Formation of a new population of DNA replication intermediates in X-irradiated human melanoma cells.

DNA synthesis was investigated in human melanoma cells irradiated with X-rays. The cells were lysed in dilute alkali which results in the release from the parental DNA of replication intermediates; these are then analyzed by agarose gel electrophoresis. In cells irradiated with 10 Gy we can detect the formation of a new heterogeneous population of DNA replication intermediates with a size greater than 10 kb. We can also demonstrate the presence of other DNA replication intermediates which were earlier described in control cells. The results imply that in melanoma cells changes may occur in th replication in order to comply with alterations in the DNA induced by X-rays.