Jensen Ellen C, Hornby Jacob M, Pagliaccetti Nicole E, Wolter Chuleeon M, Nickerson Kenneth W, Atkin Audrey L
School of Biological Sciences, College of Saint Benedict's and Saint John's University, Collegeville, MN 56321, USA.
Genome. 2006 Apr;49(4):346-53. doi: 10.1139/g05-117.
Candida albicans is a diploid fungus that undergoes a morphological transition between budding yeast, hyphal, and pseudohyphal forms. The morphological transition is strongly correlated with virulence and is regulated in part by quorum sensing. Candida albicans produces and secretes farnesol that regulates the yeast to mycelia morphological transition. Mutants that fail to synthesize or respond to farnesol could be locked in the filamentous mode. To test this hypothesis, a collection of C. albicans mutants were isolated that have altered colony morphologies indicative of the presence of hyphal cells under environmental conditions where C. albicans normally grows only as yeasts. All mutants were characterized for their ability to respond to farnesol. Of these, 95.9% fully or partially reverted to wild-type morphology on yeast malt (YM) agar plates supplemented with farnesol. All mutants that respond to farnesol regained their hyphal morphology when restreaked on YM plates without farnesol. The observation that farnesol remedial mutants are so common (95.9%) relative to mutants that fail to respond to farnesol (4.1%) suggests that farnesol activates and (or) induces a pathway that can override many of the morphogenesis defects in these mutants. Additionally, 9 mutants chosen at random were screened for farnesol production. Two mutants failed to produce detectable levels of farnesol.
白色念珠菌是一种二倍体真菌，它在出芽酵母、菌丝和假菌丝形态之间经历形态转变。这种形态转变与毒力密切相关，部分受群体感应调节。白色念珠菌产生并分泌法尼醇，法尼醇可调节酵母到菌丝的形态转变。无法合成或响应法尼醇的突变体可能会被锁定在丝状模式。为了验证这一假设，分离出了一组白色念珠菌突变体，这些突变体的菌落形态发生了改变，这表明在白色念珠菌通常仅以酵母形式生长的环境条件下存在菌丝细胞。所有突变体都对它们响应法尼醇的能力进行了表征。其中，95.9%在添加了法尼醇的酵母麦芽（YM）琼脂平板上完全或部分恢复为野生型形态。所有对法尼醇有反应的突变体在没有法尼醇的YM平板上重新划线时恢复了菌丝形态。相对于无法响应法尼醇的突变体（4.1%），法尼醇补救突变体如此常见（95.9%）这一观察结果表明，法尼醇激活和（或）诱导了一条可以克服这些突变体中许多形态发生缺陷的途径。此外，随机选择了9个突变体来检测法尼醇的产生。有两个突变体未能产生可检测水平的法尼醇。
