| Summary: | 碩士 === 國立新竹教育大學 === 應用科學系碩士班 === 101 === Abstract
Candida tropicalis, a commensal and opportunisitic human fungal pathogen, is prevalent in clinical environment. In this study, a total of 169 C. tropicalis strains were collected from natural, anthropogenic, and clinical environment. First authenticated and preliminary typed by electrophoretic karyotyping with pulsed field gel electrophoresis (PFGE) and random amplified polymorphism DNA (RAPD) with the primer RSD8. At last, 65 strains were selected to stand for the C. tropicalis population, and a DNA sequence connected together by MDR1, SAPT4, XYR1 and ZWF1-α genes with a total length of 1705 bp were used to assess the phylogeography of C. tropicalis. There were 60 haplotypes generated from the 65 strains. The high nucleotide diversity (π=0.0062±0.004) and high haplotype diversity (h=0.998±0.003) indicated a large stable population with long evolutionary history. Genetic variation extent was not corresponded to the distance between two of populations. We guess it might be interfered by the high popupation expansion of C. tropicalis. Analysis of molecular variance (AMOVA) revealed significant genetic subdivision occurred within the population. The results of nested clade analysis suggest that C. tropicalis population originated from natural environment flowed to clinical environment as a pathogen. Forward analysis of Geodis suggested that the present population structure was a result of contiguous range expansion, restricted gene flow with isolation by distance, and long distance colonization. At the last, sensitiveity test shows that strains isolated from natural environment present lower MIC in fluconazole than that of strains from anthropogenic and clinical environment.
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