Benefits of <Emphasis Type="Italic">Helicobacter pylori</Emphasis><Emphasis Type="Italic">cagE</Emphasis> genotyping in addition to <Emphasis Type="Italic">cagA</Emphasis> genotyping: a Bulgarian study

Associations of Helicobacter pylori cagE status with complex patient characteristics remain to be elucidated in Eastern Europe. The aim of this study was to assess the frequencies of cagE gene and cagA/cagE combinations in H. pylori strains from symptomatic Bulgarian patients and to improve cagA detection. cagA and cagE genotypes were evaluated in 219 patients with single-strain infections. In total, 84.9% of strains were cagA ⁺, while 68.5% were cagE ⁺. cagA ⁺, cagE ⁺, and cagA ⁺/cagE ⁺ strains were more prevalent in peptic ulcer (93.8%, 84.4%, and 84.4%) compared with nonulcer patients (81.3%, 61.9%, and 61.3%, respectively). In elderly patients, cagE ⁺ and cagA ⁺/cagE ⁺ strains were 1.9-fold more common than in the 12 children evaluated. Only 10% of the elderly subjects harbored low-virulence cagA ⁺/cagE ⁻ strains compared with 16.8% of adults and 41.7% of children. Intriguingly, prevalence of the cagA ⁺/cagE ⁻ genotype was 2.1-fold lower in men than in women, suggesting a higher frequency of more virulent strains in men. The presence of both cag genes and combinations was not linked to strain susceptibility to clarithromycin or metronidazole, place of residence, or prior therapy. Use of an extra primer pair increased cagA detection in 14.7% of 31 cagA ⁻ strains. In conclusion, use of a second primer pair for the cagA gene can be recommended in countries with common cagA ⁺ strains. Although both cag genes were linked to severe diseases in Bulgarian patients, the best discrimination of virulent strains was obtained by the cagA/cagE combination or by the cagE gene alone. cagE prevalence increased gradually with patient age, while the cagA ⁺/cagE ⁻ genotype, implying a disrupted cag pathogenicity island, was associated with both younger age and female gender.     

Solvent extraction of divalent palladium and platinum from aqueous solutions of their chloro complexes using an N,N-dimethyldithiocarbamoylethoxy substituted calix[4]arene

The compound 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-bromoethoxy)calix[4]arene has been prepared by first converting 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-hydroxyethoxy)calix[4]arene into the tosylate, and then to the product by reaction with LiBr. The compound crystallizes in the trigonal space group P3₂21 with A = 13.160(2), C = 25.595(6) Å, A = 90.00(2), β = 90.00(1), γ = 120.000(9)⁰, Z = 3, _calc = 1.40 g cm⁻³. The final R value for 2391 unique reflections was 0.061. The compound reacts with excess sodium N,N-dimethyldithiocarbamate to give 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-N,N-dimethyldithiocarbamoylethoxy)calix[4]arene. This compound is an effective extractant for transferring palladium(II) from an aqueous to a chloroform phase. No extraction of PtCl₄²⁻ is observed under thermal conditions. Under photochemical conditions using a mixture of PtCl₄²⁻ and PtCl₆²⁻, extraction of platinum into the chloroform layer is observed. An explanation for this observation is given.     

Orthogonal intercellular signaling for programmed spatial behavior

Bidirectional intercellular signaling is an essential feature of multicellular organisms, and the engineering of complex biological systems will require multiple pathways for intercellular signaling with minimal crosstalk. Natural quorum‐sensing systems provide components for cell communication, but their use is often constrained by signal crosstalk. We have established new orthogonal systems for cell–cell communication using acyl homoserine lactone signaling systems. Quantitative measurements in contexts of differing receiver protein expression allowed us to separate different types of crosstalk between 3‐oxo‐C6‐ and 3‐oxo‐C12‐homoserine lactones, cognate receiver proteins, and DNA promoters. Mutating promoter sequences minimized interactions with heterologous receiver proteins. We used experimental data to parameterize a computational model for signal crosstalk and to estimate the effect of receiver protein levels on signal crosstalk. We used this model to predict optimal expression levels for receiver proteins, to create an effective two‐channel cell communication device. Establishment of a novel spatial assay allowed measurement of interactions between geometrically constrained cell populations via these diffusible signals. We built relay devices capable of long‐range signal propagation mediated by cycles of signal induction, communication and response by discrete cell populations. This work demonstrates the ability to systematically reduce crosstalk within intercellular signaling systems and to use these systems to engineer complex spatiotemporal patterning in cell populations.     

