spotty blots

[John Nash]

In article <1994Jan20.144250.6258 at ncsu.edu>,
Charles M Griswold <grswld at unity.ncsu.edu> 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 
>hybridizations:
>
>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 nrcbsa.bio.nrc.ca)
Institute for Biological Sciences,  National Research Council of Canada,
                 Yet another Aussie-in-exile ;-)
      *** Disclaimer:  All opinions are mine, not NRC's! ***