ESCRT-I Mediates FLS2 Endosomal Sorting and Plant Immunity

The plant immune receptor FLAGELLIN SENSING 2 (FLS2) is present at the plasma membrane and is internalized following activation of its ligand flagellin (flg22). We show that ENDOSOMAL SORTING COMPLEX REQUIRED FOR TRANSPORT (ESCRT)-I subunits play roles in FLS2 endocytosis in Arabidopsis. VPS37-1 co-localizes with FLS2 at endosomes and immunoprecipitates with the receptor upon flg22 elicitation. Vps37-1 mutants are reduced in flg22-induced FLS2 endosomes but not in endosomes labeled by Rab5 GTPases suggesting a defect in FLS2 trafficking rather than formation of endosomes. FLS2 localizes to the lumen of multivesicular bodies, but this is altered in vps37-1 mutants indicating compromised endosomal sorting of FLS2 by ESCRT-I loss-of-function. VPS37-1 and VPS28-2 are critical for immunity against bacterial infection through a role in stomatal closure. Our findings identify that VPS37-1, and likewise VPS28-2, regulate late FLS2 endosomal sorting and reveals that ESCRT-I is critical for flg22-activated stomatal defenses involved in plant immunity.     

Treadmill desks: A 1‐year prospective trial

Objective: Sedentariness is associated with weight gain and obesity. A treadmill desk is the combination of a standing desk and a treadmill that allow employees to work while walking at low speed. Design and Methods: The hypothesis was that a 1‐year intervention with treadmill desks is associated with an increase in employee daily physical activity (summation of all activity per minute) and a decrease in daily sedentary time (zero activity). Employees (n = 36; 25 women, 11 men) with sedentary jobs (87 ± 27 kg, BMI 29 ± 7 kg/m², n = 10 Lean BMI < 25 kg/m², n = 15 Overweight 25 < BMI < 30 kg/m², n = 11 Obese BMI > 30 kg/m²) volunteered to have their traditional desk replaced with a treadmill desk to promote physical activity for 1 year. Results: Daily physical activity (using accelerometers), work performance, body composition, and blood variables were measured at Baseline and 6 and 12 months after the treadmill desk intervention. Subjects who used the treadmill desk increased daily physical activity from baseline 3,353 ± 1,802 activity units (AU)/day to, at 6 months, 4,460 ± 2,376 AU/day (P < 0.001), and at 12 months, 4,205 ± 2,238 AU/day (P < 0.001). Access to the treadmill desks was associated with significant decreases in daily sedentary time (zero activity) from at baseline 1,020 ± 75 min/day to, at 6 months, 929 ± 84 min/day (P < 0.001), and at 12 months, 978 ± 95 min/day (P < 0.001). For the whole group, weight loss averaged 1.4 ± 3.3 kg (P < 0.05). Weight loss for obese subjects was 2.3 ± 3.5 kg (P < 0.03). Access to the treadmill desks was associated with increased daily physical activity compared to traditional chair‐based desks; their deployment was not associated with altered performance. For the 36 participants, fat mass did not change significantly, however, those who lost weight (n = 22) lost 3.4 ± 5.4 kg (P < 0.001) of fat mass. Weight loss was greatest in people with obesity. Conclusions: Access to treadmill desks may improve the health of office workers without affecting work performance.     

Spatial Differences in East Scotia Ridge Hydrothermal Vent Food Webs: Influences of Chemistry,Microbiology and Predation on Trophodynamics

