Salut Sebastien,

Is the plugin ready? Is it integrated in the Ray assembly or used on 
.fasta contigs after assembly is done? I noticed the files for it have 
been uploaded.

Adrian

On 3/18/2013 5:15 PM, Sébastien Boisvert wrote:
> Hi,
>
> On 18/03/13 12:20 PM, Adrian Pelin wrote:
>> Hello,
>>
>> It seems like the answer I got from the velvet mailing list for this issue 
>> is that there is no solution.
>> Is there a strategy I could use use with Ray to avoid getting the following 
>> issue?:
>>
>> My organism seems to be full of SNPs in a perfect 50/50 ratio which is
>> probably due to it being diploid. My expirience with assembling velvet
>> data is that it generates multiple contigs with very high nucleotide
>> identity between some contigs. The only diffrences are SNPs.
>>
>> I was wondering, is there any way to assemble only the haploid genome
>> for a start? I am afraid to overestimate the haploid genome size. Also,
>> velvet doesn't generate identical contigs for each piece of sequence,
>> just in some cases there are giant contigs over a few kb overlapping.
>>
>> Any strategy to avoid this or remove these from assembly? My data is
>> MiSeq fragments 300bp and hiseq mate pair jumping lib 3kb.
>>
> I happen to be working on exactly this problem in Ray today
> (I have been working on that for a few weeks now).
>
>
> See these two tickets:
>
> * https://github.com/sebhtml/ray/issues/136
>
> * https://github.com/sebhtml/ray/issues/153
>
>
> The thing is that in a de Bruijn graph (such as the one in Velvet or Ray), a 
> variation of one nucleotide
> leads to alternate branches containing k vertices.
>
>
> A typical SNP in a de Bruijn graph (in Ray Cloud Browser):
>
>        => 
> http://genome.ulaval.ca:10111/client/?map=0&section=0&region=1&location=132207&zoom=1.191270483217418
>
>
>
>   From an algorithm point of view, if you use a large k-mer length, 
> assemblers will spawn contigs for each
> allele because each branch will be "good enough".
>
> Therefore, some of these assembly seeds need to be filtered out. As far as I 
> know, all de Bruijn assemblers have
> this problem right now with large kmers.
>
>
>
> The two issues above should be fixed this week by this new plugin in Ray:
>
>      => 
> https://github.com/sebhtml/ray/tree/master/code/SpuriousSeedAnnihilator
>
> As its name suggests, SpuriousSeedAnnihilator will annilihate spurious seeds 
> which otherwise will lead
> to duplicated genetic regions.
>
> -Séb
>
>> Adrian
>>
>>
>>
>>
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