512 research outputs found
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Yield benefits of additional pollination to faba bean vary with cultivar, scale, yield parameter and experimental method
The benefits of insect pollination to crop yield are used to justify management decisions across agricultural landscapes but current methods for assessing these benefits may underestimate the importance of context. We quantify how the effects of simulated insect pollination vary between five faba bean cultivars, and to what extent this changes between years, scales, yield parameters, and experimental methods. We do this by measuring responses to standardised hand pollination treatments in controlled experiments in flight cages and in the field. Pollination treatments generally improved yield, but in some cases yield was lower with additional pollination. Pollination dependence varied with cultivar, ranging from 58% (loss in yield mass per plant without pollination) in one cultivar, to a lower yield with pollination in another (-51%). Pollination dependence also varied between flight cage and field experiments (-10% to 37% in the same cultivar and year), year (4 to 33%; same cultivar and yield parameter), and yield parameter (-4% to 46%; same cultivar and year). This variability highlights that to be robust, assessments of pollination benefits need to focus upon marketable crop outputs at a whole-plant or larger scale while including and accounting for the effects of different years, sites, methodologies and cultivars
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Susceptibility of faba bean (Vicia faba L.) to heat stress during floral development and anthesis
Experiments were conducted over two years to quantify the response of faba bean (Vicia faba L.) to heat stress. Potted winter faba bean plants (cv. Wizard) were exposed to temperature treatments (18/10; 22/14; 26/18; 30/22; 34/26°C day/night) for five days during floral development and anthesis. Developmental stages of all flowers were scored prior to stress, plants were grown in exclusion from insect pollinators to prevent pollen movement between flowers, and yield was harvested at an individual pod scale, enabling effects of heat stress to be investigated at a high resolution. Susceptibility to stress differed between floral stages, flowers were most affected during initial green-bud stages. Yield and pollen germination of flowers present before stress showed threshold relationships to stress, with lethal temperatures (t50) ~28°C and ~32°C, while whole plant yield showed a linear negative relationship to stress with high plasticity in yield allocation, such that yield lost at lower nodes was partially compensated at higher nodal positions. Faba bean has many beneficial attributes for sustainable modern cropping systems but these results suggest that yield will be limited by projected climate change, necessitating the development of heat tolerant cultivars, or improved resilience by other mechanisms such as earlier flowering times
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Quantifying crop pollinator dependence and its heterogeneity using multi-level meta-analysis
1. Biotic pollination can benefit crop production, but its effects are highly variable. To maximise benefits from this ecosystem service, we need a greater understanding of the factors that cause variation so that ecological intensification can be more effectively applied.
2. We focus on understanding the benefits of pollination to faba bean (Vicia faba). We use a literature review followed by multi-level meta-analysis to estimate overall benefits of pollination to faba bean yield and to quantify variation (heterogeneity) in these benefits associated with different contextual factors (e.g. plant genotype, growing environment).
3. Our overall estimate of pollination benefit to faba bean yield, expressed as the percentage yield reduction without pollination, is 32.9% (confidence interval 21 to 43%). Based on the prediction intervals, which include the heterogeneity in pollination benefit, there is an 80% chance that pollination will increase yield of a faba bean crop.
4. Half of all heterogeneity in pollination dependence was due to differences between plant genotypes. The number of beans per plant showed similar pollination dependence to yield mass per plant, while pod number and number of beans per pod underestimated yield benefits. There was weak evidence to suggest pollination benefits vary between pollinator species, with honeybees showing a smaller yield increase.
5. Differences in the experimental method used to assess pollination benefit did not significantly affect the estimate, including the growing environment, measurement scale, or whether the effects of experimental pollinator enclosures were controlled. This suggests that simplified experimental studies comparing yield of open-pollinated and enclosed plants can provide reliable insights into pollination benefits across a large range of plant genotypes and landscapes.
