Dynamic structural changes of ensemble and single supported Pt particles during ammonia oxidation

The dynamics of the structure of polyhydroxyalkanoate-producing mixed microbial cultures (PHA-MMCs) during enrichment and maintenance is an unsolved problem. The effect of phages has been proposed as a cause of dynamic changes in community structure, but evidence is lacking. To address this question, five PHA-MMCs were enriched, and biological samples were sampled temporally to study the interactions between phage and bacterial members by combining metagenomics and metatranscriptomics. A total of 963 metagenome-assembled genomes (MAGs) and 4,294 phage operational taxonomic units (pOTUs) were assembled from bulk metagenomic data. The dynamic changes in the structure of phage and bacterial communities were remarkably consistent. Structural equation modeling analysis showed that phages could infect and lyse dominant species to vacate ecological niches for other species, resulting in a community succession state in which dominant species alternated. Seven key auxiliary metabolic genes (AMGs), phaC, fadJ, acs, ackA, phbB, acdAB, and fadD, potentially contributing to PHA synthesis were identified from phage sequences. Importantly, these AMGs were transcribed, indicating that they were in an active expression state. The meta-analysis provides the first catalog of phages in PHA-MMCs and the AMGs they carry, as well as how they affect the dynamic changes in bacterial communities. This study provides a reference for subsequent studies on understanding and regulating the microbial community structure of open microbial systems.IMPORTANCEThe synthesis of biodegradable plastic PHA from organic waste through mixed microbial cultures (PHA-MMCs), at extremely low cost, has the potential for expanded production. However, the dynamics of dominant species in PHA-MMCs are poorly understood. Our results demonstrate for the first time the impact of phages on the structure of bacterial communities in the PHA-MMCs. There are complex interactions between the PHA producers (e.g., Azomonas, Paracoccus, and Thauera) and phages (e.g., Casadabanvirus and unclassified Hendrixvirinae). Phage communities can regulate the activity and structure of bacterial communities. In addition, the AMGs related to PHA synthesis may hitchhike during phage-host infection cycles, enabling their dissemination across bacterial communities, and phages may act as a critical genetic reservoir for bacterial members, facilitating access to PHA synthesis-related functional traits. This study highlights the impact of phages on bacterial community structure, suggesting that phages have the potential to be used as a tool for better controlling the microbial community structure of PHA-MMCs.

It remains a major challenge to ascertain the specific structurally dynamic changes that underpin protein functional switching. There is a growing need in molecular biology and drug discovery to complement structural models with the ability to determine the dynamic structural changes that occur as these proteins are regulated and function. The archetypal allosteric enzyme glycogen phosphorylase is a clinical target of great interest to treat type II diabetes and metastatic cancers. Here, we developed a time-resolved nonequilibrium millisecond hydrogen/deuterium-exchange mass spectrometry (HDX-MS) approach capable of precisely locating dynamic structural changes during allosteric activation and inhibition of glycogen phosphorylase. We resolved obligate transient changes in the localized structure that are absent when directly comparing active/inactive states of the enzyme and show that they are common to allosteric activation by AMP and inhibition by caffeine, operating at different sites. This indicates that opposing allosteric regulation by inhibitor and activator ligands is mediated by pathways that intersect with a common structurally dynamic motif. This mass spectrometry approach uniquely stands to discover local transient structural dynamics and could be used broadly to identify features that influence the structural transitions of proteins.

The paper deals with the statistical study of the structural changes in the local labour market. It has been pointed out that one of the basic statistical study of the complex socio-economic systems, which is considered the local labour market are structural dynamic changes. It is caused by the structure which always has a certain mobility and ability to change under the influence of the internal and external factors. Therefore, in the study the analysis was carried out to identify the trends of local labour market functioning, as well as to assess the summary characteristics of the structural differences in the dynamics. It has been grounded that the functioning of the local labour market in the whole is characterized by certain structural and dynamic changes which can be estimated on the bases of measurements of total and current local labour market by using indicators of labour market statistics. The most common indicators include linear coefficient of absolute structural changes, the average coefficient of absolute structural changes, the average coefficient of relative structural changes, the integral coefficient of structural changes of Gateva, a general indicator of structural changes of Salai. Despite the complexity and diversity of the processes the most relevant study is that one that analyze the dynamics of economically active population number by gender, number of employed population by gender, number of vacancies by type of economic activity. The constant monitoring of indicators of labour market statistics makes it possible to optimize the activity of local governments involved in planning and monitoring the implementation of the decisions taken to promote employment, reduce unemployment, to balance and improve the effectiveness of management decisions

