TABLE 2.

Enumeration of the transposition events after transfer of pYT645 into TM4000^a

Mutagen	Mating	Tetr coloniesb			Clnr coloniesc
		Total no. of colonies tested	Clns	Clnr	Tets	Tetr
pYT645A	1	24	19	5	3	0
	2	20			2	0
	3	24			2	0
	4	30	28	2	2	0
	5	36			4	0
pYT645B	6	103	88	15	31	4
	7	19			3	0
	8	50			9	0
	9	45	41	4	9	0
	10	23			4	3

^aEach mating filter was resuspended in 3 ml of MPBS buffer. Aliquots of 0.2 ml were added to BHIS-gentamicin-rifampin-tetracycline or BHIS-gentamicin-rifampin-clindamycin plates. 

^bColonies on one tetracycline plate from each mating were counted, and the numbers are shown. Four plates, from matings 1, 4, 6, and 9, were replica plated onto BHIS-clindamycin plates to count Cln^s and Cln^r colonies among the Tet^r colonies. 

^cThe number of colonies on one clindamycin plate from each mating is shown. Cln^r colonies were transferred to tetracycline plates individually with sterile toothpicks. There is a discrepancy between the numbers of Tet^r Cln^r colonies obtained in this way and the numbers obtained after an initial tetracycline selection. This may suggest that the structures of the cointegrates allow the loss of the tetQ gene by homologous recombination.