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  • slny
    Member
    • Mar 2011
    • 54

    trim 3' adapter sequence for mRNA-Seq?

    Hi,

    Should I trim 3' adapter sequence for mRNA-Seq? Why?

    Thanks,
    Slny
  • shurjo
    Senior Member
    • Jan 2009
    • 132

    #2
    Not sure what you mean by 3' adapter here as the adapter for most mRNA-Seq protocols is the same at both ends of the ds cDNA.

    Comment

    • slny
      Member
      • Mar 2011
      • 54

      #3
      Actually any adapter. I just wonder whether I need to trim adapter sequences from the reads for mRNA Seq.

      Comment

      • shurjo
        Senior Member
        • Jan 2009
        • 132

        #4
        Under normal circumstances no trimming should be needed as the adapters are not part of the read (they contain the binding sites for the sequencing primers, hence the actual read starts after the adapter). Some people filter the raw data for reads arising from adapter dimers, but that issue is seperate from your question about trimming the reads.

        HTH,

        Shurjo

        Comment

        • slny
          Member
          • Mar 2011
          • 54

          #5
          Very good explanation. Thanks.

          Comment

          • steven
            Senior Member
            • Aug 2009
            • 269

            #6
            Yes, thanks Shurjo, this makes sense.
            Still, slny, you may be interested in having a look at SeqTrim.

            Comment

            • slny
              Member
              • Mar 2011
              • 54

              #7
              Thanks a lot. It's a very good paper.

              Comment

              • volks
                Member
                • Jun 2010
                • 80

                #8
                when your sequencing reads are longer than the fragments of your library (which are usually somewhat normally distributed), then you should do 3' trimming.

                i recommend cutadapt cutadapt.

                Comment

                • slny
                  Member
                  • Mar 2011
                  • 54

                  #9
                  Thanks, volks. It's a very useful tool for small non-coding RNA studies.

                  Comment

                  • slny
                    Member
                    • Mar 2011
                    • 54

                    #10
                    steven, can SeqTrim take fastq file as input files? I didn't find any input option for fastq format.

                    Comment

                    • steven
                      Senior Member
                      • Aug 2009
                      • 269

                      #11
                      Looks like quality values have to be provided separately (http://www.scbi.uma.es/bio/soft/seqt...TrimReadme.pdf). Feel free to contact the authors -I am not one of them .

                      Comment

                      • volks
                        Member
                        • Jun 2010
                        • 80

                        #12
                        Originally posted by slny View Post
                        Thanks, volks. It's a very useful tool for small non-coding RNA studies.
                        yes. but also useful for RNAseq and genomic sequencing. give it a try.

                        Comment

                        • slny
                          Member
                          • Mar 2011
                          • 54

                          #13
                          Thanks a lot for all the responses. The suggestions helped me a lot.

                          Comment

                          • steven
                            Senior Member
                            • Aug 2009
                            • 269

                            #14
                            A new one: Btrim. Check also this thread.

                            Comment

                            • slny
                              Member
                              • Mar 2011
                              • 54

                              #15
                              Thanks a lot, steven.

                              Comment

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