Sampling and quantitative analysis of clean B. subtilis spores at sub-monolayer coverage by reflectance fourier transform infrared microscopy using gold-coated filter substrates

A study was conducted to determine the concentration dependency of the mid-infrared (MIR) absorbance of bacterial spores. A range of concentrations of Bacillus subtilis endospores filtered across gold-coated filter membranes were analyzed by Fourier transform infrared (FT-IR) reflectance microscopy. Calibration curves were derived from the peak absorbances associated with Amide A, Amide I, and Amide II vibrational frequencies by automatic baseline fitting to remove most of the scattering contribution. Linear relationships (R2 >or= 0.99) were observed between the concentrations of spores and the baseline-corrected peak absorbance for each frequency studied. Detection limits for our sampled area of 100 x100 microm2 were determined to be 79, 39, and 184 spores (or 7.92 x 10(5), 3.92 x 10(5), and 1.84 x 10(6) spores/cm2) for the Amide A, Amide I, and Amide II peaks, respectively. Absorbance increased linearly above the scattering baseline with particle surface concentration up to 0.9 monolayer (ML) coverage, with the monolayer density calculated to be approximately 1.17 x 10(8) spores/cm2. Scattering as a function of surface concentration, as estimated from extinction values at wavelengths exhibiting low absorbance, becomes nonlinear at a much lower surface concentration. The apparent scattering cross-section per spore decreased monotonically as concentrations increased toward 1.2 ML, while the absolute scattering decreased between 0.9 ML and 1.2 ML coverage. Calculations suggest that transverse spatial coherence effects are the origin of this nonlinearity, while the onset of nonlinearity in the baseline-corrected absorption is probably due to multiple scattering effects, which appear at a high surface concentration. Absorption cross-sections at peaks of the three bands were measured to be (2.15 +/- 0.05) x 10(-9), (1.48 +/- 0.03) x 10(-9), and (0.805 +/- 0.023) x 10(-9) cm2, respectively. These values are smaller by a factor of 2-4 than expected from the literature. The origin of the reduced cross-section is hypothesized to be an electric field effect related to the surface selection rule.     

Secretome Survey of Human Plexiform Neurofibroma Derived Schwann Cells Reveals a Secreted form of the RARRES1 Protein

To bring insights into neurofibroma biochemistry, a comprehensive secretome analysis was performed on cultured human primary Schwann cells isolated from surgically resected plexiform neurofibroma and from normal nerve tissue. Using a combination of SDS-PAGE and high precision LC-MS/MS, 907 proteins were confidently identified in the conditioned media of Schwann cell cultures combined. Label free proteome profiling revealed consistent release of high levels of 22 proteins by the four biological replicates of NF1 Schwann cell cultures relative to the two normal Schwann cell cultures. Inversely, 9 proteins displayed decreased levels in the conditioned media of NF1 relative to normal Schwann cells. The proteins with increased levels included proteins involved in cell growth, angiogenesis and complement pathway while proteins with decreased levels included those involved in cell adhesion, plasminogen pathway and extracellular matrix remodeling. Retinoic acid receptor responder protein-1 (RARRES1), previously described as an integral membrane tumor suppressor, was found exclusively secreted by NF1 Schwann cells but not by normal Schwann cells. All-trans retinoic acid modulated secretion of RARRES1 in a dose dependent manner. This study shows altered secretion of key proteins in NF1 derived Schwann cells. The potential implication of these proteins in neurofibroma biology is discussed.     

