Effects of DNP on the cell surface properties of marine bacteria and its implication for adhesion to surfaces

Abstract

The effect of 2, 4-dinitrophenol (DNP) on the extracelluar polysaccharides (EPS), cell surface charge, and the hydrophobicity of six marine bacterial cultures was studied, and its influence on attachment of these bacteria to glass and polystyrene was evaluated. DNP treatment did not influence cell surface charge and EPS production, but had a significant effect on hydrophobicity of both hydrophilic (p = 0.05) and hydrophobic (p = 0.01) cultures. Significant reduction in the attachment of all the six cultures to glass (p = 0.02) and polystyrene (p = 0.03) was observed after DNP treatment. Moreover, hydrophobicity but not the cell surface charge or EPS production influenced bacterial cell attachment to glass and polystyrene. From this study, it was evident that DNP treatment influenced bacterial cell surface hydrophobicity, which in turn, reduced bacterial adhesion to surfaces.     

Polarization of Diploid Daughter Cells Directed by Spatial Cues and GTP Hydrolysis of Cdc42 in Budding Yeast

Cell polarization occurs along a single axis that is generally determined by a spatial cue. Cells of the budding yeast exhibit a characteristic pattern of budding, which depends on cell-type-specific cortical markers, reflecting a genetic programming for the site of cell polarization. The Cdc42 GTPase plays a key role in cell polarization in various cell types. Although previous studies in budding yeast suggested positive feedback loops whereby Cdc42 becomes polarized, these mechanisms do not include spatial cues, neglecting the normal patterns of budding. Here we combine live-cell imaging and mathematical modeling to understand how diploid daughter cells establish polarity preferentially at the pole distal to the previous division site. Live-cell imaging shows that daughter cells of diploids exhibit dynamic polarization of Cdc42-GTP, which localizes to the bud tip until the M phase, to the division site at cytokinesis, and then to the distal pole in the next G1 phase. The strong bias toward distal budding of daughter cells requires the distal-pole tag Bud8 and Rga1, a GTPase activating protein for Cdc42, which inhibits budding at the cytokinesis site. Unexpectedly, we also find that over 50% of daughter cells lacking Rga1 exhibit persistent Cdc42-GTP polarization at the bud tip and the distal pole, revealing an additional role of Rga1 in spatiotemporal regulation of Cdc42 and thus in the pattern of polarized growth. Mathematical modeling indeed reveals robust Cdc42-GTP clustering at the distal pole in diploid daughter cells despite random perturbation of the landmark cues. Moreover, modeling predicts different dynamics of Cdc42-GTP polarization when the landmark level and the initial level of Cdc42-GTP at the division site are perturbed by noise added in the model.     

cDNA Cloning and Molecular Modeling of Procerain B,a Novel Cysteine Endopeptidase Isolated from Calotropis procera

Procerain B, a novel cysteine protease (endopeptidase) isolated from Calotropis procera belongs to Asclepiadaceae family. Purification of the enzyme, biochemical characterization and potential applications are already published by our group. Here, we report cDNA cloning, complete amino acid sequencing and molecular modeling of procerain B. The derived amino acid sequence showed high sequence homology with other papain like plant cysteine proteases of peptidase C1A superfamily. The three dimensional structure of active procerain B was modeled by homology modeling using X-ray crystal structure of actinidin (PDB ID: 3P5U), a cysteine protease from the fruits of Actinidia arguta. The structural aspect of the enzyme is also discussed.     

Somatic Variations in Cervical Cancers in Indian Patients

There are very few reports that describe the mutational landscape of cervical cancer, one of the leading cancers in Indian women. The aim of the present study was to investigate the somatic mutations that occur in cervical cancer. Whole exome sequencing of 10 treatment naïve tumour biopsies with matched blood samples, from a cohort of Indian patients with locally advanced disease, was performed. The data revealed missense mutations across 1282 genes, out of 1831 genes harbouring somatic mutations. These missense mutations (nonsynonymous + stop-gained) when compared with pre-existing mutations in the COSMIC database showed that 272 mutations in 250 genes were already reported although from cancers other than cervical cancer. More than 1000 novel somatic variations were obtained in matched tumour samples. Pathways / genes that are frequently mutated in various other cancers were found to be mutated in cervical cancers. A significant enrichment of somatic mutations in the MAPK pathway was observed, some of which could be potentially targetable. This is the first report of whole exome sequencing of well annotated cervical cancer samples from Indian women and helps identify trends in mutation profiles that are found in an Indian cohort of cervical cancer.     

Environmental and spatial characterisation of an unknown fauna using DNA sequencing – an example with Himalayan Hydropsychidae (Insecta: Trichoptera)

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In silico discovery of potential drug molecules to improve the treatment of isoniazid-resistant Mycobacterium tuberculosis

The emergence of multidrug-resistant Mycobacterium tuberculosis (M.tb) has become one of the major hurdles in the treatment of tuberculosis (TB). Drug-resistant M.tb has evolved with various strategies to avoid killing by the anti-tubercular drugs. Thus, there is a rising need to develop effective anti-TB drugs to improve the treatment of these strains. Traditional drug design approach has earned little success due to time and the cost involved in the process of development of anti-infective drugs. Numerous reports have demonstrated that several mutations in the drug target sites cause emergence of drug-resistant M.tb strains. In this study, we performed computational mutational analysis of M.tb inhA, fabD, and ahpC genes, which are the primary targets for first-line isoniazid (INH) drug. In silico virtual drug screening was performed to identify the potent drugs from a ChEMBL compound library to improve the treatment of INH-resistant M.tb. Further, these compounds were analyzed for their binding efficiency against active drug binding cavity of M.tb wild-type and mutant InhA, FabD and AhpC proteins. The drug efficacy of predicted lead compounds was verified by molecular docking using M.tb wild-type and mutant InhA, FabD and AhpC protein template models. Different in silico and pharmacophore analysis predicted three potent lead compounds with better drug-like properties against both M.tb wild-type and mutant InhA, FabD, and AhpC proteins as compared to INH drug, and thus may be considered as effective drugs for the treatment of INH-resistant M.tb strains. We hypothesize that this work may accelerate drug discovery process for the treatment of drug-resistant TB.

Communicated by Ramaswamy H. Sarma