Comparison of resistance to drought of three bean cultivars

The aim of the present work was to evaluate oxidative stress and plant antioxidant system of three contrasting bean (Phaseolus vulgaris L.) genotypes in the response to drought. Drought was imposed 14 d after emergence, by withholding water, until leaf relative water content reached 65 %. Water stress increased lipid peroxidation (LPO), membrane injury index, H₂O₂ and OH^⋅ production in leaves of stressed plants. Activities of the antioxidative enzymes superoxide dismutase (SOD) and ascorbate peroxidase (APOX) increased significantly under water stress in all the studied cultivars, while catalase (CAT) increased in cvs. Plovdiv 10 and Prelom, but decreased in cv. Dobrudjanski ran. Furthermore cv. Plovdiv 10 which had the highest APOX and CAT activities also showed the lowest increase in H₂O₂ and OH^⋅ production and LPO while cv. Dobrudjanski ran showed the lowest increases (and often the lowest values) in the antioxidant enzyme activities and the highest increases of H₂O₂ and OH^⋅ production, and LPO. On the basis of the data obtained we could specify cv. Plovdiv 10 and cv. Prelom as drought tolerant and cv. Dobrudjanski ran as a drought sensitive.     

Proteome of the phytopathogen <Emphasis Type="Italic">Xanthomonas citri</Emphasis> subsp. <Emphasis Type="Italic">citri</Emphasis>: a global expression profile

Background  

Citrus canker is a disease caused by Xantomonas citri subsp.citri (Xac), and has emerged as one of the major threats to the worldwide citrus crop because it affects all commercial citrus varieties, decreases the production and quality of the fruits and can spread rapidly in citrus growing areas. In this work, the first proteome of Xac was analyzed using two methodologies, two-dimensional liquid chromatography (2D LC) and tandem mass spectrometry (MS/MS).     

Biosynthetic cause of in vivo acquired thermotolerance of photosynthetic light reactions and metabolic responses of chloroplasts to heat stress

Thermotolerance of photosynthetic light reactions in vivo is correlated with a decrease in the ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol and an increased incorporation into thylakoid membranes of saturated digalactosyl diacylglycerol species. Although electron transport remains virtually intact in thermotolerant chloroplasts, thylakoid protein phosphorylation is strongly inhibited. The opposite is shown for thermosensitive chloroplasts in vivo. Heat stress causes reversible and irreversible inactivation of chloroplast protein synthesis in heat-adapted and nonadapted plants, respectively, but doe not greatly affect formation of rapidly turned-over 32 kilodalton proteins of photosystem II. The formation on cytoplasmic ribosomes and import by chloroplasts of thylakoid and stroma proteins remain preserved, although decreased in rate, at supraoptimal temperatures. Thermotolerant chloroplasts accumulate heat shock proteins in the stroma among which 22 kilodalton polypeptides predominate. We suggest that interactions of heat shock proteins with the outer chloroplast envelope membrane might enhance formation of digalactosyl diacylglycerol species. Furthermore, a heat-induced recompartmentalization of the chloroplast matrix that ensures effective transport of ATP from thylakoid membranes towards those sites inside the chloroplast and the cytoplasm where photosynthetically indispensable components and heat shock proteins are being formed is proposed as a metabolic strategy of plant cells to survive and recover from heat stress.     

Plant regeneration from interspecific hybrid and backcross progeny of Helianthus eggertii × Helianthus annuus

An efficient protocol for plant regeneration from leaves of the interspecific hybrid Helianthus eggertii Small. × Helianthus annuus L. was developed. The regeneration capacity of the first backcross progeny is reported. Leaves from the F1 interspecific hybrid were cultured on Murashige and Skoog basal media (MS) supplemented with -naphthalenacetic acid (NAA), N ⁶-benzyladenine (BA), AgNO₃, KNO₃, casein hydrolysate and adenine sulfate. Embryo-like structures and/or shoots regeneration were observed on most of the tested media. The best results were obtained on media with a higher concentration of cytokinin (8.8 M BA) and lower concentration of auxin (1.08 M NAA). The addition of casein hydrolysate in the media increased the regeneration efficiency. Plant regeneration was achieved via somatic embryogenesis and direct organogenesis. The regeneration potential of leaf, stem and root explants of eighteen first backcross lines was studied. Most of the tested lines were highly regenerable and some of them had DNA content closely related to that of Helianthus annuus L.