An evolutionary disruption of the buzz pollination syndrome in neotropical montane plants.

PREMISE: Under pollinator limitations, specialized pollination syndromes may evolve toward contrasting responses: a generalized syndrome with increased pollinator attraction, pollinator reward, and pollen transfer capacity; or the selfing syndrome with increased self-pollen deposition, but reduced pollinator attraction and pollen transfer capacity. The buzz-pollination syndrome is specialized to explore female vibrating bees as pollinators. However, vibrating bees become less-active pollinators at montane areas of the Atlantic Forest (AF) domain. This study investigated whether the specialized buzz-pollination syndrome would evolve toward an alternative floral syndrome in montane areas of the AF domain, considering a generalized and the selfing syndromes as alternative responses. METHODS: We utilized a lineage within the buzz-pollinated Miconia as study system, contrasting floral traits between montane AF-endemic and non-endemic species. We measured and validated floral traits that were proxies for pollinator attraction, reward access, pollen transfer capacity, and self-pollen deposition. We inferred the evolution of floral trait via phylogenetic comparative methods. RESULTS: AF-endemic species have selectively evolved greater reward access and more frequently had generalist pollination. Nonetheless, AF-endemic species also have selectively evolved toward lower pollen transfer capacity and greater self pollination. These patterns indicated a complex evolutionary process that has jointly favored a generalized and the selfing syndromes. CONCLUSIONS: The buzz pollination syndrome can undergo an evolutionary disruption in montane areas of the AF domain. This floral syndrome is likely more labile than often assumed, allowing buzz-pollinated plants to reproduce in environments where vibrating bees are less-reliable pollinators.

Phosphate limitation enhances malic acid production on nitrogen-rich molasses with Ustilago trichophora.

BACKGROUND: An important step in replacing petrochemical products with sustainable, cost-effective alternatives is the use of feedstocks other than, e.g., pure glucose in the fermentative production of platform chemicals. Ustilaginaceae offer the advantages of a wide substrate spectrum and naturally produce a versatile range of value-added compounds under nitrogen limitation. A promising candidate is the dicarboxylic acid malic acid, which may be applied as an acidulant in the food industry, a chelating agent in pharmaceuticals, or in biobased polymer production. However, fermentable residue streams from the food and agricultural industry with high nitrogen content, e.g., sugar beet molasses, are unsuited for processes with Ustilaginaceae, as they result in low product yields due to high biomass and low product formation. RESULTS: This study uncovers challenges in evaluating complex feedstock applicability for microbial production processes, highlighting the role of secondary substrate limitations, internal storage molecules, and incomplete assimilation of these substrates. A microliter-scale screening method with online monitoring of microbial respiration was developed using malic acid production with Ustilago trichophora on molasses as an application example. Investigation into nitrogen, phosphate, sulphate, and magnesium limitations on a defined minimal medium demonstrated successful malic acid production under nitrogen and phosphate limitation. Furthermore, a reduction of nitrogen and phosphate in the elemental composition of U. trichophora was revealed under the respective secondary substrate limitation. These adaptive changes in combination with the intricate metabolic response hinder mathematical prediction of product formation and make the presented screening methodology for complex feedstocks imperative. In the next step, the screening was transferred to a molasses-based complex medium. It was determined that the organism assimilated only 25% and 50% of the elemental nitrogen and phosphorus present in molasses, respectively. Due to the overall low content of bioavailable phosphorus in molasses, the replacement of the state-of-the-art nitrogen limitation was shown to increase malic acid production by 65%. CONCLUSION: The identification of phosphate as a superior secondary substrate limitation for enhanced malic acid production opens up new opportunities for the effective utilization of molasses as a more sustainable and cost-effective substrate than, e.g., pure glucose for biobased platform chemical production.

Species turnover and functional nestedness constitute the geographic patterns of stream diatoms in the Three Parallel Rivers region, China.

