Bill Melchior, NCTR/FDA wmelchior at NTBTOX.NCTR.FDA.GOV
Tue May 12 07:55:17 EST 1992

In responding to the following comment about a sequencing problem:

>>Our gels occasionally show all four 
>>nucleotides lighting up in each lane across a run.

Bruce Roe says:

>Sequenase is famous for "template associate compression" you describe.

I assume that Bruce's comment is about the "strong pause" phenomenon, in which
secondary structure causes the polymerase to pause, leading to bands in all
four lanes at one or a few short regions; he suggests several ways to over-
come this problem.

I had interpreted the original query as something different: bands in all
lanes in all positions, so the entire film looks like the photo of a picket
fence.  This latter problem has to do with template purity.

The appropriate solution depends on what the problem really is.
The opinions stated are mine, not those of NCTR or its sponsoring organizations.

Bill Melchior                                ||   "You have lawyers the way
National Center for Toxicological Research   ||    other people have mice."
Jefferson, AR  72079                         ||
(501) 543-7206                               ||   -Kenneth Duncan, English
                                             ||    Health & Safety Executive,
wmelchior at                   ||    to US regulators

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