Studies on Exo-Chitinase Production from Trichoderma asperellum UTP-16 and Its Characterization

The growth conditions for chitinase production by Trichoderma asperellum UTP-16 in solid state fermentation was optimized using response surface methodology based on central composite design. The chitinase production was optimized, using one-factor at a time approach, with six independent variables (temperature, pH, NaCl, incubation period, nitrogen and carbon sources) and 3.31 Units per gram dry substrate (U gds⁻¹) exo-chitinase yield was obtained. A 21.15% increase was recorded in chitinase activity (4.01 U gds⁻¹) through surface response methodology, indicates that it is a powerful and rapid tool for optimization of physical and nutritional variables. Further, efficiency of crude enzyme was evaluated against phytopathogenic Fusarium spp. and a mycelial growth inhibition up to 3.5–6.5 mm was achieved in well diffusion assay. These results could be supplemented as basic information for the development of enzyme based formulation of T. asperellum UTP-16 and its use as a biocontrol agent.     

Transbronchial fine needle aspiration of the mediastinum. Importance of lymphocytes as an indicator of specimen adequacy

To determine the effectiveness and accuracy of transbronchial fine needle aspiration of mediastinal masses for the staging of bronchogenic carcinoma, the results and histologic correlations of 97 transbronchial aspirates submitted from 78 patients over a two-year period were reviewed. Malignant cells were present in 25 of 97 aspirates. Of the remaining 75 nonmalignant aspirates, 34 had corresponding mediastinal tissue sections. Review of these 34 aspirates disclosed respiratory epithelial cells without lymphocytes in 20, lymphocytes without respiratory cells in 1 and both cell types in 8. Neither cell type was present in five aspirates. The predictive value of a negative result was 78% for nonmalignant aspirates containing lymphocytes and 36% for nonmalignant aspirates not containing lymphocytes (P less than .05). The presence of lymphocytes in transbronchial needle aspirates of the mediastinum is an essential criterion of specimen adequacy. Negative specimens lacking lymphocytes should be considered unsatisfactory, regardless of the numbers of respiratory epithelial cells present.     

Electrical detection of the temperature induced melting transition of a DNA hairpin covalently attached to gold interdigitated microelectrodes

The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5′ end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, manner. The structural state of the hairpin was assessed by measuring four different electronic properties of the GIME (capacitance, impedance, dissipation factor and phase angle) as a function of temperature from 25°C to 80°C. Consistent changes in all four electronic properties of the GIME were observed over this temperature range, and attributed to the transition of the attached single-stranded DNA (ssDNA) from an intramolecular, folded hairpin structure to a melted ssDNA. The melting curve of the self-complementary single strand was also measured in solution using differential scanning calorimetry (DSC) and UV absorbance spectroscopy. Temperature dependent electronic measurements on the surface and absorbance versus temperature values measured in solution experiments were analyzed assuming a two-state process. The model analysis provided estimates of the thermodynamic transition parameters of the hairpin on the surface. Two-state analyses of optical melting data and DSC measurements provided evaluations of the thermodynamic transition parameters of the hairpin in solution. Comparison of surface and solution measurements provided quantitative evaluation of the effect of the surface on the thermodynamics of the melting transition of the DNA hairpin.     

Bioactive compounds from marine actinomycetes

Actinomycetes are one of the most efficient groups of secondary metabolite producers and are very important from an industrial point of view. Among its various genera, Streptomyces, Saccharopolyspora, Amycolatopsis, Micromonospora and Actinoplanes are the major producers of commercially important biomolecules. Several species have been isolated and screened from the soil in the past decades. Consequently the chance of isolating a novel actinomycete strain from a terrestrial habitat, which would produce new biologically active metabolites, has reduced. The most relevant reason for discovering novel secondary metabolites is to circumvent the problem of resistant pathogens, which are no longer susceptible to the currently used drugs. Existence of actinomycetes has been reported in the hitherto untapped marine ecosystem. Marine actinomycetes are efficient producers of new secondary metabolites that show a range of biological activities including antibacterial, antifungal, anticancer, insecticidal and enzyme inhibition. Bioactive compounds from marine actinomycetes possess distinct chemical structures that may form the basis for synthesis of new drugs that could be used to combat resistant pathogens.     

