sentence: 10 µ l of each dilution were spotted onto YPAD ( 2 % glucose ) or YPAGal ( 2.5 % galactose ) plates ( always supplemented with 50 µ g / ml adenine ) , YPAD or YPAGal plates containing different concentrations of MMS ( Sigma ) , or HU ( Sigma ) , incubated at 25 ° C and scanned .