The discovery of enzymatic photoreactivation and of photolyase produced a paradigm shift in the way investigators thought about the cellular consequences of DNA damage and about how these consequences could be avoided. The in vitro photoreactivation system, which utilized crude extracts from Saccharomyces cerevisiae as the source of photolyase, not only provided information about the mechanism ...

A key issue in the ecology of viruses in the marine environment is the rate of viral production and decay. The ultraviolet (UV) radiation in sunlight has been found to cause loss of infectivity in marine bacteriophages at rates nearly equal to all other decay mechanisms combined. There are 2 main host-mediated mechanisms that can repair UV-damaged phage DNA: photoreactivation and excision repai...

coverage of the photochemistry of nucleic acids is quite complete, and from this point of view the volumes are a success. In some ofthe chapters, the authors have succeeded in laying out clearly the principal elements of the topic, with judicious evaluation of the sometimes conflicting reports and claims in the literature. Such chapters include two on the photochemistry of DNA (by R.O. Rahn and...

Ultraviolet light-inactivated frog virus 3 is efficiently photoreactivated by chick embryo cells. A cellular enzyme is presumably responsible for this repair of viral deoxyribonucleic acid, for the phenomenon is insensitive to an inhibitor of protein synthesis and is not seen in mammalian cells that are known to lack photoreactivating enzyme. Since frog virus 3 is a cytoplasmic virus, functiona...

Caffeine potentiates the mutagenic and lethal effects of genotoxic agents. It is thought that this is due, at least in some organisms, to inhibition of DNA repair. However, direct evidence for inhibition of repair enzymes has been lacking. Using purified Escherichia coli DNA photolyase and (A)BC excinuclease, we show that the drug inhibits photoreactivation and nucleotide excision repair by two...