Physical characterisation of the Candida albicans genome
Candida albicans, one of the most prevalent fungal pathogens in humans, is diploid, appears to lack a natural sexual cycle and possesses a different genetic code from most other species. These features combine to make the study of its biology by traditional methods extremely difficult, particularly with respect to gene isolation and expression. A cosmid library was constructed from C. albicans genomic DNA which represents an 11-fold coverage of its genome. Assessments made of the breadth of library coverage and clonal stability gave favourable results and the library has already proved to be of use within the Candida research community. Fluorescently-labelled restriction fingerprints of the cosmid clones were used to construct a physical map consisting of 364 contigs. Screening of the library with 22 STS markers reduced the number of contigs to 353 and allowed redundancy among the fingerprinted contigs to be estimated. The fingerprinted contigs therefore represent a first generation physical map covering 86% of the C. albicans genome, which when complete will greatly facilitate further study of the organism and its pathology. The results obtained from a pilot sequencing project, involving several of the library clones are discussed and included in an evaluation of restriction fingerprinting as a general approach to physical mapping. Finally, as the Human genome Mapping Project reaches its conclusion, the transition to a post-genomic era and its relevance to future work with C. albicans are discussed.