Publications by authors named "Hayer M"

Fungi play a crucial role in aquatic leaf litter decomposition. Aquatic fungi have long been thought to spend the majority of their lives in the water. Here, we explore the possibility of an amphibious life cycle, where phyllosphere fungi spend part of their life cycle in aquatic systems.

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  • Measuring the growth rate of microorganisms is crucial for understanding their role in ecosystems, as it reflects their resource use, biomass production, and impact on elements essential for life.
  • Microbial adaptability determines their success, where rapid reproduction in favorable conditions and survival strategies in harsher conditions are linked to their relative growth rates.
  • Advanced techniques like omics and stable isotope probing allow scientists to analyze microbial growth in soil, helping to connect microbial diversity and environmental factors to important ecosystem processes like carbon flux and nutrient cycling.
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Protists are a diverse and understudied group of microbial eukaryotic organisms especially in terrestrial environments. Advances in molecular methods are increasing our understanding of the distribution and functions of these creatures; however, there is a vast array of choices researchers make including barcoding genes, primer pairs, PCR settings, and bioinformatic options that can impact the outcome of protist community surveys. Here, we tested four commonly used primer pairs targeting the V4 and V9 regions of the 18S rRNA gene using different PCR annealing temperatures and processed the sequences with different bioinformatic parameters in 10 diverse soils to evaluate how primer pair, amplification parameters, and bioinformatic choices influence the composition and richness of protist and non-protist taxa using Illumina sequencing.

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High-temperature geothermal springs host simplified microbial communities; however, the activities of individual microorganisms and their roles in the carbon cycle in nature are not well understood. Here, quantitative stable isotope probing (qSIP) was used to track the assimilation of C-acetate and C-aspartate into DNA in 74 °C sediments in Gongxiaoshe Hot Spring, Tengchong, China. This revealed a community-wide preference for aspartate and a tight coupling between aspartate incorporation into DNA and the proliferation of aspartate utilizers during labeling.

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  • Predicting how ecosystems function is essential for understanding the impact of climate change, but current predictions often ignore the role of microbial biodiversity.* -
  • New methods allow scientists to measure specific traits of microbes, revealing that evolutionary history (phylogeny) can help predict bacterial growth rates in different environments like Arctic, boreal, temperate, and tropical ecosystems.* -
  • The study found that phylogenetic relationships can explain a significant portion of the variation in bacterial growth rates, suggesting that understanding microbial evolution can enhance predictions about ecosystem processes.*
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  • - The study investigates how density dependence affects bacterial populations in soil ecosystems, especially under nutrient addition conditions, using a method called quantitative stable isotope probing (qSIP).
  • - Results show that in soils with added nitrogen and carbon, higher bacterial population densities lead to lower growth rates and higher mortality rates, contradicting the expectation that density dependence supports biodiversity.
  • - Overall, the findings suggest that stronger negative density dependence linked to nutrient availability may actually reduce bacterial diversity rather than promote it, indicating a complex relationship between density and ecosystem dynamics in microbial communities.
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  • - Increased Arctic temperatures are causing permafrost to thaw and enhancing microbial activity in tundra soils, releasing greenhouse gases that further contribute to climate change.
  • - A study examining the growth responses of soil bacteria under short-term (3 months) and long-term (29 years) warming found that short-term warming led to a 36% increase in microbial growth rates, while long-term warming resulted in a more significant 151% increase largely among existing taxa.
  • - The research highlights that bacteria respond differently to varying durations of warming, suggesting that understanding these microbial reactions is crucial as soil carbon stocks in tundra become more vulnerable due to climate change impacts.
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  • The study examines how life history strategies, particularly the copiotroph-oligotroph framework, can predict bacterial growth rates in different soil ecosystems.
  • Researchers measured bacterial responses to glucose and ammonium to see how well these groups sorted bacteria based on their nutrient use.
  • Results showed significant nutrient response overlap among bacterial taxa, indicating that finer taxonomic classifications (like genus) are more effective than broad classifications (like phylum) in understanding microbial growth patterns in varying soil conditions.
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Biological soil crusts (biocrusts) are critical components of dryland and other ecosystems worldwide, and are increasingly recognized as novel model ecosystems from which more general principles of ecology can be elucidated. Biocrusts are often diverse communities, comprised of both eukaryotic and prokaryotic organisms with a range of metabolic lifestyles that enable the fixation of atmospheric carbon and nitrogen. However, how the function of these biocrust communities varies with succession is incompletely characterized, especially in comparison to more familiar terrestrial ecosystem types such as forests.

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  • Secondary minerals, especially short-range order minerals, significantly influence soil composition and microbial communities, affecting how bacteria grow in different soils.
  • A study examined three soils with various mineral contents, finding that the presence of short-range order minerals suppressed bacterial growth overall, impacting 25-36% of bacterial taxa across the soils.
  • The addition of carbon from plant litter or root exudates had a minor effect on bacterial growth compared to soil type, but still promoted growth for some bacterial families, indicating the complex interactions between bacteria, minerals, and organic matter in soil carbon processing.
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  • The carbon stored in soil plays a crucial role in global climate stability, surpassing carbon in plants and the atmosphere, with decomposer microorganisms significantly influencing soil carbon dynamics.
  • A 15-year warming experiment showed a consistent decrease in soil microbial growth rates, regardless of taxa, suggesting uniform responses to temperature changes across different microbial groups.
  • Long-term warming resulted in reduced soil carbon content and microbial biomass, indicating that the impacts of warming on microbial growth and soil health could contribute to feedback mechanisms affecting climate change.
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  • Microbial decomposition of leaves in rivers starts quickly and involves various species of fungi and bacteria, influenced by stream conditions and leaf type.
  • This study investigates the growth of these microbes during decomposition, comparing those that come with the leaves versus those that colonize in the water.
  • Findings show most fungi are dormant upon entering water, while bacteria are actively growing, highlighting the contrasting roles of fungal and bacterial populations in aquatic ecosystems.
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Objectives: The aims of this study were to quantify preoperative myocardial fibrosis using late gadolinium enhancement (LGE), extracellular volume fraction (ECV%), and indexed extracellular volume (iECV) on cardiac magnetic resonance; determine whether this varies following surgery; and examine the impact on postoperative outcomes.