Synthesis of Glycopolymers by Controlled Radical Polymerization Techniques and Their Applications

Natural saccharides are involved in numerous biological processes. It has been shown that these carbohydrates play a role in cell adhesion and proliferation, as well as protein stabilization, organization, and recognition. Certain carbohydrates also serve as receptors for viruses and bacteria. They are over expressed in diseases such as cancer. Hence, a lot of effort has been focused on mimicking these sugars. Polymers with pendent saccharide groups, also known as glycopolymers, are studied as oligo‐ and polysaccharide mimics. Controlled radical polymerization (CRP) techniques such as atom transfer radical polymerization (ATRP), reversible addition–fragmentation chain transfer (RAFT) polymerization, and nitroxide‐mediated polymerization (NMP), as well as cyanoxyl‐mediated free radical polymerization have allowed chemists to synthesize well‐defined glycopolymers that, in some cases, have particular end‐group functionalities. This review focuses on the synthesis of glycopolymers by these methods and the applications of glycopolymers as natural saccharide mimics.     

Freshwater DOM quantity and quality from a two-component model of UV absorbance

We present a model that considers UV-absorbing dissolved organic matter (DOM) to consist of two components (A and B), each with a distinct and constant spectrum. Component A absorbs UV light strongly, and is therefore presumed to possess aromatic chromophores and hydrophobic character, whereas B absorbs weakly and can be assumed hydrophilic. We parameterised the model with dissolved organic carbon concentrations [DOC] and corresponding UV spectra for c. 1700 filtered surface water samples from North America and the United Kingdom, by optimising extinction coefficients for A and B, together with a small constant concentration of non-absorbing DOM (0.80 mg DOC L⁻¹). Good unbiased predictions of [DOC] from absorbance data at 270 and 350 nm were obtained (r² = 0.98), the sum of squared residuals in [DOC] being reduced by 66% compared to a regression model fitted to absorbance at 270 nm alone. The parameterised model can use measured optical absorbance values at any pair of suitable wavelengths to calculate both [DOC] and the relative amounts of A and B in a water sample, i.e. measures of quantity and quality. Blind prediction of [DOC] was satisfactory for 9 of 11 independent data sets (181 of 213 individual samples).     

Characterization of interactions between Escherichia coli O157:H7 with epiphytic bacteria in vitro and on spinach leaf surfaces

This study characterized the types of interactions between Escherichia coli O157:H7 and spinach phylloepiphytic bacteria and identified those that influence persistence of E. coli O157:H7 on edible plants. A total of 1512 phylloepiphytic bacterial isolates were screened for their ability to inhibit or to enhance the growth of E. coli O157:H7 in vitro and on spinach leaf surfaces. Fifteen different genera, the majority belonging to Firmicutes and Enterobacteriaceae, reduced growth rates of E. coli O157:H7 in vitro by either nutrient competition or acid production. Reduced numbers of E. coli O157:H7 were recovered from detached spinach leaves that were co-inoculated with epiphytic isolates belonging to five genera. A 1.8 log reduction in E. coli O157:H7 was achieved when co-inoculated with Erwinina perscinia and 20% cellobiose, a carbon source used by the phylloepiphytes but not E. coli O157:H7. The reduction on leaves was significantly less than reduction measured in vitro. Phylloepiphytic bacteria belonging to eight different genera, increased numbers of E. coli O157:H7 when co-cultured in vitro on spent medium and when co-cultured on detached spinach leaves. The results, showing reduction of E. coli O157:H7 numbers by natural epiphytic bacteria, support the hypothesis that native plant microbiota can be used for bio-control of foodborne pathogens, however, other epiphytes may promote the persistence of enteric pathogens on the phyllosphere.     

The evaluation of a PCR-based method for identification of Salmonella enterica serotypes from environmental samples and various food matrices

