Enzymes involved in the utilization of carbohydrates by two strains of myxobacteria

Summary Extracts prepared from two strains of myxobacteria, grown with glucose as the primary carbon source, have been shown to contain a hexokinase that phosphorylates glucose to a greater extent than fructose. Phosphohexose isomerase, 6-phosphofructokinase, aldolase and a DPN-specific triose phosphate dehydrogenase are also present. In addition a TPN-specific glucose-6-phosphate dehydrogenase and a system catalyzing the reduction of DPN in the presence of 6-phosphogluconate have also been demonstrated.Supported in part by State of Washington funds for medical and biological research, and in part by the Office of Naval Research under Contract N80nr-520/III with the University of Washington.     

Association of DLA‐DQB1 alleles with exocrine pancreatic insufficiency in Pembroke Welsh Corgis

Exocrine pancreatic insufficiency (EPI) is a digestive disorder resulting from the insufficient secretion of enzymes from the pancreas. In dogs, this condition is often attributed to pancreatic acinar atrophy, wherein the enzyme‐producing acinar cells are believed to be destroyed through an autoimmune process. Although EPI affects many diverse breeds, to date, molecular studies have been limited to the German Shepherd dog. A recent study of major histocompatibility genes in diseased and healthy German Shepherd dogs identified both risk and protective haplotypes. Herein, we genotyped DLA‐DQB1 in Pembroke Welsh Corgis to determine whether dog leukocyte antigen alleles contribute to the pathogenesis of EPI across dog breeds. We evaluated 14 affected and 43 control Pembroke Welsh Corgis, which were selected based on an age of onset similar to German Shepherd dogs. We identified one protective allele (odds ratio = 0.13, P‐value = 0.044) and one risk allele (odds ratio = 3.8, P‐value = 0.047). As in German Shepherd dogs, the risk allele is a duplication of DLA‐DQB1 (alleles DQB1*013:03 and 017:01); however, Pembroke Welsh Corgis have acquired a single polymorphism on DQB1*017:01. Thus, the DLA‐DQB1 duplication is a risk allele for EPI in at least two breeds.     

5-(2-Pyrimidinyl)-imidazo[1,2-a]pyridines are antibacterial agents targeting the ATPase domains of DNA gyrase and topoisomerase IV

Dual inhibitors of bacterial gyrB and parE based on a 5-(2-pyrimidinyl)-imidazo[1,2-a]pyridine template exhibited MICs (μg/mL) of 0.06–64 (Sau), 0.25–64 (MRSA), 0.06–64 (Spy), 0.06–64 (Spn), and 0.03–64 (FQR Spn). Selected examples were efficacious in mouse sepsis and lung infection models at <50 mg/kg (PO dosing).     

A fungal endophyte defensive symbiosis affects plant-nematode interactions in cotton

Background and aims

Most investigations of fungi as nematode antagonists have focused on their interactions with nematodes in the soil. This study tested a foliar-isolated endophytic Phialemonium inflatum for its effects against the root-knot nematode as an endophyte in cotton using a seed treatment inoculation.

Methods

Cotton seeds were inoculated with P. inflatum spore suspensions prior to planting. Nematode infection and reproduction were quantified at Day 12 and 6 weeks after nematode egg inoculation, respectively. To establish whether the observed negative effects on nematodes were due to P. inflatum in the soil or as an endophyte in the plant, we also applied a soil fungicide treatment at the seedling stage to kill the fungi outside the plant.

Results

Persistent suppression of nematode penetration and galling, as well as subsequent reproduction, were observed in endophyte-treated plants independent of fungicide treatment, consistent with an endophytic mode of nematode suppression; and these negative effects did not depend on the concentration of fungal inoculum used to treat to the seed.

Conclusions

Our study highlights a novel role for P. inflatum as part of a plant-fungal defensive symbiosis in cotton, as well as the need for a broader understanding of endophyte-plant-nematode ecological interactions.

