Third strands can contain both purine and pyrimidine residues in irregular sequences.
In situ hybridization to specific gene or other target sequences in chromosomes for the purpose of identifying and quantitating their copy number. For these purposes we employ third strands linked to magnetic beads or third strands that can be labeled with fluorescent dyes. These various applications exploit the remarkable sequence specificity of third-strand binding to target duplexes. Mutagenic mechanisms We are experimentally evaluating the possible roles of unfavored tautomers as a source of base mispairing events in base pair-dependent reactions of nucleic acid and protein synthesis. Molecular evolution We have been attempting to develop a rationale for the organization and evolution of the genetic code, and to explore the connection of that evolution to protein folding, based in part upon an analysis of the energetics of codon-anticodon interaction and of the nonrandom nature of modern mRNA codon sequences.