Unraveling biodiversity patterns and their driving processes is paramount in ecology and biogeography. However, there remains a limited understanding regarding the underlying mechanisms of community assembly, particularly in alpine streams where significant elevation gradients and habitat heterogeneity exist. We investigated the patterns and drivers of beta diversity, explicitly focusing on taxonomic and functional diversity, in the three parallel rivers region in China. We employed a beta diversity partitioning approach to examine the turnover and nestedness components of beta diversity and further deconstructed the diatom community into attached and unattached groups. Our results revealed distinct diversity patterns and drivers for taxonomic and functional beta diversity. Specifically, taxonomic beta diversity was mainly driven by the turnover component affected by spatial processes, whereas functional beta diversity was dominated by the nestedness component affected by environmental processes. Furthermore, our analysis of the division of the whole communities demonstrated that the varying responses of benthic diatoms with different attached abilities to environmental filtering, dispersal limitation, and directional flow were the essential reasons for shaping the biodiversity patterns of species turnover and functional nestedness in the alpine stream. Our findings suggested that partitioning beta diversity and dividing the entire community can more deeply infer underlying community assembly processes, thereby providing valuable insights into understanding biodiversity patterns, drivers, and conservation strategies.

Enhancing the efficacy of synthesising PHA from nitrogen-limited activated sludge using magnetic field.

Polyhydroxyalkanes (PHA) is a biodegradable biopolyester. In this study, we introduced the biological effects of magnetic field into a sequencing batch reactor (SBR) for PHA production to evaluate the effect of different strength of magnetic field on the efficacy of PHA synthesis by activated sludge and used the magnetic field to enhance the PHA synthesis capacity of nitrogen-limited activated sludge and to optimise the percentage of the content of the two monomers in PHA. The results showed that the magnetic field of appropriate strength was favourable to increase the production of PHA and to increase the percentage of PHV. In addition, microbial community analysis showed that there was an obvious succession of key functional bacteria under different strength of magnetic field. The highest PHA accumulation was achieved after the magnetic field of 16 mT, which reached 57.65% of the dry weight of sludge. In addition, the PHV monomers were more sensitive to the response of the magnetic field, and the magnetic field of 8mT and 16mT positively promoted the synthesis of PHV. It is worth noting that too high a magnetic field would have an inhibitory effect on the synthesis of PHA.

Nasal commensals reduce Staphylococcus aureus proliferation by restricting siderophore availability.

The human microbiome is critically associated with human health and disease. One aspect of this is that antibiotic-resistant opportunistic bacterial pathogens such as methicillin-resistant Staphylococcus aureus can reside within the nasal microbiota which increases the risk of infections. Epidemiological studies of the nasal microbiome have revealed positive and negative correlations between non-pathogenic species and S. aureus, but the underlying molecular mechanisms remain poorly understood. The nasal cavity is iron-limited and bacteria are known to produce iron-scavenging siderophores to proliferate in such environments. Siderophores are public goods that can be consumed by all members of a bacterial community. Accordingly, siderophores are known to mediate bacterial competition and collaboration but their role in the nasal microbiome is unknown. Here we show that siderophore acquisition is crucial for S. aureus nasal colonization in vivo. We screened 94 nasal bacterial strains from seven genera for their capacity to produce siderophores as well as to consume the siderophores produced by S. aureus. We found that 80% of the strains engaged in siderophore mediated interactions with S. aureus. Non-pathogenic corynebacterial species were found to be prominent consumers of S. aureus siderophores. In co-culture experiments, consumption of siderophores by competitors reduced S. aureus growth in an iron dependent fashion. Our data show a wide network of siderophore mediated interactions between the species of the human nasal microbiome and provide mechanistic evidence for inter-species competition and collaboration impacting pathogen proliferation. This opens avenues for designing nasal probiotics to displace S. aureus from the nasal cavity of humans.

Galectin-9 as an indicator of functional limitations and radiographic joint damage in patients with rheumatoid arthritis.

