Hi,
I've a problem with a blast alignment (blast2 -p blastn or blastall -p blastn or megablast )
When I align a fasta file with about 3M sequences ( ~ 20 nt each sequence ) with a DB, I don't have any good alignment. But if I take a little sample of the sequences in the fasta file ( ~ 100 sequences ) , I have a few very good alignment ( ID = ~100% and e-value < 1e-5 )
I don't understand how this can occur ?
Anybody knows how to solve this problem ?
Thanks,
Nicolas
I've a problem with a blast alignment (blast2 -p blastn or blastall -p blastn or megablast )
When I align a fasta file with about 3M sequences ( ~ 20 nt each sequence ) with a DB, I don't have any good alignment. But if I take a little sample of the sequences in the fasta file ( ~ 100 sequences ) , I have a few very good alignment ( ID = ~100% and e-value < 1e-5 )
I don't understand how this can occur ?
Anybody knows how to solve this problem ?
Thanks,
Nicolas
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