Table 1.

Increases in sod2 amplification in S. pombe strains with temperature-sensitive mutations in the ligase and topoisomerase genes

Strain	Temperature (°C)	Hours at temperature shown	Viability (%)	Fold increase in amplification frequencya
cdc-17 (ligase)	25b	16	100	6
cdc-17 (ligase)	34c	16	10	600
top1 top2	25b	16	100	3
top1 top2	34c	16	20	200
top2	25b	16	100	1
top2	32c	7	5	3

Cells grown for the times and at the temperatures shown were pelleted, resuspended, and plated at 5 × 10⁷ cells per selection plate. The plates were incubated at the permissive temperature of 25°C for 5–7 d before scoring of LiCl-resistant colonies. 

^aCompared with wild type and corrected for viability. 

^bPermissive temperature. 

^cSemirestrictive temperature.