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Abstract Keystone species are more important than others for community dynamics and stability. Keystone species can be identified and evaluated by their centrality (i.e., a relative ranking of the topological positional importance of a species) in ecological networks. Studies of node centrality of plant–fungus bipartite networks, for example, have identified the keystone species that are important for maintaining network structure and stability. However, the underlying drivers of the importance of species in a network have rarely been examined. We assessed the centrality (degree, closeness, and betweenness) of plant and fungal species in a plant–ectomycorrhizal fungus network in a subtropical forest in southern China. Based on the phylogenies of plants and fungi and plant traits, we explored ecological factors that led to a species taking a central position or not. We found one plant species (Ternstroemia gymnanthera) and four species of ectomycorrhizal fungi (Russula citrina, Scleroderma sp., and two Cenococcum sp.) were characterized by the highest centrality of degree, closeness, and betweenness among the bipartite network nodes and thus played key roles in maintaining network structure. Centrality for fungi (not for plants) was phylogenetically constrained. Plant traits and abundance together explained 46.36%, 46.0%, and 43.7% of variation in the centrality of degree, closeness, and betweenness of plant species in the bipartite network, respectively. When plant or fungal species were sequentially removed on the order of higher to lower centrality, network was less stable than randomly removed. We suggest that abundance and traits determine the positional importance of plant species in a network. This work helps understand how plant–fungus association networks will respond to species extinction and changes in species abundance and functional traits due to habitat fragmentation and human activities.

Indicator taxa have been widely used in biological conservation when data on the taxa of conservation interest are lacking. However, most studies have focused on common taxa (e.g., vascular plants, birds, reptiles, amphibians, and mammals) and found little consistent correlation between taxa. In this study, we extended the investigation to cover 10 taxonomic groups from 361 nature reserves in China. We assessed the strength of competing mechanisms hypothesized to promote indicator taxa correlations. We detected significant positive correlations in species richness among most of the 10 taxonomic groups except for macrofungi-insect and bryophyte-bird pairs. Yet, we found no single taxon satisfying the criteria to be used as an indicator for other taxa, although angiosperms had the potential to predict species richness of several other groups (e.g., ferns, gymnosperms, mammals, reptiles, amphibians), and ferns were useful for indicating reptiles and amphibians. Macrofungi and insects are the two groups that cannot be effectively indicated by any other groups. We also found that energy and climatic stability played the most significant role in regulating species richness of most study taxa, and possibly their between-taxon correlations. Our study provides new evidence for understanding cross-taxon congruence and the underlying mechanisms in the nature reserves of China.

Penicillin allergy delabeling may benefit antimicrobial stewardship (AS). Cost of initial penicillin treatments following risk-stratified inpatient delabeling were compared to two hypothetical treatment regimens if delabeling had not occurred: (1) AS-guided and (2) Common Treatment. Penicillin allergy delabeling improved antimicrobial spectrum index, was cost-neutral, and averted unnecessary penicillin desensitizations.

There has been much debate on what, including evolutionary history, ecological processes or environmental change, might contribute to species extinctions. In this study, we explored how evolutionary attributes and life forms were correlated with extinction risk of Chinese flowering plants. We defined genus-level extinction risk as the ratio of threatened species over all species in each plant genus. We compiled data on extinction risk for 2731 genera representing 27332 angiosperm species from the IUCN Red List threatened species assessments. We quantified the strength of phylogenetic signal in extinction risk and used phylogenetic generalized linear mixed models to test the effects of evolutionary age, genus size, and evolutionary distinctiveness on extinction risk. We found woody plants suffered greater extinction risk than herbs. There were significant phylogenetic signals in extinction risk, but the signal was stronger in herbaceous plants than in woody plants. Genus size and genus stem age were both negatively associated with extinction risk. In constrast, we found positive correlations between evolutionary distinctiveness and extinction risk. We further indentified many genera (e.g., Cynomorium, Mytilaria, Kingdonia, Scheuchzeria, Brasenia, and Manglietia) had both high evolutionary distinctiveness and high extinction risk. Our study shows that the extinction risk of Chinese flowering plant is not randomly distributed across genera but has strong evolutionary predisposition. We suggest information on life forms, genus size, genus stem age, and evolutionary distinctiveness be considered when making priority for the protection of Chinese flowering plants.

