TABLE 1.

Marker rescue experiment^a

Host strain	No. of PFU observed after infection with:
	P1c1ts	P1 virs am 132
UT580 (supD)	6 × 1010	1 × 1010
MC1061 (sup0)	2 × 1010	3 × 105
MC1061/pUC19	4 × 1010	3 × 105
MC1061/pHAL255	6 × 1010	2 × 109

^aStock solutions of the phages P1c1ts and P1 vir^s am 132 were titrated on the indicated host strains. Phage plaques were counted after overnight incubation of the agar plates at 37°C. Values represent averages of six independent plating experiments.