Global change is altering species distributions and thus interactions among organisms. Organisms live in concert with thousands of other species, some beneficial, some pathogenic, some which have ...little to no effect in complex communities. Since natural communities are composed of organisms with very different life history traits and dispersal ability it is unlikely they will all respond to climatic change in a similar way. Disjuncts in plant-pollinator and plant-herbivore interactions under global change have been relatively well described, but plant-soil microorganism and soil microbe-microbe relationships have received less attention. Since soil microorganisms regulate nutrient transformations, provide plants with nutrients, allow co-existence among neighbors, and control plant populations, changes in soil microorganism-plant interactions could have significant ramifications for plant community composition and ecosystem function. In this paper we explore how climatic change affects soil microbes and soil microbe-plant interactions directly and indirectly, discuss what we see as emerging and exciting questions and areas for future research, and discuss what ramifications changes in these interactions may have on the composition and function of ecosystems.
Heme is an essential cofactor and signaling molecule required for virtually all aerobic life. However, excess heme is cytotoxic. Therefore, heme must be safely transported and trafficked from the ...site of synthesis in the mitochondria or uptake at the cell surface, to hemoproteins in most subcellular compartments. While heme synthesis and degradation are relatively well characterized, little is known about how heme is trafficked and transported throughout the cell. Herein, we review eukaryotic heme transport, trafficking, and mobilization, with a focus on factors that regulate bioavailable heme. We also highlight the role of gasotransmitters and small molecules in heme mobilization and bioavailability, and heme trafficking at the host-pathogen interface.
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•Heme is transported and trafficked within and between cells for use in hemoproteins and for signaling.•The mechanisms underlying heme mobilization, trafficking, and transport, which are not well understood, are reviewed.•A number of signaling molecules, including H2O2 and NO, regulate heme dynamics, bioavailability and trafficking.•The transport and trafficking of heme in most human pathogens is required for virulence.
The in vitro formation of stable G-quadruplexes (G4s) in human rRNA was recently reported. However, their formation in cells and their cellular roles were not resolved. Here, by taking a chemical ...biology approach that integrates results from immunofluorescence, G4 ligands, heme-affinity reagents, and a genetically encoded fluorescent heme sensor, we report that human ribosomes can form G4s in vivo that regulate heme bioavailability. Immunofluorescence experiments indicate that the vast majority of extra-nuclear G4s are associated with rRNA. Moreover, titrating human cells with a G4 ligand alters the ability of ribosomes to bind heme and disrupts cellular heme bioavailability as measured by a genetically encoded fluorescent heme sensor. Overall, these results suggest that ribosomes play a role in regulating heme homeostasis.
Heme is a ubiquitous and essential iron containing metallo-organic cofactor required for virtually all aerobic life. Heme synthesis is initiated and completed in mitochondria, followed by certain ...covalent modifications and/or its delivery to apo-hemoproteins residing throughout the cell. While the biochemical aspects of heme biosynthetic reactions are well understood, the trafficking of newly synthesized heme-a highly reactive and inherently toxic compound-and its subsequent delivery to target proteins remain far from clear. In this review, we summarize current knowledge about heme biosynthesis and trafficking within and outside of the mitochondria.
Roots release carbon into soil and can alleviate energy limitation of microbial organic matter decomposition. We know little about the effects of roots on microbial decomposition of different organic ...matter substrates, despite the importance for soil carbon stocks and turnover. Through implementing root–microbe interactions, the Carbon, Organisms, Rhizosphere and Protection in the Soil Environment (CORPSE) model was previously shown to represent dynamics of total soil carbon in temperate forest field experiments. However, the model permits alternative hypotheses concerning microbial‐substrate affinity.
We investigated how root inputs affect decomposition of soil organic carbon (SOC) with variable decomposability. We simulated SOC stocks in CORPSE and compared microbial degradation of two substrate types with varying root–microbe interactions under two alternative hypotheses that varied in microbial‐substrate affinity. We compared our modelled hypotheses to a forest field experiment where we quantified decomposition of isotopically labelled starch and leaf tissues in soils with manipulated root access to microbes. We tested the hypothesis that decomposition of leaves would be more sensitive to root inputs than decomposition of starch, corresponding to the alternative model hypotheses.
In the field study, leaf decomposition increased with root density, whereas starch decomposition was unchanged by root density. Microbial biomass and enzyme activity consistently increased with root inputs in CORPSE and the field study. Our field experiment supported the CORPSE simulations with high microbial‐substrate affinity.
