FIG 3.

Genes involved in galactose metabolism and respiration are induced prior to the cells’ escape from the lag phase. The figure shows so-called kymographs of single cells during growth on galactose after 8 h of growth on glucose. We tracked microcolony growth of individual single cells expressing a specific fluorescently tagged protein (the corresponding gene name is specified in the panel). Every row represents the mean fluorescent intensity profile of the microcolony grown from a single cell. Black squares depict the moment at which each single cell starts growing on galactose. Note that the GAL1 gene as well as genes involved in respiration (NDI1, CYT1, COX6, ATP4, SDH2, QCR7, COX9, and ATP5) are induced prior to each cell’s escape from the lag phase and that a large fraction of cells (typically 40% to 60% of the population) fail to induce these genes and also fail to resume growth on galactose.