Effect of physical environment on the conformation of ricin. Influence of low pH.
Ontology highlight
ABSTRACT:
SUBMITTER: Frenoy JP
PROVIDER: S-EPMC1147396 | biostudies-other | 1986 Nov
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Differential gene expression analysis of oesophageal cells stimulated with a low pH environment. Study designed to identify pathways involved in progression of gastro-oesophageal reflux disease through Barrett's oesophagus to adenocarcinoma. Identified many subsets of genes with involvement in pathogenesis.<br><br>Missing data files: GSM38763.CEL (Time 0 mins rep 1), GSM38764.CEL (Time 0 mins rep 2), GSM38771.CEL (Time 240 mins rep 1), and GSM38772.CEL (Time 240 mins rep 2).
2007-08-25 | E-GEOD-2144 | biostudies-arrayexpress
Project description:BACKGROUND:The purpose of this study was to examine the association of physical education (PE) class characteristics, such as lesson context, teacher's physical activity (PA) promotion behavior, and lesson location, with student engagement in moderate- and vigorous-intensity physical activity (MVPA) during PE lessons in elementary school (ES), middle school (MS), and high school (HS). METHODS:The study sample included 2106 PE classes from 40 schools located in low-income communities. The System for Observing Fitness Instruction Time (SOFIT) was used to assess lesson context, teacher's behavior, and student PA during PE lessons. Mixed models were used to examine the association between PE class characteristics and the probability of meeting the recommended level of MVPA during PE lessons (MVPA ?50%), accounting for within-school random effects and school characteristics. RESULTS:Almost all PE classes (90%) with ?60-70% of lesson time spent in motor content and???10-20% in teacher's in-class PA promotion met the recommended level of MVPA across the school levels. More specifically, among the sub-categories of motor content, more lesson time spent in fitness was significantly associated with MVPA ?50% in all school levels. However, more lesson time spent in game play was a significant factor only in ES (OR?=?2.1; 95% CI?=?1.4-3.0). Outdoor lessons were a significant factor in ES (OR?=?5.3; 95% CI?=?3.1-9.0) and MS (OR?=?21.0; 95% CI?=?6.3-69.4), but not HS (OR?=?1.4; 95% CI?=?0.6, 3.2). CONCLUSIONS:PE lessons with higher motor content and higher teacher's in-class PA promotion are more likely to meet the recommended level of MVPA in all school levels. However, the sub-categories of motor content and lesson location could impact student MVPA differently by school levels.
| S-EPMC6995192 | biostudies-literature
Project description:Enveloped viruses enter cells via a membrane fusion reaction driven by conformational changes of specific viral envelope proteins. We report here the structure of the ectodomain of the tick-borne encephalitis virus envelope glycoprotein, E, a prototypical class II fusion protein, in its trimeric low-pH-induced conformation. We show that, in the conformational transition, the three domains of the neutral-pH form are maintained but their relative orientation is altered. Similar to the postfusion class I proteins, the subunits rearrange such that the fusion peptide loops cluster at one end of an elongated molecule and the C-terminal segments, connecting to the viral transmembrane region, run along the sides of the trimer pointing toward the fusion peptide loops. Comparison with the low-pH-induced form of the alphavirus class II fusion protein reveals striking differences at the end of the molecule bearing the fusion peptides, suggesting an important conformational effect of the missing membrane connecting segment.
| S-EPMC380989 | biostudies-literature
Project description:Obesity is a public health problem that is due in part to low levels of physical activity. Physical activity levels are influenced by the built environment. We examined how changes in the built environment affected residents' physical activity levels in a low-income, primarily African American neighborhood in New Orleans.We built a 6-block walking path and installed a school playground in an intervention neighborhood. We measured physical activity levels in this neighborhood and in 2 matched comparison neighborhoods by self-report, using door-to-door surveys, and by direct observations of neighborhood residents outside before (2006) and after (2008) the interventions. We used Pearson ?² tests of independence to assess bivariate associations and logistic regression models to assess the effect of the interventions.Neighborhoods were comparable at baseline in demographic composition, choice of physical activity locations, and percentage of residents who participated in physical activity. Self-reported physical activity increased over time in most neighborhoods. The proportion of residents observed who were active increased significantly in the section of the intervention neighborhood with the path compared with comparison neighborhoods. Among residents who were observed engaging in physical activity, 41% were moderately to vigorously active in the section of the intervention neighborhood with the path compared with 24% and 38% in the comparison neighborhoods at the postintervention measurement (P < .001).Changes to the built environment may increase neighborhood physical activity in low-income, African American neighborhoods.
