Nicotine-mediated induction of E-selectin in aortic endothelial cells requires Src kinase and E2F1 transcriptional activity

PAF26 is a synthetic fungicidal hexapeptide with cell-penetration properties and non-lytic mode of action. We demonstrate herein the endogenous accumulation of reactive oxygen species (ROS) and nitric oxide (NO) in the model fungus Saccharomyces cerevisiae treated with PAF26. However, the S. cerevisiae deletion mutant of YAP1 - the major inductor of defense to oxidative stress - did not show high sensitivity to PAF26 but rather increased resistance, and its ROS accumulation did not differ from that of the parental strain. Cross-protection experiments suggest that the oxidant H(2)O(2) and PAF26 kill yeast through different pathways. Overall, the data indicate that ROS are not the primary antifungal mechanism of the peptide. On the contrary, the PAF26-induced intracellular production of NO was blocked in two distinct resistant mutants: the above mentioned Δyap1, which had the induction of NO disrupted, and the previously reported Δarg1 from the biosynthetic pathway of arginine, which has reduced basal NO levels. The NO synthase inhibitor l-NAME partially restored yeast growth in the presence of PAF26. These findings correlate antifungal activity of PAF26 with NO production and provide a plausible explanation for the resistance phenotype of Δarg1 through its involvement in NO biosynthesis.     

Epidemic History and Evolutionary Dynamics of Hepatitis B Virus Infection in Two Remote Communities in Rural Nigeria

Background

In Nigeria, hepatitis B virus (HBV) infection has reached hyperendemic levels and its nature and origin have been described as a puzzle. In this study, we investigated the molecular epidemiology and epidemic history of HBV infection in two semi-isolated rural communities in North/Central Nigeria. It was expected that only a few, if any, HBV strains could have been introduced and effectively transmitted among these residents, reflecting limited contacts of these communities with the general population in the country.

Methods and Findings

Despite remoteness and isolation, ∼11% of the entire population in these communities was HBV-DNA seropositive. Analyses of the S-gene sequences obtained from 55 HBV-seropositive individuals showed the circulation of 37 distinct HBV variants. These HBV isolates belong predominantly to genotype E (HBV/E) (n = 53, 96.4%), with only 2 classified as sub-genotype A3 (HBV/A3). Phylogenetic analysis showed extensive intermixing between HBV/E variants identified in these communities and different countries in Africa. Quasispecies analysis of 22 HBV/E strains using end-point limiting-dilution real-time PCR, sequencing and median joining networks showed extensive intra-host heterogeneity and inter-host variant sharing. To investigate events that resulted in such remarkable HBV/E diversity, HBV full-size genome sequences were obtained from 47 HBV/E infected persons and P gene was subjected to Bayesian coalescent analysis. The time to the most recent common ancestor (tMRCA) for these HBV/E variants was estimated to be year 1952 (95% highest posterior density (95% HPD): 1927–1970). Using additional HBV/E sequences from other African countries, the tMRCA was estimated to be year 1948 (95% HPD: 1924–1966), indicating that HBV/E in these remote communities has a similar time of origin with multiple HBV/E variants broadly circulating in West/Central Africa. Phylogenetic analysis and statistical neutrality tests suggested rapid HBV/E population expansion. Additionally, skyline plot analysis showed an increase in the size of the HBV/E-infected population over the last ∼30–40 years.

Conclusions

Our data suggest a massive introduction and relatively recent HBV/E expansion in the human population in Africa. Collectively, these data show a significant shift in the HBV/E epidemic dynamics in Africa over the last century.     

Molecular cloning and homology modelling of a subtilisin-like serine protease from the marine fungus, <Emphasis Type="Italic">Engyodontium album</Emphasis> BTMFS10

An alkaline protease gene (Eap) was isolated for the first time from a marine fungus, Engyodontium album. Eap consists of an open reading frame of 1,161 bp encoding a prepropeptide consisting of 387 amino acids with a calculated molecular mass of 40.923 kDa. Homology comparison of the deduced amino acid sequence of Eap with other known proteins indicated that Eap encode an extracellular protease that belongs to the subtilase family of serine protease (Family S8). A comparative homology model of the Engyodontium album protease (EAP) was developed using the crystal structure of proteinase K. The model revealed that EAP has broad substrate specificity similar to Proteinase K with preference for bulky hydrophobic residues at P1 and P4. Also, EAP is suggested to have two disulfide bonds and more than two Ca²⁺ binding sites in its 3D structure; both of which are assumed to contribute to the thermostable nature of the protein.     

Influence of Charge Transport and Defects on the Performance of Planar and Mesostructured Perovskite Solar Cells

Photoinduced charge selective carrier extraction by linearly increasing voltage technique allows straightforward assessment of charge transport properties within planar and mesostructured perovskite solar cells with respect to light intensity and signal delay time. Charge sensitive device architecture is realized through implementation of insulating layer between the anode or cathode to prevent extraction of unwanted type of carriers. Resulting behavior of comparatively efficient mesoporous and planar solar cells exhibits well balanced charge transport with slight dependence of charge mobility on applied laser pulse fluence, for given pulse delay times. Very similar charge carrier mobilities are present within mesoporous devices, whereas holes trail approximately half an order of magnitude behind electrons in planar structured specimens. Moreover, dispersive transport is identified in the electron selective devices with titanium oxide electron transporter, suggesting considerable presence of trapping states at the perovskite interface, whereas no such behavior characterizes planar samples. Variation in delay time between laser pulse and extraction ramp only affects initial charge concentration present within the device, while transient outlay remains unchanged, indicating absence of film charging effect.     