Background: Previous studies have revealed that Galectin-9 (Gal-9) acts as an apoptosis modulator in autoimmunity and rheumatic inflammation. In the present study, we investigated the potential role of Gal-9 as a biomarker in patients with rheumatoid arthritis (RA), especially as an indicator of functional limitations and radiographic joint damage. Methods: A total of 146 patients with RA and 52 age- and sex-matched healthy controls were included in this study. Clinical data including disease activity, physical function, and radiographic joint damage were assessed. Functional limitation was defined as the Stanford Health Assessment Questionnaire (HAQ) disability index >1. Subjects with joint erosion >0 or joint space narrowing >0 were considered to have radiographic joint damage. Serum Gal-9 levels were detected by an enzyme-linked immunosorbent assay. Univariate and multivariate logistic regression analysis were used to evaluate the association between Gal-9 and high disease activity and functional limitations, and a prediction model was established to construct predictive nomograms. Results: Serum levels of Gal-9 were significantly increased in patients with RA compared to those in healthy controls (median 13.1 ng/mL vs. 7.6 ng/mL). Patients with RA who were older (>65 years), had a longer disease duration (>5 years), longer morning stiffness (>60mins), elevated serum erythrocyte sedimentation rate and C-reactive protein, and difficult-to-treat RA had significantly higher Gal-9 levels than those in the corresponding control subgroups (all p <0.05). Patients with RA were divided into two subgroups according to the cut-off value of Gal-9 of 11.6 ng/mL. Patients with RA with Gal-9 >11.6 ng/mL had a significantly higher core clinical disease activity index, HAQ scores, Sharp/van der Heijde modified Sharp scores, as well as a higher percentage of advanced joint damage (all p<0.05) than patients with Gal-9 ≤11.6 ng/mL. Accordingly, patients with RA presenting either functional limitations or radiographic joint damage had significantly higher serum Gal-9 levels than those without (both p <0.05). Furthermore, multivariate logistic regression analysis showed that a serum level of Gal-9 >11.6 ng/mL was an independent risk factor for high disease activity (OR=3.138, 95% CI 1.150-8.567, p=0.026) and presence of functional limitations (OR=2.455, 95% CI 1.017-5.926, p=0.046), respectively. Conclusion: Gal-9 could be considered as a potential indicator in patients with RA, especially with respect to functional limitations and joint damage.

Trends and social inequalities in self-reported health and activity limitations in France between 2017 and 2021: results from four nationwide representative surveys.

BACKGROUND: Like other countries in Europe and around the world, France was hit by the COVID-19 pandemic in 2020, although it had also experienced several social crises since 2017. This study assessed the evolution of self-reported health and activity limitations and explored the dynamics of their socio-territorial inequalities among the French population aged 18-75 years between 2017 and 2021. METHODS: Self-reported health (SRH) and global activity limitation indicator (GALI) were assessed in the same way in the four last editions of the French Health Barometer surveys conducted in the general population in 2017, 2019, 2020, and 2021, with between 9,200 and 24,500 subjects interviewed depending on the year. The prevalence of good or very good SRH and GALI (any limitation) and their evolution between 2017 and 2021 were studied according to sex, age, main socioeconomic positions (SEP), and regions. Poisson regression models were used to estimate adjusted prevalence ratios and potential modification effects of sociodemographic and geographic characteristics. RESULTS: Between 2017 and 2021, SRH and GALI deteriorated in adults in France in a continuous way. Very good or good SRH decreased from 75.2% (CI95% [74.5-75.9]) of subjects in 2017 to 68.5% (CI95% [67.7-69.3]) in 2021. In parallel, GALI increased from 21.5% (CI95% [21.0-22.2) in 2017 to 25.2% (CI95% [24.5-26.0]) in 2021.The deterioration of indicators affected both sexes, all age classes (except 65-75 years), especially younger age classes (18-24 and 25-34 years), all geographical regions, and all SEP variables, with groups with a higher SEP deteriorating more than others. Negative variations exceeding 20% (8-10 percentage points on the absolute scale of indicators) were observed in several population groups from 2019 onwards. CONCLUSION: The previously observed deterioration of the SRH and GALI continued in France between 2017 and 2021, with narrowing socio-territorial gradients of inequalities. The impact of successive social and health crises on the poor evolution of self-reported health and activity limitations warrants further investigation over time and across locations using complementary and possibly more detailed indicators.

Biogeography and community assembly of soil fungi from alpine meadows in southwestern China show the importance of climatic selection.