Background: Myocardial fibrosis complicates chronic severe primary mitral regurgitation and is associated with left ventricular dilatation and dysfunction. It is not known if this nonischemic fibrosis is reversible following surgery or if it affects ventricular remodeling and patient outcomes.

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  • Nutrient amendments reduced the diversity of bacteria in soil, causing carbon flow to be dominated by fewer bacterial types.
  • Different bacterial groups were found to play distinct roles in respiration across four ecosystems, suggesting that specific taxa could control soil carbon cycling.
  • The study highlights the importance of understanding carbon flow through specific bacteria to improve soil carbon models, which could help refine predictions related to climate change.*
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  • Predation plays a crucial role in ecosystems, impacting food webs, energy flow, and nutrient cycling, though most research has focused on larger predators rather than microscopic ones like bacteria.
  • This study found that obligate predatory bacteria exhibited significantly higher growth and carbon uptake (36% and 211% more, respectively) compared to nonpredatory bacteria across various environments, while facultative predators showed only slightly enhanced rates.
  • The research indicates that increased energy flow in microbial communities boosts the role of predatory bacteria, suggesting that more productive environments lead to stronger predatory influence on lower trophic levels.
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  • Microorganisms play a crucial role in breaking down soil carbon, and their activity can change with rising temperatures, potentially influencing climate change.
  • This study investigates how different bacterial groups from various climates (Arctic, boreal, temperate, and tropical) respond to temperature changes, revealing that each group's growth sensitivity to temperature varies.
  • The research indicates that the traits of these bacterial communities can help predict how carbon cycling will respond to climate change globally.
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Background And Objectives: The Effect of a Reduction in GFR after Nephrectomy on Arterial Stiffness and Central Hemodynamics (EARNEST) study was a multicenter, prospective, controlled study designed to investigate the associations of an isolated reduction in kidney function on BP and arterial hemodynamics.

Design, Setting, Participants, & Measurements: Prospective living kidney donors and healthy controls who fulfilled criteria for donation were recruited from centers with expertise in vascular research. Participants underwent office and ambulatory BP measurement, assessment of arterial stiffness, and biochemical tests at baseline and 12 months.

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Objectives: A proof of concept cross-sectional study investigating changes in myocardial abnormalities across stages of chronic kidney disease (CKD). Characterizing noninvasive markers of myocardial fibrosis on cardiac magnetic resonance, echocardiography, and correlating with biomarkers of fibrosis, myocardial injury, and functional correlates including exercise tolerance.

Background: CKD is associated with an increased risk of cardiovascular death.

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Root endophytes are a promising tool for increasing plant growth, but it is unclear whether they perform consistently across plant hosts. We characterized the blue grama (Bouteloua gracilis) root microbiome using two sequencing methods, quantified the effects of root endophytes in the original host (blue grama) and an agricultural recipient, corn (Zea mays), under drought and well-watered conditions and examined in vitro mechanisms for plant growth promotion. 16S rRNA amplicon sequencing revealed that the blue grama root microbiome was similar across an elevation gradient, with the exception of four genera.

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Background: Late gadolinium enhancement (LGE) using cardiac magnetic resonance (CMR) characterizes myocardial disease and predicts an adverse cardiovascular (CV) prognosis. Myocardial abnormalities, are present in early chronic kidney disease (CKD). To date there are no data defining prevalence, pattern and clinical implications of LGE-CMR in CKD.

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  • - Quantitative stable isotope probing (qSIP) measures how specific microorganisms absorb elements using substrates with heavy isotopes, allowing researchers to identify which taxa are taking up certain nutrients.
  • - The qSIP laboratory process is similar to regular stable isotope probing but includes two important steps: measuring the DNA in density fractions with qPCR and sequencing multiple density fractions to capture all nucleic acids present.
  • - This method not only identifies the microorganisms that are utilizing a particular substrate but also quantifies the extent of that assimilation for each taxon in the microbial community.
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We describe a protocol for investigating microbial growth in environmental samples via stable isotope probing (SIP) with HO. Water is a universal substrate for all microorganisms and replication is required for DNA to become labeled with O. By measuring how much the DNA of each taxon becomes enriched with O when an environmental sample is incubated with HO, it is feasible to quantify that population's DNA replication rate, which is a proxy for growth.

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Increased native myocardial T1 times in chronic kidney disease (CKD) may be due to diffuse interstitial myocardial fibrosis (DIF) or due to interstitial edema/inflammation. Concerns relating to nephrogenic systemic fibrosis with gadolinium-based contrast agents (GBCA) limit their use in end-stage kidney disease (ESKD) to measure extracellular volume (ECV) and characterise myocardial fibrosis. This study aimed to examine stability of myocardial T1 and T2 times before, and within 2 months after kidney transplantation; a time frame when volume status normalises but myocardial remodelling is unlikely to have occurred, and to compare these with ECV using GBCA after transplantation.

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