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  • Oxford University Press  (30)
  • BioMed Central  (27)
  • Cambridge University Press
  • Nature Publishing Group
  • 2010-2014  (58)
  • 1
    Publication Date: 2012-06-15
    Description: Background: Single-stranded DNA binding proteins (SSB) are essential for DNA replication, repair, and recombination in all organisms. SSB works in concert with a variety of DNA metabolizing enzymes such as DNA polymerase. Results: We have cloned and purified SSB from Bacillus anthracis (SSBBA). In the absence of DNA, at concentrations [less than or equal to]100 mug/ml, SSBBA did not form a stable tetramer and appeared to resemble bacteriophage T4 gene 32 protein. Fluorescence anisotropy studies demonstrated that SSBBA bound ssDNA with high affinity comparable to other prokaryotic SSBs. Thermodynamic analysis indicated both hydrophobic and ionic contributions to ssDNA binding. FRET analysis of oligo(dT)70 binding suggested that SSBBA forms a tetrameric assembly upon ssDNA binding. This report provides evidence of a bacterial SSB that utilizes a novel mechanism for DNA binding through the formation of a transient tetrameric structure. Conclusions: Unlike other prokaryotic SSB proteins, SSBBA from Bacillus anthracis appeared to be monomeric at concentrations [less than or equal to]100 mug/ml as determined by SE-HPLC. SSBBA retained its ability to bind ssDNA with very high affinity, comparable to SSB proteins which are tetrameric. In the presence of a long ssDNA template, SSBBA appears to form a transient tetrameric structure. Its unique structure appears to be due to the cumulative effect of multiple key amino acid changes in its sequence during evolution, leading to perturbation of stable dimer and tetramer formation. The structural features of SSBBA could promote facile assembly and disassembly of the protein-DNA complex required in processes such as DNA replication.
    Electronic ISSN: 1471-2091
    Topics: Chemistry and Pharmacology
    Published by BioMed Central
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  • 2
    Publication Date: 2012-01-01
    Electronic ISSN: 1471-2091
    Topics: Chemistry and Pharmacology
    Published by BioMed Central
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  • 3
    Publication Date: 2012-04-13
    Description: Aims In recent years, coastal mangroves have been frequently affected by large disturbances (cyclones, hurricanes, flooding and tsunamis) and post-disturbance vegetation is often dominated by small stature mangrove, mangrove-associate and non-mangrove species potentially affecting ecosystem functioning. Knowledge on the processes of mangrove vegetation development and recovery (succession) following normal and large disturbances will benefit practitioners in designing robust ecosystem management/restoration plans. Here we propose a conceptual model of disturbance-mediated succession in mangroves. Methods Based on field observations and species’ life history traits, we develop conceptual models of mangrove succession under normal disturbance regime and recently experienced increased frequency of large disturbances. We evaluate our conceptual models by conducting a scenario testing experiment. Important Findings We suggest two predominant processes affecting mangrove succession after disturbance: propagule limitation due to damage of seed producing mature trees and dispersal barrier resulting from biological invasion associated with large disturbance. We argue that large disturbances affect mature trees more than the small-stature non-tree (shrubs, herbs and climbers) species creating a larger propagule shortage for mangrove tree species than non-tree species. Secondly, large disturbances facilitate invasion of free-floating aquatics, which may interfere with the flow-facilitated propagule dispersal and seedling establishment of mangrove species. In a scenario testing experiment, we have shown that similar levels of disturbance impact vegetation development and recovery differently depending on the presence or absence of invasive species. We conclude that since biological invasion is one of the major drivers of post-disturbance mangrove succession, the dimension of biological invasion should be included in prediction, management and restoration of mangrove forests.
    Print ISSN: 1752-993X
    Electronic ISSN: 1752-9921
    Topics: Biology
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  • 4
    Publication Date: 2012-08-28
    Description: Single-nucleotide substitutions and small in-frame insertions or deletions identified in human breast cancer susceptibility genes BRCA1 and BRCA2 are frequently classified as variants of unknown clinical significance (VUS) due to the availability of very limited information about their functional consequences. Such variants can most reliably be classified as pathogenic or non-pathogenic based on the data of their co-segregation with breast cancer in affected families and/or their co-occurrence with a pathogenic mutation. Biological assays that examine the effect of variants on protein function can provide important information that can be used in conjunction with available familial data to determine the pathogenicity of VUS. In this report, we have used a previously described mouse embryonic stem (mES) cell-based functional assay to characterize eight BRCA2 VUS that affect highly conserved amino acid residues and map to the N-terminal PALB2-binding or the C-terminal DNA-binding domains. For several of these variants, very limited co-segregation information is available, making it difficult to determine their pathogenicity. Based on their ability to rescue the lethality of Brca2- deficient mES cells and their effect on sensitivity to DNA-damaging agents, homologous recombination and genomic integrity, we have classified these variants as pathogenic or non-pathogenic. In addition, we have used homology-based modeling as a predictive tool to assess the effect of some of these variants on the structural integrity of the C-terminal DNA-binding domain and also generated a knock-in mouse model to analyze the physiological significance of a residue reported to be essential for the interaction of BRCA2 with meiosis-specific recombinase, DMC1.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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  • 5
    Publication Date: 2014-03-20
    Description: Neuronal ceroid lipofuscinosis (NCL) comprises ~13 genetically distinct lysosomal disorders primarily affecting the central nervous system. Here we report successful reprograming of patient fibroblasts into induced pluripotent stem cells (iPSCs) for the two most common NCL subtypes: classic late-infantile NCL, caused by TPP1(CLN2) mutation, and juvenile NCL, caused by CLN3 mutation. CLN2/TPP1- and CLN3-iPSCs displayed overlapping but distinct biochemical and morphological abnormalities within the endosomal–lysosomal system. In neuronal derivatives, further abnormalities were observed in mitochondria, Golgi and endoplasmic reticulum. While lysosomal storage was undetectable in iPSCs, progressive disease subtype-specific storage material was evident upon neural differentiation and was rescued by reintroducing the non-mutated NCL proteins. In proof-of-concept studies, we further documented differential effects of potential small molecule TPP1 activity inducers. Fenofibrate and gemfibrozil, previously reported to induce TPP1 activity in control cells, failed to increase TPP1 activity in patient iPSC-derived neural progenitor cells. Conversely, nonsense suppression by PTC124 resulted in both an increase of TPP1 activity and attenuation of neuropathology in patient iPSC-derived neural progenitor cells. This study therefore documents the high value of this powerful new set of tools for improved drug screening and for investigating early mechanisms driving NCL pathogenesis.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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  • 6
    Publication Date: 2014-11-25
    Description: We propose a multivariate generalization of the univariate two-sample run test based on the shortest Hamiltonian path. The proposed test is distribution-free in finite samples. While most existing two-sample tests perform poorly or are even inapplicable to high-dimensional data, our test can be conveniently used in high-dimension, low-sample-size situations. We investigate its power when the sample size remains fixed and the dimension of the data grows to infinity. Simulated and real datasets demonstrate our method’s superiority over existing nonparametric two-sample tests.
