How To BETTER Download Blat
Amber Kisak <[email protected]> Sat, 20 Jan 2024 15:36:56 -0800 (PST)
| Newsgroups | alt.comp.linux |
|---|---|
| Message-ID | <[email protected]> |
<div>Although many use that way, blat is not the best choice when there are many gaps. Firstly, blat does not use Smith-Waterman to refine the alignment. It does not generate the best alignment and you cannot get something equivalent to CIGAR from PSL. Secondly, blat is designed for EST alignment in mind. Sometimes it produces spurious split alignment while a better alignment is present. Blat is probably the first whole-genome cDNA aligner. It is not really an alternative to blast. SSAHA2 is.</div><div></div><div></div><div></div><div></div><div></div><div>how to download blat</div><div></div><div>Download: https://t.co/UZgVB1VC2K </div><div></div><div></div><div>The strength of blast/blat/ssaha2 is that they can give an exhaustive list of local hits for long and diverged sequences. The list is very helpful to investigate problems. It also gives users more control over what to accept. However, they are slower also because of this. Most recent fast long-read aligners do not attempt to go through all the local hits.</div><div></div><div></div><div>PS: bwa/bowtie1 are not general-purpose aligners. They designed for short reads only. Bwa-sw is more tuned for general purpose, but it does not output multiple hits. Bowtie2, I think, cannot output an exhaustive list local hits as blast/blat/ssaha2 does, either. It does not work very well with chimeric alignment. No aligners so far are good for everything. Choose based on your needs.</div><div></div><div></div><div>I have some short reads aligned using BLAT, the output is in tabular psl format (including the sequences) for each alignment. Is it possible to convert the blat output to SAM/BAM format. Myself, I would think it is not because of the lack of some data fields in psl which is required for SAM format (mainly the CIGAR string), but please proove me wrong! Normally I would advise myself to use a different tool (bwa, bowtie, lastz) and align getting a SAM file, but what if that wasn't an option (say because you really want to use BLAT or you don't have the input) is there a way to do the conversion. I can possibly code that in perl and share it if someone had an idea how to do it.</div><div></div><div></div><div>"Is Blat in the "RiskWare.Agent" classification because it one of its uses could be to send spam STMP mail via a batch? Similar to a gun being good or bad depending on its use; or does blat expose me to something dangerous? If its just the intended use, then this is ok, as I use it to send email alerts on different batch job result (backup space, backups complete, etc)"</div><div></div><div></div><div></div><div></div><div></div><div></div><div>I would say that Damien_The_Unbeliever was right. I simply moved blat from the windows directory to c:/blat/blat.exe and it works fine. For completeness and excuse me for the previous blah, blah, blah, the command that was failing is</div><div></div><div></div><div>I tried Symantec tech document 256043 for trouble-shooting but with no success. I also tried tech document 243884 and still no success. I allowed smtp relay in our Exchange server from the IP address of the server sending the email but no luck. I can successfully send an email via the blat command line but not when using the NBU script. Thanks for any help.</div><div></div><div></div><div>I worked on this for a while and found that in the nbmail.cmd file if I swap the %3 and %1 variables in the blat line and tried the command, nbmail.cmd c:\test.txt "A file for Pedro" emailaddress domain.com, and it worked. I put the variables back in the original locations and saved the file.</div><div></div><div></div><div>NOTE: - To enable blat logs while sending mail , below is the command:</div><div></div><div>blat C:\testfile.txt -s test_subject -to useraccount company.com -debug -log C:\Temp\blat.log</div><div></div><div></div><div>A tile is a contiguous set of nucleotides (or amino-acids withtranslated blat). The default DNA tileSize is 11 which meansthat 11 nucleotides in a row are read and used as a key,either to store or read information.</div><div></div><div></div><div>gfServer is designed to keep the target index in memory in a server that can be queried interactively with gfClient. However doing this may require more memory. Batch jobs are usually best done with standalone blat.</div><div></div><div></div><div>Protein or translated blat works a little differently. Various default parameters differ. It has to index both the positive and negative strand of the target. It will still reverse complement the query and search again. This means it reports the "strand" as any of ++, +-, -+, --. If the first character is (-), this means the query was RC'd. If the second char is (-) it means the target's negative strand index was searched.</div><div></div><div></div><div>This does not seem generally true. Of course it may be that blatsees many new things at stepSize 5 compared to 11,but misses a few old things that it used to see.It is after all sampling every 5th position of the targetgenome instead of every 11th position. That is all.