PfENT1 is a promising antimalarial drug target. Here, authors report cryo-EM structures of PfENT1 that, together with biochemical work, suggests PfENT1 is an inosine transporter and describe the inhibitory mechanism of the endofacial inhibitor, GSK4.

Background Occupational health risk assessment of dust-exposed operations is an important part of occupational health work. However, there is a lack of objective and effective methods for validating the risk assessment results. Objective To explore the application value of chest imaging changes in validating occupational health risk assessment results of dust-exposed operations. MethodsAlumina dust-exposed workers in an abrasive manufacturing company were selected as study subjects. The Australian Occupational Health and Safety Risk Assessment model (Australian model), and the Singapore semi-quantitative risk assessment model of occupational exposure to chemical substances (Singaporean model) were used to conduct occupational health risk assessment for the target group. Consistency of the assessment results was compared. The cumulative risk value and cumulative risk level of the subjects were calculated. The subjects were examined and diagnosed by chest radiographs, and the differences in the positive rates of aluminum dust shadows of workers at different job risk levels and different cumulative risk levels were compared. Results The average risk ratios (RR) of selected alumina dust-exposed workers estimated by the Australian model and the Singapore model were both 0.49±0.10, indicating generally medium occupational health risk level. The evaluation results of the two models were obviously consistent (kappa test, k = 0.823, P < 0.001). Among the 192 subjects, 62 (32.3%) were found to have aluminum dust shadows on their chest radiographs, and there were no case of pneumoconiosis. The aluminum dust shadows were mainly classified by shape and size as “s” (30.7%); the profusion of small opacities was mainly "less than 0/1" (31.3%); they were mostly distributed in 2 pulmonary zones (18.8%), and mostly in the right lower lung (18.8%), and none was seen in the two upper lung zones. The positive rate of aluminum dust shadows in the high-risk workplaces (41.7%) assessed by the Australian model was significantly higher than that in the medium-risk workplaces (22.9%) (P < 0.01). The positive rate of aluminum dust shadows in the medium-risk workplaces (42.7%) assessed by the Singapore model was significantly higher than that in the low-risk workplaces (23.3%) (P < 0.01). The cumulative risk levels evaluated by the two models were all atⅠ- Ⅲ levels. With the increase of cumulative risk level by the two models, the positive rates of aluminum dust shadows in the subjects both showed an obvious increase trend (P < 0.05). ConclusionThe risk assessment results of the Australian model and the Singapore model are obviously consistent for the target group. They can be jointly applied to the risk assessment of dust-exposed operations. The application of chest imaging changes is of certain value to validate the results of occupational health risk assessment for dust-exposed operations.

The relationship of mycorrhizal associations with latitudinal gradients in tree beta-diversity is unexplored. Using a global dataset approach, this study examines how trees with arbuscular mycorrhizal and ectomycorrhizal associations contribute to latitudinal beta-diversity patterns and the environmental controls of these patterns.

Plant and root fungal interactions are among the most important belowground ecological interactions, however, the mechanisms underlying pairwise interactions and network patterns of rhizosphere fungi and host plants remain unknown. We tested whether neutral process or spatial constraints individually or jointly best explained quantitative plant–ectomycorrhizal fungal network assembly in a subtropical forest in southern China. Results showed that the observed plant–ectomycorrhizal fungal network had low connectivity, high interaction evenness, and an intermediate level of specialization, with nestedness and modularity both greater than random expectation. Incorporating information on the relative abundance and spatial overlap of plants and fungi well predicted network nestedness and connectance, but not necessarily explained other network metrics such as specificity. Spatial overlap better predicted pairwise species interactions of plants and ectomycorrhizal fungi than species abundance or a combination of species abundance and spatial overlap. There was a significant phylogenetic signal on species degree and interaction strength for ectomycorrhizal fungal but not for plant species. Our study suggests that neutral processes (species abundance matching) and niche/dispersal-related processes (implied by spatial overlap and phylogeny) jointly drive the shaping of a plant-ectomycorrhizal fungal network.