     

Food provision to nestlings in the Hoopoe Upupa epops: implications for the conservation of a small endangered population in the Swiss Alps

In an attempt to recognize the possible ecological causes of the decline of a population of Hoopoes Upupa epops in the Swiss Alps, we collected data on resource exploitation. The prey provisioned to nestlings by parents was investigated at four breeding sites using photographs (n = 4353, 80% of which enabled prey identification). Molecrickets Gryllotalpa gryllotalpa and Lepidoptera (larvae and pupae) were dominant in nestling diet (93% frequency; 97% biomass). Although Molecrickets were provisioned less frequently (26%) than Lepidoptera (67%), they represented 68% of the total biomass (vs 29% for Lepidoptera). There was an overall negative relationship between the proportion of Molecricket biomass in the diet and the parents' feeding rate, whereas a comparison between broods showed that a higher provisioning activity did not lead to an increase in the biomass supplied to the chicks. A diet based on Molecrickets therefore appears to be energetically advantageous. As Molecrickets are a traditional prey of Hoopoes in central Europe, this might be relevant to other populations. In the study area, Molecrickets occur only on the intensively cultivated plain, whereas the majority of Hoopoe pairs nest at various altitudes on the foothills adjacent to the plain as the latter provides at present almost no suitable nesting sites. Hoopoes breeding higher up on the foothills seem to experience greater provisioning costs and have, on average, lower breeding success. Providing nest sites on the plain is the main conservation measure proposed for the local Hoopoe population. Further attention should also be paid to Molecrickets as these may be crucial for Hoopoes.     

FLUXNET and modelling the global carbon cycle

Measurements of the net CO₂ flux between terrestrial ecosystems and the atmosphere using the eddy covariance technique have the potential to underpin our interpretation of regional CO₂ source–sink patterns, CO₂ flux responses to forcings, and predictions of the future terrestrial C balance. Information contained in FLUXNET eddy covariance data has multiple uses for the development and application of global carbon models, including evaluation/validation, calibration, process parameterization, and data assimilation. This paper reviews examples of these uses, compares global estimates of the dynamics of the global carbon cycle, and suggests ways of improving the utility of such data for global carbon modelling. Net ecosystem exchange of CO₂ (NEE) predicted by different terrestrial biosphere models compares favourably with FLUXNET observations at diurnal and seasonal timescales. However, complete model validation, particularly over the full annual cycle, requires information on the balance between assimilation and decomposition processes, information not readily available for most FLUXNET sites. Site history, when known, can greatly help constrain the model‐data comparison. Flux measurements made over four vegetation types were used to calibrate the land‐surface scheme of the Goddard Institute for Space Studies global climate model, significantly improving simulated climate and demonstrating the utility of diurnal FLUXNET data for climate modelling. Land‐surface temperatures in many regions cool due to higher canopy conductances and latent heat fluxes, and the spatial distribution of CO₂ uptake provides a significant additional constraint on the realism of simulated surface fluxes. FLUXNET data are used to calibrate a global production efficiency model (PEM). This model is forced by satellite‐measured absorbed radiation and suggests that global net primary production (NPP) increased 6.2% over 1982–1999. Good agreement is found between global trends in NPP estimated by the PEM and a dynamic global vegetation model (DGVM), and between the DGVM and estimates of global NEE derived from a global inversion of atmospheric CO₂ measurements. Combining the PEM, DGVM, and inversion results suggests that CO₂ fertilization is playing a major role in current increases in NPP, with lesser impacts from increasing N deposition and growing season length. Both the PEM and the inversion identify the Amazon basin as a key region for the current net terrestrial CO₂ uptake (i.e. 33% of global NEE), as well as its interannual variability. The inversion's global NEE estimate of −1.2 Pg [C] yr⁻¹ for 1982–1995 is compatible with the PEM‐ and DGVM‐predicted trends in NPP. There is, thus, a convergence in understanding derived from process‐based models, remote‐sensing‐based observations, and inversion of atmospheric data. Future advances in field measurement techniques, including eddy covariance (particularly concerning the problem of night‐time fluxes in dense canopies and of advection or flow distortion over complex terrain), will result in improved constraints on land‐atmosphere CO₂ fluxes and the rigorous attribution of mechanisms to the current terrestrial net CO₂ uptake and its spatial and temporal heterogeneity. Global ecosystem models play a fundamental role in linking information derived from FLUXNET measurements to atmospheric CO₂ variability. A number of recommendations concerning FLUXNET data are made, including a request for more comprehensive site data (particularly historical information), more measurements in undisturbed ecosystems, and the systematic provision of error estimates. The greatest value of current FLUXNET data for global carbon cycle modelling is in evaluating process representations, rather than in providing an unbiased estimate of net CO₂ exchange.