[galaxy-dev] Alternative bowtie tools

Glen Beane Glen.Beane at jax.org
Tue Mar 29 11:02:37 EDT 2011


On Mar 29, 2011, at 10:25 AM, Assaf Gordon wrote:

> Hi Peter,
> 
> Peter Cock wrote, On 03/29/2011 05:39 AM:
>>> 2. the tools accepts FASTA, FASTQ in both Sanger and Illumina
>>> format (no more need for grooming). Illumina is the default for
>>> newly uploaded FASTQ files.
>> 
>> I think that's a bad idea - use Sanger FASTQ as the default to be
>> consistent with the rest of Galaxy, and also with CASAVA 1.8
>> Illumina machines will produce that too, see:
>> http://seqanswers.com/forums/showthread.php?t=8895
>> 
> 
> Thanks for the link - very interesting read, I wasn't aware of it.
> 
> However, for our local Galaxy server - I'm sticking with Illumina scale until I see real samples with phred-33 in the wild.
> 
> The defaults can be easily changed (in the XML file, simply assume a different scale when the extension is "fastq"),
> or don't accept "fastq" at all and force the user to change the format to either "fastqillumina" or "fastqsanger".
> 
> I'll explain my reasoning:
> We (at our lab) deal mostly with Illumina FASTQ files, with the Illumina scale.
> I'm trying to make life as easy as possible for our users.
> When they upload a FASTQ file, it is by default an Illumina FASTQ file, I want them to be able to use a workflow on it immediately.
> All of our internal tools assume Illumina scale.
> 
> The one time I've tried to make the built-in Bowtie tool available, I got complaints about "why isn't my FASTQ file appear in the input list" - 
> because it was "fastq" and not "fastqsanger" after grooming - this is a silly technical step that should not be a concern to users - so I'm taking it out of the equation here (not to mention that grooming two 14GB FASTQ files for every lane is a huge waste of space and time).

We've gotten into the habit of grooming everything (all of our files are also Illumina FASTQ files), so I'm looking forward to the change.  I definitely share the concern about the space wasted by essentially having two copies of the same data in Galaxy.  We had looked into making Illumina the default for our local instance of Galaxy, but in the end we stuck with Sanger (although we have talked about "pregrooming" files coming off the sequencer).  The wasted time was annoying, so I wrote my own groomer in C that could groom one of our FASTQ files in about 5 minutes although if you ran several (6-12) of our custom grooming jobs at the same time on the same node the run time would jump up to ~50 minutes for a 17GB fastq due to IO wait, but it was still  much faster than the built-in groomer.

--
Glen L. Beane
Senior Software Engineer
The Jackson Laboratory
(207) 288-6153







More information about the galaxy-dev mailing list