Expression of selected heat shock proteins after individually applied and combined drought and heat stress

Drought and heat stress are among the abiotic factors causing the most severe damage on plant crops. Their combination is quite common in dry and semi-dry regions worldwide and little is known about its effect on heat shock protein (HSP) profile in wheat plants. The expression of four HSP genes (Hsp 17.8, Hsp 26.3, Hsp 70 and Hsp 101b) in Triticum aestivum L. plants subjected to individually applied water deprivation or high temperature and their combination was monitored via one-step RT-PCR analysis. Changes in the expression levels of small HSPs (smHSPs), HSP70 and HSP100 were established also by SDS-PAGE. The combination of drought and heat induced HSP expression more effectively than the individually applied stresses. The induction of HSPs displayed greater rate in the drought-tolerant wheat variety Katya than in the drought-sensitive cv. Sadovo. The results obtained in wheat plants suggested that the effect of separately applied drought and heat shock cannot be extrapolated to their combination.     

Chemical characterization and physical and biological activities of rhamnolipids produced by Pseudomonas aeruginosa BN10

Pseudomonas aeruginosa BN10 isolated from hydrocarbon-polluted soil was found to produce rhamnolipids when cultivated on 2% glycerol, glucose, n-hexadecane, and n-alkanes. The rhamnolipids were partially purified on silica gel columns and their chemical structures elucidated by combination of one- and two-dimensional 1H and 13C NMR techniques and ESI-MS analysis. Eight structural rhamnolipid homologues were identified: Rha-C10-C8, Rha-C10-C10, Rha-C10-C12:1, Rha-C10-C12, Rha2-C10-C8, Rha2-C10-C10, Rha2-C10-C12:1, and Rha2-C10-C12. The chemical composition of the rhamnolipid mixtures produced on different carbon sources did not vary with the type of carbon source used. The rhamnolipid mixture produced by Pseudomonas aeruginosa BN10 on glycerol reduced the surface tension of pure water from 72 to 29 mN m(-1) at a critical micellar concentration of 40 mg 1(-1), and the interfacial tension was 0.9 mN m(-1). The new surfactant product formed stable emulsions with hydrocarbons and showed high antimicrobial activity against Gram-positive bacteria. The present study shows that the new strain Pseudomonas aeruginosa BN10 demonstrates enhanced production of the di-rhamnolipid Rha2-C10-C10 on all carbon sources used. Due to its excellent surface and good antimicrobial activities the rhamnolipid homologue mixture from Pseudomonas aeruginosa BN10 can be exploited for use in bioremediation, petroleum and pharmaceutical industries.     

Module-based analysis of robustness tradeoffs in the heat shock response system

Biological systems have evolved complex regulatory mechanisms, even in situations where much simpler designs seem to be sufficient for generating nominal functionality. Using module-based analysis coupled with rigorous mathematical comparisons, we propose that in analogy to control engineering architectures, the complexity of cellular systems and the presence of hierarchical modular structures can be attributed to the necessity of achieving robustness. We employ the Escherichia coli heat shock response system, a strongly conserved cellular mechanism, as an example to explore the design principles of such modular architectures. In the heat shock response system, the sigma-factor σ³² is a central regulator that integrates multiple feedforward and feedback modules. Each of these modules provides a different type of robustness with its inherent tradeoffs in terms of transient response and efficiency. We demonstrate how the overall architecture of the system balances such tradeoffs. An extensive mathematical exploration nevertheless points to the existence of an array of alternative strategies for the existing heat shock response that could exhibit similar behavior. We therefore deduce that the evolutionary constraints facing the system might have steered its architecture toward one of many robustly functional solutions.     

Lipid composition of some yeast strains from Livingston Island, Antarctica

Yeast strainsCryptococcus albidus, Cryptococcus laurentii, Rhodotorula minuta were isolated from a moss sample,Candida oleophila andRhodotorula mucilaginosa were isolated from a soil sample taken from Livingston Island. Antarctica. Fatty acid, phospholipid, sterol and tocopherol composition was determined in separated lipid fraction after fermentation in a medium containing glucose, peptone and yeast extract. Unsaturated fatty acids, mainly oleic (51–65%) and linoleic (9.5–16.8%), predominated in triacylglycerols. Sterols represent ca. 120–930 mg per kg dry biomass. The content of major phospholipids (phosphatidylcholine, phosphatidylinositol and phosphatidylethanolamine) was ca. 100–800 mg/kg. The amount of tocopherols (mainly γ- and δ-tocopherol) was 2.1–6.3 mg/kg.     

Response of barley seedlings to UV-B radiation as affected by NaCl

The response of barley seedlings, subjected to 150 mmol/L NaCl for 4 days at different light regimes (4 d in the light, 4 d in darkness and a 12 h light/dark cycle) before UV-B radiation was investigated. NaCl treatment resulted in a decrease of total chlorophyll content and an increase in H2O2, free proline and lipid peroxidation, as quantified by measurement of malondialdehyde. Significantly more proline was accumulated in the light than in darkness. The combination of UV-B and NaCl treatment produced an additive effect on most of the parameters studied. UV-B radiation reduced the chlorophyll/carotenoids ratio and photochemical efficiency of PSII as estimated by chlorophyll fluorescence. NaCl pre-exposure decreased H2O2 generation and lipid peroxidation and alleviated the inhibitory effect of UV-B on PSII activity. Proline accumulated under salt stress conditions might be one of the reasons for the observed tolerance of barley seedlings to UV-B radiation.     

Design, synthesis and structure-activity relationship of a series of fragment analogues of antistasin (ATS) and ghilantens (GLS)

A series of low molecular weight peptide inhibitors of Factor Xa, fragment analogues of ATS and GLS, was designed and synthesized by the SPPS method. The new analogues included different basic amino acids in 109 position. In order to investigate the role of these factors, the newly synthesized peptides were tested for anticoagulant activity. To investigate the change in anticoagulant activity, new peptides were synthesized by replacement of the C-terminal COOH function with CONH2. The biological activity of all compounds was measured in respect to APTT (activated partial thromboplastin time) and IC50 values (the concentrations for doubling APTT clotting times of human plasma) were determined.     

Construction of a bifunctional genetically labelled plasmid for Bacillus thuringiensis subsp. israelensis

A small cryptic plasmid of Bacillus thuringiensis subsp. israelensis was labelled in vitro with two genetic markers. One of the recombinant plasmids was mapped and transformed in Escherichia coli, Bacillus subtilis and Bacillus thuringiensis. This and similar shuttle plasmids could be very useful as vectors for the investigation of the toxin genes in their own host.Abbreviations BTI Bacillus thuringiensis subsp. israelensis - MDal megadaltons     

Type 2 diabetes whole-genome association study in four populations: the DiaGen consortium

Type 2 diabetes (T2D) is a common, polygenic chronic disease with high heritability. The purpose of this whole-genome association study was to discover novel T2D-associated genes. We genotyped 500 familial cases and 497 controls with >300,000 HapMap-derived tagging single-nucleotide-polymorphism (SNP) markers. When a stringent statistical correction for multiple testing was used, the only significant SNP was at TCF7L2, which has already been discovered and confirmed as a T2D-susceptibility gene. For a replication study, we selected 10 SNPs in six chromosomal regions with the strongest association (singly or as part of a haplotype) for retesting in an independent case-control set including 2,573 T2D cases and 2,776 controls. The most significant replicated result was found at the AHI1-LOC441171 gene region.