Sequencing gel haze near bottom

Ron Kagan rkagan at
Wed Mar 30 15:12:23 EST 1994

In article <CnAIvA.ELv at> Ronald Meis,
camron at writes:
>I realize that this topic was discussed within the past year sometime
>but do to recent moving, I didn't keep up to date, my apologies.
>For some time I've been doing cycle sequencing with S35 internal
>label with either the Circumvent and/or the fmol kit, and Long
>Ranger gels. Reproduceably, I see a radioactive "haze" across all
>lanes of any gel. This haze migrates slightly slower than the BB
>dye at about 40 b. It is not a distinct band and covers the length
>of upto 10 bases. Usually I can read the sequence from underneath
>but not always. I've heard that this can happen with P32 internal
>label but have never tried such.
>Was there a consensus answer to the cause and/or cure of this on
>the net? If I remeber correctly, it was proposed to be a thermal
>breakdown product, but I didn't read if it was the label itself,
>or a labeled compound in the reaction. How frequently is this
>encountered? Again my apologies if this is a recent FAQ.
>						Ronald Meis

I, too, have encountered the same phenomenon using the delta taq
sequencing kit from USB (with 35-S) and Long Ranger gels.  I have yet to
see an explanation for this and would also appreciate any suggestions.

Ron Kagan
rkagan at

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