798 research outputs found
gutSMASH predicts specialized primary metabolic pathways from the human gut microbiota
The gut microbiota produce hundreds of small molecules, many of which modulate host physiology. Although efforts have been made to identify biosynthetic genes for secondary metabolites, the chemical output of the gut microbiome consists predominantly of primary metabolites. Here we introduce the gutSMASH algorithm for identification of primary metabolic gene clusters, and we used it to systematically profile gut microbiome metabolism, identifying 19,890 gene clusters in 4,240 high-quality microbial genomes. We found marked differences in pathway distribution among phyla, reflecting distinct strategies for energy capture. These data explain taxonomic differences in short-chain fatty acid production and suggest a characteristic metabolic niche for each taxon. Analysis of 1,135 individuals from a Dutch population-based cohort shows that the level of microbiome-derived metabolites in plasma and feces is almost completely uncorrelated with the metagenomic abundance of corresponding metabolic genes, indicating a crucial role for pathway-specific gene regulation and metabolite flux. This work is a starting point for understanding differences in how bacterial taxa contribute to the chemistry of the microbiome.</p
gutSMASH predicts specialized primary metabolic pathways from the human gut microbiota
The gut microbiota produce hundreds of small molecules, many of which modulate host physiology. Although efforts have been made to identify biosynthetic genes for secondary metabolites, the chemical output of the gut microbiome consists predominantly of primary metabolites. Here we introduce the gutSMASH algorithm for identification of primary metabolic gene clusters, and we used it to systematically profile gut microbiome metabolism, identifying 19,890 gene clusters in 4,240 high-quality microbial genomes. We found marked differences in pathway distribution among phyla, reflecting distinct strategies for energy capture. These data explain taxonomic differences in short-chain fatty acid production and suggest a characteristic metabolic niche for each taxon. Analysis of 1,135 individuals from a Dutch population-based cohort shows that the level of microbiome-derived metabolites in plasma and feces is almost completely uncorrelated with the metagenomic abundance of corresponding metabolic genes, indicating a crucial role for pathway-specific gene regulation and metabolite flux. This work is a starting point for understanding differences in how bacterial taxa contribute to the chemistry of the microbiome.</p
Spatial coâlocalisation of extreme weather events: a clear and present danger
Extreme weather events have become a dominant feature of the narrative surrounding changes in global climate with large impacts on ecosystem stability, functioning and resilience; however, understanding of their risk of coâoccurrence at the regional scale is lacking. Based on the UK Met Officeâs longâterm temperature and rainfall records, we present the first evidence demonstrating significant increases in the magnitude, direction of change and spatial coâlocalisation of extreme weather events since 1961. Combining this new understanding with landâuse data sets allowed us to assess the likely consequences on future agricultural production and conservation priority areas. All landâuses are impacted by the increasing risk of at least one extreme event and conservation areas were identified as the hotspots of risk for the coâoccurrence of multiple event types. Our findings provide a basis to regionally guide landâuse optimisation, land management practices and regulatory actions preserving ecosystem services against multiple climate threats
Resilience of ecosystem service delivery in grasslands in response to single and compound extreme weather events
Extreme weather events are increasing in frequency and magnitude with profound effects on ecosystem functioning. Further, there is now a greater likelihood that multiple extreme events are occurring within a single year. Here we investigated the effect of a single drought, flood or compound (flood + drought) extreme event on temperate grassland ecosystem processes in a field experiment. To assess system resistance and resilience, we studied changes in a wide range of above- and below-ground indicators (plant diversity and productivity, greenhouse gas emissions, soil chemical, physical and biological metrics) during the 8 week stress events and then for 2 years post-stress. We hypothesized that agricultural grasslands would have different degrees of resistance and resilience to flood and drought stress. We also investigated two alternative hypotheses that the combined flood + drought treatment would either, (A) promote ecosystem resilience through more rapid