Phenotypic switching and filamentation in Candida glabrata
Phenotypic switching and filamentation in Candida glabrata
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DOI：
10.1099/00221287-148-9-2661
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发表时间：
2002-09-01
期刊：
影响因子：
2.8
通讯作者：
Soll, DR
中科院分区：
文献类型：
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作者：
Lachke, SA;Joly, S;Soll, DR
光滑念珠菌在含CuSO 4琼脂上通过分级菌落着色可区分的以下四种表型中自发、可逆和高频率地转换：白色（Wh）、浅棕色（LB）、深棕色（DB）和极深棕色（vDB）。这些表型在金属硫蛋白基因MTII的表达水平（Wh < LB < DB小于或等于vDB）、转换频率（Wh > LB > DO > vDB）和在含荧光桃红B的琼脂上的着色（Wh > LB > DO > vDB）方面也以分级方式不同。四个分级表型之间的转换被称为“核心转换系统”。另外一种开关表型，“不规则皱纹”（IWr），已被确定，表现出高度褶皱的菌落形态。IWr的特征表明，切换到和从这个表型代表了第二个高频开关系统。显微镜分析显示，在菌落发育的前3天，Wh、LB、DO和vDB菌落中心的细胞几乎只表达芽殖酵母表型。然而，3天后，假菌丝和细胞延伸管积累，因此，到7天，这两种细胞表型的比例分别达到40-50%和10- 20%。相反，IWr菌落几乎完全由假菌丝通过前6天的菌落发育。6天后，IWr集落开始积累芽殖酵母细胞和管。光滑念珠菌形成的菌丝管长度可达6个细胞直径，但这些菌丝管并不代表传统的区室化菌丝。当管尖膨胀形成芽时，管生长结束。然后，管充当子核迁移到顶芽的走廊，最终未被间隔化且无核。在62株临床分离株中，大多数菌株发生了核心转换、假菌丝形成和管状形成，表明这些发育程序是大多数C.光滑的
Candida glabrata switches spontaneously, reversibly and at high frequency among the following four phenotypes distinguishable by graded colony colouration on CuSO4-containing agar: white (Wh), light brown (LB), dark brown (DB) and very dark brown (vDB). These phenotypes also differ in a graded fashion in the level of expression of the metallothionein gene MTII (Wh < LB < DB less than or equal to vDB), the frequency of switching (Wh > LB > DO > vDB) and colouration on phloxine B-containing agar (Wh > LB > DO > vDB). Switching among the four graded phenotypes is referred to as 'the core switching system'. An additional switch phenotype, 'irregular wrinkle' (IWr), has been identified, which exhibits a highly wrinkled colony morphology. The characteristics of IWr suggest that switching to and from this phenotype represents a second high-frequency switching system. A microscopic analysis revealed that during the first 3 days of colony development, cells in the centres of Wh, LB, DO and vDB colonies expressed almost exclusively the budding yeast phenotype. After 3 days, however, pseudohyphae and cells extending tubes accumulated, so that by 7 days the proportions of these two cellular phenotypes reached 40-50% and 10-20%, respectively. In contrast, IWr colonies were composed almost exclusively of pseudohyphae through the first 6 days of colony development. After 6 days, IWr colonies began to accumulate both budding yeast cells and tubes. The tubes formed by C glabrata reached lengths of up to six cell diameters, but the tubes did not represent traditional compartmentalized hyphae. Tube growth ended when the tube tip expanded to form a bud. Tubes then functioned as corridors for daughter nucleus migration to the apical bud, and were ultimately left uncompartmentalized and nucleus free. Core switching, pseudohypha formation and tube formation occurred in a majority of 62 tested clinical isolates, demonstrating that these developmental programmes are general characteristics of most strains of C. glabrata.