Figure 5.

Northern blot analysis. Ten micrograms of total RNA from E. coli cells, transformed with the ribozyme-DHFR expression vector shown in Fig. 2, was subjected to electophoresis in 1.8% Metaphor agarose. After transfer to a membrane filter, the RNA was allowed to hybridize with the synthetic oligonucleotide probe (40-mer), which was complementary to part of the DHFR gene. Lane 1, active ribozyme, with G⁵ at the catalytic core; lane 2, inactive ribozyme, with A⁵ at the catalytic core. The active ribozyme expression vector produced the excised short fragment (lane 1), but there was no truncated fragment in lane 2, which originated from the inactive ribozyme expression vector. Lane 1 also shows the intact primary transcript. Fragment sizes were consistent with the expected lengths, estimated from a standard curve for mobilities of RNA size markers. The numbers indicate the length of fragments in nucleotides determined by use of size markers (not shown).