Analysis of yeast chromosome polymorphisms was performed
generally as described by Bernardi et al. (2008).
Yeast cells were pregrown in YPG (1% yeast extract
(Merck), 2% peptone (Himedia), 2% glucose (Merck)), pH
5Æ6 at 28C for 48 h. PFGE was performed on a PFGE
(pulsed-field gel electrophoresis) CHEF-DRIII unit (Bio-
Rad, CA, USA). After electrophoresis, gels were stained with
1% (v ⁄ v) ethidium bromide for 1 h and rinsed twice with
MilliQ water (Millipore, JaVrey, USA) for 15 min. The gels
were visualized via UV transillumination, and images were
captured using a Polaroid camera (Concord, USA).