The hydrothermal vents on the East Scotia Ridge are the first to be explored in the Antarctic and are dominated by large peltospiroid gastropods, stalked barnacles (Vulcanolepas sp.) and anomuran crabs (Kiwa sp.) but their food webs are unknown. Vent fluid and macroconsumer samples were collected at three vent sites (E2, E9N and E9S) at distances of tens of metres to hundreds of kilometres apart with contrasting vent fluid chemistries to describe trophic interactions and identify potential carbon fixation pathways using stable isotopes. δ¹³C of dissolved inorganic carbon from vent fluids ranged from −4.6‰ to 0.8‰ at E2 and from −4.4‰ to 1.5‰ at E9. The lowest macroconsumer δ¹³C was observed in peltospiroid gastropods (−30.0‰ to −31.1‰) and indicated carbon fixation via the Calvin-Benson-Bassham (CBB) cycle by endosymbiotic gamma-Proteobacteria. Highest δ¹³C occurred in Kiwa sp. (−19.0‰ to −10.5‰), similar to that of the epibionts sampled from their ventral setae. Kiwa sp. δ¹³C differed among sites, which were attributed to spatial differences in the epibiont community and the relative contribution of carbon fixed via the reductive tricarboxylic acid (rTCA) and CBB cycles assimilated by Kiwa sp. Site differences in carbon fixation pathways were traced into higher trophic levels e.g. a stichasterid asteroid that predates on Kiwa sp. Sponges and anemones at the periphery of E2 assimilated a proportion of epipelagic photosynthetic primary production but this was not observed at E9N. Differences in the δ¹³C and δ³⁴S values of vent macroconsumers between E2 and E9 sites suggest the relative contributions of photosynthetic and chemoautotrophic carbon fixation (rTCA v CBB) entering the hydrothermal vent food webs vary between the sites.     

An Investigation of Fecal Volatile Organic Metabolites in Irritable Bowel Syndrome

Diagnosing irritable bowel syndrome (IBS) can be a challenge; many clinicians resort to invasive investigations in order to rule out other diseases and reassure their patients. Volatile organic metabolites (VOMs) are emitted from feces; understanding changes in the patterns of these VOMs could aid our understanding of the etiology of the disease and the development of biomarkers, which can assist in the diagnosis of IBS. We report the first comprehensive study of the fecal VOMs patterns in patients with diarrhea-predominant IBS (IBS-D), active Crohn''s disease (CD), ulcerative colitis (UC) and healthy controls. 30 patients with IBS-D, 62 with CD, 48 with UC and 109 healthy controls were studied. Diagnosis of IBS-D was made using the Manning criteria and all patients with CD and UC met endoscopic, histologic and/or radiologic criteria. Fecal VOMs were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). 240 VOMs were identified. Univariate analysis showed that esters of short chain fatty acids, cyclohexanecarboxylic acid and its ester derivatives were associated with IBS-D (p<0.05), while aldehydes were more abundant in IBD (p<0.05). A predictive model, developed by multivariate analysis, separated IBS-D from active CD, UC and healthy controls with a sensitivity of 94%, 96% and 90%; and a specificity of 82%, 80% and 80% respectively (p<0.05). The understanding of the derivation of these VOMs may cast light on the etiology of IBS-D and IBD. These data show that fecal VOMs analyses could contribute to the diagnosis of IBS-D, for which there is no laboratory test, as well as IBD.     

Overexpression of IRM1 Enhances Resistance to Aphids in Arabidopsis thaliana

Aphids are insects that cause direct damage to crops by the removal of phloem sap, but more importantly they spread devastating viruses. Aphids use their sophisticated mouthpart (i.e. stylet) to feed from the phloem sieve elements of the host plant. To identify genes that affect host plant resistance to aphids, we previously screened an Arabidopsis thaliana activation tag mutant collection. In such mutants, tagged genes are overexpressed by a strong 35S enhancer adjacent to the natural promoter, resulting in a dominant gain-of-function phenotype. We previously identified several of these mutants on which the aphid Myzus persicae showed a reduced population development compared with wild type. In the present study we show that the gene responsible for the phenotype of one of the mutants is At5g65040 and named this gene Increased Resistance to Myzus persicae 1 (IRM1). Overexpression of the cloned IRM1 gene conferred a phenotype identical to that of the original mutant. Conversely, an IRM1 knockout mutant promoted aphid population development compared to the wild type. We performed Electrical Penetration Graph analysis to investigate how probing and feeding behaviour of aphids was affected on plants that either overexpressed IRM1 or contained a knockout mutation in this gene. The EPG results indicated that the aphids encounter resistance factors while reaching for the phloem on the overexpressing line. This resistance mechanism also affected other aphid species and is suggested to be of mechanical nature. Interestingly, genetic variation for IRM1 expression in response to aphid attack was observed. Upon aphid attack the expression of IRM1 was initially (after 6 hours) induced in ecotype Wassilewskija followed by suppression. In Columbia-0, IRM1 expression was already suppressed six hours after the start of the infestation. The resistance conferred by the overexpression of IRM1 in A. thaliana trades off with plant growth.     

