Hi Zhiqiang,

The regular expressions I shared are just filters. It strictly either finds sequences with an A at base position 10 (first expression) or without an A at base position 10 (second expression). All starting left -> right along the sequence text (or string). This may or may not be enough to do what you need. I just wanted to give this as an option in case it would, or perhaps it is a starting place if you can tune it to be appropriate. If your data contains more than just these two populations, or will not split appropriately based on this criteria, then this method will most likely not be the one you want to use.

The plus "+" sign means "one or more" of the proceeding variable, which in this case was a dot "." that matches any single character with the exception of a newline (end of line) character, generally noted by a dollar sign "$".

Regular expressions can be simple or quite tricky - a short crib is on the form help for the the tool "Filter and Sort -> Select", or you can search the web for many more comprehensive guidelines, as there is a component of artistry to creating these. Experimenting and testing to see what works is the best advice, when used.

Good luck!

Jen
Galaxy team

On 11/27/12 10:07 AM, Zhiqiang Shu wrote:
Thank you so much, Jennifer!

Your method is pretty good for filtering the sequences that have "A" at the 10th base position.But I'm sure if it have employed 10 bp complementary criterion? For the antisense, the 5' will be T (in complementary to A). Besides, my library contains other small RNAs. That's why I concern output files of sense and antisense must have 10bp complementary.

Another quick question, in you regular expression, what does "+" mean?


Thanks!

Zhiqiang

Quoting "Jennifer Jackson" <j...@bx.psu.edu>:

Hi Zhiqiang,

Under the tool group "NGS: QC and manipulation" is a tool named "Manipulate FASTQ". To filter for sequences containing an "A" at base position 10 and remove them, use the settings are shown in the attatched .png. Also listed here:

Click on "Add new Match Reads"
Match Reads by: "Sequence Content"
Sequence Match Type: "Regular Expression", using

   ^.{9}A.+

Click on "Add new Manipulate Reads"
Manipulate Reads on: "Miscellaneous Actions"
Miscellaneous Manipulation Type: "Remove Read"

This will result in the antisense reads being placed in the output, minus any antisense that happened to have an A at the 10th base position, which I am not sure is a concern or not.

To output the sense reads, or rather reads with an A at the 10 base position, change the regular expression to be:

  ^.{9}[^A].+


The logic is a bit backwards - you are filtering for what you will be removing - the opposite will be in the output.

Hopefully this helps! Peter's advice about aligning to the genome and determining strand/orientation vs known transcripts from the results is mostly likely your second best choice (and more complicated). Tools in "Interval Operation" group will be of help if you go down that path.

Best,
Jen
Galaxy team

On 11/26/12 10:47 AM, Zhiqiang Shu wrote:
Hi, Galaxy users!

I have a question on how to find out sense and antisense sequence. I've got RNA seq data in the fastq format. The sequences inside are partially complementary to each other (complementary is 10nt, while entire is about 30nt). How can I separate these sequences into two groups: sense and antisense (one thing I know is for the sense sequence the 10th nucleotide is always "A")?

Thanks a lot!

Best,
Zhiqiang

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--------------------------
Zhiqiang Shu/Deng Lab
Department of Biological Science
Florida State University
319 Stadium Dr.
Tallahassee, FL, USA, 32306-4295
z...@bio.fsu.edu



--
Jennifer Jackson
http://galaxyproject.org

___________________________________________________________
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