Interaction of 3-hydroxybenzoate-6-hydroxylase with cibacron blue

Cibacron blue is a potent inhibitor of 3-HBA-6-hydroxylase at a concentration < 1 μM. Kinetic analyses revealed that at a concentration below 0.5 μM the dye behaves as an uncompetitive inhibitor with respect to 3-HBA and competes with NADH for the same site on the enzyme. The alteration of the near-UV CD spectrum and quenching of the emission fluorescence of the enzyme by cibacron blue indicates a significant alteration in the environment of aromatic amino acid residues due to a stacking interaction and subtle conformatiodnal changes in the enzyme. The concentration-dependent quenching of the intrinsic fluorescence of the enzyme by cibacron blue was employed to determine the binding parameters such as association constant (K_a) and stoichiometry (r) for the enzyme-dye complex.     

Persistence of gut mucosal innate immune defenses by enteric α-defensin expression in the simian immunodeficiency virus model of AIDS

Gastrointestinal mucosa is an early target of HIV and a site of viral replication and severe CD4(+) T cell depletion. However, effects of HIV infection on gut mucosal innate immune defense have not been fully investigated. Intestinal Paneth cell-derived α-defensins constitute an integral part of the gut mucosal innate defense against microbial pathogens. Using the SIV-infected rhesus macaque model of AIDS, we examined the level of expression of rhesus enteric α-defensins (REDs) in the jejunal mucosa of rhesus macaques during all stages of SIV infection using real-time PCR, in situ hybridization, and immunohistochemistry. An increased expression of RED mRNAs was found in PC at the base of the crypts in jejunum at all stages of SIV infection as compared with uninfected controls. This increase correlated with active viral replication in gut-associated lymphoid tissue. Loss of RED protein accumulation in PC was seen in animals with simian AIDS. This was associated with the loss of secretory granules in PC, suggesting an increase in degranulation during advanced SIV disease. The α-defensin-mediated innate mucosal immunity was maintained in PC throughout the course of SIV infection despite the mucosal CD4(+) T cell depletion. The loss of RED protein accumulation and secretion was associated with an increased incidence of opportunistic enteric infections and disease progression. Our findings suggest that local innate immune defense exerted by PC-derived defensins contributes to the protection of gut mucosa from opportunistic infections during the course of SIV infection.     

Oxidants and antioxidants affect the expression of glycodelin

Glycodelin is a glycoprotein that has immunosuppressive activity. We have shown that K562 cells, hematopoitic progenitor cells, are capable of synthesizing glycodelin peptide (Gp) and, perhaps, contribute to Gp in tissues. In addition, several reproductive and nonreproductive tissues themselves are capable of synthesis of glycodelin. In this study, we report that lipid peroxides induce the synthesis of Gp. Antioxidants vitamin E and pyrrolidine dithiocarbamate (PDTC) and antioxidizing enzymes catalase and superoxide dismutase (SOD) effectively blocked phorbol myristate acetate- (PMA-) and lyso phosphatidic acid- (LPA-) induced synthesis of Gp. Dioctanoin (a mimic of diacylglycerol) activated Gp synthesis, and an inhibitor of protein kinase C (PKC) downregulated the response. Based on these observations, we postulate that oxidants by way of PKC might potentiate the angiogenic process.     

Nanotopography Alters Nuclear Protein Expression,Proliferation and Differentiation of Human Mesenchymal Stem/Stromal Cells

Mesenchymal stem/stromal cells respond to physical cues present in their microenvironment such as substrate elasticity, geometry, or topography with respect to morphology, proliferation, and differentiation. Although studies have demonstrated the role of focal adhesions in topography-mediated changes of gene expression, information linking substrate topography to the nucleus remains scarce. Here we show by two-dimensional gel electrophoresis and western blotting that A-type lamins and retinoblastoma protein are downregulated in mesenchymal stem/stromal cells cultured on 350 nm gratings compared to planar substrates; these changes lead to a decrease in proliferation and changes in differentiation potential.     

Transmissibility of intra-host hepatitis C virus variants

Background

Intra-host hepatitis C virus (HCV) populations are genetically heterogeneous and organized in subpopulations. With the exception of blood transfusions, transmission of HCV occurs via a small number of genetic variants, the effect of which is frequently described as a bottleneck. Stochasticity of transmission associated with the bottleneck is usually used to explain genetic differences among HCV populations identified in the source and recipient cases, which may be further exacerbated by intra-host HCV evolution and differential biological capacity of HCV variants to successfully establish a population in a new host.

Results

Transmissibility was formulated as a property that can be measured from experimental Ultra-Deep Sequencing (UDS) data. The UDS data were obtained from one large hepatitis C outbreak involving an epidemiologically defined source and 18 recipient cases. k-Step networks of HCV variants were constructed and used to identify a potential association between transmissibility and network centrality of individual HCV variants from the source. An additional dataset obtained from nine other HCV outbreaks with known directionality of transmission was used for validation.Transmissibility was not found to be dependent on high frequency of variants in the source, supporting the earlier observations of transmission of minority variants. Among all tested measures of centrality, the highest correlation of transmissibility was found with Hamming centrality (r?=?0.720; p?=?1.57 E-71). Correlation between genetic distances and differences in transmissibility among HCV variants from the source was found to be 0.3276 (Mantel Test, p?=?9.99 E-5), indicating association between genetic proximity and transmissibility. A strong correlation ranging from 0.565–0.947 was observed between Hamming centrality and transmissibility in 7 of the 9 additional transmission clusters (p?<?0.05).

Conclusions

Transmission is not an exclusively stochastic process. Transmissibility, as formally measured in this study, is associated with certain biological properties that also define location of variants in the genetic space occupied by the HCV strain from the source. The measure may also be applicable to other highly heterogeneous viruses. Besides improving accuracy of outbreak investigations, this finding helps with the understanding of molecular mechanisms contributing to establishment of chronic HCV infection.