Yeast Colony hybridizations

[Roland J Saldanha]

A friend of mine is attempting to screen a Yac library by colony hybridization.
They are using a protocol developed in Maynard Olson's laboratory (Science 
244, 1348-1351).  Thus far it appears  that they get no lysis since they get no
signal using a probe directed against yeast mitochondrial DNA.  I would 
appreciate any protocols or pointers for performing colony hybridizations in 
yeast.