An action spectrum for UV-induced attachment of V79 Chinese hamster cells to a substratum

When cells growing in monolayers are exposed to ultraviolet radiation (UV) their binding to the substratum is increased in strength. An action spectrum for such UV-induced binding was determined, using the time needed for trypsin-EDTA to detach the cells as a measure of the binding strength. This action spectrum was significantly different from the action spectrum for cell inactivation, which was also determined. At the shortest wavelengths (297/302, 313 nm) lethal fluences were needed to induce measurable binding while at the longest wavelengths (365, 405 nm) completely nonlethal fluences induced strong and persistent binding. Thus, different chromophores are involved in the two processes: while DNA may be the main chromophore for cell inactivation, other and unidentified chromophores may be more important for induction of increased cell binding to the substratum.