To mismatch or not to mismatch :)

[vebaev]

hi

I'n just wondering since everybody is using different options in mapping....What is most relevant thing when I'm mapping small RNAs to ref. genome - zero mismatches or one?

Isn't allowing a mismatch can place a tag align not on his real genomic location?

I want to annotate my small seqs but need an advice which option of bowtie to use?

thanks!