Soil fungi are pivotal in alpine and arctic ecosystems that are vulnerable to climate changes. Previous studies have shown broad connections between soil fungi in the arctic and alpine regions, but most of these studies are mainly from Europe and North America, with more sporadic studies from East Asia. Currently, little is known about the biogeographic relationships between soil fungi in alpine meadows of southwestern China (AMSC) and other regions of the world. In addition, the regional-scale spatial patterns of fungal communities in the AMSC, as well as their driving factors and ecological processes, are also poorly understood. In this study, we collected roots and surrounding soils of two dominant ectomycorrhizal plants, Bistorta vivipara and B. macrophylla from the AMSC, and performed bioinformatic and statistical analyses based on high-throughput sequencing of ITS2 amplicons. We found that: (1) fungi from the AMSC were closely related with those from boreal forests and tundra, and saprotrophic fungi had higher dispersal potential than ectomycorrhizal fungi; (2) community compositions exhibited clear divergences among geographic regions and between root and soil samples; (3) climate was the predominant factor driving regional-scale spatial patterns but had less explanatory power for saprotrophic and total fungi from roots than those from soils; (4) homogeneous selection and drift were the key ecological processes governing community assembly, but in communities of saprotrophic and total fungi from soil samples, drift contributed less and its role was partially replaced by dispersal limitation. This study highlights the importance of climatic selection and stochastic processes on fungal community assembly in alpine regions, and emphasizes the significance of simultaneously investigating fungi with different trophic modes and from both roots and soils.

Association Between Osteoporosis Self-Assessment Tool for Asians and Airflow Limitation in Japanese Post-Menopausal Women.

Purpose: This study aimed to reveal the association between the osteoporosis self-assessment tool for Asians (OSTA) and airflow limitation (AL) in post-menopausal Japanese women. Participants and Methods: This cross-sectional study included 1580 participants undergoing a comprehensive health examination using spirometry and dual-energy X-ray absorptiometry. The OSTA was calculated by subtracting the age in years from the body weight (BW) in kilograms, and the result was multiplied by 0.2. The OSTA risk level was defined as low (>-1), moderate (-4 to -1), or high (<-4). AL was defined as forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) <0.7. The association between the OSTA and AL was assessed using logistic regression analysis. Results: The prevalence of AL was significantly higher in the high OSTA group (15.3%) than in the low OSTA group (3.1%) (p<0.001). In multiple linear regression analysis, the OSTA was independently associated with FEV1/FVC. In logistic regression models adjusted for smoking status, alcohol consumption, current use of medication for diabetes, hyperglycemia, rheumatoid arthritis, second-hand smoke, and ovary removal showed a significantly higher risk of AL (odds ratio: 5.48; 95% confidence interval: 2.90-10.37; p<0.001) in participants with OSTA high risk than in those with OSTA low risk. Conclusion: These results suggest that the OSTA high risk indicates reduced BMD at the femoral neck and presence of AL in Japanese post-menopausal women aged ≥45 years.

Effects of carbon limitation and carbon fertilization on karst lake-reservoir productivity.

Nitrogen and phosphorus are universally recognized as limiting elements in the eutrophication processes affecting the majority of the world's lakes, reservoirs, and coastal ecosystems. However, despite extensive research spanning several decades, critical questions in eutrophication science remain unanswered. For example, there is still much to understand about the interactions between carbon limitation and ecosystem stability, and the availability of carbon components adds significant complexity to aquatic resource management. Mounting evidence suggests that aqueous CO2 could be a limiting factor, influencing the structure and succession of aquatic plant communities, especially in karstic lake and reservoir ecosystems. Moreover, the fertilization effect of aqueous CO2 has the potential to enhance carbon sequestration and phosphorus removal. Therefore, it is important to address these uncertainties to achieve multiple positive outcomes, including improved water quality and increased carbon sinks in karst lakes and reservoirs.

Sexual Function of Women with and without Pregnancy-Related Pelvic Girdle Pain and its Relationship with Physical Activity, Kinesiophobia and Body Image: A Cross-Sectional Comparative Study.

