replication was performed by extracts of hela cells in the presence of simian virus 40 ( sv40 ) large tumor antigen by using a double-stranded phage m13mp2 dna template containing the sv40 origin of replication and either of two different target sequences for scoring mutations in the lacz alpha-complementation gene , which encodes the alpha region ( specifying the amino-terminal portion ) of beta-galactosidase .
C0598312
replication
C0012854
double-stranded