Summary: viously expected (18, 19). This also suggests
that, in mammalian cells, initiation zones
rather than individual origins may represent
the functional units regulating DNA replica-
tion at the locus level.
Compared with other studies on DNA fi-
bers (16, 2023), SMARD can provide qual-
itative and quantitative information about
many aspects of DNA replication [supple-
mentary table 1 (5)] and is potentially appli-
cable to the study of endogenous loci in the
References and Notes
1. J. L. Yates, in DNA Replication in Eukaryotic Cells, M. L.
DePamphilis, Ed. (Cold Spring Harbor Laboratory,
Plainview, NY, 1996), p. 751.
2. E. Kieff, in Fields Virology, B. N. Fields et al., Eds.
(Lippincott-Raven, Philadelphia, 1996), p. 2343.
3. J. L. Yates, N. Guan, J. Virol. 65, 483 (1991).
4. R. D. Little, C. L Schildkraut, Mol. Cell. Biol. 15, 2893