Activation tagging identifies Arabidopsis transcription factor AtMYB68 for heat and drought tolerance at yield determining reproductive stages.

Heat stress occurring at reproductive stages can result in significant and permanent damage to crop yields. However, previous genetic studies in understanding heat stress response and signaling were performed mostly on seedling and plants at early vegetative stages. Here we identify, using a developmentally defined, gain-of-function genetic screen with approximately 18 000 Arabidopsis thaliana activation-tagged lines, a mutant that maintained productive seed set post-severe heat stress during flowering. Genome walking indicated this phenotype was caused by the insertion of 35S enhancers adjacent to a nuclear localized transcription factor AtMYB68. Subsequent overexpression analysis confirmed that AtMYB68 was responsible for the reproductive heat tolerance of the mutant. Furthermore, these transgenic Arabidopsis plants exhibited enhanced abscisic acid sensitivity at and post-germination, reduced transpirational water loss during a drought treatment, and enhanced seed yield under combined heat and drought stress during flowering. Ectopic expression of AtMYB68 in Brassica napus driven either by 35S or by heat-inducible promoter recapitulated the enhanced reproductive heat stress and drought tolerance phenotypes observed in the transgenic Arabidopsis. The improvement to heat stress is likely due to enhanced pollen viability observed in the transgenic plants. More importantly, the transgenic canola showed significant yield advantages over the non-transgenic controls in multiple locations, multiple season field trials under various drought and heat stress conditions. Together these results suggest that AtMYB68 regulate plant stress tolerance at the most important yield determining stage of plant development, and is an effective target for crop yield protection under current global climate volatility.

Device-associated infection rates, device use, length of stay, and mortality in intensive care units of 4 Chinese hospitals: International Nosocomial Control Consortium findings.

BACKGROUND: Little data exist on the burden of device-associated health care-associated infection (DA-HAI) in China. This study examined the DA-HAI rate and evaluated its association with device use (DU), length of stay (LOS), and mortality in intensive care units (ICUs) in 4 Chinese hospitals. METHODS: This was a prospective cohort surveillance study conducted in 7 ICUs in 4 hospitals. We applied International Nosocomial Control Consortium methods and Centers for Disease Control and Prevention (CDC)/National Health and Safety Network (NHSN) definitions to determine rates of central line-associated blood stream infection (CLABSI), ventilator-associated pneumonia (VAP), catheter-associated urinary tract infection (CAUTI), DU, crude extra length of hospital stay (LOS), and mortality. RESULTS: Between August 2008 and July 2010, there were a total of 2,631 admissions to the 7 ICUs in the study hospitals. The rate of VAP was 10.46/1,000 mechanical ventilator (MV)-days, the CLABSI rate was 7.66/1,000 central line (CL)-days, and the CAUTI rate was 1.29/1,000 urinary catheter (UC)-days. Pooled DU ratios were 0.43 for MV, 0.71 for CL, and 0.76 for UC. Crude extra LOS was 15 days for patients with CLABSI, 20.5 days for patients with VAP, and 27 days for patients with CAUTI. Crude extra mortality was 14% for patients with CLABSI, 22% for patients with VAP, and 43% for patients with CAUTI. CONCLUSIONS: In the study ICUs, VAP and CLABSI rates were higher than CDC/NHSN's reported data, and LOS and mortality were increased. Compared with the CDC/NHSN and INICC data, the pooled DU ratio for MV was similar, and DU ratios for CL and UC use ratios were slightly higher.