DNA "refusing" to be run in agarose gel

Adam Greene agreene at bih.harvard.edu
Fri Aug 25 07:44:09 EST 1995

I think there are 2 possible causes-- one is residual ethanol in the
sample (if it was precipitated and the pellet not dried). The other is if
there is a huge amount of genomic DNA in the sample that is not digested. 
Could either be the case?
 Adam Greene

On Fri, 25 Aug 1995, Ketil Thorstensen wrote:

> Honored contributors to the molbio.methds-reagnts!
> I have a peculiar problem with persuading some of my DNA samples to run in 
> agarose gels.
> When loading DNA samples on agarose gels I have on several occasions observed 
> a strange (to me) phenomenon: after application of a sample into a well a 
> streak of the sample may follow the pipette tip upon withdrawal. When the 
> sample in this way comes in contact with the buffer surface, the sample very 
> rapidly spreads out to cover the entire surface. During this process most of 
> the sample in the well is "sucked" out.
> There is no recognizable pattern as to what sample this may happen with. It 
> is, however, frustrating when precious samples are lost (the last one was a 
> 1.9 kb DNA probe)  :í-(
> Could anyone enlighten me as to what I am observing, and how to prevent 
> this from happening again?
> Thank you very much,
> Ketil Thorstensen, Ph.D.
> Dept. Clinical Chemistry
> University Hospital
> Trondheim, Norway

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