TopHat now uses Bowtie2by default (if found in the system )although it can also fall back on Bowtie 1 (which is still required for SOLiD reads ).Bowtie 2 integration features: most of the optional SAM fields (AS ,MD ,NM ,and etc .)generated by Bowtie 2are now reported by TopHat as well (reconstructed as necessary )many of the Bowtie 2 options can now be directly given as TopHat options using --b2-. manual section.These apply to initial read mappings ,not to segment mappings -please see the corresponding
the Bowtie2 websiteTopHat 2maps reads against transcriptome (optional ),genome ,and novel /known splice sites using Bowtie 2 (or 1)in a fashion meant to increase the overall mapping sensitivity and accuracy .In the case of Bowtie 2,reads poorly mapped in the initial stages (with lower scoring alignments due to indels etc .)will be made available for re-mapping in downstream stages .Alignments obtained in all participating stages are pooled and the best alignments will be finally reported for each read .Please note that this TopHat version requires the installation of Bowtie version 2.0.0-beta5or later ;also note that Bowtie1and Bowtie2indexes are different ,so it is necessary to use the new Bowtie 2indexes with TopHat 2 (unless --bowtie1option is used or bowtie 2is not found in the system ).Since the iGenome Bowtie indexes do not include Bowtie 2indexes ,you may want to download Bowtie 2indexes from or build them using bowtie2-build. Most of the time-consuming steps in the TopHat 2pipeline are now parallelized ,reducing the total running time substantially on multi-processor systems . the separate pageIn addition to mapping across splice sites ,TopHat 2can now align reads across fusion points ,which usually occur due to genomic translocations ,read-through transcription ,or trans-splicing ;Tophat 2integrates the fusion discovery engine previously found in TopHat-Fusion (fusion mapping is optional ,please see for fusion mapping and the --fusion-...options in the manual). - Colorspace (SOLiD) reads require the older version of Bowtie, since Bowtie 2 does not provide support for this kind of reads.
- --closure-search and --butterfly-search options have been deprecated
In addition to reporting the best (or primary )alignments (the original TopHat behavior ),TopHat 2can report the secondary alignments up to 20 (the default )paired or single alignments (see --report-secondary-alignments and -g /--max-multihits )- The installation of the Boost package is now required in order to build TopHat 2 from source (see Installation).
- New options affecting TopHat's output:
- --keep-fasta-order (for those who prefer the order of reference sequences in the SAM output to match the order of the sequences in the genome fasta file)
- --
report-discordant-pair-alignments If you had some older versions of TopHat and TopHat-Fusion installed on your system ,we suggest that you remove both programs before installing the new version and make sure that your system PATH includes the new version but does not include the other ones .
2012年5月14日星期一
TopHat - Parallel mapping of transcriptomes to detect indels, gene fusions, and more
http://tophat.cbcb.umd.edu/index.html
Version 2.0.0 is a major release adding Bowtie 2 support , better parallelization and the ability to align RNA-Seq reads across potential fusion points .
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