Plaque PCR mystery

"Alexander Kraev" bckraev at bckraev at wawona
Wed Mar 8 05:50:29 EST 1995

Dear netters,
We use PCR on genomic library plaques to confirm hybridisation positive
clones at all stages of plaque purification. Although the technique works,
there is a mysterious phenomenon that we encounter, which is the presence
of the expected band in all tracks, including various negative controls.
In the negative control track the band intensity is much much lower, than
in the true positive tracks and in genomic DNA track. We tried all possible
remedies, including purchase of a new pipette and using aerosol-resistant
tips. Those measures reduce the phenomenon, but do not eliminate it completely
Can anybody explain this? Had anybody a similar experience? ( It does not
look like a carryover during gel loading, we have checked that )
Any response welcome
Alexander Kraev, Ph.D.                 Internet: bckraev at
Lab. of Biochemistry III               Phone: 0041-1-632-31-47
Swiss Federal Institute of Technology  FAX:   0041-1-632-12-13
CH-8092 Zurich
"Some ideas are obscure not because they are complex, but because they 
 are excluded from our circle of comprehension" - Kozma Prutkov

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