Benzamide-inhibitable alterations in spectral properties of chromatin accompany DNA repair in UVC-exposed L5178Y cells.

We examined the response of chromatin to increasing NaCl and MgCl2 concentrations in UVC-irradiated L5178Y (LY) R and S cells, using the spectral index method (Dixon and Burkholder 1985). We have found an alteration in chromatin properties 1 h after UVC-irradiation of repair proficient LY-S cells, but no change in repair deficient LY-R cells. The change was shown as lowered spectral index, indicating that at given Na+ and Mg++ concentrations (1 or 200 mM NaCl, 0 or 0.5 mM MgCl2) chromatin from UVC-irradiated LY-S cells was more compact than that from unirradiated ones. Benzamide treatment reversed the effect of UVC-irradiation in LY-S cells and did not change the response pattern of chromatin from LY-R cells or unirradiated LY-S cells.