FIGURE 6.

NBD-PS flip is dependent on growth medium and culture density. Overnight cultures (BY4141 and HCY13) were diluted into YPD (A) or SDC (B) to ∼0.1 A₆₀₀ and grown for various times to the indicated A₆₀₀ values. At the various times, cultures were diluted to ∼0.1 A₆₀₀ in SDC, labeled with 10 μm NBD-PS or 5 μm NBD-PC for 1 h at 2 °C, and washed with ice-cold SC-azide three times before analysis of NBD-PS internalization by flow cytometry. Fluorescence was normalized to that of the parent strain (BY4141) at the lowest A₆₀₀ for each medium. Data presented are the mean of at least three independent experiments, and the error bars represent the S.D. between experiments.