Characterization of Different Sized Cells of Bakers Yeast

Commercial baker's yeast cells were fractionated into small and large sized cells by repeated centrifugation, and characterization of the small cells was carried out by comparison with the original cells. The small cell preparation consists of more than 90% of small sized age 0 cells, whose length of major axis ranged from 2.5 to 4.5μ. There was no significant difference in DNA content and nuclear appearance between the small and original cell preparations. Respiratory activities were also essentially the same, but a marked difference was observed not only in RNA content but in MAR-column chromatograms. The amount of rRNA corresponding to 28S rRNA was greatly decreased in small cells and that of unidentified peak III was increased. The large cells whose length of major axis ranged from 4.5 to 6.5μ showed excellent synchrony when placed in a synthetic medium. The situation of small cells in the cell division cycle was discussed.