TABLE 3.

Fpg-sensitive damage in DNA from heat-killed B. subtilis spores^a

Spore typeb	Degree of heat killingc	No. of nicks/molecule of pUB110d
		With no treatment	With Fpg added
Wild type	None	0.2	0.5
Wild type	86% (1 h)	0.2	0.6
Wild type	99.98% (4 h)	0.3	0.6
α−β−	None	0.9	1.4
α−β−	98% (30 min)	1.7	2.2

^aHeated or unheated spores were decoated, DNA was isolated, and the number of nicks per pUB110 molecule with or without Fpg treatment was quantitated as described in the text. 

^bThe strains used for this experiment were PS533 (wild type) and PS578 (α⁻β⁻), which are isogenic with PS832 and PS356, respectively, but carry pUB110. 

^cSpores were heated at 80°C (PS578) or 85°C (PS533) for various times (shown in parentheses), and the degree of spore killing was determined as described in the text. 

^dAll values are averages of quadruplicate determinations except those for the non-heat-treated samples, which are averages of duplicate determinations from four different DNA samples. All values are ±25%.