Candida albicans strains that are homozygous at the mating type locus (MTL >a or MTLα) can spontaneously switch at a low frequency from the normal yeast cell morphology (white) to an elongated cell type (opaque), which is the mating-competent form of the fungus. The ability to switch reversibly between these two cell types also contributes to the pathogenicity of C. albicans, as white and opaque cells are differently adapted to specific host niches. We found that in strain WO-1, a strain in which genomic alterations have occurred, but not in other tested strains, switching from the white to the opaque phase can also be induced by environmental conditions. Transient incubation of white cells under anaerobic conditions programmed the cells to switch en masse to the opaque phase. The anaerobic induction of white–opaque switching was controlled by the transcription factor CZF1, which in heterozygous MTL >a/α cells regulates filamentous growth under embedded, hypoxic conditions. Intriguingly, passage of white cells of strain WO-1 through the mouse intestine, a host niche in which the cells are likely to be exposed to anaerobic conditions, resulted in a strongly increased frequency of switching to the opaque phase. These results demonstrate that white–opaque switching is not only a spontaneous process but, in combination with genomic alterations, can also be induced by environmental signals, suggesting that switching and mating of C. albicans may occur with high efficiency in appropriate niches within its human host.
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机译:在交配型位点纯合的白色念珠菌菌株(MTL > a strong>或MTLα)可以从正常的酵母细胞形态(白色)以低频自发切换为细长的细胞类型(不透明)。是具有交配能力的真菌形式。在这两种细胞类型之间可逆切换的能力也有助于白色念珠菌的致病性,因为白细胞和不透明细胞不同地适应于特定宿主壁ni。我们发现,在菌株WO-1中,发生了基因组改变的菌株,但在其他测试菌株中没有发生,从白相到不透明相的转换也可能是由环境条件引起的。在厌氧条件下对白细胞进行短暂温育可对细胞进行编程,使其整体转换为不透明相。厌氧诱导白不透明转换受转录因子CZF1的控制,该转录因子在杂合MTL > a strong> /α细胞中在嵌入式低氧条件下调节丝状生长。有趣的是,菌株WO-1的白细胞通过小鼠肠道(宿主壁n中的细胞很可能暴露于厌氧条件),导致转换为不透明相的频率大大增加。这些结果表明,白色至不透明转换不仅是自发过程,而且与基因组改变结合,也可以由环境信号诱导,这表明白色念珠菌的转换和交配可能在其人类适当的生态位中高效发生。主办。
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