Structural rearrangements within single molecules occur on ultrafast time scales. Many aspects of molecular dynamics, such as the energy flow through excited states, have been studied using ...spectroscopic techniques, yet the goal to watch molecules evolve their geometrical structure in real time remains challenging. By mapping nuclear motions using femtosecond x-ray pulses, we have created real-space representations of the evolving dynamics during a well-known chemical reaction and show a series of time-sorted structural snapshots produced by ultrafast time-resolved hard x-ray scattering. A computational analysis optimally matches the series of scattering patterns produced by the x rays to a multitude of potential reaction paths. In so doing, we have made a critical step toward the goal of viewing chemical reactions on femtosecond time scales, opening a new direction in studies of ultrafast chemical reactions in the gas phase.
Classically closo-carborane anions, particularly HCB11H11− and HCB9H9−, and their derivatives have primarily been used as weakly coordinating anions to isolate reactive intermediates, platforms for ...stoichiometric and catalytic functionalization, counteranions for simple Lewis acid catalysis, and components of materials like liquid crystals. The aim of this article is to educate the reader on the contemporary nonclassical applications of these anions. Specifically, this review will cover new directions in main group catalysis utilized to achieve some of the most challenging catalytic reactions such as C–F, C–H, and C–C functionalizations that are difficult or impossible to realize with transition metals. In addition, the review will cover the utilization of the clusters as dianionic C σ-bound ligands for coordination chemistry, ligand substituents for coordination chemistry and advanced catalyst design, and covalently bound spectator substituents to stabilize radicals. Furthermore, their applications as solution-based and solid-state electrolytes for Li, Na, and Mg batteries will be discussed.
Objective
Characterise the vaginal metabolome of cervical HPV‐infected and uninfected women.
Design
Cross‐sectional.
Setting
The Center for Health Behavior Research at the University of Maryland ...School of Public Health.
Sample
Thirty‐nine participants, 13 categorised as HPV‐negative and 26 as HPV‐positive (any genotype; HPV+), 14 of whom were positive with at least one high‐risk HPV strain (hrHPV).
Method
Self‐collected mid‐vaginal swabs were profiled for bacterial composition by 16S rRNA gene amplicon sequencing, metabolites by both gas and liquid chromatography mass spectrometry, and 37 types of HPV DNA.
Main outcome measures
Metabolite abundances.
Results
Vaginal microbiota clustered into Community State Type (CST) I (Lactobacillus crispatus‐dominated), CST III (Lactobacillus iners‐dominated), and CST IV (low‐Lactobacillus, ‘molecular‐BV’). HPV+ women had higher biogenic amine and phospholipid concentrations compared with HPV– women after adjustment for CST and cigarette smoking. Metabolomic profiles of HPV+ and HPV− women differed in strata of CST. In CST III, there were higher concentrations of biogenic amines and glycogen‐related metabolites in HPV+ women than in HPV– women. In CST IV, there were lower concentrations of glutathione, glycogen, and phospholipid‐related metabolites in HPV+ participants than in HPV– participants. Across all CSTs, women with hrHPV strains had lower concentrations of amino acids, lipids, and peptides compared with women who had only low‐risk HPV (lrHPV).
Conclusions
The vaginal metabolome of HPV+ women differed from HPV− women in terms of several metabolites, including biogenic amines, glutathione, and lipid‐related metabolites. If the temporal relation between increased levels of reduced glutathione and oxidised glutathione and HPV incidence/persistence is confirmed in future studies, anti‐oxidant therapies may be considered as a non‐surgical HPV control intervention.
Tweetable
Metabolomics study: Vaginal microenvironment of HPV+ women may be informative for non‐surgical interventions.
Tweetable
Metabolomics study: Vaginal microenvironment of HPV+ women may be informative for non‐surgical interventions.
BACKGROUND: Environmental conditions, such as water supply, temperature and salinity, strongly affect plant growth and development. Extremes of these conditions (abiotic stresses) adversely affect ...many different mechanisms associated with plant responses and adaptation to stress: photosynthetic mechanisms, e.g. stomatal control of CO₂ diffusion, photosystem II repair, ribulose bisphosphate carboxylase/oxygenase (Rubisco) activity and scavenging of reactive oxygen species (ROS), are susceptible to damage, and photosynthetic efficiency can be greatly decreased. Responses and adaptations require differential gene expression, which is regulated by specific transcription factors (TFs). SCOPE: The role and regulation of several TFs involved in abiotic stress response pathways are considered, with emphasis on new findings regarding expression of genes related to both stomatal and non-stomatal limitations to CO₂ photosynthetic assimilation. CONCLUSIONS: Many TFs, belonging to different families (e.g. MYB, bZIP and DREB), have been related to abiotic stress responses; however, only a few are known to regulate the expression of photosynthesis-related genes in response to stress. Several TFs belonging to the MYB family play an important role in both stomatal and non-stomatal responses by regulation of stomatal numbers and sizes, and metabolic components, respectively. To obtain more insight into this area of potentially large agronomic impact, it is essential to identify and functionally characterize new TFs that mediate the stress responses regulating the expression of genes associated with photosynthesis and related metabolism.
