Antigenic variation of pilin regulates adhesion of Neisseria meningitidis to human epithelial cells

Pili have been shown to play an essential role in the adhesion of Neisseria meningitidis to epithelial cells. However, among piliated strains, both inter- and intrastrain variability exist with respect to their degree of adhesion to epithelial cells in vitro (Virji et al., 1992). This suggests that factors other than the presence of pili per se are involved in this process. The N. meningitidis pilin subunit undergoes extensive antigenic variation. Piliated low- and high-adhesive derivatives of the same N. meningitidis strain were selected and the nucleotide sequence of the pilin gene expressed in each was determined. The highly adhesive derivatives had the same pilin sequence. The alleles encoding the pilin subunit of the low-adhesive derivatives were completely different from the one found in the high-adhesive isolates. Using polyclonal antibodies raised against one hyperadhesive variant, it was confirmed that the low-adhesive piliated derivatives expressed pilin variants antigenically different from the highly adhesive strains. The role of antigenic variation in the adhesive process of N. meningitidis was confirmed by performing allelic exchanges of the pilE locus between low-and high-adhesive isolates. Antigenic variation has been considered a means by which virulent bacteria evade the host immune system. This work provides genetic proof that a bacterial pathogen, N. meningitidis, can use antigenic variation to modulate their degree of virulence.     

Cloning and characterization of the Brucella ovis heat shock protein DnaK functionally expressed in Escherichia coli.

The Brucella ovis dnaK gene, homolog to the eukaryotic hsp70 genes, was cloned by using a Drosophila melanogaster probe. Comparison of B. ovis and Escherichia coli sequences revealed a similar organization for the dnaK and dnaJ genes and putative regulatory signals. In E. coli transfected with the cloned fragment, B. ovis hsp70 was expressed at 30 and 50 degrees C apparently under the control of its own promoter. The recombinant protein and a B. ovis native protein displaying the same molecular weight were both recognized by anti-E. coli DnaK serum. Native B. ovis protein was also recognized by sera of sheep either infected or vaccinated with an attenuated Brucella strain, suggesting that Brucella hsp70 could be up-regulated during host colonization. A thermosensitive E. coli dnaK mutant transfected with the cloned fragment recovered colony-forming ability at 42 degrees C, showing that the B. ovis DnaK protein could behave as a functional heat shock protein in E. coli.     

Mikanokryptin,a new guianolide from Mikania

The isolation and structure determination of mikanokryptin, a stereoisomer of 11,13-dehydrogeigerin, from what appears to be a previously undescribed Mikania species is reported. Mikania micrantha HBK. yielded mikanolide and dihydromikanolide.     

Draft genome sequencing and functional annotation and characterization of biofilm-producing bacterium Bacillus novalis PD1 isolated from rhizospheric soil

Antonie van Leeuwenhoek - Biofilm forming bacterium Bacillus novalis PD1 was isolated from the rhizospheric soil of a paddy field. B. novalis PD1 is a Gram-positive, facultatively anaerobic,...     

A Dermal Gel Made of Rutilus Kutum Skin Collagen-Chitosan for Deep Burn Healing

International Journal of Peptide Research and Therapeutics - Natural compounds extracted from marine organisms consisting of biological active materials like collagen provide a major source of...     

Understanding the function of the tumor microenvironment,and compounds from marine organisms for breast cancer therapy

The pathology and physiology of breast cancer(BC),including metastasis,and drug resistance,is driven by multiple signaling pathways in the tumor microenvironment(TME),which hamper antitumor immunity.Recently,long non-coding RNAs have been reported to mediate pathophysiological developments such as metastasis as well as immune suppression within the TME.Given the complex biology of BC,novel personalized therapeutic strategies that address its diverse pathophysiologies are needed to improve clinical outcomes.In this review,we describe the advances in the biology of breast neoplasia,including cellular and molecular biology,heterogeneity,and TME.We review the role of novel molecules such as long non-coding RNAs in the pathophysiology of BC.Finally,we provide an up-to-date overview of anticancer compounds extracted from marine microorganisms,crustaceans,and fishes and their synergistic effects in combination with other anticancer drugs.Marine compounds are a new discipline of research in BC and offer a wide range of anti-cancer effects that could be harnessed to target the various pathways involved in BC development,thus assisting current therapeutic regimens.     

First-principles vdW-DF investigation on the interaction between the oxazepam molecule and C60 fullerene

The interaction between oxazepam and C₆₀ fullerene was explored using first-principles vdW-DF calculations. It was found that oxazepam binds weakly to the fullerene cage via its carbonyl group. The binding of oxazepam to C₆₀ is affected drastically by nonlocal dispersion interactions, while vdW forces affect the corresponding geometries only a little. Furthermore, aqueous solution affects the geometries of the oxazepam approaching to fullerene slightly, while oxazepam binds slightly farther away from the nanocage. The results presented provide evidence for the applicability of the vdW-DF method and serve as a practical benchmark for the investigation of host–guest interactions in biological systems.

Inhibition of enteropathogenic Escherichia coli biofilm formation by DNA aptamer

Molecular Biology Reports - Enteropathogenic Escherichia coli (EPEC) is a bioagent that causes diarrhea through the formation of biofilm. The recalcitrant of EPEC to the current conventional...     

Gibberellin mediates the development of gelatinous fibres in the tension wood of inclined Acacia mangium seedlings

Background and Aims

Gibberellin stimulates negative gravitropism and the formation of tension wood in tilted Acacia mangium seedlings, while inhibitors of gibberellin synthesis strongly inhibit the return to vertical growth and suppress the formation of tension wood. To characterize the role of gibberellin in tension wood formation and gravitropism, this study investigated the role of gibberellin in the development of gelatinous fibres and in the changes in anatomical characteristics of woody elements in Acacia mangium seedlings exposed to a gravitational stimulus.

Methods

Gibberellin, paclobutrazol and uniconazole-P were applied to the soil in which seedlings were growing, using distilled water as the control. Three days after the start of treatment, seedlings were inclined at 45 ° to the vertical and samples were harvested 2 months later. The effects of the treatments on wood fibres, vessel elements and ray parenchyma cells were analysed in tension wood in the upper part of inclined stems and in the opposite wood on the lower side of inclined stems.

Key Results

Application of paclobutrazol or uniconazole-P inhibited the increase in the thickness of gelatinous layers and prevented the elongation of gelatinous fibres in the tension wood of inclined stems. By contrast, gibberellin stimulated the elongation of these fibres. Application of gibberellin and inhibitors of gibberellin biosynthesis had only minor effects on the anatomical characteristics of vessel and ray parenchyma cells.

Conclusions

The results suggest that gibberellin is important for the development of gelatinous fibres in the tension wood of A. mangium seedlings and therefore in gravitropism.