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Search Results: 1 - 10 of 224740 matches for " Pradeep R. Marri "
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Identification of Novel Pathogenicity Loci in Clostridium perfringens Strains That Cause Avian Necrotic Enteritis
Dion Lepp,Bryan Roxas,Valeria R. Parreira,Pradeep R. Marri,Everett L. Rosey,Joshua Gong,J. Glenn Songer,Gayatri Vedantam,John F. Prescott
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0010795
Abstract: Type A Clostridium perfringens causes poultry necrotic enteritis (NE), an enteric disease of considerable economic importance, yet can also exist as a member of the normal intestinal microbiota. A recently discovered pore-forming toxin, NetB, is associated with pathogenesis in most, but not all, NE isolates. This finding suggested that NE-causing strains may possess other virulence gene(s) not present in commensal type A isolates. We used high-throughput sequencing (HTS) technologies to generate draft genome sequences of seven unrelated C. perfringens poultry NE isolates and one isolate from a healthy bird, and identified additional novel NE-associated genes by comparison with nine publicly available reference genomes. Thirty-one open reading frames (ORFs) were unique to all NE strains and formed the basis for three highly conserved NE-associated loci that we designated NELoc-1 (42 kb), NELoc-2 (11.2 kb) and NELoc-3 (5.6 kb). The largest locus, NELoc-1, consisted of netB and 36 additional genes, including those predicted to encode two leukocidins, an internalin-like protein and a ricin-domain protein. Pulsed-field gel electrophoresis (PFGE) and Southern blotting revealed that the NE strains each carried 2 to 5 large plasmids, and that NELoc-1 and -3 were localized on distinct plasmids of sizes ~85 and ~70 kb, respectively. Sequencing of the regions flanking these loci revealed similarity to previously characterized conjugative plasmids of C. perfringens. These results provide significant insight into the pathogenetic basis of poultry NE and are the first to demonstrate that netB resides in a large, plasmid-encoded locus. Our findings strongly suggest that poultry NE is caused by several novel virulence factors, whose genes are clustered on discrete pathogenicity loci, some of which are plasmid-borne.
Genome Sequencing Reveals Widespread Virulence Gene Exchange among Human Neisseria Species
Pradeep Reddy Marri,Mary Paniscus,Nathan J. Weyand,María A. Rendón,Christine M. Calton,Diana R. Hernández,Dustin L. Higashi,Erica Sodergren,George M. Weinstock,Steven D. Rounsley,Magdalene So
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011835
Abstract: Commensal bacteria comprise a large part of the microbial world, playing important roles in human development, health and disease. However, little is known about the genomic content of commensals or how related they are to their pathogenic counterparts. The genus Neisseria, containing both commensal and pathogenic species, provides an excellent opportunity to study these issues. We undertook a comprehensive sequencing and analysis of human commensal and pathogenic Neisseria genomes. Commensals have an extensive repertoire of virulence alleles, a large fraction of which has been exchanged among Neisseria species. Commensals also have the genetic capacity to donate DNA to, and take up DNA from, other Neisseria. Our findings strongly suggest that commensal Neisseria serve as reservoirs of virulence alleles, and that they engage extensively in genetic exchange.
The Emergence and Fate of Horizontally Acquired Genes in Escherichia coli
Mark W. J. van Passel ,Pradeep Reddy Marri ,Howard Ochman
PLOS Computational Biology , 2008, DOI: 10.1371/journal.pcbi.1000059
Abstract: Bacterial species, and even strains within species, can vary greatly in their gene contents and metabolic capabilities. We examine the evolution of this diversity by assessing the distribution and ancestry of each gene in 13 sequenced isolates of Escherichia coli and Shigella. We focus on the emergence and demise of two specific classes of genes, ORFans (genes with no homologs in present databases) and HOPs (genes with distant homologs), since these genes, in contrast to most conserved ancestral sequences, are known to be a major source of the novel features in each strain. We find that the rates of gain and loss of these genes vary greatly among strains as well as through time, and that ORFans and HOPs show very different behavior with respect to their emergence and demise. Although HOPs, which mostly represent gene acquisitions from other bacteria, originate more frequently, ORFans are much more likely to persist. This difference suggests that many adaptive traits are conferred by completely novel genes that do not originate in other bacterial genomes. With respect to the demise of these acquired genes, we find that strains of Shigella lose genes, both by disruption events and by complete removal, at accelerated rates.
