FIGURE 2.

H-DNA stalls DNA replication forks in mammalian cells. Replication intermediates of pCON and pMYC plasmids recovered from mammalian COS-7 cells (24 h post-transfection) were separated via 2-D gel electrophoresis and the region containing the H-DNA-forming or control sequence was probed by Southern blotting. The SV40 Ori is not included in the probed regions, thus the products resulted in a typical Y-arc. The arrow designates the bulge on the Y-shaped replication arc, indicative of the accumulation of stalled replication intermediates. The lighter signal on the left arm of the arc (indicated with a bracket) on the pMYC sample suggests fewer replication forks passing through the H-DNA-containing region reducing the full-length products. A representative image of three independent repeats is shown.