Search results for "Meta-"
showing 10 items of 1069 documents
Quasi-RRHO approximation and DFT study for understanding the mechanism and kinetics of nitration reaction of benzonitrile with nitronium ion
2021
Abstract The nitration reaction of benzonitrile with nitronium cation, NO2+, has been studied within the Molecular Electron Density Theory at the MN15-L/aug-cc-pVTZ level of theory. For this electrophilic aromatic substitution (EAS) reaction, three regioisomeric reaction paths have been studied. Quasi-RRHO approximation was applied to consider the vibrational contribution to entropy and correct the Gibbs free energy profile of the reaction in the solvent phase. Benzonitrile is less nucleophilically activated than benzene due to the presence of the electron-withdrawing CN group the meta position is the more favorable reaction path of this EAS reaction. The analysis of ELF and AIM demonstrate…
Arene C−H Activation at Aluminium(I): meta Selectivity Driven by the Electronics of S N Ar Chemistry
2020
The reactivity of the electron-rich anionic Al(I) ('aluminyl') compound K 2 [(NON)Al] 2 (NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di- tert -butyl-9,9-dimethylxanthene) towards mono- and disubstituted arenes is reported. C-H activation chemistry with n -butylbenzene gives exclusively the product of activation at the arene meta position. Mechanistically, this transformation proceeds in a single step via a concerted Meisenheimer-type transition state. Selectivity is therefore based on similar electronic factors to classical S N Ar chemistry, which implies the destabilization of transition states featuring electron-donating groups in either the ortho or the para positions. In the cases of tolu…
Associations between air pollution and pediatric eczema, rhinoconjunctivitis and asthma: A meta-analysis of European birth cohorts
2020
Background: Uncertainly continues to exist regarding the role of air pollution on pediatric asthma and allergic conditions, especially as air pollution levels have started to decrease in recent decades. Objective: We examined associations of long-term air pollution levels at the home address with pediatric eczema, rhinoconjunctivitis and asthma prevalences in five birth cohorts (BIB, EDEN, GASPII, RHEA and INMA) from seven areas in five European countries. Methods: Current eczema, rhinoconjunctivitis and asthma were assessed in children aged four (N = 6527) and eight years (N = 2489). A multi-morbidity outcome (≥2 conditions versus none) was also defined. Individual outdoor levels of nitrog…
Pneumothorax and the environment: A systematic review of the impact of air pollution and meteorology, and a meta-analysis on meteorology factors.
2021
Abstract A relationship between the occurrence of spontaneous pneumothorax (SP) and meteorological factors has been observed but with contradictory results. The objectives of this systematic review was to synthesis the current body of evidence to the relationships between the occurrence of SP and environmental determinants such as meteorological factors and air pollutants. We conducted a systematic search of MEDLINE, Scopus, Cochrane Library and gray literature from inception up to 31st December 2020, to find published scientific research articles based on the following eligibility criteria: original studies and population-based articles describing the relationship between meteorological fa…
Change in dominance determines herbivore effects on plant biodiversity
2018
Herbivores alter plant biodiversity (species richness) in many of the world’s ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet, empirical support for the importance of site productivity as a mediator of these herbivore impacts is equivocal. Here, we synthesize data from 252 large-herbivore exclusion studies, spanning a 20-fold range in site productivity, to test an alternative hypothesis—that herbivore-induced changes in the competitive environment determine the response …
Climate Change Genomics Calls for Standardized Data Reporting
2020
The advent of new and affordable high-throughput sequencing techniques allows for the investigation of the genetic basis of environmental adaptation throughout the plant and animal kingdom. The framework of genotype-environment associations (GEA) provides a powerful link by correlating the geographic distribution of genotype patterns of individuals or populations with environmental factors on a spatial scale. We coarsely review the short history of GEA studies, summarizing available studies, organisms, data type, and data availability for these studies. GEA is a powerful tool in climate change research and we therefore focus on climate variables as environmental factors. While our initial a…
Identification of key genes and its chromosome regions linked to drought responses in leaves across different crops through meta-analysis of RNA-Seq …
2019
Background Our study is the first to provide RNA-Seq data analysis related to transcriptomic responses towards drought across different crops. The aim was to identify and map which genes play a key role in drought response on leaves across different crops. Forty-two RNA-seq samples were analyzed from 9 published studies in 7 plant species (Arabidopsis thaliana, Solanum lycopersicum, Zea mays, Vitis vinifera, Malus X domestica, Solanum tuberosum, Triticum aestivum). Results Twenty-seven (16 up-regulated and 11 down-regulated) drought-regulated genes were commonly present in at least 7 of 9 studies, while 351 (147 up-regulated and 204 down-regulated) were commonly drought-regulated in 6 of 9 …
Transcriptomic responses to biotic stresses in Malus x domestica: a meta-analysis study.
2017
AbstractRNA-Seq analysis is a strong tool to gain insight into the molecular responses to biotic stresses in plants. The objective of this work is to identify specific and common molecular responses between different transcriptomic data related to fungi, virus and bacteria attacks in Malus x domestica. We analyzed seven transcriptomic datasets in Malus x domestica divided in responses to fungal pathogens, virus (Apple Stem Grooving Virus) and bacteria (Erwinia amylovora). Data were dissected using an integrated approach of pathway- and gene- set enrichment analysis, Mapman visualization tool, gene ontology analysis and inferred protein-protein interaction network. Our meta-analysis revealed…
Gaining Insight into Exclusive and Common Transcriptomic Features Linked with Biotic Stress Responses in Malus
2017
Identifying key information in transcriptomic data is very important, especially when the “omic” study deals with plant responses to stresses in field conditions where a high number of variables and disturbing factors may affect the analysis. In this meta-analysis we collected 12 transcriptomic works in Malus in order to identify which key genes, proteins, gene categories are involved in general plant pathological conditions and those features linked with exclusive biotic stress responses. Those genes that are only related with molecular responses to pathogen attacks and those linked with other plant physiological processes were identified. A pipeline composed by pathway and gene set enrich…
Identification of conserved genes linked to responses to abiotic stresses in leaves among different plant species
2020
As a consequence of global climate change, certain stress factors that have a negative impact on crop productivity such as heat, cold, drought and salinity are becoming increasingly prevalent. We conducted a meta-analysis to identify genes conserved across plant species involved in (1) general abiotic stress conditions, and (2) specific and unique abiotic stress factors (drought, salinity, extreme temperature) in leaf tissues. We collected raw data and re-analysed eight RNA-Seq studies using our previously published bioinformatic pipeline. A total of 68 samples were analysed. Gene set enrichment analysis was performed using MapMan and PageMan whereas DAVID (Database for Annotation, Visuali…