(A). Schematic representation of genome analogs that possess an mRNA 2 initiation signal positioned at increasing distances upstream of the mRNA1 termination signal, up to a distance of 200 nucleotides. The mRNA1 and mRNA2 transcription products are also shown schematically, all of which are predicted to terminate at the mRNA1 termination signal. (B). RNAs generated by templates M97, M122, M150 and M200 were harvested from BHK cells and analyzed by primer extension analysis using end-labeled oligonucleotide T7–14, which anneals within the 3’ end of mRNAs 1 and 2, shown schematically in panel A. Bands representing mRNA2-templated extension products from five separate experiments were quantified and their abundance shown as a percentage of mRNA1 levels from the same template. Percent abundance relative to template M97 was also determined.