Repair of damaged DNA in a eucaryotic cell: Tetrahymena pyriformis.

Damage induced by ultraviolet light or x-rays to the DNA of a eucaryotic organism, Tetrahymena pyriformis, is repaired by a process similar to the repair system present in bacteria. This repair process, which involves defect excision and subsequent resynthesis of the damaged section of DNA, occurs in the dark. Photoreactivation of damage induced by ultraviolet light is also indicated by a reduction in observed repair synthesis. An improved method for detecting repair synthesis is described. Repair synthesis is measured in parental DNA strands isolated from cultures that have undergone normal DNA replication after the repair process.