Figure 4.

Schematic diagram of the in vivo selection system. Competent cells are transformed with a mixture of equimolar amounts of active- and inactive-ribozyme-expression plasmids. In the absence of selection pressure (ampicillin plate), both active- and inactive-ribozyme-expressing colonies are expected to grow at the same rate. In contrast, active-ribozyme-expressing colonies are expected to grow faster on the ampicillin/TMP plate. Amp^r, ampicillin resistance.