Pfge Analysis Of The Pathogenic Yeast Karyotype And Taxonomic Identification And Clinical Diagnosis

Candida species and Cryptococcus neoformans are the most common human opportunistic fungi. The infection caused by the pathogenic yeasts are quickly increasing with rising numbers of the immunopromised patients. Till now, the interspecias identification and the intraspecies typing for fungal pathogens are based on the phenotypic characters of the anamorph stags, so it is difficult to obtain adequate precision, stability and reproducibility in the researches of taxology and epidemiology. Pulsed-field gel electrophoresis(PFGE) techniques which can separate large molecular size DNAs(1000-10000kb) provides a new way of studying molecular genetics and genotypic classification of medical fungi. In this study, we analysed the eletrophoretic karyotype(EK) of 187 Candida strains and 23C. neoformans strains, including standard strains and clinical isolated strains, by CHEF system. In addition, we inquired into the phylogeny relations between different Candida specias by using DNA DNA hybridization method.First, we established a set of standardized methods of karyotype analysis of pathogenic yeasts by PFGE. Suitable procedures of preparing total chromosomal DNA are selected and the best electrophoretic conditions, giving clear bands as well as saving time, are found out, it contains four groups of different electrophoretic parameters. The factors of influencing EK are analysed besides.Second, the basic data about the genoae organization of pathogenic yeasts were obtained. The chromosoaal DNAs of the Candida species were separated into 5 14 bands ranging in size from 0.5 to 2.8 Mb. The haploid number of chromosomes was 8 for C, albicans, 5 for C. tropicalis, 10 for C. pseudotropicalis, 9 for C. parapsilosis, 6 for C. guilliermondii, 4 for C.Krusei 10 for C. stellatoidea and 12 for C. glabrate. The number of chromosomes of C. neoformans was 11 for var. gattii while 10 or 12 for var.neoformans, ranging in size from 0.4 to 2.1 Mb.