uses increasingly taller blocks to represent the different DNA bases. While reminiscent of Cowin et al.'s spatially distributed Stave Projection, the DNA Skyline font is easy to download and permits translation to and from the IUPAC notation by simply changing the font in most standard word processing applications. Ambigraphic notations Ambigrams (symbols that convey different meaning when viewed in a different orientation) have been designed to mirror structural symmetries found in the DNA double helix. By assigning ambigraphic characters to complementary bases (i.e. guanine: b, cytosine: q, adenine: n, and thymine: u), it is possible to complement DNA sequences by simply rotating the text 180 degrees. An ambigraphic nucleic acid notation also makes it easy to identify genetic palindromes, such as endonuclease restriction sites, as sections of text that can be rotated 180 degrees without changing the sequence. One example of an ambigraphic nucleic acid notation is AmbiScript, a rationally designed nucleic acid notations that combined many of the visual and functional features of its predecessors. Its notation also uses spatially offset characters to facilitate the visual review and analysis of genetic data. AmbiScript was also designed to indicate ambiguous nucleotide positions via compound symbols. This strategy aimed to offer a more intuitive solution to the use of ambiguity characters first proposed by the IUPAC. As with Jarvius and Landegren's DNA Skyline fonts, AmbiScript fonts can be downloaded and applied to IUPAC-encoded sequence data. Triple Helix Base Pairing Watson and Crick base pairs are indicated by a "•" or a "-" or a "." (example: A•T, or poly(rC)•2poly(rC)). Hoogsteen triple helix base pairs are indicated by a "*" or a ":" (example: C•G*G+, or T•A*T, or C•G*G, or T•A*A). See also IUPAC for amino acids DNA replication Nucleotide References DNA Notation DNA replication Nucleic acids Nucleotides