tokens: MsEPV genes with putative functions in prevention and repair of DNA damage include a complete base excision repair pathway ( uracil DNA glycosylase , AP endonuclease , DNA polymerase beta , and an NAD + - dependent DNA ligase ) , a photoreactivation repair pathway ( cyclobutane pyrimidine dimer photolyase ) , a LINE - type reverse transcriptase , and a mutT homologue .