Blocking nonspecifics on Southerns-your choice

[Victor V. Levenson]

James:

A little while ago there was a post in this newsgroup about Salmon Testes
DNA (degraded) from Sigma; I cannot find the original post right now, but
I am sure that it is archived somewhere. The essense of the post - I think -
was that instead of using relatively expensive Salmon Sperm (or Testes) DNA 
which is a pain in the neck to dissolve and then you have to shear it somehow
one can use related product "Degraded" Salmon Testes DNA; it is really cheap
- ~10$ for a 100 g (or smthng like this); it dissolves readily; it is approx.
500 bp long (at least the batch that we tried is) - in other words, it SHOULD
be a good blocker... but it is not!

Now - after several HIGHLY unsuccessful attempts - I am wondering what
could have gone wrong...

BTW, I like your method of autoclaving and shearing HMW DNA - I will try it 
someday.

Cheers,

Victor (VVL2H at galen.med.virginia.edu)