Epiphytic fitness of a biological control agent of fire blight in apple and pear orchards under Mediterranean weather conditions

The behaviour of Pseudomonas fluorescens EPS62e was investigated in apple and pear orchards under Mediterranean climatic conditions. The trials studied the influence of weather conditions, plant host species, presence of indigenous microbial community and spread from treated to nontreated trees on colonization and survival. Population dynamics were assessed by real-time PCR and CFU-counting methods. With inoculated flowers, weather conditions were optimal for colonization, and EPS62e established high and stable population levels around 10(8) CFU per organ, according to both methods of analysis. The plant host species did not influence the colonization rate, and the biocontrol agent dominated the microbial communities of blossoms, representing up to 100% of the total cultivable population. With inoculated leaves, the EPS62e population decreased to nondetectable levels 30 days after treatment according to both methods used. EPS62e spread moderately in the orchard, being detected in nontreated flowers of trees 15-35 m from the inoculation site. The combined use of real-time PCR and CFU-counting methods of analysis permitted the identification of three physiological states for EPS62e in the field, which consisted of active colonization, survival and entry into a viable but nonculturable state, and cell death.     

Population dynamics ofTelenomus fariai [Hym.: Scelionidae], a parasite of chagas' disease vectors VIII. Morphological and ecological comparison between two allopatric populations under laboratory conditions

Telenomus fariai Lima ranges from Argentina and Chile to Mexico; some ecological parameters and morphological characters were compared between tropical (Costa Rica) and temperate (Argentina) populations, as reared on tropical and temperate hosts. The results of the 4 combinations between the 2 parasite populations and the 2 host species (Triatoma phyllosoma pallidipennis Stal) andTriatoma infestans Klug) [Hym.: Reduviidae] showed that only the parasite's geographical origin was statistically significant when evaluated through adult female life expectancy at time of emergence from the host, development time, total progeny per host per female 0–24 h old, and generation time. No difference was found between parasite populations with respect to total progeny per female and net reproductive rate. The morphometry proved statistically significant for all body measurements except the antennae.     

Antioxidant-chemoprevention diet ameliorates late effects of total-body irradiation and supplements radioprotection by MnSOD-plasmid liposome administration

Abstract Many acute and chronic effects of ionizing radiation are mediated by reactive oxygen species and reactive nitrogen species, which deplete antioxidant stores, leading to cellular apoptosis, stem cell depletion and accelerated aging. C57BL/6NHsd mice receiving intravenous MnSOD-PL prior to 9.5 Gy total-body irradiation (TBI) show increased survival from the acute hematopoietic syndrome, and males demonstrated improved long-term survival (Epperly et al., Radiat. Res. 170, 437-444, 2008). We evaluated the effect of an antioxidant-chemopreventive diet compared to a regular diet on long-term survival in female mice. Twenty-four hours before the LD(50/30) dose of 9.5 Gy TBI, subgroups of mice were injected intravenously with MnSOD-PL (100 μg plasmid DNA in 100 μl of liposomes). Mice on either diet treated with MnSOD-PL showed decreased death after irradiation compared to irradiated mice on the house diet alone (P = 0.031 for the house diet plus MnSOD-PL or 0.015 for antioxidant diet plus MnSOD-PL). The mice on the antioxidant-chemoprevention diet alone or with MnSOD-PL that survived 30 days after irradiation had a significant increase in survival compared to mice on the regular diet (P = 0.04 or 0.01, respectively). In addition, mice treated with MnSOD-PL only and surviving 30 days after radiation also had increased survival compared to those on the regular diet alone (P = 0.02). Survivors of acute ionizing radiation damage have ameliorated life shortening if they are fed an antioxidant-chemopreventive diet.     

