colony PCR of CEN plasmids

[B. Drees]

	I'm trying to use PCR from yeast colonies to identify inserts in
CEN plasmids.  I've collected a few protocols, which are all basically the
same- suspend a small amount of yeast from a colony in 5-10 ul of water,
boil for 5-10 min., then use this as a template for the PCR reaction.  It
sounds very simple but hasn't worked yet.  I have talked to people who
have used colony PCR to get things out of genomic DNA or from high copy
number plasmids, but nobody who has tried from a CEN plasmid.  I don't see
how it could be harder than genomic DNA, though.  Does anybody have any
suggestions?  Secret buffer additions?  Is the age of the colonies a
factor?  

Thanks for your help!

Becky Drees