GC skews around ATG and stop codon in three fungal species. All genes are superposed to the ATG (a) or stop codon (b), and total skew for each position calculated. GC skew at the G of the ATG is 1.0 by definition, as is GC skew at the G of the stop codon. GC skews in the coding region have been averaged over the three bases, and data has been smoothed slightly for clarity. Candida albicans skews are substantially larger than for the other species. (c) GC skew for a selected region of chromosome 3 in C. albicans, with a window size of 2000 nucleotides. Many but not all genes show a pattern of increasing GC skew in the direction of transcription.