Temperature-dependent froamtion and photorepair of DNA damage induced by UV-B radiation in suspension-cultured tobacco cells

摘要

Two photoproducts of DNA damage, i.e. cyclobutane pyrimidine dimers (CPDs) and 6-4 photproducts (6-4PPs), induced by UV-B radiation in suspension-cultured tobacco cells were quantiified by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies. CPDs and 6-4PPs wer induced in tobacco cells by UV-B radiation. Photorepair of CPDs was faster than that of 6-4PPs. UV-B radiation induces formation of CPDs and 6-4PPs even at 0deg C, but low temperatur significantly decreases the UV-B-induced (in contrast to UV-C-induced) formation of CPDs and 6-PPs. Low temperatue also retarded the removal of CPDs and 6-4PPs under white light, and almost no photorepair of CPDs and 6-4PPS was detected at -deg C. When purified DNA from tobacco cells grown in darkness was irradiated with UV-B, formation of CPDs and 6-4PPs took place at the same speed at different temperatues. It indicated that formation of CPDs and 6-4PPs induced by UV-B was temperature-indepenent in a non-celular system. Based on our results for suspension-cultured tobacco cells, not only the photrepair but also UV-B-induced foramtion of CPDs and 6-4PPs are temperature-dependent.