Effectiveness of Inactivated Influenza Vaccines in Preventing Influenza-Associated Deaths and Hospitalizations among Ontario Residents Aged ≥65 Years: Estimates with Generalized Linear Models Accounting for Healthy Vaccinee Effects

Background

Estimates of the effectiveness of influenza vaccines in older adults may be biased because of difficulties identifying and adjusting for confounders of the vaccine-outcome association. We estimated vaccine effectiveness for prevention of serious influenza complications among older persons by using methods to account for underlying differences in risk for these complications.

Methods

We conducted a retrospective cohort study among Ontario residents aged ≥65 years from September 1993 through September 2008. We linked weekly vaccination, hospitalization, and death records for 1.4 million community-dwelling persons aged ≥65 years. Vaccine effectiveness was estimated by comparing ratios of outcome rates during weeks of high versus low influenza activity (defined by viral surveillance data) among vaccinated and unvaccinated subjects by using log-linear regression models that accounted for temperature and time trends with natural spline functions. Effectiveness was estimated for three influenza-associated outcomes: all-cause deaths, deaths occurring within 30 days of pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations.

Results

During weeks when 5% of respiratory specimens tested positive for influenza A, vaccine effectiveness among persons aged ≥65 years was 22% (95% confidence interval [CI], −6%–42%) for all influenza-associated deaths, 25% (95% CI, 13%–37%) for deaths occurring within 30 days after an influenza-associated pneumonia/influenza hospitalization, and 19% (95% CI, 4%–31%) for influenza-associated pneumonia/influenza hospitalizations. Because small proportions of deaths, deaths after pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations were associated with influenza virus circulation, we estimated that vaccination prevented 1.6%, 4.8%, and 4.1% of these outcomes, respectively.

Conclusions

By using confounding-reducing techniques with 15 years of provincial-level data including vaccination and health outcomes, we estimated that influenza vaccination prevented ∼4% of influenza-associated hospitalizations and deaths occurring after hospitalizations among older adults in Ontario.     

Genome-Wide Identification,Phylogeny and Expression Profile of Vesicle Fusion Components in Verticillium dahliae

Vesicular trafficking plays a crucial role in protein localization and movement, signal transduction, and multiple developmental processes in eukaryotic cells. Vesicle fusion is the final and key step in vesicle-mediated trafficking and mainly relies on SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors), the regulators including SM (Sec1/Munc18) family proteins, Rab GTPases and exocyst subunits. Verticillium dahliae is a widespread soil fungus that causes disruptive vascular diseases on a wide range of plants. To date, no genes involved in vesicular fusion process have been identified and characterized in V. dahliae. The recent publication of the draft genome sequence of V. dahliae allowed us to conduct a genome-wide identification, phylogeny and expression profile of genes encoding vesicular fusion components. Using compared genomics and phylogenetic methods, we identified 44 genes encoding vesicle fusion components in the V. dahliae genome. According to the structural features of their encoded proteins, the 44 V. dahliae genes were classified into 22 SNAREs (6 Qa-, 4 Qb-, 6 Qc-, 1 Qbc- and 5 R-types), 4 SM family proteins, 10 Rab GTPases and 8 exocyst proteins. Based on phylogeny and motif constitution analysis, orthologs of vesicle fusion component in filamentous fungi were generally clustered together into the same subclasses with well-supported bootstrap values. Analysis of the expression profiles of these genes indicated that many of them are significantly differentially expressed during vegetative growth and microsclerotia formation in V. dahliae. The analysis show that many components of vesicle fusion are well conserved in filamentous fungi and indicate that vesicle fusion plays a critical role in microsclerotia formation of smoke tree wilt fungus V. dahliae. The genome-wide identification and expression analysis of components involved in vesicle fusion should facilitate research in this gene family and give new insights toward elucidating their functions in growth, development and pathogenesis of V. dahliae.     

Diversity and temperature indirectly reduce CO2 concentrations in experimental freshwater communities

Oecologia - Biodiversity loss and climate warming are occurring in concert, with potentially profound impacts on ecosystem functioning. We currently know very little about the combined effects of...     

Demographic,seed and microsite limitations to seedling recruitment in semi-arid mine site restoration

Plant and Soil - Understanding limitations to plant recruitment is a key element in devising effective restoration of semi-arid ecosystems: only when these limitations are identified can management...