Cell cycle analysis of yeasts

Staining protocols generally designed for the flow cytometric analysis of the cell cycle in mammalian cells are frequently not satisfactory for quantification of the various cell-cycle phases in yeasts. High CVs limit the accuracy of DNA content measurement and estimates of populations in cell-cycle compartments. This unit describes a staining procedure for yeasts using the sensitive nucleic acid stain SYBR Green I, which binds to double-stranded DNA with high selectivity and which has a much higher fluorescence quantum yield upon binding than most other commonly used fluorophores. The properties of this dye combined with optimized sample processing provide high-resolution DNA analysis, with half-peak CVs around 3 to 4% and clear-cut identification of the S phase.