TABLE 3.

Recombinational DNA repair, cell viability, and homologous recombination in recB1067 recD mutants lacking activities of major single-strand DNA exonucleases

		Relative cellular viability	Relative fractional survival		λ zygotic induction in Hfr cross	Relative recombination frequency
Strain	Description		UV (20 J m−2)	γ (150 Gy)		Pro+ transconjugants	Pro+ transductants
DE1080	RecB*a RecD−	1.0b	1.0	1.0	1.0	1.0	1.0
DE1081	RecB* RecD− ExoI−	0.72	0.67	0.44	0.87	0.12	0.55
DE1088c	RecB* RecD− RecJ−	0.53	0.000008	0.011	0.74	0.015	0.50
DE1089	RecB* RecD− RecJ− ExoI−	0.02	ND	0.00005	0.63	0.0011	0.008
DE1090	RecB* RecD− RecJ− ExoVII−	0.012	ND	0.00006	0.59	0.0007	<0.0005

ND, not determined.

^aRecB* designates a nuclease-deficient recB1067 mutation.

^bCellular viability of 1.0 corresponds to 1.3 × 10⁸ recB1067 recD colony-forming units ml⁻¹ at an OD₆₀₀ of 0.3. UV and γ-survival of 1.0 correspond to 9.5 and 63 survivors/100 irradiated recB1067 recD cells, respectively. Frequency 1.0 for λ zygotic induction corresponds to 41 infective centers/100 IRB100 donors. Recombination frequency of 1.0 corresponds to 10.5 Pro⁺ transconjugants/100 Hfr3000 donor cells and 9.5 × 10⁻⁵ Pro⁺ transductants per P1 plaque-forming unit. Recombination efficiency is corrected for the viability of the recipients. All values are averages of at least three independent experiments except for zygotic induction in Hfr crosses, which are averages of two determinations.

^cIvančić-Baće et al. (2005) reported a cellular viability of 0.75, a UV fractional survival of 0.0003, a γ fractional survival of ∼0.001, and a relative conjugal recombination of 0.013.