1,194 research outputs found

    Evaluating the properties, fate and individual-to-ecosystem level impacts of contrasting microplastics in freshwaters

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    Microplastic particles (MPs) are fragments, fibres and other shapes derived fromplastic polymers in the size range of 1‚Äď5 000 őľm. Concern about the environmentalimpacts of MPs and their implications for human wellbeing has never been higher.Unfortunately, growth in the empirical understanding of the dynamics and impactsof MPs lags behind. This hinders the capacity of scientists, managers and policymakers to address public concerns about the true level of risk posed by MPs, andto develop effective management, policy and governance strategies for eliminatingor reducing those risks. Research on the behaviour and impacts of MPs in freshwater ecosystems is especiallydeficient, despite their vulnerability to inputs of plastic waste (e.g. via storm waterand other terrestrial runoff), and their capacity to act as key transport pathwaysthrough the landscape. This represents a substantial black box in our understandingof the dynamics of MPs from inland to the ocean. In seven research activities (5 mesocosm experiments, 1 field study and 1 literaturereview) we addressed two broad research questions:a) Initial fate and environmental interactions of MP particles in streams, includingbiofilm formation and sorption of chemical stressorsb) Ecological impacts of MPs on resource consumption, growth and survival oforganisms, and on key ecosystem processes. Among our key results addressing the initial fate and biofilm formation of MPparticles, we found that (i) biofilm formation generally made denser particles morebuoyant and caused more buoyant particles to sink faster, (ii) biofilms on polystyreneMPs supported more cyanobacteria than other polymers, and (iii) aquatic macrophytesincrease MP retention by up to 94 %. Among our key results addressing the ecological impacts of MPs, we found that almostall MP shapes and polymers studied had one or more effects on stream microbialorganisms and associated ecosystem processes (e.g. microbial respiration, detritusbreakdown), and/or on the life history of a model macroinvertebrate detritivore. We also provide evidence that effects of MPs on microbial organisms can propagateup food-chains to affect consumer growth and fat storage. Some MP impacts were similar to those of naturally occurring organic and inorganicparticles, whilst others represented a risk over and above that associated with naturalparticles. The number of MP impacts detected in our experiments provides sufficient basis for‚Äúmoving beyond the precautionary principle‚ÄĚ when motivating a need for monitoringand management ‚Äď there is now sufficient evidence that MPs alter key aspects of thefunctioning of stream benthic food webs to motivate a need for action. Based on our results, we further provide a series of recommendations formonitoring,policy and management targeting MPs, and for future research

    The recovery of European freshwater biodiversity has come to a halt

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    Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss(1). Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity(2). Here, using 1,816 time series of freshwater invertebrate communities collected across 22 European countries between 1968 and 2020, we quantified temporal trends in taxonomic and functional diversity and their responses to environmental pressures and gradients. We observed overall increases in taxon richness (0.73% per year), functional richness (2.4% per year) and abundance (1.17% per year). However, these increases primarily occurred before the 2010s, and have since plateaued. Freshwater communities downstream of dams, urban areas and cropland were less likely to experience recovery. Communities at sites with faster rates of warming had fewer gains in taxon richness, functional richness and abundance. Although biodiversity gains in the 1990s and 2000s probably reflect the effectiveness of water-quality improvements and restoration projects, the decelerating trajectory in the 2010s suggests that the current measures offer diminishing returns. Given new and persistent pressures on freshwater ecosystems, including emerging pollutants, climate change and the spread of invasive species, we call for additional mitigation to revive the recovery of freshwater biodiversity

    Effects of ulotaront on brain circuits of reward, working memory, and emotion processing in healthy volunteers with high or low schizotypy

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    Ulotaront, a trace amine-associated receptor 1 (TAAR1) and serotonin 5-HT1A receptor agonist without antagonist activity at dopamine D2 or the serotonin 5-HT2A receptors, has demonstrated efficacy in the treatment of schizophrenia. Here we report the phase 1 translational studies that profiled the effect of ulotaront on brain responses to reward, working memory, and resting state connectivity (RSC) in individuals with low or high schizotypy (LS or HS). Participants were randomized to placebo (n‚ÄČ=‚ÄČ32), ulotaront (50‚ÄČmg; n‚ÄČ=‚ÄČ30), or the D2 receptor antagonist amisulpride (400‚ÄČmg; n‚ÄČ=‚ÄČ34) 2‚ÄČh prior to functional magnetic resonance imaging (fMRI) of blood oxygen level-dependent (BOLD) responses to task performance. Ulotaront increased subjective drowsiness, but reaction times were impaired by less than 10% and did not correlate with BOLD responses. In the Monetary Incentive Delay task (reward processing), ulotaront significantly modulated striatal responses to incentive cues, induced medial orbitofrontal responses, and prevented insula activation seen in HS subjects. In the N-Back working memory task, ulotaront modulated BOLD signals in brain regions associated with cognitive impairment in schizophrenia. Ulotaront did not show antidepressant-like biases in an emotion processing task. HS had significantly reduced connectivity in default, salience, and executive networks compared to LS participants and both drugs reduced this difference. Although performance impairment may have weakened or contributed to the fMRI findings, the profile of ulotaront on BOLD activations elicited by reward, memory, and resting state is compatible with an indirect modulation of dopaminergic function as indicated by preclinical studies. This phase 1 study supported the subsequent clinical proof of concept trial in people with schizophrenia.Clinical trial registration: Registry# and URL: ClinicalTrials.gov NCT01972711, https://clinicaltrials.gov/ct2/show/NCT01972711

    Comparing effects of microplastic exposure, FPOM resource quality, and consumer density on the response of a freshwater particle feeder and associated ecosystem processes

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    Fine particulate organic matter (FPOM) is an important basal resource in stream ecosystems for deposit- and filter-feeding macroinvertebrates (collectively ‚Äėparticle feeders‚Äô). Microplastics (MP) share many characteristics with FPOM (e.g. size range, surface area to volume ratios) and are potentially consumed by particle feeders. Accordingly, MP contamination of natural FPOM pools might affect particle feeder growth and survival, particularly when background FPOM resource quality is low, or intraspecific competition is high. We conducted a microcosm experiment to evaluate how a realistic (1400 particles/kg sediment) polyethylene MP (√ł‚ÄČ=‚ÄČ45‚Äď53 ¬Ķm) concentration interacts with FPOM (√ł‚ÄČ=‚ÄČ63‚Äď250 ¬Ķm) resource quality (low versus high nutrient content) and consumer density (10 versus 20 individuals per microcosm) to affect growth and survival of larval Chironomus riparius (Diptera: Chironomidae), a model particle feeder. We additionally quantified community respiration, based on three hour measurements of oxygen consumption in the microcosms at the end of the experiment. MP exposure reduced larval body lengths by 26.7%, but only under the low consumer density treatment. MPs reduced community respiration by 26.2%, but only in the absence of chironomids, indicating an impact on microbial respiration. In comparison, low resource quality and high consumer density were associated with 53.5‚Äď70.2% reductions in community respiration, chironomid body length and/or body mass. These results suggest that effects of contamination of FPOM with MPs at environmentally realistic concentrations on the life histories of particle feeders such as C. riparius might be limited, especially relative to the effects of resource quality and consumer density. However, the reduction in microbial respiration when MPs were present highlights the need for further research addressing MP impacts on microbes, given their key roles in ecosystem functioning.publishedVersio

    A second update on mapping the human genetic architecture of COVID-19

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