ISOLATION OF CRYPTOCOCCUS-NEOFORMANS CHROMOSOME-SPECIFIC PROBES USINGEXPRESSED SEQUENCE TAGS

Clinical and environmental isolates of Cryptococcus neoformans exhibit a high degree of karyotypic variability. Analysis of the molecular ba sis of karyotypic differences requires a large set of chromosome-speci fic probes. We have determined the chromosomal distribution of a set o f randomly selected C. neoformans cDNA clones and have explored the fe asibility of identifying these clones through partial DNA sequencing. Forty-four randomly selected cDNA clones were labelled and hybridized to PFGE blots of C. neoformans. Expressed sequence tags were generated by sequencing the 5'-end of each clone. Thirty-five clones hybridized to single bands on PFGE blots. At least seven chromosomes were recogn ized by these probes. Homology searches identified potential homologs of several groups of proteins not previously studied in C. neoformans. PFGE hybridization and sequencing of random cDNA clones is an efficie nt method for identifying chromosomal-specific probes in fungi that la ck extensive sets of genetic markers.