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Southern Smiles

Dr R. Dalgleish ray at uk.ac.le
Mon Aug 3 02:42:18 EST 1992

> G. J. Boulnois in his book Gene Cloning & Analysis
> (Blackwell, Oxford, 1987) suggested the addition of a
> microliter of 10 mg/ml EtBr in each lane after sample
> loading to preclude smiling. I have this phobia really with
> EtBr so I never tried his suggestion. But if it really works
> then I suppose it supports Dalgleish's hypothesis.

Perhaps I should clarify this point. The chapter on Southern blotting in the
Boulnois book was written by me and I did suggest that it was worth adding 1
microliter of EtBr but this is done _prior_ to loading the sample onto the gel.
The idea is to saturate the DNA with EtBr and so not have to rely there being
sufficient EtBr in the gel.
Adding this amount of EtBr ususally causes a slight precipitate to from in the
tube but this causes no problems at all. Just load the total contents of the
tube onto the gel - preciptate and all.

  Dr Raymond Dalgleish,          JANET: ray at uk.ac.leicester
  Department of Genetics,  EARN/BITNET: ray%leicester.ac.uk at ukacrl
  University of Leicester,    INTERNET: ray%leicester.ac.uk at nsfnet-relay.ac.uk
  University Road,                UUCP: ray%leicester.ac.uk at ukc.uucp
  Leicester LE1 7RH,          ICBM NET: 52 37' 23" N, 01 07' 24" W
  United Kingdom.                  Tel: (+44) 0533 523425
                                   FAX: (+44) 0533 523489
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