DNA repair is a subject which avoids being pigeon-holed. Researchers may call themselves radiobiologists, biochemists, cell biologists, geneticists, photobiologists, chemists . . . fortunately, there is no such term as 'DNA repairologist'. Recently, the topic has become even more interdisciplinary with an influx of molecular biologists, and recombinant DNA technology and the molecular genetic approach are the order of the day. In many areas of biology, the application of these new techniques holds great promise. But perhaps this is especially so for DNA repair, since conventional biochemistry is hampered by the fact that repair, though vital, usually goes unnoticed among more celebrated activities of the cell; it is hard to get sufficient quantities of repair enzymes for normal enzymology. Devious strategies have been adopted: interfering with repair pathways using metabolic inhibitors is one, producing mutants defective in specific steps of repair is another. Currently, the most desirable route is seen to be through DNA transfection and the cloning of repair genes. Much progress has been made in prokaryotic systems towards the reconstitution of fully functional DNA repair complexes using proteins made in vitro from cloned genes. In eukaryotes, such investigations are at a more preliminary stage; one early impression is that there is a surprising and encouraging overlap at the molecular level between prokaryotic and eukaryotic systems. In addition, prokaryotic organisms introduced into eukaryotic cells (e.g. as plasmid shuttle vectors) promise to be of great value as probes for DNA repair and mutagenesis.

An international symposium was held in Manchester in the spring of 1986 with the theme 'The Molecular Biology of DNA Repair'. This book is based on the main presentations at the symposium. The title does not imply a definitive account, but more of a prospectus for the next few years. We are aware that we have stretched the term 'molecular biology' to cover investigations whose claim to be included rests only on the fact that DNA is a biological molecule. We do not apologize for this; it is important to be conscious all the time of the relations between phenomena occurring at molecular and cellular levels (and, indeed, at the level of whole organisms). If there are no DNA repairologists there is at least a DNA Repair Information Network, which, together with the British Photobiology Society, organized the Manchester symposium. We could not have achieved such a successful meeting without the support of the following sponsors, to whom we express our sincere thanks: The Company of Biologists Limited; Cancer Research Campaign; International Agency for Research on Cancer; Beckman; Wellcome Trust; British Petroleum Company; Smith Kline and French Research; Amersham International; Gibco; Anachem; Packard; Scientific and Medical Products; Leec.

We also thank the contributors to this volume for their prompt delivery of manuscripts of uniformly high quality, which has enabled us to produce what we believe is an up-to-date review of the molecular biology of DNA repair.

Andrew Collins

Bob Johnson

John Boyle