Heterogeneity of cell membrane structure studied by single molecule tracking

Heterogeneity in cell membrane structure, typified by microdomains with different biophysical and biochemical properties, is thought to impact on a variety of cell functions. Integral membrane proteins act as nanometre-sized probes of the lipid environment and their thermally-driven movements can be used to report local variations in membrane properties. In the current study, we have used total internal reflection fluorescence microscopy (TIRFM) combined with super-resolution tracking of multiple individual molecules, in order to create high-resolution maps of local membrane viscosity. We used a quadrat sampling method and show how statistical tests for membrane heterogeneity can be conducted by analysing the paths of many molecules that pass through the same unit area of membrane. We describe experiments performed on cultured primary cells, stable cell lines and ex vivo tissue slices using a variety of membrane proteins, under different imaging conditions. In some cell types, we find no evidence for heterogeneity in mobility across the plasma membrane, but in others we find statistically significant differences with some regions of membrane showing significantly higher viscosity than others

TOXIC LIVER DAMAGE IN ACUTE PHASE OF ETHANOL INTOXICATION AND ITS EXPERIMENTAL CORRECTION WITH CHELATE ZINC COMPOUND

It was established, that ethanol in the dose of 12 g/kg in experimental animals (white non-inbred male rats) had. expressed damaging effect on the liver, that is shown in statistically significant increase of activity of hepatic enzymes (alanine aminotransferase, alkaline phosphatase), hypoglycemia, development of albuminous and. hydropic degeneration. It is proved, that application of new chelate zinc (2,8,9-trigidrotsinkatrane) in experimental correction of acute ethanol poisoning promotes reduction of metabolic and morphological derangements

OXIDATIVE STRESS AS A PATHOGENETIC LINK OF ACUTE ETHANOL POISONING AND ITS CORRECTION WITH CHELATE ZINC COMPOUNDS

The data on the expressed toxic effect of ethanol in dose DL50 (12 g/kg) on experimental rats were received. The toxic effect was expressed in significant stimulation of processes of lipid peroxidation against the background of antioxidant system suppression. While evaluating the results of statistic analysis it was proved, that new chelate zinc (2,8,9-trihydrozincatrane) in the protective dose of 4 mg/kg under conditions of the acute ethanol poisoning reduces the severity of oxidative stress and normalizes indicators of antioxidant system

Acute ethanol poisoning and its complex damaging effect on functionality of the liver

It is established, that ethanol in the dose of 12 g/kg at experimental animals (white noninbred male rats) has the pronounced damaging effect on the liver, which is manifested in the dynamics of the aggregate biochemical, histological and histochemical indicators

Correction of dyscrasia of the organism of rats in the conditions of acute ethanol poisoning by the introduction of chelate zinc compound. Morphofunctional characteristics of protective action of the 2,8,9-trihydrozincatrane

It is experimentally proved that the new zinc chelate compound 2,8,9-trihydrozinkatrane has a protective effect on the organism of experimental animals contributing to the improvement of essential metabolic processes. Single intragastric introduction of 2,8,9-trihydrozincatrane in protective dose of 4 mg/kg is an effective method of limitation of development of acute alcoholic poisoning in experimental rats that promotes an increase of tolerance of animals' organisms to multiple negative effects of ethanol and its metabolites

Inferring hidden Markov models from noisy time sequences: a method to alleviate degeneracy in molecular dynamics

We present a new method for inferring hidden Markov models from noisy time sequences without the necessity of assuming a model architecture, thus allowing for the detection of degenerate states. This is based on the statistical prediction techniques developed by Crutchfield et al., and generates so called causal state models, equivalent to hidden Markov models. This method is applicable to any continuous data which clusters around discrete values and exhibits multiple transitions between these values such as tethered particle motion data or Fluorescence Resonance Energy Transfer (FRET) spectra. The algorithms developed have been shown to perform well on simulated data, demonstrating the ability to recover the model used to generate the data under high noise, sparse data conditions and the ability to infer the existence of degenerate states. They have also been applied to new experimental FRET data of Holliday Junction dynamics, extracting the expected two state model and providing values for the transition rates in good agreement with previous results and with results obtained using existing maximum likelihood based methods.Comment: 19 pages, 9 figure

New Insights into Mutable Collagenous Tissue: Correlations between the Microstructure and Mechanical State of a Sea-Urchin Ligament

The mutable collagenous tissue (MCT) of echinoderms has the ability to undergo rapid and reversible changes in passive mechanical properties that are initiated and modulated by the nervous system. Since the mechanism of MCT mutability is poorly understood, the aim of this work was to provide a detailed morphological analysis of a typical mutable collagenous structure in its different mechanical states. The model studied was the compass depressor ligament (CDL) of a sea urchin (Paracentrotus lividus), which was characterized in different functional states mimicking MCT mutability. Transmission electron microscopy, histochemistry, cryo-scanning electron microscopy, focused ion beam/scanning electron microscopy, and field emission gun-environmental scanning electron microscopy were used to visualize CDLs at the micro- and nano-scales. This investigation has revealed previously unreported differences in both extracellular and cellular constituents, expanding the current knowledge of the relationship between the organization of the CDL and its mechanical state. Scanning electron microscopies in particular provided a three-dimensional overview of CDL architecture at the micro- and nano-scales, and clarified the micro-organization of the ECM components that are involved in mutability. Further evidence that the juxtaligamental cells are the effectors of these changes in mechanical properties was provided by a correlation between their cytology and the tensile state of the CDLs