The study of post-irradiation recovery of yeast: the 'premolecular period'.

Recovery of yeast cells after exposure to ionizing radiation was discovered in 1957. During the following decade, i.e., in the 'premolecular period' of studying this phenomenon, its basic features including dependence on cell ploidy, cellular energy exchange and radiation linear energy transfer (LET) were determined and a mathematical model of recovery was proposed. In addition, DNA double-strand breaks were shown to be the damage causing death of irradiated haploid and diploid cells. The results of these investigations led to the formulation of the concept that the ability of a cell to repair genetic damage was of universal biological importance.