6. Synthesis and application: We found high variability in pollination benefits both between and within publications in our meta-analysis. Plant genotype, how yield was measured, and pollinator species affected the level of pollination benefit. Despite variability in pollination benefits due to various contextual factors (both inside and outside of grower control), there is a high likelihood that biotic pollination will increase faba bean yield. Our findings support ecological intensification and specifically the management of pollinators to maximise pollination benefits to faba bean production
The bilateral deficit during jumping tasks: Relationship with speed and change of direction speed performance
Research to date has investigated the phenomenon of the bilateral deficit (BLD); however, limited research exists on its association with measures of athletic performance. The purpose of the present study was to investigate the magnitude of the BLD and examine its relationship with linear speed and change of direction speed (CODS) performance. Eighteen physically active and healthy university students performed double and single leg countermovement jumps (CMJ), drop jumps (DJ) and standing broad jumps (SBJ), to calculate the BLD across jump tasks. Subjects also performed 10m and 30m sprints and a 505 CODS test, which were correlated with all BLD metrics. Results showed varying levels of BLD across CMJ metrics (jump height, peak force, eccentric impulse, concentric impulse, peak power), DJ metrics (ground contact time, flight time), and the SBJ (distance). However, a bilateral facilitation (BLF) was shown for jump height and reactive strength index (RSI) during the DJ test. The main findings of the present study were that: 1) a larger BLD in CMJ jump height related to a faster 505 change of direction (COD) (left leg) (r = -0.48; p = 0.04), 505 COD (right leg) (r = -0.53; p = 0.02) and COD deficit (right leg) (r = -0.59; p = 0.01), 2) a larger BLD in CMJ concentric impulse related to faster 505 COD (left leg) (r = -0.51; p = 0.03), 505 COD (right leg) (r = -0.64, p = 0.01) and COD deficit (right leg) (r = -0.60; p = 0.01), 3) a larger BLD in DJ flight time related to a faster 505 COD (left leg) (r = -0.48; p = 0.04). These results suggest that a larger BLD is associated with faster CODS performance, but not linear speed. This highlights the individual nature of the BLD and may support the notion of developing movement competency on one limb for enhanced CODS performance
Data Management Plan Implementation, Assessments, and Evaluations: Implications and Recommendations
Data management plans (DMPs) have become nearly a worldwide requirement for research funding. To meet these new funding agency expectations, information professionals across domains and the world have worked to create resources and services to successfully implement and sometimes assess DMPs. This essay presents a series of case studies from different institutions across the globe to highlight current practices and share recommendations for future work. A summary of various projects related to DMP implementation, assessment, and evaluation in different contexts provides a useful overview of current practices. The essay concludes with recommendations for practical oversight and scoring to improve DMPsâ utility in enabling the sharing of data
The microRNAâ200 family acts as an oncogene in colorectal cancer by inhibiting the tumor suppressor RASSF2
This study aimed to determine whether manipulation of the microRNAâ200 (miRâ200) family could influence colon adenocarcinoma cell behavior. The miRâ200 family has a significant role in tumor suppression and functions as an oncogene. In vitro studies on gain and loss of function with small interfering RNA demonstrated that the miRâ200 family could regulate RASSF2 expression. Knockdown of the miRâ200 family in the HTâ29 colon cancer cell line increased KRAS expression but decreased signaling in the MAPK/ERK signaling pathway through reduced ERK phosphorylation. Increased expression of the miRâ200 family in the CCDâ841 colon epithelium cell line increased KRAS expression and led to increased signaling in the MAPK/ERK signaling pathway but increased ERK phosphorylation. Functionally, knockdown of the miRâ200 family led to decreased cell proliferation in the HTâ29 cells; therefore, increased miRâ200 family expression could increase cell proliferation in the CCDâ841 cell line. The present study included a large paired miR array dataset (n=632), in which the miRâ200 family was significantly found to be increased in colon cancer when compared with normal adjacent colon epithelium. In a miRâseq dataset (n=199), the study found that miRâ200 family expression was increased in localized colon cancer compared with metastatic disease. Decreased expression was associated with poorer overall survival. The miRâ200 family directly targeted RASSF2 and was inversely correlated with RASSF2 expression (n=199, all P<0.001). Despite the wellâdefined role of the miRâ200 family in tumor suppression, the present findings demonstrated a novel function of the miRâ200 family in tumor proliferation
Graphical models for inferring single molecule dynamics
<p>Abstract</p> <p>Background</p> <p>The recent explosion of experimental techniques in single molecule biophysics has generated a variety of novel time series data requiring equally novel computational tools for analysis and inference. This article describes in general terms how graphical modeling may be used to learn from biophysical time series data using the variational Bayesian expectation maximization algorithm (VBEM). The discussion is illustrated by the example of single-molecule fluorescence resonance energy transfer (smFRET)<it> versus</it> time data, where the smFRET time series is modeled as a hidden Markov model (HMM) with Gaussian observables. A detailed description of smFRET is provided as well.</p> <p>Results</p> <p>The VBEM algorithm returns the modelâs evidence and an approximating posterior parameter distribution given the data. The former provides a metric for model selection via maximum evidence (ME), and the latter a description of the modelâs parameters learned from the data. ME/VBEM provide several advantages over the more commonly used approach of maximum likelihood (ML) optimized by the expectation maximization (EM) algorithm, the most important being a natural form of model selection and a well-posed (non-divergent) optimization problem.</p> <p>Conclusions</p> <p>The results demonstrate the utility of graphical modeling for inference of dynamic processes in single molecule biophysics.</p
A chemical survey of exoplanets with ARIEL
Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planetâs birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25â7.8 ÎŒm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10â100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed â using conservative estimates of mission performance and a full model of all significant noise sources in the measurement â using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL â in line with the stated mission objectives â will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio
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