Dynamic changes and the role of the cytoskeleton during the cell cycle in higher plant cells

BackgroundFirst-generation and second-generation dual-source computed tomography (DSCT) are useful for analyzing left ventricle (LV) structure and function. This pilot study aimed to investigate the feasibility and role of third-generation DSCT for the evaluation of dynamic changes in LV structural and functional characteristics in a Diannan small-ear pig model of acute myocardial infarction (AMI).Material/MethodsThe model of AMI was established by balloon occlusion of the distal third of the left anterior descending (LAD) coronary artery in 14 Diannan small-eared pigs. Third-generation DSCT was performed to observe dynamic changes in LV structure and function before and after AMI was induced, with a follow-up period of 30 days.ResultsThe mean structural measurements at baseline included interventricular septum thickness (8.50±0.90 mm), LV anterior wall thickness (8.40±1.30 mm), LV posterior wall thickness (7.80±1.20 mm), LV end-diastolic dimension (LVEDD) (45.00±4.90 mm), and LV end-systolic dimension (LVESD) (25.90±4.10 mm). The mean functional measurements at baseline included the LV end-diastolic volume (LVEDV) (74.62±13.54 ml), LV end-systolic volume (LVESV) (23.06±7.46 ml), LV ejection fraction (LVEF) (69.29±6.83%), LV mass (86.35±14.02 g), stroke volume (SV) (51.56±9.77 ml), and cardiac output (CO) (4.22±2.14 l/min). Trends of time-dependent changes were observed for LVESV, LVEF, SV, and CO, but not for LVEDV or LV mass.ConclusionsThird-generation DSCT was validated as a tool for assessing dynamic changes in LV global function in a porcine model of AMI.

Calcium-dependent changes in the internal dynamics and average structures of the opposing globular domains of calmodulin (CaM), as well as their relative spatial arrangement, contribute to the productive association between CaM and a range of different target proteins, affecting their functional activation. To identify dynamic structural changes involving individual alpha-helical elements and their modulation by calcium activation, we have used site-directed mutagenesis to engineer a tetracysteine binding motif within helix A near the amino terminus of calmodulin (CaM), permitting the selective and rigid attachment of the fluorescent probe 4',5'-bis(1,3,2-dithioarsolan-2-yl)fluorescein (FlAsH) with full retention of function. The rigid tetracoordinate linkage of FlAsH to CaM, in conjunction with frequency domain fluorescence anisotropy measurements, allows assessment of dynamic changes associated with calcium activation without interference from independent probe motion. Taking advantage of the large fluorescence enhancement associated with binding of FlAsH to CaM, we determined rates of binding of FlAsH to apo-CaM and calcium-activated CaM to be 2800 +/- 80 and 310 +/- 10 M(-)(1) s(-)(1), respectively. There is no difference in the solvent accessibility of the bound FlAsH irrespective of calcium binding to CaM. Thus, given that FlAsH selectively labels disordered structures, the large difference in rates of FlAsH binding indicates that calcium binding stabilizes helix A. Frequency domain anisotropy measurements of bound FlAsH indicate that prior to calcium activation, helix A undergoes large amplitude nanosecond motions. Following calcium activation, helix A becomes immobile, and structurally coupled to the overall rotation of CaM. We discuss these results in the context of a model that suggests stabilization of helix A relative to other domain elements in the CaM structure is critical to defining high-affinity binding clefts, and in promoting specific and ordered binding of the opposing lobes of CaM to target proteins.

