Fundamental aspects of the nucleic acid i-motif structures

The latest research on fundamental aspects of i-motif structures is reviewed with special attention to their hypothetical rolein vivo.

Herbicides induce change in metabolic and genetic diversity of bacterial community from a cold oligotrophic lake

Pristine cold oligotrophic lakes show unique physical and chemical characteristics with permanent fluctuation in temperature and carbon source availability. Incorporation of organic toxic matters to these ecosystems could alter the bacterial community composition. Our goal was to assess the effects of simazine (Sz) and 2,4 dichlorophenoxyacetic acid (2,4-D) upon the metabolic and genetic diversity of the bacterial community in sediment samples from a pristine cold oligotrophic lake. Sediment samples were collected in winter and summer season, and microcosms were prepared using a ration 1:10 (sediments:water). The microcosms were supplemented with 0.1 mM 2,4-D or 0.5 mM Sz and incubated for 20 days at 10 °C. Metabolic diversity was evaluated by using the Biolog Ecoplate™ system and genetic diversity by 16S rDNA amplification followed by denaturing gradient gel electrophoresis analysis. Total bacterial counts and live/dead ratio were determined by epifluorescence microscopy. The control microcosms showed no significant differences (P > 0.05) in both metabolic and genetic diversity between summer and winter samples. On the other hand, the addition of 2,4-D or Sz to microcosms induces statistical significant differences (P < 0.05) in metabolic and genetic diversity showing the prevalence of Actinobacteria group which are usually not detected in the sediments of these non-contaminated lacustrine systems. The obtained results suggest that contaminations of cold pristine lakes with organic toxic compounds of anthropic origin alter their homeostasis by inhibiting specific susceptible bacterial groups. The concomitant increase of usually low representative bacterial groups modifies the bacterial composition commonly found in this pristine lake.

Soy isoflavones improve insulin sensitivity without changing serum leptin among postmenopausal women

OBJECTIVE

To investigate the effect of a soy isoflavone extract over insulin sensitivity and plasma leptin levels.

METHODS

Eighty postmenopausal women were randomly assigned to participate for 24 months either to a physical exercise and Mediterranean diet program (Control group: CG) or this intervention plus a daily oral intake of a soy isoflavone extract (Soy isoflavone group: SIG). Anthropometry, body composition analysis, blood biochemistry, menopausal symptoms and health-related quality of life were assessed at baseline and every 6 months.

RESULTS

Sixty-five women completed the protocol with no differences found among groups at baseline in age and time since the menopause. At month 24, body mass index (BMI) was lower in the SIG as compared to the CG. Fat mass, glucose, insulin, HOMA-IR, tumor necrosis factor-α (TNF-α), Kupperman Index and Cervantes Scale values significantly decreased in the SIG as compared to baseline and to CG values. Kupperman scores and serum TNF-α levels significantly decreased in both studied groups. No changes in plasma leptin levels were observed after 24 months within and between groups. When analysis was stratified according to BMI values, changes in the aforementioned parameters displayed a similar trend; however, the impact over glucose, insulin and HOMA-IR values was more evident among obese women assigned to the SIG.

CONCLUSION

Diet, physical exercise and a daily oral intake of soy isoflavones exerted a beneficial effect on the homeostatic model in postmenopausal women which was not related to significant changes in plasma leptin levels, despite a decrease in TNF-α, fat mass and Kupperman values.

Reduction of 4-ethylphenol production in red wines using HCDC+ yeasts and cinnamyl esterases

Hydroxycinnamate decarboxylase (HCDC) activity has been evaluated in several commercial yeast strains. The combined effect of using cinnamyl esterases (CE) and HCDC+ Saccharomyces cerevisiae strains has been studied in the formation of vinylphenolic pyranoanthocyanins (VPAs) during fermentation, analysing the kind and concentration of pigments formed according to the yeast strain used. Wines fermented with yeasts HCDC+ were contaminated with Dekkera bruxellensis and afterwards analysed to evaluate the formation of ethylphenols (EPs). The musts treated with CE and later fermented with HCDC+ yeast strains showed lower contents of 4-ethylphenol than those fermented with HCDC- strains. This reduction in the EP content is due to the transformation of hydroxycinnamic acids in stable VPAs pigments. The associated use of CEs and HCDC+ Saccharomyces strains is a natural strategy to reduce the formation of EPs in wines contaminated by Dekkera/Brettanomyces.

Improvement of scanning tunneling microscopy resolution with H-sensitized tips

Recent scanning tunneling hydrogen microscopy (STHM) experiments on PTCDA (perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride)/Au(111) have shown unprecedented intramolecular and intermolecular spatial resolution. The origin of this resolution is studied using an accurate STHM theoretical simulation technique that includes a detailed description of the electronic structure of both the tip and sample. Our results show that H2 molecules are dissociated on the Au tip; the adsorbed H atoms change the density of states at the Fermi level (E(F)) of the tip, increasing its p-orbital character and reducing the s-orbital contribution. Also, due to the interaction with the H-decorated tip, E(F) is shifted to the middle of the PTCDA lowest unoccupied molecular orbital peak, increasing dramatically the density of states of the sample at E(F). These effects give rise to the enhanced STHM resolution.