Polymorphisms in vitamin D receptor,toll-like receptor 2 and Toll-Like receptor 4 genes links with Dengue susceptibility

Host genetic factors are known to determine disease susceptibility in dengue virus infection. Therefore, in this study association of gene polymorphisms of Vitamin D Receptor [rs731236 (Taq) and rs7975232 (Apa1)], Toll-like receptor 2 [rs5743708 (Arg735Gln) and rs5743704 (Pro631His)] and Toll-like receptor 4 [rs4986790A/G(Asp299Gly13843) and rs4986791 C/T(Thr399Ile)] were studied in cases with dengue as compared to controls. Total 98 cases of confirmed dengue virus infection and 98 age, sex and geographically matched healthy controls were enrolled and their genetic polymorphisms for the above mentioned regions were studied by Sanger sequencing. Mutant genotypes CC of VDR rs731236 (Taq1) [(OR 3.808, p value =0.02, CI 1.160-12.498)], GG of VDR rs7975232 (Apa1) [(OR 3.485, p value =0.02, CI 1.162-10.45)] and heterozygous genotypes of TLR4 rs4986790 A/G Asp299Gly [OR 2.40, p value= 0.02, CI 1.12-5.14], TLR4 rs4986791 C/T Thr399Ile [OR 2.09, p value=0.02, CI 1.12-5.14] were found to be significantly more in cases with dengue virus infection as compared to the controls. Also, at these positions mutant alleles were observed in significantly higher number of cases than controls. The values for C allele at VDR rs731236 (Taq1) were OR 1.86, p value 0.009, CI 1.162-3.001; for allele G at rs7975232( Apa1) were OR 2.71, p value 0.006, CI 1.196-2.98 for allele G at TLR4s rs4986790 A/G Asp299Gly were OR 2.35, p value 0.009, CI 1.23-4.50 and for allele T at rs4986791 C/T Thr399Ile were OR 2.36, p value=0.006, CI 1.28-4.38. VDR and TLR4 but not TLR2 gene polymorphisms were found to be associated with dengue susceptibility in Indian population.     

Pathogenicity of Mycobacterium tuberculosis Is Expressed by Regulating Metabolic Thresholds of the Host Macrophage

The success of Mycobacterium tuberculosis as a pathogen derives from its facile adaptation to the intracellular milieu of human macrophages. To explore this process, we asked whether adaptation also required interference with the metabolic machinery of the host cell. Temporal profiling of the metabolic flux, in cells infected with differently virulent mycobacterial strains, confirmed that this was indeed the case. Subsequent analysis identified the core subset of host reactions that were targeted. It also elucidated that the goal of regulation was to integrate pathways facilitating macrophage survival, with those promoting mycobacterial sustenance. Intriguingly, this synthesis then provided an axis where both host- and pathogen-derived factors converged to define determinants of pathogenicity. Consequently, whereas the requirement for macrophage survival sensitized TB susceptibility to the glycemic status of the individual, mediation by pathogen ensured that the virulence properties of the infecting strain also contributed towards the resulting pathology.     

Structural Characterization of a Gcn5-Related N-Acetyltransferase from Staphylococcus aureus

The Gcn5-related N-acetyltransferases (GNATs) are ubiquitously expressed in nature and perform a diverse range of cellular functions through the acetylation of small molecules and protein substrates. Using activated acetyl coenzyme A as a common acetyl donor, GNATs catalyse the transfer of an acetyl group to acceptor molecules including aminoglycoside antibiotics, glucosamine-6-phosphate, histones, serotonin and spermidine. There is often only very limited sequence conservation between members of the GNAT superfamily, in part, reflecting their capacity to bind a diverse array of substrates. In contrast, the secondary and tertiary structures are highly conserved, but then at the quaternary level there is further diversity, with GNATs shown to exist in monomeric, dimeric, or tetrameric states. Here we describe the X-ray crystallographic structure of a GNAT enzyme from Staphyloccocus aureus with only low sequence identity to previously solved GNAT proteins. It contains many of the classical GNAT motifs, but lacks other hallmarks of the GNAT fold including the classic β-bulge splayed at the β-sheet interface. The protein is likely to be a dimer in solution based on analysis of the asymmetric unit within the crystal structure, homology with related GNAT family members, and size exclusion chromatography. The study provides the first high resolution structure of this enzyme, providing a strong platform for substrate and cofactor modelling, and structural/functional comparisons within this diverse enzyme superfamily.     

Purification and characterization of trypsin inhibitor from seeds of faba bean (Vicia faba L.)

A trypsin inhibitor from seeds of faba bean (Vicia faba L.) was purified to near homogeneity as judged by native-PAGE with about 11 % recovery using ammonium sulphate fractionation, ion-exchange chromatography on DEAE-cellulose and gel filtration through Sephadex G-100. The inhibitor had a molecular weight of 18 kD as determined by SDS-PAGE and Sephadex G-100. The inhibitor inhibited trypsin and chymotrypsin to the extent of 48 and 12 %, respectively. The inhibtion was of non-competitive type with dissociation constant for the enzyme inhibitor complex in the region of 0.07 mg·ml⁻¹. The inhibtor was stable between pH 4 and 5. It completely lost its activity when heated at 125 °C for 1 h or at 100 °C for 2 h. The inhibitor also lost its activity on exposure to 2-mercaptoethanol. Based on these properties, it could be concluded that Vicia faba trypsin inhibitor belongs to Bowman-Birk type of inhibitors, as it has molecular weight lower than generally observed for Kunitz type inhibitors.     

