Leaf surface wax is a source of plant methane formation under UV radiation and in the presence of oxygen.

The terrestrial vegetation is a source of UV radiation-induced aerobic methane (CH4 ) release to the atmosphere. Hitherto pectin, a plant structural component, has been considered as the most likely precursor for this CH4 release. However, most of the leaf pectin is situated below the surface wax layer, and UV transmittance of the cuticle differs among plant species. In some species, the cuticle effectively absorbs and/or reflects UV radiation. Thus, pectin may not necessarily contribute substantially to the UV radiation-induced CH4 emission measured at surface level in all species. Here, we investigated the potential of the leaf surface wax itself as a source of UV radiation-induced leaf aerobic CH4 formation. Isolated leaf surface wax emitted CH4 at substantial rates in response to UV radiation. This discovery has implications for how the phenomenon should be scaled to global levels. In relation to this, we demonstrated that the UV radiation-induced CH4 emission is independent of leaf area index above unity. Further, we observed that the presence of O2 in the atmosphere was necessary for achieving the highest rates of CH4 emission. Methane formation from leaf surface wax is supposedly a two-step process initiated by a photolytic rearrangement reaction of the major component followed by an α-cleavage of the generated ketone.

Metabolic outcomes of matched patient populations initiating exenatide BID vs. insulin glargine in an ambulatory care setting.

AIM: This observational study evaluated the clinical effectiveness of exenatide BID (exenatide) vs. insulin glargine (glargine) in patients with type 2 diabetes mellitus in ambulatory clinical practice. METHODS: Retrospective analyses were conducted using an electronic medical record (EMR) database among adult patients with type 2 diabetes mellitus initiating exenatide or glargine between 1 November 2006 and 30 April 2009. The cohorts were propensity-score matched to control baseline demographics, clinical measures, health status and medication use. The changes from baseline to a 12-month follow-up period for A1C (primary outcome), weight, body mass index (BMI), blood pressure and lipid levels were compared between the matched cohorts using paired tests. RESULTS: Propensity-score matching between the exenatide (n = 4494) and glargine (n = 5424) cohorts led to 2683 matched pairs with comparable characteristics, including age, gender and baseline clinical values. The exenatide cohort achieved a greater mean reduction in A1C (-0.6% vs. -0.4%, p < 0.01), weight (-2.6 kg vs. -0.2 kg, p < 0.01), BMI (-0.8 kg/m(2) vs. -0.04 kg/m(2) , p < 0.01) and systolic blood pressure (SBP) (-1.8 mmHg vs. -0.1 mmHg, p < 0.01) in the follow-up period. The changes in diastolic blood pressure and lipid levels were not significantly different between cohorts. CONCLUSIONS: Compared to glargine, exenatide-treated patients experienced significant reductions in A1C, weight, BMI and SBP. Acknowledging the limitations of observational research, exenatide showed greater clinical effectiveness than glargine from a large EMR database in the ambulatory care setting.

Effects of temperature, ultraviolet radiation and pectin methyl esterase on aerobic methane release from plant material.

This study examines the effects of different irradiance types on aerobic methane (CH(4)) efflux rates from terrestrial plant material. Furthermore, the role of the enzyme pectin methyl esterase (PME) on CH(4) efflux potential was also examined. Different types of plant tissue and purified pectin were incubated in glass vials with different combinations of irradiation and/or temperature. Purified dry pectin was incubated in solution, and with or without PME. Before and after incubation, the concentration of CH(4) was measured with a gas chromatograph. Rates of CH(4) emission were found to depend exponentially on temperature and linearly on UV-B irradiance. UV-B had a greater stimulating effect than UV-A, while visible light had no effect on emission rates. PME was found to substantially reduce the potential for aerobic CH(4) emissions upon demethylation of pectin.

Responses of two provenances of Fagus sylvatica seedlings to a combination of four temperature and two CO2 treatments during their first growing season: gas exchange of leaves and roots.

Physiological responses of two provenances of European beech (Fagus sylvatica) were studied in seedlings grown at two [CO2 ] in combination with four temperature treatments. For the local Danish provenance, the average effect of elevated [CO2 ] during growth was to increase light-saturated net photosynthesis (An ) and instantaneous water-use efficiency or transpiration efficiency (ITE). These increases were strongly related to the temperature treatment. Stomatal conductance (gs ) was reduced in seedlings in high [CO2 ], but there was no statistically significant effect of temperature treatment. Stomatal conductance was 13-26% lower at elevated [CO2 ] and ITE was 89-156% higher, depending on growth temperature. The effects of [CO2 ] on An were considerably larger than those shown for many other woody species, but similar to those in other studies on European beech. The absolute value of An for a Romanian provenance of beech was 5-18% lower than in the Danish provenance at low [CO2 ] and 14-26% lower at high [CO2 ]. There was no statistically significant interaction between the provenances and [CO2 ], or between provenance and temperature. A model of the response of An to [CO2 ] at different temperatures gave predictions close to the measured results, except at the lowest temperature treatment where the model over-predicted the effect of elevated [CO2 ]. This and measurements of An made at a common, low [CO2 ] indicated a down-regulation of photosynthesis in the lowest temperature treatment at high [CO2 ]. Root plus soil respiration on a whole-tree basis (Rtr ) was increased by elevated [CO2 ] at all but the lowest temperature, but no effect was seen of [CO2 ] on root respiration per unit root d. wt. Mean Rtr on any given date was significantly correlated with An , except at the lowest temperature treatment. It is hypothesized that low temperature limited the ability of the roots to use photosynthates resulting in a feedback inhibition of An when elevated [CO2 ] was combined with low temperature.

The arsenical resistance operon of IncN plasmid R46.

The arsenical resistance operon of the IncN plasmid R46 consists of 4696 bp and starts with predicted transcriptional control and initiation signals, followed by five genes, arsD, arsA, and arsC. The corresponding Escherichia coli chromosomal ars operon and two staphylococcal ars operons lack arsA and arsD genes. The R46 system contains only the second known versions of arsA and arsD, after those of plasmid R773. Western blot analysis identified the R46 proteins using antibodies against R773 ArsA, ArsD and ArsR.