The unfolded protein response (UPR) is one of the most important protein quality control mechanisms in cells. At least, three factors are predicted to activate the UPR in yeast cells during fermentation. Using UPRE-lacZ as a reporter, we constructed two indicator strains, KZ and WZ, based on Angel-derived K-a and W303-1A strains, respectively, and investigated their UPR response to tunicamycin, ethanol, and acetic acid. Then, four strains carrying plasmids BG-cwp2 and BG were obtained to realize the displaying and secretion of β-glucosidase, respectively. The results of cellobiose utilization assays indicated interactions between the UPR and the metabolic burden between the strain source, anchoring moiety, oxygen supply, and cellobiose concentration. Meanwhile, as expected, growth (OD600), β-glucosidase, and β-galactosidase activities were shown to have a positive inter-relationship, in which the values of the KZ-derived strains were far lower than those of the WZ-derived strains. Additionally, extra metabolic burden by displaying over secreting was also much more serious in strain KZ than in strain WZ. The maximum ethanol titer of the four strains (KZ (BG-cwp2), KZ (BG), WZ (BG-cwp2), and WZ (BG)) in oxygen-limited 10% cellobiose fermentation was 3.173, 5.307, 5.495, and 5.486% (v/v), respectively, and the acetic acid titer ranged from 0.038 to 0.060% (v/v). The corresponding maximum values of the ratio of β-galactosidase activity to that of the control were 3.30, 5.29, 6.45, and 8.72, respectively. Under aerobic conditions with 2% cellobiose, those values were 3.79, 4.97, 6.99, and 7.67, respectively. A comparison of the results implied that β-glucosidase expression durably induced the UPR, and the effect of ethanol and acetic acid depended on the titer produced. Further study is necessary to identify ethanol- or acid-specific target gene expression. Taken together, our results indicated that the host strain W303-1A is a better secretory protein producer, and the first step to modify strain K-a for cellulosic ethanol fermentation would be to relieve the bottleneck of UPR capacity. The results of the present study will help to identify candidate host strains and optimize expression and fermentation by quantifying UPR induction.

Current liquid biopsy assays lack sufficient sensitivity to detect copy number loss, which limits the interrogation of critical tumor suppressor gene deletions during cancer progression and treatment. Here we describe a liquid biopsy assay with improved sensitivity for detection of copy number loss in blood samples with low levels of circulating tumor DNA, and demonstrate its utility by profiling PTEN, RB1, and TP53 genetic loss in metastatic prostate cancer patients.

Abstract Background Butanol is an important biofuel and chemical. The development of butanol-tolerant strains and the identification of functional butanol-tolerant genes is essential for high-yield bio-butanol production due to the toxicity of butanol. Results Escherichia coli BW25113 was subjected for the first time to error-prone PCR-based whole-genome shuffling. The resulting mutants BW1847 and BW1857 were found to tolerate 2% (v/v) butanol and short-chain alcohols, including ethanol, isobutanol, and 1-pentanol. The mutants exhibited good stability under butanol stress, indicating that they are potential host strains for the construction of butanol pathways. BW1847 had better butanol tolerance than BW1857 under 0–0.75% (v/v) butanol stress, but showed a lower tolerance than BW1857 under 1.25–2% (v/v) butanol stress. Genome resequencing and PCR confirmation revealed that BW1847 and BW1857 had nine and seven single nucleotide polymorphisms, respectively, and a common 14-kb deletion. Functional complementation experiments of the SNPs and deleted genes demonstrated that the mutations of acrB and rob gene and the deletion of TqsA increased the tolerance of the two mutants to butanol. Genome-wide site-specific mutated strains DT385 (acrB C1198T) and DT900 (rob AT686–7) also showed significant tolerance to butanol and had higher butanol efflux ability than the control, further demonstrating that their mutations yield an inactive protein that enhances butanol resistance characteristics. Conclusions Stable E. coli mutants with enhanced short alcohols and high concentrations of butanol tolerance were obtained through a rapid and effective method. The key genes of butanol tolerance in the two mutants were identified by comparative functional genomic analysis.

