Texas Citrus Disease Management.

4 p

Texas Citrus Disease Management.

4 p

Weeds, as ancillary hosts, pose disproportionate risk for virulent pathogen transfer to crops

BACKGROUND: The outcome of the arms race between hosts and pathogens depends heavily on the interactions between their genetic diversity, population size and transmission ability. Theory predicts that genetically diverse hosts will select for higher virulence and more diverse pathogens than hosts with low genetic diversity. Cultivated hosts typically have lower genetic diversity and thus small effective population sizes, but can potentially harbour large pathogen population sizes. On the other hand, hosts, such as weeds, which are genetically more diverse and thus have larger effective population sizes, usually harbour smaller pathogen population sizes. Large pathogen population sizes may lead to more opportunities for mutation and hence more diverse pathogens. Here we test the predictions that pathogen neutral genetic diversity will increase with large pathogen population sizes and host diversity, whereas diversity under selection will increase with host diversity. We assessed and compared the diversity of a fungal pathogen, Rhynchosporium commune, on weedy barley grass (which have a large effective population size) and cultivated barley (low genetic diversity) using microsatellites, effector locus nip1 diversity and pathogen aggressiveness in order to assess the importance of weeds in the evolution of the neutral and selected diversity of pathogens. RESULTS: The findings indicated that the large barley acreage and low host diversity maintains higher pathogen neutral genetic diversity and lower linkage disequilibrium, while the weed maintains more pathotypes and higher virulence diversity at nip1. Strong evidence for more pathogen migration from barley grass to barley suggests transmission of virulence from barley grass to barley is common. CONCLUSIONS: Pathogen census population size is a better predictor for neutral genetic diversity than host diversity. Despite maintaining a smaller pathogen census population size, barley grass acts as an important ancillary host to R. commune, harbouring highly virulent pathogen types capable of transmission to barley. Management of disease on crops must therefore include management of weedy ancillary hosts, which may harbour disproportionate supplies of virulent pathogen strains.CCL was funded by the Grains Research Development Council (GRDC) (ANU00012 and DAQ00187). The authors thank Hugh Wallwork (SARDI) for assisting in some isolate collections and Megan Head (ANU) for statistical advice

Neck/shoulder pain in adolescents is not related to the level or nature of self-reported physical activity or type of sedentary activity in an Australian pregnancy cohort

<p>Abstract</p> <p>Background</p> <p>An inconsistent relationship between physical activity and neck/shoulder pain (NSP) in adolescents has been reported in the literature. Earlier studies may be limited by not assessing physical activity in sufficient detail. The aim of this study was to comprehensively examine the association between NSP and the level and nature of physical activity, and type of sedentary activity in adolescents.</p> <p>Methods</p> <p>A cross-sectional analysis using data from 924 adolescents in the Western Australian Pregnancy Cohort (RAINE) study was performed. Complete data were available for 643 adolescents (54.6% female) at the 14-year follow-up. Physical activity was measured using a detailed self-report electronic activity diary requiring participants to input details of all physical activities over the day in segments of 5 minutes for a one-week period. Physical activity <it>levels </it>were categorised as: sedentary, light, moderate, or vigorous based on metabolic energy equivalents. <it>Nature </it>of activity was determined by assigning each activity to categories based on the amount of movement (static/dynamic) and the main posture assumed for the activity (standing/sitting/lying). <it>Type of sedentary activity </it>was characterised by exposure time to watching TV, using a computer, and reading. Logistic regression was used to explore the association between NSP and activity.</p> <p>Results</p> <p>Females reported a higher prevalence of lifetime, 1-month and chronic NSP than males (50.9 vs 41.7%, 34.1 vs 23.5%, and 9.2 vs 6.2% respectively). No consistent, dose-response relationship was found between NSP and the level, nature, and type of physical activity.</p> <p>Conclusion</p> <p>Self-reported one month and lifetime NSP prevalence in adolescents is <it>not </it>related to the level or intensity of physical activity or the type of sedentary activity over a one week period.</p

Safety assessment of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA determined in trials with Wistar rats

Colonization of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA in the gastro-intestinal tract was determined by using Wistar rats as model. The strains were administered through intragastric gavage over 14 days. FISH with strain-specific oligonucleotide probes indicated that Lact. plantarum 423 adhered to the surfaces of the ileum and the cecum. Enterococcus mundtii ST4SA, on the other hand, adhered to the surfaces of the cecum and colon. Results obtained by DGGE have shown that strains 423 and ST4SA excluded Enterobacteriaceae, but not lactic acid bacteria, from the cecum and colon. No signs of perforation of epithelial cells by strains 423 and ST4SA were detected. The spleen and liver appeared healthy and blood counts were normal, suggesting that the strains are not pathogenic. Both strains produce antimicrobial peptides active against a number of pathogens and may be considered as probiotics

The well-being of carers of older Aboriginal people living in the Kimberley region of remote Western Australia: Empowerment, depression, and carer burden

