| Summary: | 碩士 === 國立交通大學 === 生物科技系所 === 92 === Candida albicans (C. albicans) is an opportunistic pathogenic fungus and one of the most commonly isolated human pathogens. Especially in immunocompromised patients, it can lead to lethal candidiasis. It is believed that filamentous growth is involved in virulence. Researchers have developed the avirulent cph1/cph1 efg1/efg1 C. albicans, which is unable to form filaments.
In recent years, the abuse of antibiotics and the emerging of resistance to existing antifungal drugs have made the treatment of fungal infection more and more difficult. To search for a new drug with higher efficiency and less toxicity, I have screened and isolated the virulence genes of C. albicans with the technique of suppression subtractive hybridization in the hope of unveiling suitable new targets for drug development.
Two sets of suppression substrate hybridization were performed. One subtracted mutant RNA from wild type RNA (WT-Mut). The other subtracted wild-type RNA from mutant RNA (Mut-WT). Genes in the WT-Mut group are expressed only in the wild type C. albicans or expressed at a higher level in wild-type than in mutant strain. Virulence genes could be in this group. 32 islated cDNA fragments were subjected for sequence analysis. Among them, 18 were EFG1 DNA fragments. Since EFG1 gene was included in the WT-Mut group as expected, this performance of this technique is reliable. It demonstrated that this suppression subtractive hybridization can indicate not only whether certain genes are expressed or not but also the difference in the expression level.
In the remaining 14 clones, grouped into 12 different genes, some have been reported to be associated in morphology or virulence: Serine/threonine kinase is involved in filamentous growth; squalene epoxidase (CAERG1) is in the pathway of synthesis of cell membrane; hxt6 gene for galactose/glucose transporter is responsible for the metabolism of energy.
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