</div><div></div><div></div><div>In general, blat is good for cDna and RNA of the size you mentioned(100-500bp). However, as Jim pointed out, as the %Identity dropsover greater evolutionary distance, it's harder for BLAT to findthe exact tile hits which reduces its sensitivity. Lastz tends to dobetter for human-rodent distances or greater.</div><div></div><div></div><div>The blat is a widely used sequence alignment tool. It is especially useful for aligning long sequences and gapped mapping, which cannot be performed properly by other fast sequence mappers designed for short reads. However, the blat tool is single threaded and when used to map whole genome or whole transcriptome sequences to reference genomes this program can take days to finish, making it unsuitable for large scale sequencing projects and iterative analysis. Here, we present pblat (parallel blat), a parallelized blat algorithm with multithread and cluster computing support, which functions to rapidly fine map large scale DNA/RNA sequences against genomes.</div><div></div><div></div><div>The pblat algorithm takes advantage of modern multicore processors and significantly reduces the run time with the number of threads used. pblat utilizes almost equal amount of memory as when running blat. The results generated by pblat are identical with those generated by blat. The pblat tool is easy to install and can run on Linux and Mac OS systems. In addition, we provide a cluster version of pblat (pblat-cluster) running on computing clusters with MPI support.</div><div></div><div></div><div>pblat is open source and free available for non-commercial users. It is easy to install and easy to use. pblat and pblat-cluster would facilitate the high-throughput mapping of large scale genomic and transcript sequences to reference genomes with both high speed and high precision.</div><div></div><div></div><div>Blat [1] is a sequence alignment tool designed to map DNA, RNA and protein sequences to reference genomes. It is commonly used to locate sequences in a reference genome, find homologous sequences from genomes of closely related species, identify exon-intron boundaries from mRNA sequences and determine gene structures, and to help assemble and annotate genome and transcriptome sequences [2]. Although many fast sequence aligners, like BWA [3] and Bowtie [4], have been developed to map short sequence reads generated by high-throughput sequencing, they are not capable of mapping long reads or sequences with abundant gaps or spliced sequences from discontinues genomic regions [5]. In contrast, blat is an ideal tool for such applications with its high sensitivity and precision [6, 7].</div><div></div><div></div><div>However, with the increasing quantity of sequences generated by high throughput sequencing projects, blat cannot meet the speed requirements needed for large-scale analysis and regularly updated annotations. For example, when used to map the whole transcriptome sequences of vertebrates to a reference genome, it would take days to finish using blat. This is due to the blat algorithm being single threaded and, thus, not taking full advantage of modern multicore processors. One might use the GNU parallel [8] tool to execute multiple instances of blat in parallel using one or more computers. However, each blat process would load a copy of the whole reference genome and build and store the index of the genome into memory, which might exceed the available physical memory of conventional computers if multiple blat processes run simultaneously.</div><div></div><div></div><div>To overcome these limitations, we present pblat (parallel blat), which functions to speed up blat alignments by implementing multiple thread and cluster computing support. With pblat, all threads share the same memory copy of the whole reference genome and the index. As such, pblat utilizes almost the same amount of memory as blat. The run time is reduced with the number of threads used, and the output results of pblat are identical with that of blat. The cluster version of pblat (pblat-cluster) runs on computer clusters with MPI (Message Passing Interface) support, which is able to help reduce the run time of blat from days to minutes.</div><div></div><div></div><div>The cluster version of pblat extends the multithread version of pblat with MPI support. The master process of the pblat-cluster distributes the virtual input query file parts to all of the spawned processes in each computing node via MPI. The spawned processes running in the same computing node are automatically merged and switched to the multithread mode of pblat, sharing the same memory copy of the reference genome and index to minimize the memory requirement per computing node. After all the spawned processes in each computing node finish, the master process combines all of the output files generated by each process to form the final output file.</div><div></div><div></div><div>Performance evaluation of pblat. a timing benchmarks of blat and pblat using different thread numbers (from 2 to 64). Each time represents the mean of three independent executions performed with the same arguments and on the same machine. b Speedup of pblat with different number of threads, compared to blat</div><div></div><div></div><div>We appreciate the early users of pblat for their valuable feedback towards improving the program. Part of the analysis was performed on the Computing Platform of the Center for Life Science, Peking University.</div><div></div><div> df19127ead</div>