FIG. 3.

BY4741 cells were spotted at low density onto solid YPA medium. One group of cells was continuously perfused with an atmosphere of pure N₂ for 2 days and then was returned to room air to restart growth (top row). A second group of cells was similarly perfused with CO for 2 days and then returned to room air (middle row). A control group of cells was kept in room air for 4 days (bottom row). Cells that were made anoxic for 2 days halt their cell divisions but readily restart growth after return to room air.