    Print ISSN: 0006-3444
    Electronic ISSN: 1464-3510
    Topics: Biology , Mathematics , Medicine
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  • 7
    Publication Date: 2014-09-04
    Description: Background: Elevated glucose concentrations lead to increased insulin secretion and suppression of glucagon secretion. In fact, insulin is a physiological inhibitor of glucagon secretion. Type 2 diabetes mellitus (T2DM) patients have defects in insulin secretion. In addition to this, lack of suppression of glucagon secretion under elevated glucose concentrations is also observed in T2DM patients. We have earlier shown that GPR40 activation by CNX-011-67 stimulates glucose stimulated insulin secretion (GSIS). Here we extended our studies to examine the impact of GPR40 activation by CNX-011-67 on glucagon secretion from intact islets under both normal and glucolipotoxic conditions.FindingsGlucagon secretion from intact rat islets was suppressed under elevated glucose concentration. Activation of GPR40 by CNX-011-67 further suppressed glucagon secretion. Culturing islets under chronic glucolipotoxic (GL) conditions, we have observed increased high glucose mediated glucagon secretion and content which were reduced with GPR40 activation by CNX-011-67. Interestingly, expression of pre-proglucagon gene (GCG) remained unchanged under glucolipotoxicity in the presence or absence of GPR40 activation. Conclusion: Activation of GPR40 by CNX-011-67 can reduce glucagon secretion from pancreatic islets.
    Electronic ISSN: 1756-0500
    Topics: Biology , Medicine
    Published by BioMed Central
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  • 8
    Publication Date: 2014-10-11
    Description: Background: Heat stress leads to accelerated production of reactive oxygen species (ROS) which causes a huge amount of oxidative damage to the cellular components of plants. A large number of heat stress related genes as HSPs, catalases, peroxidases are overexpressed at the time of stress. A potent stress responsive gene peroxisomal ascorbate peroxidase (TapAPX) obtained from heat stress (42[degree sign]C) responsive subtractive cDNA library from a thermo tolerant wheat cv. Raj3765 at anthesis stage was cloned, characterized and its role was validated under heat stress by proteomics and in-silico studies.. In the present study we report the characterization at molecular and in-silico level of peroxisomal TapAPX gene isolated from heat tolerant wheat cultivar of India. Results: qPCR studies of TapAPX gene displayed up to 203 fold level of expression at 42[degree sign]C heat stress exposure. A full length cDNA of 876 bp obtained by RACE deduced a protein of 292 amino acid residues which gives a complete 3D structure of pAPX by homology modeling. TapAPX cDNA was cloned in expression vector pET28 (a+) and the recombinant protein over-expressed in E. coli BL21 showed highest homology with APX protein as deduced by peptide mass fingerprinting. Conclusions: TapAPX gene from wheat cv Raj3765 has a distinct role in conferring thermo tolerance to the plants and thus can be used in crop improvement programmes for development of crops tolerant to high temperature.
    Electronic ISSN: 1756-0500
    Topics: Biology , Medicine
    Published by BioMed Central
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  • 9
    Publication Date: 2014-07-17
    Description: We consider the Zariski–Lipman Conjecture on a free module of derivations for algebraic surfaces. Using the theory of non-complete algebraic surfaces, and some basic results about ruled surfaces, we will prove the conjecture for several classes of affine and projective surfaces.
    Print ISSN: 0024-6107
    Electronic ISSN: 1469-7750
    Topics: Mathematics
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  • 10
    Publication Date: 2014-07-18
    Description: Background: Procalcitonin is useful for the diagnosis of sepsis but its prognostic value regarding mortality is unclear. This prospective observational study was designed to study the prognostic value of procalcitonin in prediction of 28 day mortality in patients of sepsis. Fifty-four consecutive patients of sepsis, severe sepsis and septic shock defined using the 2001 Consensus Conference SCCM/ESICM/ACCP/ATS/SIS criteria from medical Intensive Care Unit (ICU) of a tertiary care center in New Delhi, India were enrolled from July 2011 to June 2013. Procalcitonin (PCT), C-reactive protein (CRP) measurements were recorded on day 1, day 7 and day 28 of follow up. Results: Procalcitonin value was a better predictor of all-cause short-term mortality than C-reactive protein. Those patients with Procalcitonin levels
    Electronic ISSN: 1756-0500
    Topics: Biology , Medicine
    Published by BioMed Central
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