The aim of this study was to compare the sexual function of women with and without pregnancy-related PGP, and to investigate its relationship with physical activity (PA), kinesiophobia, and body image (BI). Demographic characteristics, sexual function (Pregnancy Sexual Response Inventory), PA (Pregnancy Physical Activity Questionnaire), kinesiophobia (Tampa Kinesiophobia Scale), and BI (Body Image in Pregnancy Scale) of 125 pregnant women were recorded. In the PGP group (n = 46), visual analogue scales were used to assess the pain intensity during resting and sexual activity, and Pelvic Girdle Questionnaire was used to evaluate the activity limitation. Although total sexual function and BI scores of the groups were similar (p > 0.05), dyspareunia during pregnancy and level of kinesiophobia were higher, and energy expenditure during moderate-intensity PA was lower in pregnant women with PGP (p < 0.05). The PGP group had moderate activity limitation and reported increased PGP intensity during sexual activities (p < 0.001). PA level was significantly correlated with sexual desire (r = 0.180), and overall sexual function was correlated with kinesiophobia (r = -0.344) and BI (r = -0.199) during pregnancy (p < 0.05). These findings suggest that pregnant women with PGP are more vulnerable to sexual dysfunctions, and there is a need to develop biopsychosocial framework-oriented management strategies which aim to improve PA level and to eliminate psychological factors such as kinesiophobia and negative BI.Clinical Trial Registration: NCT05990361.

Physiology, fast and slow: bacterial response to variable resource stoichiometry and dilution rate.

Microorganisms grow despite imbalances in the availability of nutrients and energy. The biochemical and elemental adjustments that bacteria employ to sustain growth when these resources are suboptimal are not well understood. We assessed how Pseudomonas putida KT2440 adjusts its physiology at differing dilution rates (to approximate growth rates) in response to carbon (C), nitrogen (N), and phosphorus (P) stress using chemostats. Cellular elemental and biomolecular pools were variable in response to different limiting resources at a slow dilution rate of 0.12 h-1, but these pools were more similar across treatments at a faster rate of 0.48 h-1. At slow dilution rates, limitation by P and C appeared to alter cell growth efficiencies as reflected by changes in cellular C quotas and rates of oxygen consumption, both of which were highest under P- and lowest under C- stress. Underlying these phenotypic changes was differential gene expression of terminal oxidases used for ATP generation that allows for increased energy generation efficiency. In all treatments under fast dilution rates, KT2440 formed aggregates and biofilms, a physiological response that hindered an accurate assessment of growth rate, but which could serve as a mechanism that allows cells to remain in conditions where growth is favorable. Our findings highlight the ways that microorganisms dynamically adjust their physiology under different resource supply conditions, with distinct mechanisms depending on the limiting resource at slow growth and convergence toward an aggregative phenotype with similar compositions under conditions that attempt to force fast growth. IMPORTANCE: All organisms experience suboptimal growth conditions due to low nutrient and energy availability. Their ability to survive and reproduce under such conditions determines their evolutionary fitness. By imposing suboptimal resource ratios under different dilution rates on the model organism Pseudomonas putida KT2440, we show that this bacterium dynamically adjusts its elemental composition, morphology, pools of biomolecules, and levels of gene expression. By examining the ability of bacteria to respond to C:N:P imbalance, we can begin to understand how stoichiometric flexibility manifests at the cellular level and impacts the flow of energy and elements through ecosystems.

Gas supply apparatus using rotational motion of shaking incubator for flask culture of aerobic microorganisms.

Shake flask cultivation, a cornerstone in bioprocess research encounters limitations in supplying sufficient oxygen and exchanging gases, restricting its accuracy in assessing microbial growth and metabolic activity. In this communication, we introduce an innovative gas supply apparatus that harnesses the rotational motion of a shaking incubator to facilitate continuous air delivery, effectively overcoming these limitations. We measured the mass transfer coefficient (kLa) and conducted batch cultures of Corynebacterium glutamicum H36LsGAD using various working volumes to assess its performance. Results demonstrated that the gas supply apparatus significantly outperforms conventional silicone stoppers regarding oxygen delivery, with kLa values of 2531.7 h-1 compared to 20.25 h-1 at 230 rpm. Moreover, in batch cultures, the gas supply apparatus enabled substantial improvements in microbial growth, maintaining exponential growth even at larger working volumes. Compared to the existing system, an increase in final cell mass by a factor of 3.4-fold was observed when utilizing 20% of the flask's volume, and a remarkable 9-fold increase was achieved when using 60%. Furthermore, the gas supply apparatus ensured consistent oxygen supply and efficient gas exchange within the flask, overcoming challenges associated with low working volumes. This approach offers a simple yet effective solution to enhance gas transfer in shake flask cultivation, bridging the gap between laboratory-scale experiments and industrial fermenters. Its broad applicability holds promise for advancing research in bioprocess optimization and scale-up endeavors.