Cargo crowding at actin‐rich regions along axons causes local traffic jams

Steady axonal cargo flow is central to the functioning of healthy neurons. However, a substantial fraction of cargo in axons remains stationary up to several minutes. We examine the transport of precursors of synaptic vesicles (pre‐SVs), endosomes and mitochondria in Caenorhabditis elegans touch receptor neurons, showing that stationary cargo are predominantly present at actin‐rich regions along the neuronal process. Stationary vesicles at actin‐rich regions increase the propensity of moving vesicles to stall at the same location, resulting in traffic jams arising from physical crowding. Such local traffic jams at actin‐rich regions are likely to be a general feature of axonal transport since they also occur in Drosophila neurons. Repeated touch stimulation of C. elegans reduces the density of stationary pre‐SVs, indicating that these traffic jams can act as both sources and sinks of vesicles. This suggests that vesicles trapped in actin‐rich regions are functional reservoirs that may contribute to maintaining robust cargo flow in the neuron. A video abstract of this article can be found at: Video S1 ; Video S2      

Impact of oxidative and osmotic stresses on Candida albicans biofilm formation

Candida albicans possesses an ability to grow under different host-driven stress conditions by developing robust protective mechanisms. In this investigation the focus was on the impact of osmotic (2M NaCl) and oxidative (5 mM H₂O₂) stress conditions during C. albicans biofilm formation. Oxidative stress enhanced extracellular DNA secretion into the biofilm matrix, increased the chitin level, and reduced virulence factors, namely phospholipase and proteinase activity, while osmotic stress mainly increased extracellular proteinase and decreased phospholipase activity. Fourier transform infrared and nuclear magnetic resonance spectroscopy analysis of mannan isolated from the C. albicans biofilm cell wall revealed a decrease in mannan content and reduced β-linked mannose moieties under stress conditions. The results demonstrate that C. albicans adapts to oxidative and osmotic stress conditions by inducing biofilm formation with a rich exopolymeric matrix, modulating virulence factors as well as the cell wall composition for its survival in different host niches.     

Hydrophobized triphenyl phosphonium derivatives for the preparation of mitochondriotropic liposomes: choice of hydrophobic anchor influences cytotoxicity but not mitochondriotropic effect

Context: Nanocarrier-based strategies to achieve delivery of bioactives specifically to the mitochondria are being increasingly explored due to the importance of mitochondria in critical cellular processes.

Objective: To test the ability of liposomes modified with newly synthesized triphenylphosphonium (TPP)–phospholipid conjugates and to test their use in overcoming the cytotoxicity of stearyl triphenylphosphonium (STPP)-modified liposomes when used for delivery of therapeutic molecules to the mitochondria.

Methods: TPP–phospholipid conjugates with the dioleoyl, dimyristoyl or dipalmitoyl lipid moieties were synthesized and liposomes were prepared with these conjugates in a 1?mol% ratio. The subcellular distribution of the liposomes was tested by confocal microscopy. Furthermore, the liposomes were tested for their effect on cell viability using a MTS assay, on cell membrane integrity using a lactate dehydrogenase assay and on mitochondrial membrane integrity using a modified JC-1 assay.

Results: The liposomes modified with the new TPP–phospholipid conjugates exhibited similar mitochondriotropism as STPP-liposomes but they were more biocompatible as compared to the STPP liposomes. While the STPP-liposomes had a destabilizing effect on cell and mitochondrial membranes, the liposomes modified with the TPP–phospholipid conjugates did not demonstrate any such effect on biomembranes.

Conclusions: Using phospholipid anchors in the synthesis of TPP–lipid conjugates can provide liposomes that exhibit the same mitochondrial targeting ability as STPP but with much higher biocompatibility.     

Selective Targeting of TRPV1 Expressing Sensory Nerve Terminals in the Spinal Cord for Long Lasting Analgesia

Chronic pain is a major clinical problem and opiates are often the only treatment, but they cause significant problems ranging from sedation to deadly respiratory depression. Resiniferatoxin (RTX), a potent agonist of Transient Receptor Potential Vanilloid 1 (TRPV1), causes a slow, sustained and irreversible activation of TRPV1 and increases the frequency of spontaneous excitatory postsynaptic currents, but causes significant depression of evoked EPSCs due to nerve terminal depolarization block. Intrathecal administration of RTX to rats in the short-term inhibits nociceptive synaptic transmission, and in the long-term causes a localized, selective ablation of TRPV1-expressing central sensory nerve terminals leading to long lasting analgesia in behavioral models. Since RTX actions are selective for central sensory nerve terminals, other efferent functions of dorsal root ganglion neurons can be preserved. Preventing nociceptive transmission at the level of the spinal cord can be a useful strategy to treat chronic, debilitating and intractable pain.     

Speckled SiO2@Au Core–Shell Particles as Surface Enhanced Raman Scattering Probes

Silica particles of ~800 nm size were functionalized using 3-amino propyl triethoxysilane molecules on which gold particles (~20 nm size) were deposited. The resulting particles appeared to form speckled SiO₂@Au core–shell particles. The surface roughness, along with hot spots, due to nanogaps between the gold nanoparticles was responsible for the enhancement of the Raman signal of crystal violet molecules by ~3.2?×?10⁷ and by ~1.42?×?10⁸ of single-wall carbon nanotubes. It has also been observed that the electromagnetic excitation near surface plasmon resonance (SPR) of core–shell particles is more effective than off resonance SPR excitation.     

Evaluating the effect of codon optimization on expression of bar gene in transgenic tobacco plants

Journal of Plant Biochemistry and Biotechnology - Information of codon usage bias has been used for modifying genes for improved expression in heterologous systems. Codon modifications are carried...