Our understanding of the process by which eukaryotes regulate initiation of
DNA replication has made remarkable advances in the past few years, thanks
in large part to the explosion of genetic and biochemical information on t
he budding yeast, Saccharomyces cerevisiae. At least three major concepts h
ave emerged: 1) The sequence of molecular events that determines when repli
cation begins and how frequently each replication site is used are conserve
d among most, if not all, eukaryotes; 2) specific replication origins are u
sed in most, if not all, eukaryotes that consist of a flexible modular anat
omy; and 3) epigenetic factors such as chromatin structure and nuclear orga
nization determine which of many potential replication origins are used at
different stages in animal development. Thus, the current state of our know
ledge suggests a simple unifying concept-all eukaryotes utilize the same ba
sic proteins and DNA sequences to initiate replication, but the metazoa can
change both the number and locations of replication origins In response to
the demands of animal development. J. Cell. Biochem. Suppls. 30/31:8-17, 1
998. Published 1998 Wiley-Liss, Inc.dagger.