Combined effects of herbicides and insecticides reduce biomass of sensitive aquatic invertebrates.

The structure and biomass of aquatic invertebrate communities play a crucial role in the matter dynamics of streams. However, biomass is rarely quantified in ecological assessments of streams, and little is known about the environmental and anthropogenic factors that influence it. In this study, we aimed to identify environmental factors that are associated with invertebrate structure and biomass through a monitoring of 25 streams across Germany. We identified invertebrates, assigned them to taxonomic and trait-based groups, and quantified biomass using image-based analysis. We found that insecticide pressure generally reduced the abundance of insecticide-vulnerable populations (R2 = 0.43 applying SPEARpesticides indicator), but not invertebrate biomass. In contrast, herbicide pressure reduced the biomass of several biomass aggregations. Especially, insecticide-sensitive populations, that were directly (algae feeder, R2 = 0.39) or indirectly (predators, R2 = 0.29) dependent on algae, were affected. This indicated a combined effect of possible food shortage due to herbicides and direct insecticide pressure. Specifically, all streams with increased herbicide pressure showed a reduced overall biomass share of Trichoptera from 43 % to 3 % and those of Ephemeroptera from 20 % to 3 % compared to streams grouped by low herbicide pressure. In contrast, insecticide-insensitive Gastropoda increased from 10 % to 45 %, and non-vulnerable leaf-shredding Crustacea increased from 10 % to 22 %. In summary, our results indicate that at the community level, the direct effects of insecticides and the indirect, food-mediated effects of herbicides exert a combined effect on the biomass of sensitive insect groups, thus disrupting food chains at ecosystem level.

Experimental, theoretical and numerical simulation-based investigations on the fabricated Cu2ZnSn thin-film-based Schottky diodes with enhanced electron transport for solar cell.

Copper-zinc-tin Cu2ZnSn (CZT) thin films are promising materials for solar cell applications. This thin film was deposited on a fluorine-doped tin oxide (FTO) using an electrochemical deposition hierarchy. X-ray diffraction of thin-film studies confirms the variation in the structural orientation of CZT on the FTO surface. As the pH of the solution is increased, the nature of the CZT thin-film aggregate changes from a fern-like leaf CZT dendrite crystal to a disk pattern. The FE-SEM surface micrograph shows the dendrite fern leaf and sharp edge disks. The 2-D diffusion limitation aggregation under slippery conditions for ternary thin films was performed for the first time. The simulation showed that by changing the diffusing species, the sticking probability was responsible for the pH-dependent morphological change. Convincingly, diffusion-limited aggregation (DLA) simulations confirm that the initial structure of copper is responsible for the final structure of the CZT thin films. An experimental simulation with pH as a controlled parameter revealed phase transition in CZT thin films. The top and back contact of Ag-CZT thin films based on Schottky behavior give a better electronic mechanism in superstrate and substrate solar cells.

Competition and drought affect cleistogamy in a non-additive way in the annual ruderal Lamium amplexicaule.