Identifying indicator taxa is a solution to the problem of a lack of diverse data. However, the variation between studies on richness correlations (RCs) among taxa from different climate regions makes the application value of indicator taxa questionable. Few studies have compared the RCs among climatic regions in a single study, leaving the variation in RCs and the underlying ecological drivers among climatic regions unknown. In this study, data were compiled on vascular plants, vertebrates (including mammals, birds, reptiles, and amphibians), and environmental factors across 219 nature reserves located in subtropical and temperate regions of China to examine RCs among taxonomic groups and underlying ecological mechanisms. Results showed that the climatic region could affect between-taxon correlations in species richness and that the effectiveness of vascular plants as suitable indicator taxa for vertebrates varied with the climatic region and target taxa. Energy (temperature and evapotranspiration) and habitat heterogeneity (area and elevation range) were ecological drivers of RCs among taxonomic groups in the subtropical and temperate regions. The differences in the effect of abiotic factors on RCs among taxonomic groups caused the difference in RCs between subtropical and temperate regions. Our findings provide new evidence for understanding the variation of RCs and the underlying mechanisms and highlight the positive role of climatic variables and habitat heterogeneity in determining RCs between vascular plants and vertebrates.

Two distinct expression cassettes were synthesized by overlapping PCR for expressing the endoglucanase I gene (egl1) from Aspergillus aculeatus and the endoglucanase II gene (egl2) from Trichoderma reesei in a Saccharomyces cerevisiae host. One contained the anchored sequence from the S. cerevisiae cwp2 gene, while the other did not. The low and high copy number plasmids YCplac33 and YEplac195 were used. The enzymatic activities and viscosity changes in the YP-CMC medium varied between the eight recombinant yeast strains produced, and the greatest values were obtained with the YE-TrEII’ strain, which had an activity of 347.7 U/g dry cell weight (DCW) and viscosity at 12 h of 4.7% of the initial control value, respectively; YE-TrEII’ was YEplac195-based and contained T. reesei egl2 and no Cwp2 sequence. Strains YC-AaEI and YC-TrEII showed the lowest enzyme activitiy (80.5 and 30.4 U/g DCW, respectively) and viscosity changes at 12 h (20.5 and 26.2% of the initial control viscosity, respectively), which were YCplac33-based and contained the Cwp2 sequence. The results showed that gene copy number was the most significant factor to influence the expression of endoglucanases in S. cerevisiae, and the existence of Cwp2 sequence led to decreased enzymatic level and viscosity-reducing performance, while it was shown not to realize efficient surface display of these two endoglucanases.Keywords

Gait abnormalities are one of the distinguishing symptoms of patients with Parkinson’s disease (PD) that contribute to fall risk. Our study compares the gait parameters of people with PD when they walk through a predefined course under different haptic speed cue conditions (1) without assistance, (2) pushing a conventional rolling walker, and (3) holding onto a self-navigating motorized walker under different speed cues. Six people with PD were recruited at the New York Institute of Technology College of Osteopathic Medicine to participate in this study. Spatial posture and gait data of the test subjects were collected via a VICON motion capture system. We developed a framework to process and extract gait features and applied statistical analysis on these features to examine the significance of the findings. The results showed that the motorized walker providing a robust haptic cue significantly improved gait symmetry of PD subjects. Specifically, the asymmetry index of the gait cycle time was reduced from 6.7% when walking without assistance to 0.56% and below when using a walker. Furthermore, the double support time of a gait cycle was reduced by 4.88% compared to walking without assistance.