Identification and mapping of yield and yield related QTLs from an Indian accession of Oryza rufipogon
Pradeep Marri, Sarla N, Laxminarayana V Reddy, EA Siddiq
BMC Genetics , 2005, DOI: 10.1186/1471-2156-6-33
Abstract: Advanced backcross method was used to introgress and map new quantitative trait loci (QTLs) relating to yield and its components from an Indian accession of Oryza rufipogon. An interspecific BC2 testcross progeny (IR58025A/O. rufipogon//IR580325B///IR58025B////KMR3) was evaluated for 13 agronomic traits pertaining to yield and its components. Transgressive segregants were obtained for all the traits. Thirty nine QTLs were identified using interval mapping and composite interval mapping. In spite of it's inferiority for most of the traits studied, O. rufipogon alleles contributed positively to 74% of the QTLs. Thirty QTLs had corresponding occurrences with the QTLs reported earlier, indicating that these QTLs are stable across genetic backgrounds. Nine QTLs are novel and reported for the first time.The study confirms that the progenitor species constitute a prominent source of still unfolded variability for traits of complex inheritance like yield. With the availability of the complete genome sequence of rice and the developments in the field of genomics, it is now possible to identify the genes underlying the QTLs. The identification of the genes constituting QTLs would help us to understand the molecular mechanisms behind the action of QTLs.The modern day cultivars of rice, in spite of all their high yielding potential and other desirable features are handicapped with narrow genetic base for most of the agronomically important traits including the dwarf habit, which is the major yield enhancing trait. Recent study of high yielding Indian rice varieties for their ancestry revealed that hardly 5 to 6 accessions accounted for more than 90% of their genetic constitution, confirming that the cultivar gene pool being depended on now for improvement represent hardly 15% of the total genetic variability available in rice germplasm (E A Siddiq, personal communication). Rice is endowed with very rich genetic diversity. Wild/weedy species along with very large number of primi
Biochemical Composition and Disease Resistance in Newly Synthesized Amphidiploid and Autotetraploid Peanuts  [PDF]
Krishna Shilpa, Gururaj Sunkad, Srinivasu Kurella, Swati Marri, Kollipara Padmashree, Deepak R. Jadhav, Kanwar Lal Sahrawat, Nalini Mallikarjuna
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.42024

Genetic diversity in peanut (Arachishypogaea L.) is narrow due to its evolution and domestication processes. Amphidiploids and autotetraploids (newly synthesized tetraploids) were created to broaden its genetic base. Molecular analysis has shown that the newly synthesized tetraploids had broader genetic base; and were genetically divergent when compared to cultivated peanut. Nutritional composition relative to oil, fatty acid composition, O/L ratio, protein, iodine value and presence of plant proteinase inhibitors such as trypsin and chymotrypsin inhibitors were studied in the synthesized tetraploids. Some of the newly synthesized tetraploids had higher amounts of proteinase inhibitors. Evaluation of newly synthesized tetraploids revealed several lines resistant to late leaf spot (LLS) and peanut bud necrosis disease (PBND).

Knowledge Discovery in Learning Management System Using Piecewise Linear Regression  [PDF]
S. Mythili, R. Pradeep Kumar, P. Nagabhushan
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.711322
Abstract: Recent developments in database technology have seen a wide variety of data being stored in huge collections. The wide variety makes the analysis tasks of a generic database a strenuous task in knowledge discovery. One approach is to summarize large datasets in such a way that the resulting summary dataset is of manageable size. Histogram has received significant attention as summarization/representative object for large database. But, it suffers from computational and space complexity. In this paper, we propose an idea to transform the histogram object into a Piecewise Linear Regression (PLR) line object and suggest that PLR objects can be less computational and storage intensive while compared to those of histograms. On the other hand to carry out a cluster analysis, we propose a distance measure for computing the distance between the PLR lines. Case study is presented based on the real data of online education system LMS. This demonstrates that PLR is a powerful knowledge representative for very large database.
Computation of Topological Indices of Dutch Windmill Graph  [PDF]
M. R. Rajesh Kanna, R. Pradeep Kumar, R. Jagadeesh
Open Journal of Discrete Mathematics (OJDM) , 2016, DOI: 10.4236/ojdm.2016.62007
Abstract: In this paper, we compute Atom-bond connectivity index, Fourth atom-bond connectivity index, Sum connectivity index, Randic connectivity index, Geometric-arithmetic connectivity index and Fifth geometric-arithmetic connectivity index of Dutch windmill graph.
Fabrication of Schottky-Barrier Diodes Using a Thick Film Technique
R. Sarin,Y. R. Pradeep
Active and Passive Electronic Components , 1984, DOI: 10.1155/apec.11.173
Characterization of the 3-HKT gene in important malaria vectors in India, viz: Anopheles culicifacies and Anopheles stephensi (Diptera: Culicidae)
Vidhyanandhini, R;Kumar, N Pradeep;
Memórias do Instituto Oswaldo Cruz , 2008, DOI: 10.1590/S0074-02762008000600014
Abstract: the 3-hydroxykynurenine transaminase (3-hkt) gene plays a vital role in the development of malaria parasites by participating in the synthesis of xanthurenic acid, which is involved in the exflagellation of microgametocytes in the midgut of malaria vector species. the 3-hkt enzyme is involved in the tryptophan metabolism of anophelines. the gene had been studied in the important global malaria vector, anopheles gambiae. in this report, we have conducted a preliminary investigation to characterize this gene in the two important vector species of malaria in india, anopheles culicifacies and anopheles stephensi. the analysis of the genetic structure of this gene in these species revealed high homology with the an. gambiae gene. however, four non-synonymous mutations in an. stephensi and seven in an. culicifacies sequences were noted in the exons 1 and 2 of the gene; the implication of these mutations on enzyme structure remains to be explored.
Comparative genomic studies and in-silco strategies on Leishmania brazilensis, Leishmania infantum and Leishmania major: Conserved features, putative functions and potential drug target
Rakesh N. R.,Pradeep S.
International Journal of Applied Sciences and Biotechnology , 2013, DOI: 10.3126/ijasbt.v1i2.8077
Abstract: Leishmaniasis is a parasitic disease found largely in the tropics, which the World Health Organization has estimated infects 12 million people worldwide each year. More recently cases have been reported in Europe among intravenous drug users with HIV. At least 20 Leishmania species infect humans. New world parasite Leishmania. braziliensis is the causative agent of mucocutaneous Leishmaniasis. The old world species Leishmania. major and Leishmania. infantum, which are present in Africa, Europe and Asia, are parasites that cause cutaneous and visceral Leishmaniasis respectively. Aim of this Study is determination of major common genes and Protein identified Gene location on each of the chromosomes, and identification of a common protein drug target Promastigote surface antigen with available lead molecule acetylglucosamine (6-(acetylamino)-6-deoxyhexopyranose) and docking studies on those considered Leishmania species.
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