  We explore the large-scale behavior of nucleotide compositional strand
asymmetries along human chromosomes. As we observe for 7 of 9 origins of
replication experimentally identified so far, the (TA+GC) skew displays rather
sharp upward jumps, with a linear decreasing profile in between two successive
jumps. We present a model of replication with well positioned replication
origins and random terminations that accounts for the observed characteristic
serrated skew profiles. We succeed in identifying 287 pairs of putative
adjacent replication origins with an origin spacing approximately 1-2 Mbp that
are likely to correspond to replication foci observed in interphase nuclei and
recognized as stable structures that persist throughout subsequent cell
generations.