The most commonly used method for serotyping Salmonella spp. is based on the Kaufmann–White scheme, and is composed of serological reactions using antibodies to LPS agglutinins. The multiplex PCR used in this investigation was established by Kim et al. to serotype the 30 most common clinical Salmonella serotypes, as determined by CDC. The PCR assay consists of two five-plex reactions and a single two-plex PCR reaction, based on six genetic loci from Salmonella enterica serotype Typhimurium and four loci from S. enterica serotype Typhi. In this investigation, we further evaluated the method for serotyping Salmonella spp. using a reference collection, environmental samples collected from a Mid-Atlantic region tomato farm study, four food matrices spiked with different Salmonella serotypes and a proficiency test. The PCR assay was first evaluated using DNA isolated from pure cultures of isolates obtained from various clinical and environmental samples, and then DNA isolated from broth cultures of food matrices of “Red round” and Roma tomatoes, Romaine lettuce, green onions and Serrano peppers spiked with serotypes Newport, Typhimurium, Javiana and Saintpaul, respectively. The results showed that the PCR assay correctly serotyped Salmonella spp. from the clinical, environmental, spiked food matrices, and proficiency test samples. These findings are significant because the PCR assay was successful in the identification of Salmonella in the spiked samples in a broth culture containing other non-salmonella organism. This method may be a useful resource for the food safety community.     

Growth, yield and seed composition of native Australian legumes with potential as grain crops

BACKGROUND: Many Australian native legumes grow in arid and nutrient‐poor environments. Yet few Australian herbaceous legumes have been investigated for domestication potential. This study compared growth and reproductive traits, grain yield and seed composition of 17 native Australian legumes with three commercial grain legumes. RESULTS: Seed yields of seven native legumes were > 40% of Cicer arietnum, with highest seed yields and harvest indices in Glycine sp. (14.4 g per plant, 0.54 g g^?1) and Lotus cruentus (10.2 g per plant, 0.65 g g^?1). Five native species flowered earlier than field pea (Pisum sativa) (109 days), though many were slower to flower and set seed. Largest seeds were found in Glycine canescens (17 mg), with seed of other native species 14 times smaller than commercial cultivars. Seed composition of many native legumes was similar to commercial cultivars (200–330 g protein kg^?1 dry weight (DW), 130–430 g dietary fibre kg^?1 DW). Two Cullen species had high fat content (>110 g kg^?1 DW) and Trigonella sauvissima had the highest crude protein content (370 g kg^?1 DW). CONCLUSION: The seed composition and reproductive traits of some wild native Australian legumes suggest they could offer potential as grain crops for soils and environments where the current grain legumes are uneconomic. Further evaluation of genetic diversity, especially for seed size, overall productivity, and reproductive development is needed. Copyright © 2011 Society of Chemical Industry     

Performance of Silica-Titania Carbon Composites for Photocatalytic Degradation of Gray Water

The objective of this research was to develop a photocatalytic reactor that will reduce the total organic carbon (TOC) concentration of a gray water influent. The system used a reactor packed with titanium dioxide (TiO2) supported by silica gel (SiO2) and was optimized with respect to several system parameters. The SiO2–TiO2 composites (STCs) were capable of reducing the TOC concentration from 3,000 ppb to below the targeted concentration of 500 ppb in a recirculating system. An optimum empty bed contact time of 7 min was found based on the fastest destruction rate to reach below 500 ppb of TOC. Also based on destruction rate, a STC having a TiO2 loading of 12 g/100 mL of SiO2 precursor and approximately 120-? pore size was shown to have the best performance among several composites of different TiO2 loadings and pore sizes. The addition of activated carbon to the STC was found to improve the overall performance of the system by increasing the composite’s adsorption capabilities.     

Focalism and the underestimation of future emotion: When it's worse than imagined.

People typically exaggerate the emotional impact of future events. This occurs because of focalism, the tendency to focus on one event and neglect to consider how emotion will be mitigated by the surrounding context. Neglecting context, however, should lead people to underestimate future emotion when context focuses attention on the event. In Study 1, participants underestimated the intensity of their future negative emotions when they reported reactions to a romantic break-up on Valentine's Day versus 1 week before. This relationship was mediated by how frequently they thought about the break-up. In Study 2, participants underestimated the emotional impact of a lost prize when the experimental context forced them to focus on the prize versus when the prize was less evident. Thus, failing to account for the extent to which context would focus attention on the event, a form of focalism, led to underestimation of emotional reactions to a negative event. (PsycINFO Database Record (c) 2011 APA, all rights reserved)