Computer Science Research Works
Permanent URI for this collectionhttp://hdl.handle.net/1903/1593
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Item Genome re-annotation: a wiki solution?(Springer Nature, 2007-02-01) Salzberg, Steven LThe annotation of most genomes becomes outdated over time, owing in part to our ever-improving knowledge of genomes and in part to improvements in bioinformatics software. Unfortunately, annotation is rarely if ever updated and resources to support routine reannotation are scarce. Wiki software, which would allow many scientists to edit each genome's annotation, offers one possible solution.Item Genome sequence and rapid evolution of the rice pathogen Xanthomonas oryzae pv. oryzae PXO99A(Springer Nature, 2008-05-01) Salzberg, Steven L; Sommer, Daniel D; Schatz, Michael C; Phillippy, Adam M; Rabinowicz, Pablo D; Tsuge, Seiji; Furutani, Ayako; Ochiai, Hirokazu; Delcher, Arthur L; Kelley, David; Madupu, Ramana; Puiu, Daniela; Radune, Diana; Shumway, Martin; Trapnell, Cole; Aparna, Gudlur; Jha, Gopaljee; Pandey, Alok; Patil, Prabhu B; Ishihara, Hiromichi; Meyer, Damien F; Szurek, Boris; Verdier, Valerie; Koebnik, Ralf; Dow, J Maxwell; Ryan, Robert P; Hirata, Hisae; Tsuyumu, Shinji; Lee, Sang Won; Ronald, Pamela C; Sonti, Ramesh V; Van Sluys, Marie-Anne; Leach, Jan E; White, Frank F; Bogdanove, Adam JXanthomonas oryzae pv. oryzae causes bacterial blight of rice (Oryza sativa L.), a major disease that constrains production of this staple crop in many parts of the world. We report here on the complete genome sequence of strain PXO99A and its comparison to two previously sequenced strains, KACC10331 and MAFF311018, which are highly similar to one another. The PXO99A genome is a single circular chromosome of 5,240,075 bp, considerably longer than the genomes of the other strains (4,941,439 bp and 4,940,217 bp, respectively), and it contains 5083 protein-coding genes, including 87 not found in KACC10331 or MAFF311018. PXO99A contains a greater number of virulence-associated transcription activator-like effector genes and has at least ten major chromosomal rearrangements relative to KACC10331 and MAFF311018. PXO99A contains numerous copies of diverse insertion sequence elements, members of which are associated with 7 out of 10 of the major rearrangements. A rapidly-evolving CRISPR (clustered regularly interspersed short palindromic repeats) region contains evidence of dozens of phage infections unique to the PXO99A lineage. PXO99A also contains a unique, near-perfect tandem repeat of 212 kilobases close to the replication terminus. Our results provide striking evidence of genome plasticity and rapid evolution within Xanthomonas oryzae pv. oryzae. The comparisons point to sources of genomic variation and candidates for strain-specific adaptations of this pathogen that help to explain the extraordinary diversity of Xanthomonas oryzae pv. oryzae genotypes and races that have been isolated from around the world.Item Ultrafast and memory-efficient alignment of short DNA sequences to the human genome(Springer Nature, 2009-03-04) Langmead, Ben; Trapnell, Cole; Pop, Mihai; Salzberg, Steven LBowtie is an ultrafast, memory-efficient alignment program for aligning short DNA sequence reads to large genomes. For the human genome, Burrows-Wheeler indexing allows Bowtie to align more than 25 million reads per CPU hour with a memory footprint of approximately 1.3 gigabytes. Bowtie extends previous Burrows-Wheeler techniques with a novel quality-aware backtracking algorithm that permits mismatches. Multiple processor cores can be used simultaneously to achieve even greater alignment speeds. Bowtie is open source http://bowtie.cbcb.umd.edu .Item Thousands of missed genes found in bacterial genomes and their analysis with COMBREX(Springer Nature, 2012-10-30) Wood, Derrick E; Lin, Henry; Levy-Moonshine, Ami; Swaminathan, Rajiswari; Chang, Yi-Chien; Anton, Brian P; Osmani, Lais; Steffen, Martin; Kasif, Simon; Salzberg, Steven LThe dramatic reduction in the cost of sequencing has allowed many researchers to join in the effort of sequencing and annotating prokaryotic genomes. Annotation methods vary considerably and may fail to identify some genes. Here we draw attention to a large number of likely genes missing from annotations using common tools such as Glimmer and BLAST. By analyzing 1,474 prokaryotic genome annotations in GenBank, we identify 13,602 likely missed genes that are homologs to non-hypothetical proteins, and 11,792 likely missed genes that are homologs only to hypothetical proteins, yet have supporting evidence of their protein-coding nature from COMBREX, a newly created gene function database. We also estimate the likelihood that each potential missing gene found is a genuine protein-coding gene using COMBREX. Our analysis of the causes of missed genes suggests that larger annotation centers tend to produce annotations with fewer missed genes than smaller centers, and many of the missed genes are short genes <300 bp. Over 1,000 of the likely missed genes could be associated with phenotype information available in COMBREX. 359 of these genes, found in pathogenic organisms, may be potential targets for pharmaceutical research. The newly identified genes are available on COMBREX’s website.Item TopHat2: accurate alignment of transcriptomes in the presence of insertions, deletions and gene fusions(Springer Nature, 2013-04-25) Kim, Daehwan; Pertea, Geo; Trapnell, Cole; Pimentel, Harold; Kelley, Ryan; Salzberg, Steven LTopHat is a popular spliced aligner for RNA-sequence (RNA-seq) experiments. In this paper, we describe TopHat2, which incorporates many significant enhancements to TopHat. TopHat2 can align reads of various lengths produced by the latest sequencing technologies, while allowing for variable-length indels with respect to the reference genome. In addition to de novo spliced alignment, TopHat2 can align reads across fusion breaks, which can occur after genomic translocations. TopHat2 combines the ability to identify novel splice sites with direct mapping to known transcripts, producing sensitive and accurate alignments, even for highly repetitive genomes or in the presence of pseudogenes. TopHat2 is available at http://ccb.jhu.edu/software/tophat .Item TopHat-Fusion: an algorithm for discovery of novel fusion transcripts(2011-08-11) Kim, Daehwan; Salzberg, Steven LTopHat-Fusion is an algorithm designed to discover transcripts representing fusion gene products, which result from the breakage and re-joining of two different chromosomes, or from rearrangements within a chromosome. TopHat-Fusion is an enhanced version of TopHat, an efficient program that aligns RNA-seq reads without relying on existing annotation. Because it is independent of gene annotation, TopHat-Fusion can discover fusion products deriving from known genes, unknown genes and unannotated splice variants of known genes. Using RNA-seq data from breast and prostate cancer cell lines, we detected both previously reported and novel fusions with solid supporting evidence. TopHat-Fusion is available at http://tophat-fusion.sourceforge.net/.