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Screening of actinobacteria for antimicrobial activities by a modified "Cross-Streak" method
No full textNew molecule discovery from natural sources, such as that of actinobacteria, has proved to be an interesting area in antibiotic research, as most of these antibiotics are difficult to synthesize. Out of 30 actinobacterial cultures screened for antimicrobial activity, 28 cultures were found to produce active products against various pathogenic microorganisms such as Gram-negative, Gram-positive bacteria and yeast, using a ‘modified cross streak method.' The modified method helped in easy quantification of results and also in ruling out probable mutual antibiosis. 53%, 13% and 10% of tested actinobacterial strains belonging to Streptomyces, Micromonospora and Actinomadura genera, respectively, showed the ability of producing antimicrobial compounds. Streptomyces sp. strain MMA-5 showed the highest percentage multispecific antibiosis efficiency score value. Broad antibiotic spectrum activity was exhibited by Streptomyces sp. strain MMA-2 and Micromonospora sp. strain MMA-8. The multidrug resistant human pathogenic yeast strain Candida albicans was inhibited by 18 actinobacterial strains
Genetic incorporation of D-Lysine into diketoreductase in Escherichia coli cells
Full text linkD-Lysine has been genetically introduced into diketoreductase in E. coli cells by utilization of an orthogonal Ph tRNA /Lysyl-tRNA synthetase pair. This is the first report on the genetic incoporation of D-amino acids into proteins, which may be generally applicable to a wide variety of applications
Detecting differential usage of exons from RNA-Seq data
Full text linkRNA-Seq is a powerful tool for the study of alternative splicing and other forms of alternative isoform expression. Understanding the regulation of these processes requires comparisons between treatments, tissues or conditions. For the analysis of such experiments, we present _DEXSeq_, a statistical method to test for differential exon usage in RNA-Seq data. _DEXSeq_ employs generalized linear models and offers good detection power and reliable control of false discoveries by taking biological variation into account. An implementation is available as an R/Bioconductor package
Universality of a mesenchymal transition signature in invasive solid cancers
Full text linkIn this brief communication, additional computational validation is provided consistent with the unifying hypothesis that a shared biological mechanism of mesenchymal transition, reflected by a precise gene expression signature, may be present in all types of solid cancers when they reach a particular stage of invasiveness
Dispersal of _Aedes aegypti_: field study in temperate areas and statistical approach
Full text linkWe studied the dispersion of _Aedes aegypti_ during egg laying in natural conditions. Two independent experiments involving mosquitoes dispersing from urbanization towards adjacent un-urbanized areas were carried out and analyzed in statistical terms. We find relations between stochastic variables related to the egg laying mosquito activity (ELMA), useful to assess dispersion probabilities, despite the lack of knowledge of the total number of ovipositions in the zone. We propose to evaluate the activity as minus the logarithm of the fraction of negative ovitraps at different distances from buildings. We also estimate the average number of eggs laid per oviposition using a regression between the ELMA and the number of eggs found. Three zones with different oviposition activity were determined: a corridor surrounding the urbanized area, a second region between 10m and 25m and the third region extending from 30m to 45m from the urbanization. The landscape (plant cover) and the human activity in the area appear to have an influence in the dispersal of _Aedes aegypti_
Translational neuroscience requires better design and analysis of preclinical studies
Full text linkAnimal models are often used to obtain a better understanding of psychiatric, neurodegenerative, and neurodevelopmental disorders. Despite many years of research, these models have not led to many novel therapies or treatments. Translating results between species will always be difficult, and it is argued that inappropriate statistical analyses, failure to identify the experimental unit, lack of random assignment to treatment conditions, and unblinded assessment of outcomes contribute to the low rate of translating preclinical in vivo studies into successful therapies. It is known that these shortcomings can generate biased estimates, too many false positives and false negatives, and unreproducible results. These issues have been raised repeatedly, but have largely gone unheeded by scientists. Two recommendations are made to improve the situation
Structural Analysis of Outer Membrane Beta-stranded Porins using Temperature Factor
Full text linkComputational and statistical analysis has formed a large component of the biophysical efforts put forth to understand protein structure and function, due to the diversity and complexity of their structure. Outer membrane proteins form a diverse and complex set of proteins. Of these, porins which allow passage of molecules across the membrane interface have been analyzed here from a biophysical and structural perspective. The objective of this study is to analyze the structural organization of porins using atomic temperature factor as a parameter. Generally atomic temperature factors of molecules from crystal structures indicate the degree of mobility or disorder seen in the crystal structure. As good crystal structures have fewer possibilities of errors so there is less chance that errors are playing roles in temperature factors. Structures of six porins (four 16 stranded beta barrel porins and two 8 stranded beta barrel porins) were taken from the PDB for the analysis based on resolution and R-factor. Programs and scripts were written for extracting the temperature factors for the beta strands, loops and turns so that the analysis could be done for different atom-types and residue-types. The residue distribution and mobility distribution was found to be characteristic of each of the porins. The mobility and residue distribution amongst the secondary structural elements were found to follow the level of homology at the sequence and structural level. The loops that had defined functional roles in structural terms were found to have lower temperature factors than the other loops. The turn regions that are thought to face the periplasmic region in the cell, showed higher temperature factors. For both the 16 stranded and the 8 stranded barrels it was found one part of the barrel (the lower wall or ‘inner’ wall comprising the trimer interface in the case of the 16 stranded barrels) was more rigid and the other half of the barrel (the higher or ‘outer’ wall) showed more mobility as seen from the temperature factors. This seems to be an intrinsic structural component of the beta barrels
FAIRE-seq data analysis of Chlamydomonas reinhardtii under carbon deprivation
Full text linkFor the genome-wide identification of nucleosome depleted regions under carbon deprivation, we analyze an available set of data from an assay of formaldehyde-assisted isolation of regulatory elements followed by sequencing (FAIRE-seq). Mapping to the sequenced nuclear genome of C.reinhardtii, followed by the identification of the enrichment-sequenced fragments was performed. We examined the location of these fragments relative to annotated genes. The related genes were associated to the corresponding Gene-Ontology (GO), for an evaluation of over-representate GO categories. Some genes, link with functions or locations, that have been previous described, indicating the success of the method finding carbon-metabolism related fragments
Category of Metabolic-Replication Systems in Biology and Medicine
Full text linkMetabolic-repair models, or (M,R)-systems were introduced in Relational Biology by Robert Rosen. Subsequently, Rosen represented such (M,R)-systems (or simply MRs)in terms of categories of sets, deliberately selected without any structure other than the discrete topology of sets. Theoreticians of life's origins postulated that Life on Earth has begun with the simplest possible organism, called the primordial. Mathematicians interested in biology attempted to answer this important question of the minimal living organism by defining the functional relations that would have made life possible in such a minimal system- a grandad and grandma of all living organisms on Earth
Mining the Largest Quasi-clique in Human Protein Interactome
Full text linkA clique is a complete subgraph of a graph. Often, a clique is interpreted as a dense module of vertices within a graph. However, in many real-world situations, the classical problem of finding a clique is required to be relaxed. This motivates the problem of finding quasicliques that are almost complete subgraphs of a graph. In sparse and very large scale-free networks, the problem of finding the largest quasi-clique becomes hard to manage with the existing approaches. Here, we propose a heuristic algorithm in this paper for locating the largest quasi-clique from the human protein-protein interaction networks. The results show promise in computational biology research by the exploration of significant protein modules