Genome-wide patterns of origin firing. (a) The extent of replication in HU-arrested cells is depicted in red. The locations of centromeres are indicated by blue dots. (b) The Swi6(HP1)-binding region of Dfp1 from S. pombe, S. octosporus and S. japonicus. The S. pombe Swi6-binding motif is in bold. The three amino acids mutated in dfp1-3A are indicated by asterisks. Amino acids similar in two of the three species are boxed in gray. The presence of the dfp1-3A allele inHM1826 was confirmed from the genomic sequence used to generate the replication profiles. Wt, wild type.