Estimation of chromosome number and size by pulsed-field gel electrophoresis (PFGE) in medically important Candida species.

The chromosomal DNAs of eight medically important Candida species, C. albicans, C. stellatoidea, C. tropicalis, C. parapsilosis, C. krusei, C. guilliermondii, C. kefyr and C. glabrata, were analysed by pulsed-field gel electrophoresis under various conditions. The corresponding bands in the gels were assigned by three kinds of DNA probe which hybridized to DNA of all the species: rDNA, TUB2 and PEP4. The best conditions for separating the chromosomal DNAs were investigated and the numbers and molecular sizes of the chromosome bands were determined for each species. The chromosomal DNAs of the species were separated into 5-14 bands ranging in size from 0.5 to 4.5 Mb. Based on the quantification of the chromosome band intensities using a laser fluorescent gel scanner, the chromosome numbers were estimated. The apparent average total number of chromosomes per cell was 16 for C. albicans, 16 for C. stellatoidea, 12 for C. tropicalis, 14 for C. parapsilosis, 8 for C. krusei, 8 for C. guilliermondii, 18 for C.kefyr, and 14 for C. glabrata; the total chromosomal DNA size of each species per cell was calculated at about 31 Mb, 33 Mb, 31 Mb, 26 Mb, 20 Mb, 12 Mb, 29 Mb and 14 Mb, respectively.