Roots stimulated microbial growth and enzyme production, which increased the degradation of more complex substrates such as leaf tissues. Substrates that were easily decomposed, such as starch, may already be degrading at a maximum rate in the absence of rhizosphere influence because their decomposition rate was unchanged by root inputs. We found that the degree to which roots stimulate microbial decomposition depends on the substrate being decomposed, and that root–microbe interactions influenced SOC stocks in both our model and field experiment. Environmental changes that alter root–microbe interactions could, therefore, alter soil C stocks and biogeochemical cycling, and models of these interactions should incorporate differential influence of rhizosphere inputs on different substrates.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
Time for evidence-based, standardized donor size matching for pediatric heart transplantation Riggs, Kyle W.; Giannini, Courtney M.; Szugye, Nicholas ...
Journal of thoracic and cardiovascular surgery/The Journal of thoracic and cardiovascular surgery/The journal of thoracic and cardiovascular surgery,
December 2019, 2019-12-00, 20191201, Letnik:
158, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Accurately predicting cardiac size by other body parameters has long been problematic to determine whether a donor heart will serve a given waitlist candidate, yet hundreds of heart donors are turned ...down annually for size mismatch.
We sought to describe how donor body weight parameters are currently utilized in cardiac transplantation and its influence on waitlist outcomes.
From the United Network for Organ Sharing database, pediatric (age <18 years) heart transplant candidates were divided into lower quartile, interquartile, and upper quartile categories based on final maximum acceptable donor–candidate weight ratio (DCW), expressed as percentage. Baseline characteristics and waitlist outcomes, including monthly offers/candidate and survival were compared.
Overall median DCW was 200% (range, 159%-241%). Patients with congenital heart disease had higher DCW than those with cardiomyopathy (223% vs 203%; P < .001). Number of monthly offers/candidate (5.0, 5.6, and 7.2, respectively; P < .001) increased with quartile of DCW. Posttransplant survival was similar amongst the groups (log-rank P > .05). Subgroup analysis of critically ill children showed a waitlist survival advantage in those listed with a DCW ≥200% (P < .001).
Despite substantial practice variation in acceptable donor weight in pediatric heart transplantation, patients listed with variable DCW had similar posttransplant survival. However, in critically ill patients, higher DCW was associated with greater waitlist survival. Better understanding of the importance of donor weight could reduce practice variability and improve organ use and waitlist outcomes for pediatric cardiac transplant candidates.
The Prostate Health Index is validated for prostate cancer detection but has not been well validated for Gleason grade group 2-5 prostate cancer detection in Black men. We hypothesize that the ...Prostate Health Index has greater accuracy than prostate specific antigen for detection of Gleason grade group 2-5 prostate cancer. We estimated probability of overall and Gleason grade group 2-5 prostate cancer across previously established Prostate Health Index ranges and identified Prostate Health Index cutoffs that maximize specificity for Gleason grade group 2-5 prostate cancer with sensitivity >90%.
We recruited a "cancer-free" Black control cohort (135 patients) and a cohort of biopsy naïve Black men (158) biopsied for elevated prostate specific antigen. Descriptive statistics compared the prostate cancer cases and controls and the frequency of Gleason grade group 2-5 prostate cancer across Prostate Health Index scores. Receiver operating characteristics compared the discrimination of prostate specific antigen, Prostate Health Index and other prostate specific antigen related biomarkers. Sensitivity and specificity for Gleason grade group 2-5 prostate cancer detection were assessed at prostate specific antigen and Prostate Health Index thresholds alone and in series.
Of biopsied subjects 32.9% had Gleason grade group 2-5 prostate cancer. In Blacks with prostate specific antigen from 4.0-10.0 ng/ml, Prostate Health Index and prostate specific antigen had similar discrimination for Gleason grade group 2-5 prostate cancer (0.63 vs 0.57, p=0.27). In Blacks with prostate specific antigen ≤10.0, a threshold of prostate specific antigen ≥4.0 had 90.4% sensitivity for Gleason grade group 2-5 prostate cancer; a threshold of prostate specific antigen ≥4.0 with Prostate Health Index ≥35.0 in series avoided unnecessary biopsy in 33.0% of men but missed 17.3% of Gleason grade group 2-5 prostate cancer. Prostate specific antigen ≥4.0 with Prostate Health Index ≥28.0 in series spared biopsy in 17.9%, while maintaining 90.4% sensitivity of Gleason grade group 2-5 prostate cancer.
The Prostate Health Index has moderate accuracy in detecting Gleason grade group 2-5 prostate cancer in Blacks, but Prostate Health Index ≥28.0 can be safely used to avoid some unnecessary biopsies in Blacks.
