DNA don't migrate...

rcowherd at mail.med.upenn.edu rcowherd at mail.med.upenn.edu
Tue Aug 27 18:36:02 EST 1996

In article <4vrmpg$3pl at oravannahka.Helsinki.FI>, jpalo at cc.Helsinki.FI
(Jukka U Palo) wrote:
> One stupid question again. Recently I started to extract DNA from shrimps (which, btw, seems to be difficult - any suggestions?). When I'm checking the DNA in agarose gels, a great portion of the DNA stays in the wells. What is the reason for this? First I thought it is due to proteins and other impurities, but the samples behave in a similar way after second phenol/chlorofom extraction, too. This happens with some of the samples, and even seems to be somewhat species-specific phenomenon. These samples still work reasonably well as PCR templates, but I'm just curious. Any similar experiences?

It seems to me to you actually have high molecular weight genomic
DNA (unsheared that is...). Perhaps I may be missing an understood
restriction digest attempt or some other manipulation which causes
suspicion that the DNA is faulty...  PCR results would seem to argue
the DNA is adequate.  

Could some of the samples have been more roughly handled than others
thereby yielding variable shearing of the DNA?  The more aggressively
manipulated samples would give smaller randomly sheared DNA fragments.

Just my $0.02 worth...

Bob Cowherd
Univ. of Penn.
(215) 662-2071

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