[mira_talk] Re: 454 and solexa pared-end
- From: hpaces <hpaces@xxxxxxxxx>
- To: mira_talk@xxxxxxxxxxxxx
- Date: Wed, 15 Apr 2009 08:40:58 +0200
Hi Bastien,
hehe, you had busy night to answer all our emails. Thanks 8)
Bastien Chevreux wrote:
> There no such guide :-) I refused until now to think of de-novo assembly with
> 36mers. Now that SOlexa has 76mers (and with a pretty good quality), I have
> started work on de-novo hybrid 454/Solexa assembly.
>
I am really looking forward to.
We are using 36mers for mate-pairs paired-end on solexa, because 76 mers
seems to have too much chimeras in them. For 36mers there is ~1%
chimeras, for 76mers >10%. From the technology point of view
(preparation of the library) I think you cannot get rid of them. 76mers
are ok for normal paired-end, but then your insert size is ~500, which
would be almost covered by one 454 read and IMHO this kind of paired-end
do not really improve assembly. For longer insert sizes on solexa people
are now stuck with 36mers - until solexa starts to use linker to find
exact position of ligation (like 454) or some other trick.
> Current best alternative so far: assemble the 454 sequences and use these as
> backbone for a Solexa mapping. Or use Velvet or any other Solexa de-novo
> program, fragment that data and mix with the 454 reads. Then use that for a
> mapping with the Solexa data.
>
> All of these approaches already work quite well. Not ideal, but doable.
>
I tried this, but it looks mira do not use paired-end info from solexa
reads to join appropriate contigs or to split wrong assemblies (which is
probably not possible in mapping). Am I right or I set it up wrong?
Also when using output from velvet, I loose that valuable paired-end
information.
Well, mira is best, I'll wait for new version. I have real-life data and
I will do beta-testing, if needed.
Thanks,
Jan
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