| S-EPMC3359102 | biostudies-other
Project description:Researchers investigating relationships between the neighbourhood environment and health first need to decide on the spatial extent of the neighbourhood they are interested in. This decision is an important and ongoing methodological challenge since different methods of defining and delineating neighbourhood boundaries can produce different results. This paper explores this issue in the context of a New Zealand-based study of the relationship between the built environment and multiple measures of physical activity. Geographic information systems were used to measure three built environment attributes-dwelling density, street connectivity, and neighbourhood destination accessibility-using seven different neighbourhood definitions (three administrative unit boundaries, and 500, 800, 1000- and 1500-m road network buffers). The associations between the three built environment measures and five measures of physical activity (mean accelerometer counts per hour, percentage time in moderate-vigorous physical activity, self-reported walking for transport, self-reported walking for recreation and self-reported walking for all purposes) were modelled for each neighbourhood definition. The combination of the choice of neighbourhood definition, built environment measure, and physical activity measure determined whether evidence of an association was detected or not. Results demonstrated that, while there was no single ideal neighbourhood definition, the built environment was most consistently associated with a range of physical activity measures when the 800-m and 1000-m road network buffers were used. For the street connectivity and destination accessibility measures, associations with physical activity were less likely to be detected at smaller scales (less than 800 m). In line with some previous research, this study demonstrated that the choice of neighbourhood definition can influence whether or not an association between the built environment and adults' physical activity is detected or not. This study additionally highlighted the importance of the choice of built environment attribute and physical activity measures. While we identified the 800-m and 1000-m road network buffers as the neighbourhood definitions most consistently associated with a range of physical activity measures, it is important that researchers carefully consider the most appropriate type of neighbourhood definition and scale for the particular aim and participants, especially at smaller scales.
| S-EPMC6540146 | biostudies-literature
Project description:The goal of this study is to explore the alterations in gene expression in lungs of mice 48 hours after exposure to low-dose ricin compared to lungs of naive mice, in order to provide a framework for comparative investigation of genes and mechanisms that may contribute to the developing lung disease. Methods: Total RNA was extracted from lungs of naive or ricin intoxicated mice (intranasally exposure to 1.7 µg/kg ricin), using the RNeasy mini kit (Qiagen). RNA-seq libraries were constructed and sequencing of 100bp paired-end was performed on the Illumina NovaSeq 6000 system. Sequencing yielded about 21M reads per sample that were mapped to the mouse genome. The expression of the infected sample was compared to mock sample, and RNA ratios were clustered using partitioning clustering. We next carried out GO term enrichment analysis. Results: Principal component analysis revealed distinct transcriptional signatures between naïve and ricin mice. We found 8545 differentially expressed genes in the ricin group, including 4394 upregulated and 4151 downregulated genes.
2020-10-14 | GSE159461 | GEO
Project description:Many studies have shown the effect of solution chemistry on the environmental behavior of metal-based nanoparticles (NPs), except CuO NPs. Here, we investigated the agglomeration, sedimentation, dissolution, and speciation of CuO NPs by varying pH, ionic strength, ionic valence, and natural organic matter (NOM). The results showed that as the pH moved away from 6, the size of CuO agglomerates decreased, along with the enhanced NP suspension stabilization, due to the increase of electrostatic repulsive force. Increasing ionic strength and valence intensified the agglomeration and sedimentation of CuO NPs because of the compression of electrical double layers. The presence of humic acid and citric acid enhanced the dispersion and stabilization of CuO NP suspension, but l-cysteine showed a different impact. Decreasing pH, increasing ionic strength and all NOM improved the dissolution of CuO NPs, but the divalent electrolyte (CaCl₂) inhibited the Cu2+ release from CuO NPs compared to the monovalent electrolyte (NaCl). In addition, X-ray absorption near edge structure (XANES) analysis demonstrated that the presence of l-cysteine transformed more than 30% of CuO NPs to Cu(I)-cysteine by coordinating with thiol group. This study can give us an in-depth understanding on the environmental behavior and fate of CuO NPs in the aquatic environment.
