FIG. 3.

UGA readthrough caused by the antisense and sense fragments. “GROWTH” plates are the GM plates supplemented with Ind (see Materials and Methods). On these plates, general growth is monitored. “READTHROUGH” plates are the GM plates supplemented with a low level of Trp, to detect readthrough (see Materials and Methods). Bacterial patches growing on an Ind plate were replicated to the low-Trp plates (with and without IPTG) and to Ind plates (with and without IPTG) (see Materials and Methods). The “−” column corresponds to the plates without IPTG, and the “+” column corresponds to the plates with 1 mM IPTG. The “UAG,” “UGA,” and “UAA” columns correspond to the isogenic strains with the UAG, UGA, and UAA nonsense codons, respectively, at position 115 of trpA. Rows 1, 2, and 3 correspond to the strains transformed with pPOT1, pPOT1 with the sense fragment, and pPOT1 with the antisense fragment, respectively. The “GROWTH” plates were photographed after 24 h of incubation at 37°C. The “READTHROUGH” plates were photographed after 42 h of incubation at 37°C. (A negative of the photograph was scanned [SprintScan 35; Polaroid], and the figure was generated with the help of Adobe Photoshop 3.0 [Macintosh].)