TABLE 2.

IM-HR frequency and patterns in samples of different preparations^a

Sample prepn	No. of blue colonies		% IM-HR	Outcome (%) of IM-HR
	Ampr	Kanr		Sequence replacement	Sequence insertion
First round
Supernatant	482	1,470	32.8	NDb	ND
Cell pellet	396	1,288	30.7	12/19 (63)	7/19 (37)
Cell pellet, undigested DNA	56	160	35.0	13/15 (87)c	2/15 (13)
P1 cell pellet	754	1,218	61.9	26/28 (93)d	2/28 (7)

^aThe colony numbers represent average numbers in two repeated experiments.

^bND, not done.

^cP < 0.05.

^dP < 0.01 compared with first-round cell pellet.