Antibiotics from Extremophilic Micromycetes

Russian Journal of Bioorganic Chemistry - Extremophilic microorganisms, which are capable of functioning normally at extremely high or low temperatures, pressure, and in other environmental...     

Associations of Forest Type,Parasitism and Body Condition of Two European Passerines,Fringilla coelebs and Sylvia atricapilla

Human-induced forest modification can alter parasite-host interactions and might change the persistence of host populations. We captured individuals of two widespread European passerines (Fringilla coelebs and Sylvia atricapilla) in southwestern Germany to disentangle the associations of forest types and parasitism by haemosporidian parasites on the body condition of birds. We compared parasite prevalence and parasite intensity, fluctuating asymmetries, leukocyte numbers, and the heterophil to lymphocyte ratio (H/L-ratio) among individuals from beech, mixed-deciduous and spruce forest stands. Based on the biology of bird species, we expected to find fewer infected individuals in beech or mixed-deciduous than in spruce forest stands. We found the highest parasite prevalence and intensity in beech forests for F. coelebs. Although, we found the highest prevalence in spruce forests for S. atricapilla, the highest intensity was detected in beech forests, partially supporting our hypothesis. Other body condition or health status metrics, such as the heterophil to lymphocyte ratio (H/L-ratio), revealed only slight differences between bird populations inhabiting the three different forest types, with the highest values in spruce for F. coelebs and in mixed-deciduous forests for S. atricapilla. A comparison of parasitized versus non-parasitized individuals suggests that parasite infection increased the immune response of a bird, which was detectable as high H/L-ratio. Higher infections with blood parasites for S. atricapilla in spruce forest indicate that this forest type might be a less suitable habitat than beech and mixed-deciduous forests, whereas beech forests seem to be a suboptimal habitat regarding parasitism for F. coelebs.     

Genome tailoring powered production of isobutanol in continuous CO2/H2 blend fermentation using engineered acetogen biocatalyst

The cell energy fraction that powered maintenance and expression of genes encoding pro-phage elements, pta-ack cluster, early sporulation, sugar ABC transporter periplasmic proteins, 6-phosphofructokinase, pyruvate kinase, and fructose-1,6-disphosphatase in acetogen Clostridium sp. MT871 was re-directed to power synthetic operon encoding isobutanol biosynthesis at the expense of these genes achieved via their elimination. Genome tailoring decreased cell duplication time by 7.0 ± 0.1 min (p < 0.05) compared to the parental strain, with intact genome and cell duplication time of 68 ± 1 min (p < 0.05). Clostridium sp. MT871 with tailored genome was UVC-mutated to withstand 6.1 % isobutanol in fermentation broth to prevent product inhibition in an engineered commercial biocatalyst producing 5 % (674.5 mM) isobutanol during two-step continuous fermentation of CO₂/H₂ gas blend. Biocatalyst Clostridium sp. MT871RG₁₁IB^R6 was engineered to express six copies of synthetic operon comprising optimized synthetic format dehydrogenase, pyruvate formate lyase, acetolactate synthase, acetohydroxyacid reductoisomerase, 2,3-dihydroxy-isovalerate dehydratase, branched-chain alpha-ketoacid decarboxylase gene, aldehyde dehydrogenase, and alcohol dehydrogenase, regaining cell duplication time of 68 ± 1 min (p < 0.05) for the parental strain. This is the first report on isobutanol production by an engineered acetogen biocatalyst suitable for commercial manufacturing of this chemical/fuel using continuous fermentation of CO₂/H₂ blend thus contributing to the reversal of global warming.     

Activation of NO donors in mitochondria: peroxidase metabolism of (2-hydroxyamino-vinyl)-triphenyl-phosphonium by cytochrome c releases NO and protects cells against apoptosis

In mitochondrial apoptosis, the formation of cytochrome c-cardiolipin complex ([CL-cyt c]) with peroxidase properties is an early event in the cascade of reactions that leads to cell death. Herein, we report the synthesis of a new prodrug, (2-hydroxyamino-vinyl)-triphenyl-phosphonium (HVTP), which compartmentalizes exclusively into mitochondria, undergoes a [CL-cyt c]-catalyzed bioactivation to nitric oxide (NO), inhibits peroxidase activity, and protects cells from apoptosis.     

Stochastic analysis of the GAL genetic switch in Saccharomyces cerevisiae: Modeling and experiments reveal hierarchy in glucose repression

Background

Most mathematical models of biochemical pathways consider either signalling events that take place within a single cell in isolation, or an 'average' cell which is considered to be representative of a cell population. Likewise, experimental measurements are often averaged over populations consisting of hundreds of thousands of cells. This approach ignores the fact that even within a genetically-homogeneous population, local conditions may influence cell signalling and result in phenotypic heterogeneity. We have developed a multi-scale computational model that accounts for emergent heterogeneity arising from the influences of intercellular signalling on individual cells within a population. Our approach was to develop an ODE model of juxtacrine EGFR-ligand activation of the MAPK intracellular pathway and to couple this to an agent-based representation of individual cells in an expanding epithelial cell culture population. This multi-scale, multi-paradigm approach has enabled us to simulate Extracellular signal-regulated kinase (Erk) activation in a population of cells and to examine the consequences of interpretation at a single cell or population-based level using virtual assays.