| S-EPMC5666491 | biostudies-literature
Project description:BACKGROUND:Social and environmental factors can profoundly impact an individual's investment of resources into different components of reproduction. Such allocation trade-offs are expected to be amplified under challenging environmental conditions. To test these predictions, we used a desert-dwelling fish, the desert goby, Chlamydogobius eremius, to experimentally investigate the effects of prior social experience (with either a male or a female) on male investment in courtship and aggression under physiologically benign and challenging conditions (i.e., low versus high salinity). RESULTS:We found that males maintained a higher level of aggression towards a rival after a recent encounter with a female, compared to an encounter with a male, under low (but not high) salinity. In contrast, male investment in courtship behaviour was unaffected by either salinity or social experience. CONCLUSION:Together, our results suggest that male investment in aggression and courtship displays can differ in their sensitivity to environmental conditions and that not all reproductive behaviours are similarly influenced by the same environmental context.
| S-EPMC4721148 | biostudies-literature
Project description:In moths, pheromone-binding proteins (PBPs) are responsible for the transport of the hydrophobic pheromones to the membrane-bound receptors across the aqueous sensillar lymph. We report here that recombinant Antheraea polyphemus PBP1 (ApolPBP1) picks up hydrophobic molecule(s) endogenous to the Escherichia coli expression host that keeps the protein in the "open" (bound) conformation at high pH but switches to the "closed" (free) conformation at low pH. This finding has bearing on the solution structures of undelipidated lepidopteran moth PBPs determined thus far. Picking up a hydrophobic molecule from the host expression system could be a common feature for lipid-binding proteins. Thus, delipidation is critical for bacterially expressed lipid-binding proteins. We have shown for the first time that the delipidated ApolPBP1 exists primarily in the closed form at all pH levels. Thus, current views on the pH-induced conformational switch of PBPs hold true only for the ligand-bound open conformation of the protein. Binding of various ligands to delipidated ApolPBP1 studied by solution NMR revealed that the protein in the closed conformation switches to the open conformation only at or above pH 6.0 with a protein to ligand stoichiometry of approximately 1:1. Mutation of His(70) and His(95) to alanine drives the equilibrium toward the open conformation even at low pH for the ligand-bound protein by eliminating the histidine-dependent pH-induced conformational switch. Thus, the delipidated double mutant can bind ligand even at low pH in contrast to the wild type protein as revealed by fluorescence competitive displacement assay using 1-aminoanthracene and solution NMR.
| S-EPMC2797287 | biostudies-literature
Project description:Ricin is a highly-toxic compound derived from castor plant beans. Several incidents involving contamination of residences and buildings due to ricin production or dissemination have occurred in recent years. The goal of this study was to determine whether ricin bioactivity could be attenuated in reasonable time via simple modifications of the indoor environment. Attenuation was assessed on six different materials as a function of temperature, relative humidity (RH), and contact time, using both a pure and crude preparation of the toxin. Ricin bioactivity was quantified via a cytotoxicity assay, and attenuation determined as the difference in ricin recovered from test and positive controls. The results showed that pure ricin could be attenuated successfully, while the crude ricin was generally more persistent and results more variable. We found no significant attenuation in crude ricin after two weeks at typical indoor environmental conditions, except on steel. Attenuation mostly improved with increasing temperature, but the effect of RH varied. For pure ricin, heat treatments at 40°C for 5 days or 50°C for 2-3 days achieved greater than 96% attenuation on steel. In contrast, appreciable recovery of the crude ricin preparation still occurred at 40°C after two weeks.
| S-EPMC6082540 | biostudies-literature