I tried to contact you by e-mail, but it didn't work. My suggestion is
that you should avoid blotting your membrane on whatman paper. I
usually put my membrane directly in pre-hyb. solution after stripping.
Another observation we made is when we do Southern blot with the dig
non-radioactive detection system, blotting a wet membrane on whatman
paper always gives high background. I hope this will help you.
ash at biotech.lan.nrc.ca