Stable isotope probing in the metagenomics era: A bridge towards improved bioremediation

Microbial biodegradation and biotransformation reactions are essential to most bioremediation processes, yet the specific organisms, genes, and mechanisms involved are often not well understood. Stable isotope probing (SIP) enables researchers to directly link microbial metabolic capability to phylogenetic and metagenomic information within a community context by tracking isotopically labeled substances into phylogenetically and functionally informative biomarkers. SIP is thus applicable as a tool for the identification of active members of the microbial community and associated genes integral to the community functional potential, such as biodegradative processes. The rapid evolution of SIP over the last decade and integration with metagenomics provide researchers with a much deeper insight into potential biodegradative genes, processes, and applications, thereby enabling an improved mechanistic understanding that can facilitate advances in the field of bioremediation.     

No effect of TETRA hand portable transmission signals on human cognitive function and symptoms

Current radio frequency radiation exposure guidelines rest on well‐established thermal effects. However, recent research into analogue and digital transmission fields at levels covered by the exposure guidelines has indicated possible detrimental effects on human cognitive performance. To investigate this, we conducted a controlled climate chamber study of possible changes in cognitive performance in healthy volunteers exposed to transmission signals from TETRA hand portables (TETRA handsets). The trial deployed a balanced, randomized, double‐blinded cross‐over design. Performance on different paper‐and‐pencil, auditory and computer‐based cognitive tasks was monitored in 53 male volunteers (mean age 36.41 years, SD 8.35) during 45‐min exposure to a TETRA handset and sham control signals remotely controlled from a laboratory more than 100 km away. The main cognitive outcome was the Trail Making B (TMB) test. In addition, the participants completed a computer‐based questionnaire measuring self‐reported psychological and physical symptoms. No statistically significant differences (P < 0.05) between the TETRA and sham conditions were found for either TMB (estimated difference 3.8%, confidence interval (CI) ?1.6% to 9.2%) or any of the remaining cognitive tasks or symptoms. In conclusion, we found no evidence that brief exposure to hand‐held TETRA transmitters' affects human cognitive function or subjective symptoms. Bioelectromagnetics 31:380–390, 2010. © 2010 Wiley‐Liss, Inc.     

Theoretical study of electronic absorptions in aminopyridines – TCNE CT complexes by quantum chemical methods, including solvent

The geometric and electronic structure of donor-acceptor complexes of TCNE with aniline, o-, m- and p- aminopyridines and pyridine has been studied in gas phase and in solution using CC2, TDDFT and CIS methods. Concerning interaction energy between particular donor and TCNE acceptor it is fairly described by both CC2 (MP2) and DFT-D approaches. Transition energies in gas phase calculated by CC2 approach are in good agreement with available experimental data for aniline. TDDFT calculations with LC-BLYP functional (with standard value of range separation factor μ?=?0.47) gives transition energies too high although not as high as CIS. The red solvent shifts, calculated by PCM model with CIS method are qualitative correct, but error in the range of 0.1-0.2 eV should be expected.     

Structured illumination microscopy of a living cell

Due to diffraction, the resolution of imaging emitted light in a fluorescence microscope is limited to about 200 nm in the lateral direction. Resolution improvement by a factor of two can be achieved using structured illumination, where a fine grating is projected onto the sample, and the final image is reconstructed from a set of images taken at different grating positions. Here we demonstrate that with the help of a spatial light modulator, this technique can be used for imaging slowly moving structures in living cells. This article has been submitted as a contribution to the Festschrift entitled “Uncovering cellular sub-structures by light microscopy” in honour of Professor Cremer’s 65th birthday.     

The effect of gold and silver nanoparticles,chitosan and their combinations on bacterial biofilms of food-borne pathogens

Abstract

The antimicrobial activity of gold and silver nanoparticles (AuNPs, AgNPs), chitosan (CS) and their combinations was established by determining the minimum inhibitory concentration for planktonic (MICPC₈₀) and biofilm growth (MICBC₈₀), for biofilm formation (MICBF₈₀), metabolic activity (MICBM₈₀) and reduction (MICBR₈₀), and for the metabolic activity of preformed biofilm (MICMPB₈₀). Biofilms were quantified in microtitre plates by crystal violet staining and metabolic activity was evaluated by the MTT assay. Chitosan effectively suppressed biofilm formation (0.31–5?mg ml^?1) in all the tested strains, except Salmonella enterica Infantis (0.16–2.5?mg ml^?1) where CS and its combination with AgNPs induced biofilm formation. Nanoparticles inhibited biofilm growth only when the highest concentrations were used. Even though AuNPs, AgNPs and CS were not able to remove biofilm mass, they reduced its metabolic activity by at least 80%. The combinations of nanoparticles with CS did not show any significant positive synergistic effect on the tested target properties.