Dear Noa,

I also feel the same. So I think it would be better to use these three steps

remove sequencing artifacts

then trim the sequences by from the 5' end or if needed from the 3'end also
(2-5 bases, depending on your sequence quality)

finally filter the sequences by quality (I used the default parameters).
Although it removed 15% of the sequences but I feel confident with the high
quality data.

Any better suggestion will be appreciated.

CHeers,

Bomba

On Thu, Mar 1, 2012 at 10:48 AM, Noa Sher <noa.s...@gmail.com> wrote:

>  Hi
>
> I am looking at various options of quality trimming sequences for RNA Seq
> analysis
>
> I know I can chop off a certain number of bases off the 3' or 5' ends of
> the reads.
>
> Is it possible to use a sliding window to chop reads to different lengths,
> leaving everything above quality score 20 (for example) or would this be
> inadvisable as the differing lengths of reads would skew the downstream
> FPKM analysis?
>
> Thanks
>
> noa
>
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-- 
Dr. BOMBA DAM
Alexander von Humboldt Postdoctoral Research Fellow
Max-Planck-Institut für terrestrische Mikrobiologie
Karl-von-Frisch-Straße 10
D-35043 Marburg, Germany
E mail: bomba....@mpi-marburg.mpg.de
PHONE: +49 176 321 321 75 (Mobile); +49 6421 178 721 (LAB); +49 6421
2828516 (ROOM)

Assistant Professor of Microbiology
Department of Botany, Institute of Science
Visva-Bharati (A Central University)
Santiniketan, West Bengal 731235, India.
E mail: bumba_mi...@visva-bhatari.ac.in, bumba_mi...@rediffmail.com;
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