FIG. 3.

RNAs synthesized by genomic analogs with increasingly longer first transcriptional units. The fluorogram shows an agarose-urea gel of actinomycin D-resistant RNAs synthesized in cells transfected with the indicated VSV genomic analog and the VSV N, P, and L support plasmids. RNAs were labeled, harvested, purified, annealed with oligo(dT), and exposed to RNase H as described in Materials and Methods. Replication products, the N/L mRNA, and the I-N/L read-through transcript are indicated. The I mRNA (which varied in size) is indicated by a bracket (see text for details). Replicons were named according to the size of the inserted transcriptional unit (indicated above the lanes). To indicate the efficiency with which polymerase terminated transcription at the I gene-end sequence, the molar ratio of the I-N/L read-through transcript to the N/L mRNA was determined as described in the text. These values are shown below the lanes.