23.3 Group I introns form a characteristic secondary structure ntron in serted in co don 10 Figure 23.5 Placing the Promoter Tetrahymena intron within the AUG B-galactosida galactosidase codon co dons Intron codons b-galactoSidase coding sequence creates an assay for self-splicing in E coli. Synthesis ofb Transcription galactosidase can be tested by Splicing adding a compound that is turned blue by the enzyme. The Translation sequence is carried by a B-gala ctosidase bacteriophage, so the presence of blue plaques indicates successful splicing Blue plaques generate d by staining for阝 galacto sidase 消当Figure 23.5 Placing the Tetrahymena intron within the b-galactosidase coding sequence creates an assay for self-splicing in E. coli. Synthesis of b￾galactosidase can be tested by adding a compound that is turned blue by the enzyme. The sequence is carried by a bacteriophage, so the presence of blue plaques indicates successful splicing. 23.3 Group I introns form a characteristic secondary structure