A number of molecular genetic tools and methods have recently been developed for filamentous fungi which rely on genetic recombination and integration of donor DNA into a chromosomal locus. Genetic recombination is a fundamental cellular process ubiquitous among living organisms and underlying most classical genetics techniques. However, the efficiency of more modern homology-based gene targeting techniques in filamentous fungi such as Aspergillus nidulans can be affected by many factors and often results in complex ectopic integration events. In sexually reproducing eukaryotic organisms, homologous recombination is required for pairing of homologs and ensures proper chromosome segregation. Sexual development in A. nidulans involves the development of specific sexual structures and probable gene expression patterns different from vegetative mycelia. Further, gene products required for sexual development likely include products involved in meiotic homologous recombination. For example, meiosis-specific RecA homologs have been identified in yeast (Dmcl) and other fungi, plants and animals. Interestingly, examination of sequences upstream of the uvsC transcription start site (a gene of A. nidulans homologous to dmcl from yeast) reveals a putative MIuI cell cycle box. In addition, uvsC cDNA is detectable in sexual structure-specific ESTs but not in asexual-specific ESTs. Combined, these observations indicate a strong correlation between homologous recombination and sexual development in A. nidulans. In an effort to better understand homologous recombination and possibly improve homology-based gene targeting rates in A. nidulans, we have compared the frequencies of gene targeting by circular and linear plasmid DNA constructs in various A. nidulans hyperrecombinant and DNA repair mutants.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)