DNA repair and recombination

Investigations using filamentous fungi have made major contributions to the understanding of the core biological processes of DNA repair and recombination, as certain model species provide particularly favorable opportunities for insight. The Ascomycete fungi, including the filamentous fungus Neurospora crassa, conveniently provide a full set of the products of a single meiosis packaged in spores inside a single ascus. The study of DNA repair began with the discovery of photoreactivation and UV-sensitive mutants in bacteria, followed by isolation and characterization of mutants with sensitivity to UV, IR, and chemical mutagens in both Escherichia coli and the yeast S. cerevisiae. The segregation patterns of parental DNA in recombinant chromosomes from yeasts and filamentous fungi as considered stimulated Whitehouse and Holliday to formulate models of meiotic recombination, and aspects of both models remain valid to this day. Research into DNA repair and recombination can now proceed apace by deletion of each annotated gene with a predicted role in these processes, enabling to move beyond understanding individual repair systems to an understanding of more complex networks. Epigenetic control of DNA metabolism undoubtedly plays a part in DNA repair and recombination. The isolation of mutants sensitive to mutagens remains as an indispensable tool if a comprehensive understanding of DNA repair and recombination is developed. The filamentous fungi have greater genetic complexity than yeast and are more similar to complex organisms such as mammals. The filamentous fungi will continue to provide efficient model systems for such investigation.