Competition affects mixed-mating strategies by limiting available abiotic or biotic resources such as nutrients, water, space, or pollinators. Cleistogamous species produce closed (cleistogamous, CL), obligately selfed, simultaneously with open (chasmogamous, CH), potentially outcrossed flowers. The effects of intraspecific competition on fitness and cleistogamy variation can range from limiting the production of costly CH flowers because of resource limitation, to favouring CH production because of fitness advantages of outcrossed, CH offspring. Moreover, the effects of competition can be altered when it co-occurs with other environmental variations. We grew plants from seven populations of the ruderal Lamium amplexicaule, originating from different climates and habitats, in a common garden experiment combining drought, interspecific competition, and seasonal variation. All these parameters have been shown to influence the degree of cleistogamy in the species on their own. In spring, competition and drought negatively impacted fitness, but the CL proportion only increased when plants were exposed to both treatments combined. We did not observe the same results in autumn, which can be due to non-adaptive phenotypic variation, or to differences in soil compactness between seasons. The observed responses are largely due to phenotypic plasticity, but we also observed phenotypic differentiation between populations for morphological, phenological, and cleistogamy traits, pointing to the existence of different ecotypes. Our data do not support the hypothesis that CL proportion should decrease when resources are scarce, as plants with reduced growth had relatively low CL proportions. We propose that variation in cleistogamy could be an adaptation to pollinator abundance, or to environment-dependent fitness differences between offspring of selfed and outcrossed seeds, two hypotheses worth further investigation. This opens exciting new possibilities for the study of the maintenance of mixed-mating systems using cleistogamous species as models that combine the effects of inbreeding and reproductive costs.

Taxonomic and genomic attributes of oligotrophic soil bacteria.

Not all bacteria are fast growers. In soil as in other environments, bacteria exist along a continuum-from copiotrophs that can grow rapidly under resource-rich conditions to oligotrophs that are adapted to life in the "slow lane." However, the field of microbiology is built almost exclusively on the study of copiotrophs due, in part, to the ease of studying them in vitro. To begin understanding the attributes of soil oligotrophs, we analyzed three independent datasets that represent contrasts in organic carbon availability. These datasets included 185 samples collected from soil profiles across the USA, 950 paired bulk soil and rhizosphere samples collected across Europe, and soils from a microcosm experiment where carbon availability was manipulated directly. Using a combination of marker gene sequencing and targeted genomic analyses, we identified specific oligotrophic taxa that were consistently more abundant in carbon-limited environments (subsurface, bulk, unamended soils) compared to the corresponding carbon-rich environment (surface, rhizosphere, glucose-amended soils), including members of the Dormibacterota and Chloroflexi phyla. In general, putative soil oligotrophs had smaller genomes, slower maximum potential growth rates, and were under-represented in culture collections. The genomes of oligotrophs were more likely to be enriched in pathways that allow oligotrophs to metabolize a range of energy sources and store carbon, while genes associated with energy-intensive functions like chemotaxis and motility were under-represented. However, few genomic attributes were shared, highlighting that oligotrophs likely use a range of different metabolic strategies and regulatory pathways to thrive in resource-limited soils.

Stockpiling turf alters microbial carbon and nitrogen use efficiency on the Tibetan Plateau.

Microbial carbon use efficiency (CUE) and nitrogen use efficiency (NUE) are crucial parameters reflecting soil C and N sequestration. Concerns about how artificial activities disturb alpine meadow ecosystem are increasing, but the knowledge of variances in microbial CUE and NUE in response to turf storage remains scarce. Here, we conducted a turf storage experiment on the Tibetan Plateau with two common storage methods, laying turfs method (LT) and stacking turfs method (ST). Plant litter, aboveground and belowground biomass declined considerably in the LT and ST than those in natural meadow. Soil pH and available phosphorus were significantly lower, but soil organic carbon, total nitrogen, dissolved organic carbon, and available nitrogen were substantially higher in stored turfs (both ST and LT) than in natural meadow. These results led to a differentiation in nutrient status among treatments. Vetor model indicated a stronger C limitation (vector length > 0.61) in ST than that in the LT and a shift from N to P limitation (vector angle >55°) in all stored turfs. Microbial CUE was prominently higher in the LT than those in the ST, signifying that microbes allocated more exogenous C to self-growth in the LT. Microbial NUE declined considerably in stored turfs, indicating a great proportion of N used for catabolic process instead of anabolic process. Microbial CUE and NUE were tightly linked to nutrient content and availability, enzymatic stoichiometry, microbial traits and plant biomass. Our results suggest that variations in microbial CUE and NUE were indirectly regulated by soil physicochemical properties via mediating nutrient imbalance and enzymatic stoichiometry in stored turfs.

