Skip to main content
. 2022 Sep 15;50(17):9909–9929. doi: 10.1093/nar/gkac746

Figure 2.

Figure 2.

UVC irradiation leads to long ssDNA stretches at the elongation point and to post-replicative gaps as analysed by TEM in annular dark field mode. (A) Usual replication fork arising from the hydrolysis of a replication bubble by enzymatic restriction. The fork does not display ssDNA regions and is symmetric as regards to the identical daughter strand lengths. (B–I) Replication intermediates observed 30 min after exposure to UVC (25 J m–2). Inlays represent enlargements of the regions framed with dotted lines (scale bar = 50 nm). Panels B, D, E and G show uncoupled replication forks with ssDNA starting from the elongation point because of DNA synthesis block on the leading strand. Panel C shows a fork with an internal ssDNA gap on one daughter strand. The gap can appear on the leading strand (D), the lagging strand (E) or both (F, G). Gaps can accumulate successively on the same daughter strand (H). Forks displaying ssDNA at and behind the elongation point can also be observed (D, E, G). Unusually long gaps are rarely observed (I, internal gap length = 545 nm). ep: elongation point; ss: ssDNA. All images are from irradiated XPV cell samples.