Salmonella enterica Serotype Bredeney: Antimicrobial Susceptibility and Molecular Diversity of Isolates from Ireland and Northern Ireland

Salmonella enterica serotype Bredeney has emerged as the third most commonly identified serotype among human clinical isolates referred to the Irish National Salmonella Reference Laboratory in the years 1998 to 2000. A collection of 112 isolates of S. enterica serotype Bredeney collected during the period 1995 to 1999 from animal, food, and human sources from both Ireland and Northern Ireland were studied. Antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and DNA amplification fingerprinting (DAF) were performed on all isolates. Plasmid profiles were examined on a subset of 33 isolates. A high proportion (74%) of isolates were susceptible to all antimicrobial agents tested. Resistance to both sulfonamide and trimethoprim was observed in 21% of isolates, and resistance to multiple (five) antimicrobial agents was observed in a single isolate (0.9%). Eight different PFGE patterns were obtained, with 87% of isolates grouping as PFGE type A. PFGE type A was predominant in animals, food, and humans. There was good overall concordance between the groups identified by PFGE and DAF. Overall results indicate that most S. enterica serotype Bredeney isolates in Ireland and Northern Ireland from animal and human sources are clonally related.     

An aromatic schiff base stabilised as a coordinated enol iminium zwitterion by complex formation with a series of divalent metal ions

The Schiff base N-(2-hydroxy-3-carboxy-1-naphthylidine)-4-methyl-2-sulphonic acid aniline (bonsaH₃) has been found to react with a range of divalent metal ions (Mg²⁺, Mn²⁺, Co²⁺, Ni²⁺ and Zn²⁺ and UO₂²⁺ to give red-yellow insoluble complexes (bonsaH)_m(H₂O)_n. The solid state diffuse reflectance spectra of all the complexes have an intense visible band at ca. 470 nm. This fact, together with evidence from infrared spectra and room-temperature magnetic-moment measurements, suggests that in all cases the ligand is coordinated to the metal ion in the solid state in the enol-iminium zwitterionic form. The ¹H NMR spectra of the Mg²⁺ and Zn²⁺ complexes in DMSO-d₆ indicate that a different structure is adopted in this solvent. Comparisons with the spectra of bonsa-H₃ and (bonsa-H₂)K·H₂O suggest that the solution structure is that of an enol-imine.     

EFFECTS OF O2 ON AMMONIUM UPTAKE AND ROOT RESPIRATION BY SPARTINA ALTERNIFLORA

Previously the growth of Spartina alterniflora has been found to be limited by nitrogen and correlated with sediment redox potential. In this study we have investigated a possible connection between these two factors. We have found that internal O₂ transport is insufficient to saturate NH₄⁺ uptake in short S. alterniflora in hydroponic culture. Rates of NH₄⁺ uptake and root respiration were very sensitive to O₂ concentration in the rhizosphere, saturating at about 5% O₂. Ammonium uptake continued at a reduced rate for at least 4 hr under anaerobic conditions. Plant to plant variations in anaerobic rates of NH₄⁺ uptake and root respiration were significantly correlated to the diffusion rate of CH₄ tracer gas from the leaves to the roots of individual plants.     

ESTIMATING POPULATION SIZE IN ASYNCHRONOUS AGGREGATIONS: A BAYESIAN APPROACH AND TEST WITH ELEPHANT SEAL CENSUSES

Many organisms reproduce in temporary aggregations where estimates of colony size can be made by direct counts. When individuals are not synchronous, however, early breeders depart before the last arrive, so counts underestimate the total breeding population. We present a model describing a colony's census as a function of arrival, breeding tenure, and the correlation between them, and we use it to illustrate how variance in arrival and tenure affect the census. Counts of breeding female northern elephant seals ( Mirounga angustirostris ) from 1975 to 2007 were used to test the model. Four of the model's parameters—population size, mean and variance of arrival date, and the correlation between arrival date and breeding tenure—could be estimated from census data using a Bayesian approach; prior estimates of two other parameters—mean tenure and its variance—had to be used to avoid overparameterization. The model's predictions fit observed censuses well and produced reliable estimates of population size and arrival behavior, showing that the maximum census was 8%–16% below the total number of breeding females. This method could be used for estimating abundance in any asynchronous aggregation, given independent information on one of the defining distributions: arrival, tenure, or departure.     

Comparative Proteomics of Dehalococcoides spp. Reveals Strain-Specific Peptides Associated with Activity

Anaerobic reductive dehalogenation by Dehalococcoides spp. is an ideal system for studying functional diversity of closely related strains of bacteria. In Dehalococcoides spp., reductive dehalogenases (RDases) are key respiratory enzymes involved in the anaerobic detoxification of halogenated compounds at contaminated sites globally. Although housekeeping genes sequenced from Dehalococcoides spp. are >85% identical at the amino acid level, different strains are capable of dehalogenating diverse ranges of compounds, depending largely on the suite of RDase genes that each strain harbors and expresses. We identified RDase proteins that corresponded to known functions in four characterized cultures and predicted functions in an uncharacterized Dehalococcoides-containing mixed culture. Homologues within RDase subclusters containing PceA, TceA, and VcrA were among the most frequently identified proteins. Several additional proteins, including a formate dehydrogenase-like protein (Fdh), had high coverage in all strains and under all growth conditions.     

Porphyra-334, a potential natural source for UVA protective sunscreens.

The mycosporine-like amino acid (MAA), porphyra-334 (lambda(max) = 334 nm; epsilon = 42,300 M(-1) cm(-1)), was isolated from the aquatic cyanobacterium Aphanizomenon flos-aquae (AFA) and its structure was verified by spectroscopic methods. The UVA absorption properties of the crude methanolic extract were determined against two commercial sun care products in terms of mean critical wavelength, mean UVA/UVB ratios and UVA protection category (Boots the Chemists, Ltd.). The crude methanolic extract from AFA exhibited maximum UVA protection comparable to that determined for Boots SPF 4.     

Interactions of amphipathic carrier peptides with membrane components in relation with their ability to deliver therapeutics.

To identify rules for the design of efficient CPPs that can deliver therapeutic agents such as nucleic acids (DNAs, siRNAs) or proteins and PNAs into subcellular compartments, we compared the properties of several primary and secondary amphipathic CPPs. Studies performed with lipid monolayers at the air-water interface have enabled identification of the nature of the lipid-peptide interactions and characterization of the influence of phospholipids on the ability of these peptides to penetrate into lipidic media. Penetration and compression experiments reveal that both peptides interact strongly with phospholipids, and observations on Langmuir-Blodgett transfers indicate that they can modify the lipid organization. Conformational investigations indicate that the lipid-peptide interactions govern the conformational state(s) of the peptides. On the basis of the ability of both peptides to promote ion permeation through both natural and artificial membranes, models illustrating the translocation processes have been proposed. One is based on the formation of a beta-barrel pore-like structure while another is based on the association of helices.