What is the minimum DNA concentration requried for double digestion? - (Apr/13/2010 )

i have less DNA and i like to digest the DNA using BglII and KpnI, product size is 400 and 8000kb. can any one suggest how much DNA in µg, i have to use to see the positive clones from this digest.

You need about 10 ng to see a band, so you need about 20x that much (8000/400) or 200 ng of DNA in your digestion, if you run the entire digestion. A standard digestion of 1 ug in 50 ul would be a good start, running 20 ul on a gel.