Genetic analysis of Candida albicans germ tude mutants

A spontaneous Candida albicans mutant incapable of forming germ tubes in serum was isolated from a doubly auxotrophic strain by successive rounds of filtration enrichment.

The above strain and three other independently derived germ tube mutants were tested for complementation of the mutant germ tube phenotypes by spheroplast fusion. The four mutants fell into three complementation groups.

The parasexual cycle was used to construct and analyze hybrids from a germ tube mutant or its derivatives, and two mapping strains. The analysis indicated that one mutant germ tube locus (gtfl) is on either chromosome 5 or 6. This analysis also revealed that two previously unmapped marker loci (MPAI and SF186) are on chromosome 2.

During this work, it was discovered that UV irradiation, which is known to induce mitotic recombination, also induces random chromosome loss in C. albicans hybrids.

The parasexual cycle was also used to construct a ura3 gtfl strain which served as a host for a C. albicans genomic library in a C. albicans/S. cerevisiae/E. coli shuttle vector. The attempt to isolate a gene which complements the gtfl mutation was unsuccessful. However, the library was shown to contain single copy nuclear genes by the isolation of PTR2.