Oxazolidinone: search for highly potent antibacterial

A number of substituted piperazinyl oxazolidinone derivatives have been synthesized and their antibacterial activities were evaluated by MIC determination. A systematic SAR was carried out to get highly potent oxazolidinone derivatives.     

Fingerprinting method for phylogenetic classification and identification of microorganisms based on variation in 16S rRNA gene sequences

The paper describes a method for the classification and identification of microorganisms based on variations in 16S rRNA sequences. The 16S rRNA is one of the most conserved molecules within a cell. The nature of the variable and spacer regions has been found to be specific to a given organism. Thus, the method presented here can be very useful for the classification and identification of microorganisms for which very little information is available. To automate the method, a comprehensive computer program called FPMAP has been developed for the analysis of restriction fragment pattern data. The method involves the restriction digestion of genomic DNA, preferably using four-cutters that may recognize 6-9 sites within the 16S rDNA. The fragments are separated on a polyacrylamide gel along with a suitable marker, then transferred into a nylon membrane and hybridized with a radiolabeled 16S rDNA probe. After autoradiography, the fragment sizes are calculated, and the data are analyzed using the FPMAP software. We demonstrate that the method can be used for identification of strains of Streptomyces and mycobacteria. The software is available from our ftp site ftp:?imtech.chd.nic.in/pub/com/fpmap/unix/.     

Microtubules Deform the Nuclear Membrane and Disrupt Nucleocytoplasmic Transport in Tau-Mediated Frontotemporal Dementia

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Glycoside hydrolase from the GH76 family indicates that marine Salegentibacter sp. Hel_I_6 consumes alpha-mannan from fungi

Microbial glycan degradation is essential to global carbon cycling. The marine bacterium Salegentibacter sp. Hel_I_6 (Bacteroidota) isolated from seawater off Helgoland island (North Sea) contains an α-mannan inducible gene cluster with a GH76 family endo-α-1,6-mannanase (ShGH76). This cluster is related to genetic loci employed by human gut bacteria to digest fungal α-mannan. Metagenomes from the Hel_I_6 isolation site revealed increasing GH76 gene frequencies in free-living bacteria during microalgae blooms, suggesting degradation of α-1,6-mannans from fungi. Recombinant ShGH76 protein activity assays with yeast α-mannan and synthetic oligomannans showed endo-α-1,6-mannanase activity. Resolved structures of apo-ShGH76 (2.0 Å) and of mutants co-crystalized with fungal mannan-mimicking α-1,6-mannotetrose (1.90 Å) and α-1,6-mannotriose (1.47 Å) retained the canonical (α/α)₆ fold, despite low identities with sequences of known GH76 structures (GH76s from gut bacteria: <27%). The apo-form active site differed from those known from gut bacteria, and co-crystallizations revealed a kinked oligomannan conformation. Co-crystallizations also revealed precise molecular-scale interactions of ShGH76 with fungal mannan-mimicking oligomannans, indicating adaptation to this particular type of substrate. Our data hence suggest presence of yet unknown fungal α-1,6-mannans in marine ecosystems, in particular during microalgal blooms.Subject terms: Metagenomics, Microbial ecology, Structural biology, Fungal ecology, Molecular ecology     

Mechanical programming of arterial smooth muscle cells in health and ageing

Arterial smooth muscle cells (ASMCs), the predominant cell type within the arterial wall, detect and respond to external mechanical forces. These forces can be derived from blood flow (i.e. pressure and stretch) or from the supporting extracellular matrix (i.e. stiffness and topography). The healthy arterial wall is elastic, allowing the artery to change shape in response to changes in blood pressure, a property known as arterial compliance. As we age, the mechanical forces applied to ASMCs change; blood pressure and arterial wall rigidity increase and result in a reduction in arterial compliance. These changes in mechanical environment enhance ASMC contractility and promote disease-associated changes in ASMC phenotype. For mechanical stimuli to programme ASMCs, forces must influence the cell’s load-bearing apparatus, the cytoskeleton. Comprised of an interconnected network of actin filaments, microtubules and intermediate filaments, each cytoskeletal component has distinct mechanical properties that enable ASMCs to respond to changes within the mechanical environment whilst maintaining cell integrity. In this review, we discuss how mechanically driven cytoskeletal reorganisation programmes ASMC function and phenotypic switching.