TABLE 1.

Deletion mutants as recipients in ME

γ-Ray dose (kilorads)	Avg survival	Parental strain irradiateda			Relative efficiency of deletion mutant	Parental strain irradiateda			Relative efficiency of deletion mutant
		JDS10	MR311	Neither		JDS21	MR103	Neither
100	6.8 × 10−4	0.77 ± 0.25b (8)	4.33 ± 2.46 (10)	3.94 ± 0.66 (2)	0.18	<0.007 (8)	9.80 ± 4.22 (6)	2.96 ± 0.67 (4)	<0.001
150	5.6 × 10−5	1.34 ± 0.97 (8)	4.51 ± 1.31 (8)	2.99 ± 1.05 (8)	0.30	0.007 (8)	12.2 ± 2.6 (8)	0.71 ± 0.45 (4)	0.001
200	1.6 × 10−4	0.81 ± 0.41 (8)	2.58 ± 2.64 (8)	10.1 ± 3.2 (4)	0.31	0.22 ± 0.22 (8)	70.1 ± 64.0 (8)	4.64 ± 1.94 (4)	0.003

^aValues are mean recombinant frequencies (numbers of Pyr⁺ colonies per 10⁶ CFU) ± standard deviations. Strains JDS10 and JDS21 are pyrE point mutants (10); strains MR103 and MR311 are pyrE deletion mutants (11).

^bNumbers in parentheses are numbers of replicates.