Analysis of the chromosome rearrangement mechanism in the pathogenic yeast Candida albicans

白念珠菌表型的高频变异可能是致病酵母毒力因子之一，并与脉冲场凝胶电泳法的核型变异有关。这种变异是由于染色体之间的重排造成的，其中可能涉及重复序列。我们这项研究的目的是分析我们发现并鉴定的重复序列RPSS的结构和功能。此外，我们还研究了不同临床标本中新分离的念珠菌的核型变异，以探讨其在流行病学研究中应用的可能性。我们从白色念珠菌FC18的单个染色体中克隆了重复序列RPSS，并对其重复结构的多样性进行了分析，这是由于ALT序列的短周期重复所致。这一特征被发现与人类阿尔法卫星dna相似，具有t…。更多连续重复约170个bp2。经BamH1和Xho1双酶切及与RPS杂交，发现RPSS定位于白念珠菌FC18除第4染色体外的每条染色体上的有限区域，并在6.3号染色体上构建了RPSS及其边界区域的半宏观物理图谱。对分离自住院患者的分离株进行核型分析。没有特定的核型与标本的性质或患者所住的医院病房有关。大多数分离株的带型与FC18.4相似。在反复感染期间，从单个患者身上反复分离的念珠菌的核型与每个患者几乎相同。我们用脉冲场凝胶电泳法、SmaI酶切RFLP法和白念珠菌特异性探针RPS1的Southern杂交技术检测了从白血病患儿及其床边父母分离的白色念珠菌的菌株亲缘关系。结果表明，传播可能发生在患者和他(她)的父母之间。较少

High frequency variation of phenotypes in the pathogenic yeast Candida albicans is presumed to be one of the virulence factors, and is related to the variation of the electrophoretic karyotypes by the pulsed field gel electrophoresis. The variation occurs due to rearrangements between the chromosomes, in which the repetitive sequences might be involved. Our aim of this study was to analyze the structure and function of the repeating sequences, RPSs, which we discoverd and characterized. In addition we studied the variation of electrophoretic karyotypes of freshly isolated Candida strains from various clinical specimens to examine possiblity of their application to epidemiological study.1. We cloned and sequenced the repeated sequences, RPSs, from individual chromosomes of C.albicans FC18, and characterized the diversity of their repeating structures which were due to short periodic repetitions of alt sequences. This feature was found to be similar to humanalpha-satellite DNA with its t … More andem repeat of ca.170 bp.2. RPSs were found to be localized in a limited region on every chromosomes except chromosome 4 of C.albicans FC18 as detemined by digestion with BamH1 and Xho1 and by hybridization with RPS.We constructed semi-macro physical map of the RPSs and their boundary regions on chromosome 6.3. The electrophoretic karyotypes of isolates taken from hospitalized patients were analyzed. No specific karyotypes was correlated with either the nature of the specimen or the hospital ward to which the patient had been admitted. Most isolates gave a pattern similar to that of FC18.4. The electrophoretic karyotypes of Candida strains isolated repeatedly from single patients during recurrent episodes of infections were almost identical with respect to each patient.5. We examined the strain relatedness of Candida albicans isolated from children with leukemia and their bedside parents using pulsed field gel electrophoresis, RFLP by SmaI digestion and the Southern hybridization of RFLPs by C.albicans-specific probe, RPS1. The results suggested that the transmission might have occurred between the patient and his (her) parents. Less