Plant roots, their associated microbial community and free‐living soil microbes interact to regulate the movement of carbon from the soil to the atmosphere, one of the most important and least ...understood fluxes of terrestrial carbon. Our inadequate understanding of how plant–microbial interactions alter soil carbon decomposition may lead to poor model predictions of terrestrial carbon feedbacks to the atmosphere. Roots, mycorrhizal fungi and free‐living soil microbes can alter soil carbon decomposition through exudation of carbon into soil. Exudates of simple carbon compounds can increase microbial activity because microbes are typically carbon limited. When both roots and mycorrhizal fungi are present in the soil, they may additively increase carbon decomposition. However, when mycorrhizas are isolated from roots, they may limit soil carbon decomposition by competing with free‐living decomposers for resources. We manipulated the access of roots and mycorrhizal fungi to soil in situ in a temperate mixed deciduous forest. We added ¹³C‐labelled substrate to trace metabolized carbon in respiration and measured carbon‐degrading microbial extracellular enzyme activity and soil carbon pools. We used our data in a mechanistic soil carbon decomposition model to simulate and compare the effects of root and mycorrhizal fungal presence on soil carbon dynamics over longer time periods. Contrary to what we predicted, root and mycorrhizal biomass did not interact to additively increase microbial activity and soil carbon degradation. The metabolism of ¹³C‐labelled starch was highest when root biomass was high and mycorrhizal biomass was low. These results suggest that mycorrhizas may negatively interact with the free‐living microbial community to influence soil carbon dynamics, a hypothesis supported by our enzyme results. Our steady‐state model simulations suggested that root presence increased mineral‐associated and particulate organic carbon pools, while mycorrhizal fungal presence had a greater influence on particulate than mineral‐associated organic carbon pools. Synthesis. Our results suggest that the activity of enzymes involved in organic matter decomposition was contingent upon root–mycorrhizal–microbial interactions. Using our experimental data in a decomposition simulation model, we show that root–mycorrhizal–microbial interactions may have longer‐term legacy effects on soil carbon sequestration. Overall, our study suggests that roots stimulate microbial activity in the short term, but contribute to soil carbon storage over longer periods of time.
Heme oxygenases (HOs) detoxify heme by oxidatively degrading it into carbon monoxide, iron, and biliverdin, which is reduced to bilirubin and excreted. Humans express two isoforms of HO: the ...inducible HO-1, which is upregulated in response to excess heme and other stressors, and the constitutive HO-2. Much is known about the regulation and physiological function of HO-1, whereas comparatively little is known about the role of HO-2 in regulating heme homeostasis. The biochemical necessity for expressing constitutive HO-2 is dependent on whether heme is sufficiently abundant and accessible as a substrate under conditions in which HO-1 is not induced. By measuring labile heme, total heme, and bilirubin in human embryonic kidney HEK293 cells with silenced or overexpressed HO-2, as well as various HO-2 mutant alleles, we found that endogenous heme is too limiting a substrate to observe HO-2-dependent heme degradation. Rather, we discovered a novel role for HO-2 in the binding and buffering of heme. Taken together, in the absence of excess heme, we propose that HO-2 regulates heme homeostasis by acting as a heme buffering factor that controls heme bioavailability. When heme is in excess, HO-1 is induced, and both HO-2 and HO-1 can provide protection from heme toxicity via enzymatic degradation. Our results explain why catalytically inactive mutants of HO-2 are cytoprotective against oxidative stress. Moreover, the change in bioavailable heme due to HO-2 overexpression, which selectively binds ferric over ferrous heme, is consistent with labile heme being oxidized, thereby providing new insights into heme trafficking and signaling.
Objectives
The goal of this study was to assess how the mental health of dental trainees has changed during the pandemic and to identify the most stressful aspects of trainees’ programs, stress ...coping strategies, and suggestions for individual and institution‐driven solutions to improve wellness.
Methods
The study focused on dental trainees at the University of Washington who completed a wellness survey in fall 2020 (n = 126; response rate = 35.5%) and spring 2021 (n = 105; response rate = 29.6%). The survey included self‐report measures assessing four mental health outcomes: depression, anxiety, isolation from peers, and burnout. Stressful aspects of the training program, coping strategies, and institution‐driven solutions were measured with open‐ended survey items. The chi‐square test was used to compare mental health outcome measures between fall and spring and open‐ended survey responses were inductively coded.
Results
The prevalence of self‐reported depression and anxiety did not change between fall 2020 and spring 2021 (17.2% vs. 21.1%, p = 0.473; 22.4% vs. 23.7%, p = 0.818). Isolation from peers and burnout each significantly increased by almost 20% from fall 2020 to spring 2021 (46.8% vs. 64.3%; p = 0.009 and 26.6% vs. 43.9%; p = 0.017). Trainees identified workload as the most stressful aspect of their program and described using exercise and social support to cope with stress. Trainees suggested institution‐supported increases in social events and mental health resources.
Conclusions
One year into the coronavirus disease 2019 pandemic, poor mental health outcomes were common among dental trainees because of high workload and isolation from peers. Dental schools should promote targeted programs and services aimed at improving dental trainees' well‐being.
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