In Marc Jensen's article, Just Intonation and the Frequencies of DNA: the Music of Susan Alexjander, the first full paragraph of page nine, column two, should read as follows:

As coded information, DNA is based on a relatively simple system. All DNA sequences are composed of strings of four nucleotides: adenine, cytosine, guanine, and thymine (represented by the letters A, C, G, and T). These are transcribed into RNA sequences (where uracil, U, replaces T) which provide instructions to cells for the synthesis of proteins. The RNA sequences are read by a cell's ribosomes in groups of three, called codons, producing a code with sixty-four possible characters (4 x 4 x 4 permutations of the order of nucleotides). There is significant redundancy built into this system, often with three or four codons coding for the same amino acid. Altogether, the sixty-four codons code for only twenty amino acids , with three codons that act only as punctuation by telling the ribosomes that a sequence is either beginning or ending.