Panel A shows an illustration of the experiment design, indicating a switch from SCD medium to SCGE medium and time course measurements. Panel B is a line graph plotting mean cell volume in femtoliters (fL) against time since the nutrient switch in hours. Two data series are shown: WT (wild-type) in gray and whi5 delta bck2 delta in purple, with shaded areas representing 95 percent confidence intervals. Panel C is an inset line graph showing optical density at 600 nanometers (OD600nm) over time since the switch in hours. Panel D is another line graph plotting the coefficient of variation (CV) of cell volume against time since the nutrient switch in hours, with the same data series and confidence intervals as Panel B. Orange vertical lines divide the time course into three ten-hour windows for statistical analysis. Notable trends include an initial increase in mean cell volume and CV after the nutrient switch, with significant differences between WT and whi5 delta bck2 delta cells in specific time windows.
Increase in CV of cell volume observed after a nutrient switch is stronger in whi5Δbck2Δ than wild-type cells. (A) Illustration of the experiment design for the bulk nutrient switch experiment. Steady-state cells growing in SCD were washed and inoculated into SCGE, and a time course of OD600nm and Coulter counter measurements were performed until cells reached steady state in SCGE. For the measurements taken 48 and 72 h after the nutrient switch, appropriate dilutions were made when necessary to maintain the OD600nm of the cultures between 0.1 and 1. (B and C) Mean cell volume and OD600nm (C, inset) are plotted against time since the nutrient switch. Shaded areas show 95% confidence intervals. Data for each time point are based on at least two experiments. (D) CV of cell volume is plotted against time since the nutrient switch. Shaded areas show 95% confidence intervals. For statistical analysis in B and D, the time course was divided into three 10-h windows (orange lines) and the remaining two time points were grouped together and analyzed with a mixed ANOVA test (see Materials and methods for details) (**: P < 0.01; *: P < 0.05; ns: not significant, P ≥ 0.05).