recovery of soil moisture conditions or (B) exacerbate the impact of the single flood or drought event. Our results showed that flooding had a much greater effect than drought on ecosystem processes and that the grassland was more resistant and resilient to drought than to flood. The immediate impact of flooding on all indicators was negative, especially for those related to production, and climate and water regulation. Flooding stress caused pronounced and persistent shifts in soil microbial and plant communities with large implications for nutrient cycling and long-term ecosystem function. The compound flood + drought treatment failed to show a more severe impact than the single extreme events. Rather, there was an indication of quicker recovery of soil and microbial parameters suggesting greater resilience in line with hypothesis (A). This study clearly reveals that contrasting extreme weather events differentially affect grassland ecosystem function but that concurrent events of a contrasting nature may promote ecosystem resilience to future stress
Impacts of abiotic stresses on the physiology and metabolism of cool-season grasses:A review
Grasslands cover more than 70% of the world's agricultural land playing a pivotal role in global food security, economy, and ecology due to their flexibility and functionality. Climate change, characterized by changes in temperature and precipitation patterns, and by increased levels of greenhouse gases in the atmosphere, is anticipated to increase both the frequency and severity of extreme weather events, such as drought, heat waves, and flooding. Potentially, climate change could severely compromise future forage crop production and should be considered a direct threat to food security. This review aimed to summarize our current understanding of the physiological and metabolic responses of temperate grasses to those abiotic stresses associated with climate change. Primarily, substantial decreases in photosynthetic rates of coolâseason grasses occur as a result of high temperatures, waterâdeficit or waterâexcess, and elevated ozone, but not CO2 concentrations. Those decreases are usually attributed to stomatal and nonâstomatal limitations. Additionally, while membrane instability and reactive oxygen species production was a common feature of the abiotic stress response, total antioxidant capacity showed a stressâspecific response. Furthermore, climate changeârelated stresses altered carbohydrate partitioning, with implications for biomass production. While waterâdeficit stress, increased CO2, and ozone concentrations resulted in higher carbohydrate content, the opposite occurred under conditions of heat stress and flooding. The extent of damage is greatly dependent on location, as well as the type and intensity of stress. Fortunately, temperate forage grass species are highly heterogeneous. Consequently, through intraâ and in particular interâspecific plant hybridization (e.g., Festuca x Lolium hybrids) new opportunities are available to harness, within single genotypes, gene combinations capable of combating climate change
Effect of PCI on health status in ischemic left ventricular dysfunction: insights from REVIVED-BCIS2
Background
In the REVIVED-BCIS2 (Revascularization for Ischemic Ventricular Dysfunction) trial, percutaneous coronary intervention (PCI) did not reduce the incidence of death or hospitalization for heart failure (HHF).
Objectives
This prespecified secondary analysis investigated the effect of PCI on health status measured with the Kansas City Cardiomyopathy Questionnaire (KCCQ) combined with the primary outcome in a win ratio.
Methods
Participants with severe ischemic left ventricular dysfunction were randomized to either PCI in addition to optimal medical therapy (OMT) (PCI) or OMT alone (OMT). The primary outcome was a hierarchical composite of all-cause death, HHF, and KCCQâOverall Summary Score (OSS) at 24 months analyzed using the unmatched win ratio. The key secondary endpoint was a KCCQ-OSS responder analysis.
Results
A total of 347 participants were randomized to PCI and 353 to OMT. Median age was 70.0 years (Q1-Q3: 63.3-76.1 years). Mean left ventricular ejection fraction was 27.0 Âą 6.7%. PCI did not improve the primary endpoint (win ratio for PCI vs OMT: 1.05; 95% CI: 0.88-1.26; P = 0.58). PCI resulted in more KCCQ-OSS responders than OMT at 6 months (54.1% vs 40.7%; OR: 1.96; 95% CI: 1.41-2.71; P < 0.001) and fewer deteriorators (25.2% vs 31.4%; OR: 0.69; 95% CI: 0.47-1.00; P = 0.048). PCI did not impact KCCQ-OSS responders or deteriorators at 12 or 24 months.
Conclusions
PCI did not improve the hierarchical composite of death, HHF, and health status at 2 years. PCI improved KCCQ-OSS at 6 months, but this benefit was not sustained to 1- or 2-year follow-up
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