ELECTROPHORETIC KARYOTYPES AND GENOME SIZING OF THE PATHOGENIC FUNGUSPARACOCCIDIOIDES-BRASILIENSIS

Here we present the karyotype analysis and genome sizing of Paracoccid ioides brasiliensis, a pathogen refractory to conventional genetic ana lysis. We have established pulsed-field gel electrophoresis (PFGE) con ditions to resolve the high-molecular-weight chromosomal bands of two clinical isolates of P. brasiliensis. Both isolates showed four megaba se-sized bands, ranging from 2.0 to 10.0 Mbp. Significant differences in chromosome sizes and in the chromosomal location of genes for the g p43 antigen and chitin synthase were found. Different technical approa ches were employed to estimate the DNA content and to define the ploid y of P. brasiliensis. An estimated genome size in the range of 45.7 to 60.9 Mbp was provided by the analysis of data generated by measuring the amplitude of fluorescence intensity of DAPI (4',6-diamidino-2-phen ylindole)-stained nuclei (by confocal microscopy). The nuclear genome size estimated by confocal microscopy is twice that estimated by the a verage sum of the molecular weight of chromosome-sized DNA molecules b y PFGE, suggesting that each separated P. brasiliensis chromosomal ban d is diploid.