A new type of DNA polymorphism identified in the species-specific DNA region originating from the Candida albicans mitochondrial genome.

Mitochondrial DNA of the pathogenic yeast Candida albicans contains a species-specific DNA region, designated EO3, within the duplicated region in its stem-and-loop structure, as reported in our previous paper. We have revealed that the EO3 region exhibits a DNA-size polymorphism, yielding three fragment length types: L, M, and S. This polymorphism is due to the presence (or absence) of two small nucleotide sequences of ~50 bp (designated a and b) within the EO3 region: type L possesses both a and b, type M possesses a alone, and type S possesses neither a nor b. Here we have identified a new type of EO3, which possesses b but not a, designated type M-II. Restriction fragment analyses with BglII revealed accurate discrimination of EO3 into four types: L, M-I, M-II, and S. Moreover, we show that these small nucleotide segments a and b were encompassed by the characteristic nucleotide sequence with a common inverted repeat structure. In the present report we propose a revised version of EO3 typing, suggesting epidemiological usefulness as an alternative tool for species-specific detection of C. albicans, and discuss the potentiality of EO3 for generating more variations of DNA polymorphism.