Objective: To describe demographic features and well-being of carers of Aboriginal Australians aged ≥45 years in remote Western Australia. Method: Carer burden, empowerment, and depression were assessed in 124 Aboriginal carers in four remote Aboriginal communities. Results: Carers were aged 38.8 ± 15.0 years, 73.4% were female, and 75.8% were children or grandchildren of the person cared for. The mean Zarit-6 score was 3.7 ± 3.6. Attending high school (odds ratio [OR] = 0.3; 95% confidence interval [CI] = [0.1, 0.7]) and feeling empowered (OR = 0.2; 95% CI = [0.1, 0.8]) were inversely associated with carer burden; female carers were less likely to feel empowered (OR = 0.4; 95% CI = [0.2, 0.9]); and empowerment was inversely associated with depression (OR = 0.3; 95% CI = [0.1, 0.7]). Discussion: Aboriginal carers in remote communities are relatively young and most are children or grandchildren. Carer burden was lower than anticipated. However, existing tools may not adequately measure Aboriginal perspectives. Education and empowerment are key factors which support programs must consider

Robust multi-year climate impacts of volcanic eruptions in decadal prediction systems

Major tropical volcanic eruptions have a large impact on climate, but there have only been three major eruptions during the recent relatively well-observed period. Models are therefore an important tool to understand and predict the impacts of an eruption. This study uses five state-of-the-art decadal prediction systems that have been initialized with the observed state before volcanic aerosols are introduced. The impact of the volcanic aerosols is found by subtracting the results of a reference experiment where the volcanic aerosols are omitted. We look for the robust impact across models and volcanoes by combining all the experiments, which helps reveal a signal even if it is weak in the models. The models used in this study simulate realistic levels of warming in the stratosphere, but zonal winds are weaker than the observations. As a consequence, models can produce a pattern similar to the North Atlantic Oscillation in the first winter following the eruption, but the response and impact on surface temperatures is weaker than in observations. Reproducing the pattern, but not the amplitude, may be related to a known model error. There are also impacts in the Pacific and Atlantic Oceans. This work contributes towards improving the interpretation of decadal predictions in the case of a future large tropical volcanic eruption

Observations of planetary heating since the 1980s from multiple independent datasets

Time series of global mean surface temperature are widely used to measure the rate of climate change that results from Earth's energy imbalance. However, studies based on climate model simulations suggest that on annual-to-decadal timescales global ocean heat content is a more reliable indicator. Here we examine the observational evidence for this, drawing together multiple datasets that span the past ~30 years. This observational analysis strongly supports the model-based finding that global ocean heat content and sea level are more reliable than surface temperature for monitoring Earth's energy accumulation on these timescales. Global ocean temperature anomalies in the 0–100 m and 100–250 m layers are negatively correlated (r = −0.36), primarily explained by the influence of the Tropical Pacific, and a clearer heating signal is revealed by integrating over deeper ocean layers. The striking agreement between multiple independent datasets represents unequivocal evidence of ongoing planetary heating

Examining reliability of seasonal to decadal sea surface temperature forecasts: the role of ensemble dispersion

Useful probabilistic climate forecasts on decadal timescales should be reliable (i.e. forecast probabilities match the observed relative frequencies) but this is seldom examined. This paper assesses a necessary condition for reliability, that the ratio of ensemble spread to forecast error being close to one, for seasonal to decadal sea surface temperature retrospective forecasts from the Met Office Decadal Prediction System (DePreSys). Factors which may affect reliability are diagnosed by comparing this spread-error ratio for an initial condition ensemble and two perturbed physics ensembles for initialized and uninitialized predictions. At lead times less than 2 years, the initialized ensembles tend to be under-dispersed, and hence produce overconfident and hence unreliable forecasts. For longer lead times, all three ensembles are predominantly over-dispersed. Such over-dispersion is primarily related to excessive inter-annual variability in the climate model. These findings highlight the need to carefully evaluate simulated variability in seasonal and decadal prediction systems.Useful probabilistic climate forecasts on decadal timescales should be reliable (i.e. forecast probabilities match the observed relative frequencies) but this is seldom examined. This paper assesses a necessary condition for reliability, that the ratio of ensemble spread to forecast error being close to one, for seasonal to decadal sea surface temperature retrospective forecasts from the Met Office Decadal Prediction System (DePreSys). Factors which may affect reliability are diagnosed by comparing this spread-error ratio for an initial condition ensemble and two perturbed physics ensembles for initialized and uninitialized predictions. At lead times less than 2 years, the initialized ensembles tend to be under-dispersed, and hence produce overconfident and hence unreliable forecasts. For longer lead times, all three ensembles are predominantly over-dispersed. Such over-dispersion is primarily related to excessive inter-annual variability in the climate model. These findings highlight the need to carefully evaluate simulated variability in seasonal and decadal prediction systems

Convergence towards a European strategic culture? A constructivist framework for explaining changing norms.

The article contributes to the debate about the emergence of a European strategic culture to underpin a European Security and Defence Policy. Noting both conceptual and empirical weaknesses in the literature, the article disaggregates the concept of strategic culture and focuses on four types of norms concerning the means and ends for the use of force. The study argues that national strategic cultures are less resistant to change than commonly thought and that they have been subject to three types of learning pressures since 1989: changing threat perceptions, institutional socialization, and mediatized crisis learning. The combined effect of these mechanisms would be a process of convergence with regard to strategic norms prevalent in current EU countries. If the outlined hypotheses can be substantiated by further research the implications for ESDP are positive, especially if the EU acts cautiously in those cases which involve norms that are not yet sufficiently shared across countries