TABLE 2.

Substrate requirements for in vitro packaging^a

DNA substrate	No. of blue cells
	With chloroform	Without chloroform
ds RF DNA	120	300
ss RF DNA	178	NDb
PstI pAB11	15	288
SmaI pTRLacZ	20	172
MscI pTRLacZ	8	116
BamHI pTRLacZ	14	192

^aVarious DNA substrates, described in the text and Fig. 1, were packaged in vitro in the standard 30-μl reaction mixture as described in Materials and Methods. The products were heated at 55°C for 30 min and then tested for β-gal transduction either before or after treatment with chloroform. Shown is the number of blue cells produced by the product of each 30-μl reaction mixture. 

^bND, not done.