Context:
Menopause has been hypothesized to occur when the nongrowing follicle (NGF) number falls below a critical threshold. Age at natural menopause can be predicted using NGF numbers and this ...threshold. These predictions support the use of ovarian reserve tests, reflective of the ovarian follicle pool, in menopause forecasting.
Objective:
The objective of the study was to investigate the hypothesis that age-specific NGF numbers reflect age at natural menopause.
Design and Setting:
Histologically derived NGF numbers obtained from published literature (n = 218) and distribution of menopausal ages derived from the population-based Prospect-European Prospective Investigation into Cancer and Nutrition (Prospect-EPIC) cohort (n = 4037) were combined.
Participants:
NGF data were from single ovaries that had been obtained postnatally for various reasons, such as elective surgery or autopsy. From the Prospect-EPIC cohort, women aged 58 years and older with a known age at natural menopause were selected.
Interventions:
There were no interventions.
Main Outcome Measure(s):
Conformity between observed age at menopause in the Prospect-EPIC cohort and NGF-predicted age at menopause from a model for age-related NGF decline constructed using a robust regression analysis. A critical threshold for NGF number was estimated by comparing the probability distribution of the age at which the NGF numbers fall below this threshold with the observed distribution of age at natural menopause from the Prospect-EPIC cohort.
Results:
The distributions of observed age at natural menopause and predicted age at natural menopause showed close conformity.
Conclusion:
The close conformity observed between NGF-predicted and actual age at natural menopause supports the hypothesis that that the size of the primordial follicle pool is an important determinant for the length of the individual ovarian life span and supports the concept of menopause prediction using ovarian reserve tests, such as anti-Müllerian hormone and antral follicle count, as derivatives of the true ovarian reserve.
Key message
This manuscript reports the identification and characterization of five transcription factors binding to the promoter of
OsNHX1
in a salt stress tolerant rice genotype (Hasawi). Although
...NHX1
encoding genes are known to be highly regulated at the transcription level by different abiotic stresses, namely salt and drought stress, until now only one transcription factor (TF) binding to its promoter has been reported. In order to unveil the TFs regulating
NHX1
gene expression, which is known to be highly induced under salt stress, we have used a Y1H system to screen a salt induced rice cDNA expression library from Hasawi. This approach allowed us to identify five TFs belonging to three distinct TF families: one TCP (OsPCF2), one CPP (OsCPP5) and three NIN-like (OsNIN-like2, OsNIN-like3 and OsNIN-like4) binding to the
OsNHX1
gene promoter. We have also shown that these TFs act either as transcriptional activators (OsPCF2, OsNIN-like4) or repressors (OsCPP5, OsNIN-like2) and their encoding genes are differentially regulated by salt and PEG-induced drought stress in two rice genotypes, Nipponbare (salt-sensitive) and Hasawi (salt-tolerant). The transactivation activity of OsNIN-like3 was not possible to determine. Increased soil salinity has a direct impact on the reduction of plant growth and crop yield and it is therefore fundamental to understand the molecular mechanisms underlying gene expression regulation under adverse environmental conditions.
OsNHX1 is the most abundant K
+
-Na
+
/H
+
antiporter localized in the tonoplast and its gene expression is induced by salt, drought and ABA. To investigate how
OsNHX1
is transcriptionally regulated in response to salt stress in a salt-tolerant rice genotype (Hasawi), a salt-stress-induced cDNA expression library was constructed and subsequently screened using the yeast one-hybrid system and the
OsNHX1
promoter as bait. Five transcription factors (TFs) belonging to three distinct TF families: one TCP (OsPCF2), one CPP (OsCPP5) and three NIN-like (OsNIN-like2, OsNIN-like3 and OsNIN-like4) were identified as binding to
OsNHX1
promoter. Transactivation activity assays performed in
Arabidopsis
and rice protoplasts showed that OsPCF2 and OsNIN-like4 are activators of the
OsNHX1
gene expression, while OsCPP5 and OsNIN-like2 act as repressors. The transactivation activity of OsNIN-like3 needs to be further investigated. Gene expression studies showed that
OsNHX1
transcript level is highly induced by salt and PEG-induced drought stress in both shoots and roots in both Nipponbare and Hasawi rice genotypes. Nevertheless, OsNHX1 seems to play a particular role in shoots in response to drought. Most of the TFs binding to Os
NHX1
promoter showed a modest transcriptional regulation under stress conditions, however, in response to most of the conditions studied, the
OsPCF2
was induced earlier than
OsNHX1
, indicating that OsPCF2 may activate
OsNHX1
gene expression. In addition, although the
OsNHX1
response to salt and PEG-induced drought stress in either shoots or roots was quite similar in both rice genotypes, the expression of
OsPCF2
in roots under salt stress and the
OsNIN-like4
in roots subjected to PEG was mainly up-regulated in Hasawi, indicating that these TFs may be associated with the salt and drought stress tolerance observed for this genotype.
