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Old 10-27-2010, 07:49 PM   #1
krobison
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Default BFAST indexing for 50+36 SOLiD paired end?

The BFAST manual gives one set of recommended seeds for reads <40 bp and one for greater than 40 bp

What if I have a SOLiD paired end dataset with one read above that threshold (50) and one below (35)? Suggestions?
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Old 10-27-2010, 10:09 PM   #2
Chipper
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Tried bfast+bwa (latest release)?
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Old 10-28-2010, 05:30 AM   #3
drio
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Quote:
Originally Posted by krobison View Post
The BFAST manual gives one set of recommended seeds for reads <40 bp and one for greater than 40 bp

What if I have a SOLiD paired end dataset with one read above that threshold (50) and one below (35)? Suggestions?
Those keys will work fine for 35bp reads. You'll get a small decrease in the total number of alignments compared to 50bp reads. You could also explore
bfast+bwa branch and use bwaaln for the second tag.
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Old 10-28-2010, 10:48 AM   #4
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Thanks -- I've just started trying to figure out bfast+bwa & the new options it gives
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Old 11-02-2010, 03:58 AM   #5
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In this thread I posted my experience with this kind of PE reads:
http://seqanswers.com/forums/showthread.php?t=7100
BFAST postprocess seems to rescue a lot of the 35 bp ends that did not get a match with bwaaln. (The bwaaln step might profit from allowing more mismatches instead of the default, but as I found with BWA on SOliD data that slows it down considerably.)
Note that the git version of postprocess is an improvement over the one in the bfast+bwa package but still has a bug.
Maybe it's because of the rather low quality of my data that the localalign step is now the most time-consuming part: 50 Mio read pairs on 8 CPUs usually take 70 h, some almost double the time. Multithreading is not that efficient that I'd want to use 16 threads (other people also want to use the cluster). I'm currently experimenting with the parameters.
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Old 11-02-2010, 06:04 AM   #6
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@epigen: Take a look to this.
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Old 11-02-2010, 06:25 AM   #7
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Thanks for the link, but I tried that before and it is not helping: far too many reads do not get paired. This patch is what I mean with the git version of postprocess, which does help (in terms of speedup and pairing, unfortunately with a bug):
http://sourceforge.net/mailarchive/m...mail.gmail.com
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