SENSE IN ANTISENSE

A correspondence between open reading frames in sense and antisense st rands is expected from the hypothesis that the prototypic tripler code was of general form RNY, where R is a purine base, N is any base, and Y is a pyrimidine. A deficit of stop codons in the antisense strand ( and thus long open reading frames) is predicted for organisms with hig h G + C percentages; however, two bacteria (Azotobacter vinelandii, Rh odobacter capsulatum) have larger average antisense strand open readin g frames than predicted from (G + C)%. The similar codon frequencies f ound in sense and antisense strands can be attributed to the wide dist ribution of inverted repeats (stem-loop potential) in natural DNA sequ ences.