TRANSFER-RNA PROFILING - A NEW METHOD FOR THE IDENTIFICATION OF PATHOGENIC CANDIDA SPECIES

A new molecular taxonomic method applicable to the identification of m edically important Candida species and other yeast species has been de veloped. It is based on the electrophoretic pattern of total tRNA samp les (a 'tRNA profile') isolated from Candida species and generated usi ng high-resolution semi-denaturing urea-polyacrylamide gel electrophor esis and methylene blue staining. Species-specific tRNA profiles for t he species C. albicans, C. tropicalis, C. parapsilosis, C. guilliermon dii, C. glabrata and Pichia guillieimondii were obtained. Detailed stu dies with the major human pathogen of the Candida genus, C. albicans, demonstrated that the tRNA profile for a given species was both reprod ucible and strain-independent; seven different C. albicans strains gen erated identical tRNA profiles. Minor strain-specific heterogeneities in the tRNA profiles of C. guilliermondii and C. parapsilosis were det ected, but in neither case did they significantly alter the species-sp ecific diagnostic tRNA profile. The potential of this method in clarif ying taxonomic anomalies was demonstrated by the finding that Type I a nd Type II strains of C. stellatoidea generate very different tRNA pro files, with that of a Type II strain being identical to the C. albican s tRNA profile. This method offers a number of advantages over current electrophoretic karyotype methods for species identification, both wi thin the Candida genus and with yeast species in general.