Results

A model consisting of a single pair of interacting agents predicted very different Erk activation (phosphorylation) profiles, depending on the formation rate and stability of intercellular contacts, with the slow formation of stable contacts resulting in low but sustained activation of Erk, and transient contacts resulting in a transient Erk signal. Extension of this model to a population consisting of hundreds to thousands of interacting virtual cells revealed that the activated Erk profile measured across the entire cell population was very different and may appear to contradict individual cell findings, reflecting heterogeneity in population density across the culture. This prediction was supported by immunolabelling of an epithelial cell population grown in vitro, which confirmed heterogeneity of Erk activation.

Conclusion

These results illustrate that mean experimental data obtained from analysing entire cell populations is an oversimplification, and should not be extrapolated to deduce the signal:response paradigm of individual cells. This multi-scale, multi-paradigm approach to biological simulation provides an important conceptual tool in addressing how information may be integrated over multiple scales to predict the behaviour of a biological system.     

Search for osteoarthritis genetic markers in women with undifferentiated connective tissue dysplasia

We conducted an association study of ten polymorphisms in six candidate genes of OA (rs1799750 (MMP1), rs35068180 (MMP3), rs2252070 (MMP13), rs63118460 and rs2276455 (COL2A1), rs143383 (GDF5), rs1544410, rs7975232, rs731236, and rs2228570 (VDR)) with the development of osteoarthritis (OA) in 333 women taking into account the localization of the pathological process, the age of disease manifestation, and ethnicity and investigated the presence of signs of undifferentiated connective tissue dysplasia (UCTD). On the basis of clinical and genetic data, we revealed statistically significant models to predict the development of osteoarthritis of various localizations (knee, hip, and generalized forms).     

Bacterial decomposition of insects post-Metarhizium infection: Possible influence on plant growth

Strains of entomopathogenic fungi may have substantial differences in their final stages of mycosis. Insect cadavers are usually overgrown with mycelium after colonization of the insect body, but in many cases, bacterial decomposition of the colonized hosts occurs. We used two Metarhizium robertsii strains in the work: Mak-1 (cadavers become overgrown with mycelium and conidia) and P-72 (cadavers decay after fungal colonization). We conducted a comparative analysis of gut and cadaver microbiota in Colorado potato beetle larvae using 16S rRNA gene sequencing after infection with these strains. In addition, we estimated the content of different forms of nitrogen in cadavers and the influence of cadavers on the growth of Solanum lycopersicum on sand substrates under laboratory conditions. It was shown that infections did not lead to a significant shift in the midgut bacterial communities of infected insects compared to those of untreated insects. Importantly, bacterial communities were similar in both types of cadaver, with predominantly enterobacteria. Decomposing cadavers (P-72) were characterized by increased nitrate and ammonium, and they had a stronger growth-promoting effect on plants compared to cadavers overgrown with mycelium and conidia (Mak-1). We also estimated the colonization and growth of plants after treatment with conidia of both strains cultivated on artificial medium. Both cultures successfully colonized plants, but strain P-72 showed stronger growth promotion than Mak-1. We propose that the use of deviant strains that are unable to sporulate on cadavers leads to a faster (though only passive) flow of nitrogen from killed insects to plants.     

The main features of Bacillus thuringiensis δ-endotoxin molecular structure

The crystal-forming proteins (-endotoxins) produced by various serotypes of Bacillus thuringiensis and toxic for Lepidoptera reveal the same pattern of molecular organisation. These proteins (M _r of ca. 145,000–130,000) contain an N-terminal domain (M _r of 85,000–65,000) resistant to proteolysis whereas their C-terminal moieties (M _r of 65,000) undergo an extensive degradation by trypsin that leads to stepwise cleavage off the fragments with M _r of 15,000–35,000.The N-terminal domain from serotype V -endotoxin is active when introduced into the hemocoel of Galleria mellonella larvae. Hence, it correponds to the true toxin normally formed by larva proteases action on the crystalforming protein (protoxin). Some differences were found in the properties of the N-terminal domains isolated from the crystal-forming proteins of III, V and IX serotypes, e.g., in their solubility, digestion by subtilisin, molecular weights and the distribution of methionine residues along the polypeptide chains.Abbreviations SDS sodium dodecyl sulphate - PAGE polyacryl amide gel electrophoresis - CFP crystal-forming protein - DNS 5-dimethylamino-1-naphthalene-sulphonyl     

Intermembrane transfer and antioxidant action of alpha-tocopherol in liposomes

Intermembrane transfer and exchange of tocopherol are not well understood. To study this we tested the ability of alpha-tocopherol containing unilamellar donor liposomes to inhibit the accumulation of lipid peroxidation products in acceptor liposomes. With molar ratios of alpha-tocopherol:phospholipids from 1:100 to 1:1000 in donor liposomes prepared by sonication of lipid dispersions, alpha-tocopherol was incorporated into both monolayers and was homogenously distributed in monomeric form without forming clusters in the liposomes. Concentrations of alpha-tocopherol which completely prevented the peroxidation of lipids were chosen for donor liposomes. Hence inhibition of lipid peroxidation in mixtures of donor and acceptor liposomes was determined by the antioxidant effect of alpha-tocopherol in acceptor liposomes which resulted from intermembrane transfer and exchange of alpha-tocopherol. Evidence was obtained that this was not due to fusion of donor with acceptor liposomes. The efficiency of the "intermembrane" antioxidant action of tocopherol was more pronounced when donor liposomes contained unsaturated phospholipids, indicating that the presence of unsaturated fatty acids in the outer monolayer phospholipids facilitates intermembrane tocopherol exchange.