In this study, we constructed molecular friction models for polytetrafluoroethylene (PTFE)/graphene composites with various defect ratios to represent their different wear stages and simulated their friction processes under different load conditions. The friction and wear mechanisms were revealed by analyzing the variations in their molecular architectures and energies during friction. The results indicate that the friction coefficient decreased with increasing load. When the load was constant, the friction coefficients of the composites containing defections were resemble, indicating that they remained unchanged in the different wear stages. The composite wear continued to increase during friction. However, the wear increment decreased gradually. In addition, by analyzing the changes in MSD, wear can be divided into initial, stable, and accelerated wear stages. Highlights Construct PTFE/Gr molecular models to represent their different wear stages. Simulate the dynamic changes of PTFE/Gr molecular structure during friction. The influence of PTFE/Gr dynamic structural changes was revealed. Reveal the normal force variation from an energy perspective.

Dynamic Changes in Brain Glucose Metabolism and Neuronal Structure in Rats with Heart Failure

Chromosomal replication initiation requires the regulated formation of dynamic higher order complexes. Escherichia coli ATP-DnaA forms a specific multimer on oriC, resulting in DNA unwinding and DnaB helicase loading. DiaA, a DnaA-binding protein, directly stimulates the formation of ATP-DnaA multimers on oriC and ensures timely replication initiation. In this study, DnaA Phe-46 was identified as the crucial DiaA-binding site required for DiaA-stimulated ATP-DnaA assembly on oriC. Moreover, we show that DiaA stimulation requires only a subgroup of DnaA molecules binding to oriC, that DnaA Phe-46 is also important in the loading of DnaB helicase onto the oriC-DnaA complexes, and that this process also requires only a subgroup of DnaA molecules. Despite the use of only a DnaA subgroup, DiaA inhibited DnaB loading on oriC-DnaA complexes, suggesting that DiaA and DnaB bind to a common DnaA subgroup. A cellular factor can relieve the DiaA inhibition, allowing DnaB loading. Consistently, DnaA F46A caused retarded initiations in vivo in a DiaA-independent manner. It is therefore likely that DiaA dynamics are crucial in the regulated sequential progress of DnaA assembly and DnaB loading. We accordingly propose a model for dynamic structural changes of initial oriC complexes loading DiaA or DnaB helicase.

To learn more about islet vulnerability in the immediate posttransplant period, 400 syngeneic islets were transplanted under the kidney capsule of B6AF1 mice. Three groups of recipients were used: normal mice (normal), streptozotocin (STZ)-diabetic (diabetic), and STZ-diabetic kept hypo- or normoglycemic with insulin pellets (diabetic-normalized). Normoglycemia was achieved in all three groups 14 days after transplantation; however, in the diabetic and diabetic-normalized groups, blood glucose levels throughout the posttransplantation period were respectively higher and lower than in the normal group. Grafts were harvested 1, 3, 7, and 14 days after transplantation and analyzed for morphology, beta-cell death, beta-cell mass, insulin content, and insulin mRNA expression. In all groups, substantial damage in islet grafts was found on days 1 and 3 with apoptotic nuclei and necrotic cores; on day 3, beta-cell death was significantly higher in the diabetic group than in the other groups. Tissue remodelling occurred in all groups with stable graft appearance on day 14; the actual beta-cell mass of the grafts was lowest in the diabetic group. Graft insulin content decreased in all groups on day 1 and fell even further on days 3 and 7. Insulin mRNA levels of grafts retrieved from both the diabetic and diabetic-normalized group were lower than those from the normal group already by day 1 and remained lower on day 14. In conclusion, the first few days of islet transplantation, even under the most advantageous circumstances of excellent metabolic control, are characterized by dynamic changes, with substantial islet cell dysfunction and death followed by tissue remodelling and then stable engraftment.

Operando HERFD-XANES and surface sensitive Δμ analyses identify the structural evolution of copper(II) phthalocyanine for electroreduction of CO2

Dynamic secondary structural changes in Ca2+-saturated calmodulin upon interaction with the antagonist, W-7

Dynamic study of changes in structure and morphology during the heating and sintering of iron powder

Arterial Function in Cardio-Metabolic Diseases: From the Microcirculation to the Large Conduits

Dynamic Changes during Acid-Induced Activation of Influenza Hemagglutinin