divergence among ITS types averaged 4% (maximum pairwise divergence was 13%). Preliminary analyses revealed nearly completely unresolved phylogenetic relationships and a lack of genetic structure among all sequences due to extensive homoplasy at multiple hypervariable sites. After correcting for this, still no clear phylogeographic structure was detected, and no pattern of isolation by distance was found on a global scale. Concomitantly, genetic differentiation among continents was marginal, whereas variation within continents was high and was mostly shared with all other continents. Similarly, no genetic structure across climate zones was detected. Conclusions/Significance : The high overall diversity and wide global distribution of common ITS types in combination with the lack of phylogeographic structure suggest that intercontinental dispersal of M. aeruginosa ITS types is not rare, and that this species might have a truly cosmopolitan distribution

Mindfulness - Application to diverse populations and working mechanisms

Chapter 1: General Introduction. The research described in this thesis is driven by two overall aims: [1] to investigate if mindfulness is a feasible and effective approach to relief different kinds of mental suffering as encountered in different contexts and settings such as social welfare centers (Chapter 2), schools (Chapter 3 and 4) and pediatric oncology units (Chapter 5); and [2] to investigate its working mechanisms across different study populations such as adolescents (Chapter 4 and 5) and adults (Chapter 2 and 6). Chapter 2: A Mindfulness-Based Intervention for economically disadvantaged people: Effects on symptoms of stress, anxiety and depression, and on cognitive reactivity and overgeneralization. The chronic exposure to stress of living with less money than one needs affects people's well-being. This study shows that a mindfulness-based intervention (MBI) significantly reduced symptoms of stress, anxiety and depression, cognitive reactivity and overgeneralization (both cognitive vulnerability factors for depression), and significantly improved mindfulness skills. These findings provide promising evidence of the effectiveness of MBIs to promote economically disadvantaged people’s mental well-being and show that a MBI is feasible in social welfare centers. Chapter 3: Potential Moderators of the Effects of a School-Based Mindfulness Program on Symptoms of Depression in Adolescents. A large randomized controlled trial delivering mindfulness or no treatment was conducted in secondary schools in Flanders. The mindfulness program was found to be effective in reducing symptoms of depression post-intervention and at six months follow-up. No moderation effects were found of gender, age, and school-track meaning that the training might work equally well for girls and boys, for younger and older students, and across school-tracks. The potential impact of mindfulness on curative as well as preventive aspects is discussed. Chapter 4: Processes of change in a school-based mindfulness program: cognitive reactivity and self-coldness as mediators. A moderated time-lagged mediation model was used to test the mediation of training effect in the randomized controlled trial data conducted in schools from Chapter 3. Post-treatment changes in cognitive reactivity and self-coldness, an aspect of self-compassion, mediated subsequent changes in symptoms of depression, anxiety and stress. The transdiagnostic nature of the intervention is discussed. Chapter 5: A Mindfulness-Based Intervention for adolescents and young adults after cancer treatment: Effects on quality of life, emotional distress, and cognitive vulnerability. The potential efficacy of a mindfulness based intervention to alleviate emotional distress and improve quality of life in adolescent and young adult cancer survivors was studied. Multilevel modelling showed 1) a significant reduction in emotional distress and improvement in quality of life at 3 months follow-up, 2) a significant reduction in negative attitudes toward self (i.e. a cognitive vulnerability factor for emotional distress, in particular depression) and 3) a significant improvement in mindfulness skills. Chapter 6: An Experience Sampling Study Examining the Potential Impact of a Mindfulness-Based Intervention on Emotion Differentiation. In this study we hypothesize, and study empirically, whether MBI may impact the differentiation of negative and positive emotions, an essential skill for adaptive emotion regulation. Multilevel modeling showed a significant improvement in negative emotion differentiation post-intervention and at four months of follow-up, and a significant improvement in positive emotion differentiation at four months follow-up. A time-lagged mediation model showed that post-treatment changes in mindfulness skills mediated subsequent changes in negative emotion differentiation. These results suggest that MBI is a promising approach to improve people’s emotion differentiation skills. Chapter 7: General Discussion. A summary and synthesis of the results is given in relation to the most recent findings in mindfulness research. Strengths and limitations are discussed and indications for future research are presented.status: publishe