Study on liquid-holding recovery in DEB-inactivated rad3 mutant of Saccharomyces cerevisiae

Summary

Maximal liquid-holding recovery (LHR) of the DEB-treated rad3 mutant occurs at 30° C in buffer supplemented with glucose. Addition of cycloheximide (CHX) to the buffer, the increase in cell density above 2 × 10⁷/ml as well as lowering of temperature during liquid holding (LH) below 27° C decrease considerably the cell capacity for recovery. LHR does not take place at 5° C. No measurable DNA synthesis or degradation occurs in cells held in buffer alone, while addition of 0.02% glucose results in incorporation of radioactivity into DNA both of DEB-treated and control cells. Similarly, protein synthesis was observed only in cultures held in buffer supplemented with glucose. Cells transfered to growth medium directly after treatment complete one round of DNA replication and at least one division cycle, but further DNA replication and cell division are inhibited. Cells placed in growth medium after 5 days LH show an increased rate of DNA replication and cell division. Completion of the first posttreatment round of DNA replication in growth medium abolishes ishes the cell capacity for LHR. DEB treatment results in abnormal cell division of the rad3 mutant, giving ‘colonies’ consisting of several cells, usually abnormal in shape, held together by common cell walls.