Reversal of the changes in DNA and chromosome structure which follow the inhibition of UV-induced repair in human cells

The inhibition of UV-induced repair DNA synthesis by hydroxyurea, deoxyadenosine or 1-β-D-arabinofuranosylcytosine is reflected in changes in chromosome appearance (decondensation seen in fixed preparations) and DNA structure (accumulation of unwinding points or single-strand gaps). These changes are rapidly reversed if the inhibition is neutralised by addition of precursors of DNA synthesis. The $\text{in vivo}$ organisation of chromosomes apparently survives the prolonged presence of substantial DNA breakage.