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sequence the same nucleotide - (Dec/26/2007 )

anyone knows that how long usually the sequencing company can get correct results with the same nucleotide together in a sequenceing process? such as AAAAAAAAA...., CCCCCCC......, GGGGGG....., TTTTTTT......


In my experience it's not about the number of repeats, but it is about where the repeats are. If these repeats are 100 bases away than the primer, I have seen 10 same bases giving 10 distinct and clear peaks. Nearer regions to primer gives a long flat signal with no peaks.


You should be able to get a limitless number really, at least as much clean sequence as you would usually get. The electropherogram results are just an electrophoresis that separates expension products that differ by 1 nt each and although you get some blending of the peaks it isn't too bad generally that you can't read them. If you're missing nucleotides from your sequence results it can be due to a thing called "polymerase slip" where the polymerase accidentally slips past one nucleotide in a run of the same base. When this happens in the original PCR you will get a clean sequence showing a missing base. When it happens in the sequencing reaction you get these clear double peaks after the slip.