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  • sequencer_lee
    Junior Member
    • May 2008
    • 9

    #1

    Anyone seen an intensity plot like this?

    This is the PhiX lane--anyone seen bases diverge like this? What would cause this? Thanks

  • ECO
    --Site Admin--
    • Oct 2007
    • 1360

    #2
    Image comin' up blank for me!

    Comment

    • sequencer_lee
      Junior Member
      • May 2008
      • 9

      #3
      That's weird--I can see it.
      You could try clicking this link:
      img144.imageshack.us/img144/734/picture3wz7.png

      Comment

      • ECO
        --Site Admin--
        • Oct 2007
        • 1360

        #4
        Hrm, can see it now.

        I haven't looked at enough intensity plots to know.

        Comment

        • cgb
          Member
          • May 2008
          • 50

          #5
          looking in isolation -

          looks like you have a very weak chip - or a weakish chip with very high signal loss and you are out of signal by the middle of the read. what is the signal loss rate ?

          Comment

          • bioinfosm
            Senior Member
            • Jan 2008
            • 483

            #6
            Did you use all defaults for the solexa pipeline? Chastity filter of 0.6?
            Mid way through the read, there comes a point where A and C, G and T become quite dependent on each other, and the pipeline uses all kinds of matrices to call one from the other.

            What is the dna sample, if I may ask!
            --
            bioinfosm

            Comment

            • new300
              Member
              • Mar 2008
              • 50

              #7
              Did you use all defaults for the solexa pipeline? Chastity filter of 0.6?
              Mid way through the read, there comes a point where A and C, G and T become quite dependent on each other, and the pipeline uses all kinds of matrices to call one from the other.

              What is the dna sample, if I may ask!

              Huh?

              The only corrections the Solexa pipeline performs are crosstalk and phasing corrections. Crosstalk is determined from the first cycle only, and the same matrix is applied to all cycles. The Phasing correction is cycle dependent but is unlikely to cause anything like this.

              Would need to see more plots (all intensities/called intensities) in order to figure out what's happening in this case.

              Comment

              • sequencer_lee
                Junior Member
                • May 2008
                • 9

                #8
                Thanks, guys--the plot was for the PhiX control. Tech support thinks we had a focussing issue. Anyway, it didn't happen on the next run.

                Comment

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