FIG. 2.

Suppression of a UGA nonsense mutation caused by the in vivo expression of an RNA fragment complementary to the E. coli 23S rRNA sequence comprising nucleotides 735 to 766. E. coli cells, carrying pCAT101 plasmid containing the cat gene with a nonsense UGA mutation, were transformed with either the pPOT1 vector, pA750, which encodes the suppressor RNA fragment, or a control plasmid, pNC160, which contained a 160-bp DNA fragment corresponding to nucleotides 377 to 537 of 23S rRNA inserted into pPOT1. After single-colony isolations, the cells were streaked on LB agar medium containing ampicillin (Amp) and tetracycline (Tet), with or without IPTG and chloramphenicol (Cam), as shown.