Fig. 2.

C-rich ssDNAs from lagging daughter strands contain both linear and circular DNA (A) Nuclease assay using exonuclease I, lambda, and V treatment on soluble DNA fraction of U2OS. One hundred eighty nanogram of soluble fraction DNA was used per lane. (B) Quantification of the nuclease assay in (A); Relative amount of C-rich ssDNA (mean ± SD; unpaired t test). (C) Illustration of the Iododeoxyuridine (IdU) incorporation and CsCl separation. The Right table displays the expected density of unreplicated DNA and IdU-incorporated lagging strands, leading strands, and nascent C-rich single-stranded DNAs. (D) Slot blot analysis of telomeres in CsCl separation fractions. One hundred fifty microgram of genomic DNA from U2OS cells was used. (E) Density and relative telomere intensities of fractions in (D). (F) 4SET assay of the fractions depicted in (D) and (E).