Yeast replication origin profile and information content. In both panels, solid vertical lines at coordinates -108 and +159 indicate the 268 nucleotide region used by Oriscan. (a) Yeast origins were aligned by ACS with no gaps. The frequency of each base in the ACS T-rich strand in a 9 nucleotide window is plotted by distance from the ACS center. The ACS is visible as the high central peak in T frequency; the nearby A-rich region is enclosed in dashed vertical lines. Solid vertical lines enclose the region used in the Oriscan algorithm. (b) Information content in bits is shown for each position of the aligned origins. The ACS appears as the high central peak. The A-rich region to the right also shows elevated information content. The red line indicates the average information content for an alignment of randomly chosen sequences. Between (a) and (b), the positions of A and B elements in ARS1  are shown for reference.