Filippova, Elena M.Monteleone, Denise C.Trunk, John G.Sutherland, Betsy M.Quake, Stephen R.Sutherland, John C.2011-02-282011-05-172011-02-282011-05-172003-02Biophysical Journal; 84:2 p. 1281-1290http://hdl.handle.net/10342/3265Fluorescence from a single DNA molecule passing through a laser beam is proportional to the size (contour length) of the molecule, and molecules of different sizes can be counted with equal efficiencies. Single-molecule fluorescence can thus determine the average length of the molecules in a sample and hence the frequency of double-strand breaks induced by various treatments. Ionizing radiation-induced frank double-strand breaks can thus be quantified by single-molecule sizing. Moreover, multiple classes of clustered damages involving damaged bases and abasic sites, alone or in combination with frank single-strand breaks, can be quantified by converting them to double-strand breaks by chemical or enzymatic treatments. For a given size range of DNA molecules, single-molecule sizing is as or more sensitive than gel electrophoresis, and requires several orders-of-magnitude less DNA to determine damage levels. Originally published Biophysical Journal, Vol. 84, No. 2, Feb 2003en-USAuthor notified of opt-out rights by Cammie Jennings.Laser fluorescence sizingDNADouble-strand breaksCluster damageArticlePMC1302704