Shearing DNA to ~2Kb

[Howard T. Petrie]

In article <3gp2jj$1bk at pith.uoregon.edu>, margolin at darkwing.uoregon.edu
(Brian Margolin) wrote:

> I would like to shear a sample of genomic DNA down to about 2 Kb and 
> don't know of any shearing method that will get it down that small.  Can 
> anybody recommend a shearing method that will give me the desired 
> results?  


Sonication, as in the method for shearing of fish sperm DNA as a blocking
reagent for Southern and Northern blotting (see standard methods texts),
results in fragments which average 300-500 bp (you can check it out on a
gel).