Soil salinity is a major abiotic stress that results in considerable crop yield losses worldwide. However, some plant genotypes show a high tolerance to soil salinity, as they manage to maintain a ...high K+/Na+ ratio in the cytosol, in contrast to salt stress susceptible genotypes. Although, different plant genotypes show different salt tolerance mechanisms, they all rely on the regulation and function of K+ and Na+ transporters and H+ pumps, which generate the driving force for K+ and Na+ transport. In this review we will introduce salt stress responses in plants and summarize the current knowledge about the most important ion transporters that facilitate intra- and intercellular K+ and Na+ homeostasis in these organisms. We will describe and discuss the regulation and function of the H+-ATPases, H+-PPases, SOS1, HKTs, and NHXs, including the specific tissues where they work and their response to salt stress.
Time-resolved femtosecond x-ray diffraction patterns from laser-excited molecular iodine are used to create a movie of intramolecular motion with a temporal and spatial resolution of 30 fs and 0.3 Å. ...This high fidelity is due to interference between the nonstationary excitation and the stationary initial charge distribution. The initial state is used as the local oscillator for heterodyne amplification of the excited charge distribution to retrieve real-space movies of atomic motion on ångstrom and femtosecond scales. This x-ray interference has not been employed to image internal motion in molecules before. Coherent vibrational motion and dispersion, dissociation, and rotational dephasing are all clearly visible in the data, thereby demonstrating the stunning sensitivity of heterodyne methods.
► Introduces the Agricultural Model Intercomparison and Improvement Project (AgMIP). ► Describes AgMIP Protocols for consistent research activities. ► Demonstrates AgMIP approaches using climate, ...crop, and economic model analyses. ► Wheat pilot results elucidate the relative uncertainties from crop and climate models. ► Outlines AgMIP crop-specific, regional, and global research activities.
The Agricultural Model Intercomparison and Improvement Project (AgMIP) is a major international effort linking the climate, crop, and economic modeling communities with cutting-edge information technology to produce improved crop and economic models and the next generation of climate impact projections for the agricultural sector. The goals of AgMIP are to improve substantially the characterization of world food security due to climate change and to enhance adaptation capacity in both developing and developed countries. Analyses of the agricultural impacts of climate variability and change require a transdisciplinary effort to consistently link state-of-the-art climate scenarios to crop and economic models. Crop model outputs are aggregated as inputs to regional and global economic models to determine regional vulnerabilities, changes in comparative advantage, price effects, and potential adaptation strategies in the agricultural sector. Climate, Crop Modeling, Economics, and Information Technology Team Protocols are presented to guide coordinated climate, crop modeling, economics, and information technology research activities around the world, along with AgMIP Cross-Cutting Themes that address uncertainty, aggregation and scaling, and the development of Representative Agricultural Pathways (RAPs) to enable testing of climate change adaptations in the context of other regional and global trends. The organization of research activities by geographic region and specific crops is described, along with project milestones.
Pilot results demonstrate AgMIP's role in assessing climate impacts with explicit representation of uncertainties in climate scenarios and simulations using crop and economic models. An intercomparison of wheat model simulations near Obregón, Mexico reveals inter-model differences in yield sensitivity to CO2 with model uncertainty holding approximately steady as concentrations rise, while uncertainty related to choice of crop model increases with rising temperatures. Wheat model simulations with mid-century climate scenarios project a slight decline in absolute yields that is more sensitive to selection of crop model than to global climate model, emissions scenario, or climate scenario downscaling method. A comparison of regional and national-scale economic simulations finds a large sensitivity of projected yield changes to the simulations’ resolved scales. Finally, a global economic model intercomparison example demonstrates that improvements in the understanding of agriculture futures arise from integration of the range of uncertainty in crop, climate, and economic modeling results in multi-model assessments.
To meet the food demands of an increasing world population, it is necessary to improve crop production; a task that is made more challenging by the changing climate. Several recent reports show that ...increasing the capacity of plants to assimilate carbon (source strength), or to tap into the internal carbon reservoir (sink strength), has the potential to improve plant productivity in the field under water-deficit conditions. Here, we review the effects of water deficit on the source–sink communication, as well as the respective regulatory mechanisms underpinning plant productivity. We also highlight stress-tolerant traits that can contribute to harness source and sink strengths towards producing high-yielding and drought-tolerant crops, depending on the drought scenario.
Plants have evolved intricate systems to balance carbon assimilation (source strength) and usage (sink strength), however, drought disrupts this equilibrium, causing large losses in plant productivity.Recently, our increasing understanding of the molecular mechanisms underlying plant responses to drought show that plants that are able to maintain source and sink strengths under stress are more resilient and productive.
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