spotty blots

John Nash nash at
Thu Jan 20 11:39:37 EST 1994

In article <1994Jan20.144250.6258 at>,
Charles M Griswold <grswld at> wrote:
>We are having trouble with small dark spots which appear on all of our blots.
>Our lab uses MSI's Magnagraph nylon and the following buffer for DNA 
>6x SSC
>7.5x Denhardt's
>0.7% SDS
>150 ug/ml extracted, freshly denatured S.sperm DNA (sheared)
>50% deionized formamide
>We wash with 0.1x SSC, 0.1% SDS 2xRT and 2x65C. Longer washing does not 
>reduce the spotting. We've tried preheating the prehyb before adding to 
>the blot but this does not help.
>Any suggestions would be appreciated.
>Mike Griswold
>N. C. State Univ. Genetics

Spotty blots tend to indicate dirty probe (not sufficiently removed
from unincorporated labelled nucleotides).  How are you cleaning up
your probe?  Are you cleaning up your probe?

John Nash                           (nash at
Institute for Biological Sciences,  National Research Council of Canada,
                 Yet another Aussie-in-exile ;-)
      *** Disclaimer:  All opinions are mine, not NRC's! ***

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