How dietary restriction (DR) increases lifespan and decreases disease burden are questions of major interest in biomedical research. Here we report that hypothalamic expression of CREB-binding protein (CBP) and CBP-binding partner Special AT-rich sequence binding protein 1 (SATB-1) is highly correlated with lifespan across five strains of mice, and expression of these genes decreases with age and diabetes in mice. Furthermore, in Caenorhabditis elegans, cbp-1 is induced by bacterial dilution DR (bDR) and the daf-2 mutation, and cbp-1 RNAi specifically in adults completely blocks lifespan extension by three distinct protocols of DR, partially blocks lifespan extension by the daf-2 mutation but not of cold, and blocks delay of other age-related pathologies by bDR. Inhibiting the C. elegans ortholog of SATB-1 and CBP-binding partners daf-16 and hsf-1 also attenuates lifespan extension by bDR, but not other protocols of DR. In a transgenic Abeta42 model of Alzheimer's disease, cbp-1 RNAi prevents protective effects of bDR and accelerates Abeta42-related pathology. Furthermore, consistent with the function of CBP as a histone acetyltransferase, drugs that enhance histone acetylation increase lifespan and reduce Abeta42-related pathology, protective effects completely blocked by cbp-1 RNAi. Other factors implicated in lifespan extension are also CBP-binding partners, suggesting that CBP constitutes a common factor in the modulation of lifespan and disease burden by DR and the insulin/IGF1 signaling pathway.

Obtaining synthetic natural gas from coal is an effective way to alleviate the contradiction between supply and demand of natural gas, realize clean and efficient utilization of coal, and promote the development of energy transformation. Syngas methanation is the core technology of coal-to-natural gas conversion, in which an efficient catalyst is the key. As one of the most promising methanation catalytic systems, Ni-based catalysts have attracted extensive attention in academia and industry. In this work, the mechanism of CO methanation on the surface of Ni and Ni3Fe(111) was first studied with DFT calculations, and the results were compared with previous research results. It was found that the surface activity of Ni(111) and Ni3Fe(111) is very low, while Ni(211) and Ni3Fe(211) have significantly higher activity. The (211) surface is more conducive to CH4 generation than the (111) surface. The microkinetics of CO methanation over Ni and Ni3Fe catalysts was studied using the kMC method. The comparison between (111) and (211) surfaces further indicated that, under reaction-dependent conditions, the (111) surface was not the main catalytic activity surface, but the (211) surface could be used as an effective catalytic activity surface. It is also found that the CH4 conversion frequency at Ni3Fe(211)-AA is equivalent to that at Ni(211), while the CH4 conversion frequency at Ni3Fe(211)-AB is about one order of magnitude higher than that at Ni(211), indicating that Ni3Fe(211)-AB has high activity. [ABSTRACT FROM AUTHOR]

Understanding the evolution and maintenance of plant sexual diversity needs to incorporate both regional processes and local climate factors across large geographic scales. Using data of woody flowering plants from a global set of large-scale forest plots and multinomial logistic regression, we quantified region effects on the proportion of dioecy, monoecy, and hermaphrodite species count and abundance while incorporating evolutionary history and local climate factors. We demonstrated that plants were more likely to be dioecy than monoecy in tropical regions than in temperate regions, supporting the role of colonization processes suggested by Baker’s law in structuring the geographic patterns of plant sexual systems. We further found plants were more likely to be dioecious than monoecious in areas with younger mean species age. Plants were more likely to be hermaphrodite than dioecious in areas with high annual potential evapotranspiration and precipitation seasonality but were more likely to be dioecious than monoecious in areas with high precipitation of driest month. Our results suggest that both regional processes and local climate factors play important roles in shaping the geographic distribution of plant sexual systems, providing a baseline for predicting future changes in forest communities under global change. [ABSTRACT FROM AUTHOR]