Microbial nutrient limitation and carbon use efficiency changes under different degrees of litter decomposition.

Alpine ecosystems are important terrestrial carbon (C) pools, and microbial decomposers play a key role in litter decomposition. Microbial metabolic limitations in these ecosystems, however, remain unclear. The objectives of this study aim to elucidate the characteristics of microbial nutrient limitation and their C use efficiency (CUE), and to evaluate their response to environmental factors. Five ecological indicators were utilized to assess and compare the degree of microbial elemental homeostasis and the nutrient limitations of the microbial communities among varying stages of litter decomposition (L, F, and H horizon) along an altitudinal gradient (2800, 3000, 3250, and 3500 m) under uniform vegetation (Abies fabri) on Gongga Mountain, eastern Tibetan Plateau. In this study, microorganisms in the litter reached a strictly homeostatic of C content exclusively during the middle stage of litter decomposition (F horizon). Based on the stoichiometry of soil enzymes, we observed that microbial N- and P-limitation increased during litter degradation, but that P-limitation was stronger than N-limitation at the late stages of degradation (H horizon). Furthermore, an increase in microbial CUE corresponded with a reduction in microbial C-limitation. Additionally, redundancy analysis (RDA) based on forward selection further showed that microbial biomass C (MBC) is closely associated with the enzyme activities and their ratios, and MBC was also an important factor in characterizing changes in microbial nutrient limitation and CUE. Our findings suggest that variations in MBC, rather than N- and P-related components, predominantly influence microbial metabolic processes during litter decomposition on Gongga Mountain, eastern Tibetan Plateau.

Social Determinants of Health and Limitation of Life-Sustaining Therapy in Neurocritical Care: A CHoRUS Pilot Project.

BACKGROUND: Social determinants of health (SDOH) have been linked to neurocritical care outcomes. We sought to examine the extent to which SDOH explain differences in decisions regarding life-sustaining therapy, a key outcome determinant. We specifically investigated the association of a patient's home geography, individual-level SDOH, and neighborhood-level SDOH with subsequent early limitation of life-sustaining therapy (eLLST) and early withdrawal of life-sustaining therapy (eWLST), adjusting for admission severity. METHODS: We developed unique methods within the Bridge to Artificial Intelligence for Clinical Care (Bridge2AI for Clinical Care) Collaborative Hospital Repository Uniting Standards for Equitable Artificial Intelligence (CHoRUS) program to extract individual-level SDOH from electronic health records and neighborhood-level SDOH from privacy-preserving geomapping. We piloted these methods to a 7 years retrospective cohort of consecutive neuroscience intensive care unit admissions (2016-2022) at two large academic medical centers within an eastern Massachusetts health care system, examining associations between home census tract and subsequent occurrence of eLLST and eWLST. We matched contextual neighborhood-level SDOH information to each census tract using public data sets, quantifying Social Vulnerability Index overall scores and subscores. We examined the association of individual-level SDOH and neighborhood-level SDOH with subsequent eLLST and eWLST through geographic, logistic, and machine learning models, adjusting for admission severity using admission Glasgow Coma Scale scores and disorders of consciousness grades. RESULTS: Among 20,660 neuroscience intensive care unit admissions (18,780 unique patients), eLLST and eWLST varied geographically and were independently associated with individual-level SDOH and neighborhood-level SDOH across diagnoses. Individual-level SDOH factors (age, marital status, and race) were strongly associated with eLLST, predicting eLLST more strongly than admission severity. Individual-level SDOH were more strongly predictive of eLLST than neighborhood-level SDOH. CONCLUSIONS: Across diagnoses, eLLST varied by home geography and was predicted by individual-level SDOH and neighborhood-level SDOH more so than by admission severity. Structured shared decision-making tools may therefore represent tools for health equity. Additionally, these findings provide a major warning: prognostic and artificial intelligence models seeking to predict outcomes such as mortality or emergence from disorders of consciousness may be encoded with self-fulfilling biases of geography and demographics.