Global Functional Atlas of Escherichia coli Encompassing Previously Uncharacterized Proteins

One-third of the 4,225 protein-coding genes of Escherichia coli K-12 remain functionally unannotated (orphans). Many map to distant clades such as Archaea, suggesting involvement in basic prokaryotic traits, whereas others appear restricted to E. coli, including pathogenic strains. To elucidate the orphans' biological roles, we performed an extensive proteomic survey using affinity-tagged E. coli strains and generated comprehensive genomic context inferences to derive a high-confidence compendium for virtually the entire proteome consisting of 5,993 putative physical interactions and 74,776 putative functional associations, most of which are novel. Clustering of the respective probabilistic networks revealed putative orphan membership in discrete multiprotein complexes and functional modules together with annotated gene products, whereas a machine-learning strategy based on network integration implicated the orphans in specific biological processes. We provide additional experimental evidence supporting orphan participation in protein synthesis, amino acid metabolism, biofilm formation, motility, and assembly of the bacterial cell envelope. This resource provides a “systems-wide” functional blueprint of a model microbe, with insights into the biological and evolutionary significance of previously uncharacterized proteins.     

Improvement of the efficacy of linear undecapeptides against plant-pathogenic bacteria by incorporation of D-amino acids

A set of 31 undecapeptides, incorporating 1 to 11 d-amino acids and derived from the antimicrobial peptide BP100 (KKLFKKILKYL-NH(2)), was designed and synthesized. This set was evaluated for inhibition of growth of the plant-pathogenic bacteria Erwinia amylovora, Pseudomonas syringae pv. syringae, and Xanthomonas axonopodis pv. vesicatoria, hemolysis, and protease degradation. Two derivatives were as active as BP100, and 10 peptides displayed improved activity, with the all-d isomer being the most active. Twenty-six peptides were less hemolytic than BP100, and all peptides were more stable against protease degradation. Plant extracts inhibited the activity of BP100 as well as that of the d-isomers. Ten derivatives incorporating one d-amino acid each were tested in an infectivity inhibition assay with the three plant-pathogenic bacteria by using detached pear and pepper leaves and pear fruits. All 10 peptides studied were active against E. amylovora, 6 displayed activity against P. syringae pv. syringae, and 2 displayed activity against X. axonopodis pv. vesicatoria. Peptides BP143 (KKLFKKILKYL-NH(2)) and BP145 (KKLFKKILKYL-NH(2)), containing one d-amino acid at positions 4 and 2 (underlined), respectively, were evaluated in whole-plant assays for the control of bacterial blight of pepper and pear and fire blight of pear. Peptide BP143 was as effective as streptomycin in the three pathosystems, was more effective than BP100 against bacterial blight of pepper and pear, and equally effective against fire blight of pear.     

Clinical predictors of lacunar syndrome not due to lacunar infarction

Background  

Lacunar syndrome not due to lacunar infarct is poorly characterised. This single centre, retrospective study was conducted to describe the clinical characteristics of patients with lacunar syndrome not due to lacunar infarct and to identify clinical predictors of this variant of lacunar stroke.     

Altered Na+ and Li+ Homeostasis in Saccharomyces cerevisiae Cells Expressing the Bacterial Cation Antiporter NhaA

The bacterial Na⁺(Li⁺)/H⁺ antiporter NhaA has been expressed in the yeast Saccharomyces cerevisiae. NhaA was present in both the plasma membrane and internal membranes, and it conferred lithium but not sodium tolerance. In cells containing the yeast Ena1-4 (Na⁺, Li⁺) extrusion ATPase, the extra lithium tolerance conferred by NhaA was dependent on a functional vacuolar H⁺ ATPase and correlated with an increase of lithium in an intracellular pool which exhibited slow efflux of cations. In yeast mutants without (Na⁺, Li⁺) ATPase, lithium tolerance conferred by NhaA was not dependent on a functional vacuolar H⁺ ATPase and correlated with a decrease of intracellular lithium. NhaA was able to confer sodium tolerance and to decrease intracellular sodium accumulation in a double mutant devoid of both plasma membrane (Na⁺, Li⁺) ATPase and vacuolar H⁺ ATPase. These results indicate that the bacterial antiporter NhaA expressed in yeast is functional at both the plasma membrane and the vacuolar membrane. The phenotypes conferred by its expression depend on the functionality of plasma membrane (Na⁺, Li⁺) ATPase and vacuolar H⁺ ATPase.