Table 1.

β-Galactosidase activities and gene sequences of suppressor tRNAs

β-Galactosidase activity was determined using the method of Miller (21) in the presence of 50 μg/ml ampicillin and the use of chloroform and SDS. The activity is presented as a percentage of the activity of the control tRNA_su+^Ala. The same plasmid without a tRNA insert gave 0.075% activity. tRNA genes were sequenced using the Sanger method by the Organellar Genome Megasequencing Project Laboratory of the Université de Montréal under the direction of G. Burger. Sequences were grouped depending on the predicted number of base pairs in the anticodon stem. Type 7-1 and 7-2 tRNAs differ in the number of nucleotides (1 or 2) in the Connector 1. ∗ indicates the presence of a bulged nucleotide in the anticodon stem (15). Nucleotides in the randomized positions are in bold; and those unexpected from the original design are underlined. Noncanonical base pairs are in italics. These sequence data have been submitted to the GenBank database under accession numbers AF003201–AF003233. AC refers to the aminoacceptor stem; D, to the D-stem; AN, to the anticodon stem; and T, to the T stem.