MOLECULAR BASIS OF PHENOTYPIC SWITCHING IN 24067 MUTANT

我的研究项目的目标是更好地了解新生隐球菌表型转换背后的分子机制。有证据表明，表型转换是这种真菌逃避宿主根除并导致持久性的一种手段。我将研究实验室菌株24067的一个变种，这种变种在“光滑”和“皱纹”表型之间切换频率很高。除了细胞表面的改变外，“皱纹”表型还表现出更大的被膜、丝状生长和体内持久性增加。因此，这种转换产生了一个复杂的表型。向“皱纹”表型的转变似乎涉及到与这种病原体的毒力相关的基因的上调。此外，这种转换与两条染色体的长度变化有关。需要检验的假设是，染色体重排导致一个中央调节因子的差异表达，而中央调节因子反过来调节与毒力相关的基因。我的项目的第一部分将涉及复杂表型的形态研究。第二部分的目的是克隆介导这种复杂表型的基因，第三部分的目的是确定染色体重排和转换之间是否存在因果关系。

The goal of my research project is to better understand the molecular mechanism underlying phenotypic switching in Cryptococcus neoformans. There is evidence that phenotypic switching is a means by which this fungus escapes eradication by the host and results in persistence. I will study a variant of the laboratory strain 24067 that switches at high frequency between a "smooth" and "wrinkled" phenotype. In addition to an altered cell surface the "wrinkled" phenotype exhibits a bigger capsule, filamentous growth and an increased in vivo persistence. Thus the switch yields a complex phenotype. The switch to a "wrinkle" phenotype appears to involve the upregulation of genes that are associated with virulence in this pathogen. In addition the switch is associated with a length change of two chromosomes. The hypothesis to be tested is that chromosomal rearrangement results in differential expression of a central regulator, which in turn regulates genes, which are associated with virulence. The first part of my project will involve morphological studies of the complex phenotype. The second part is designed to clone the gene mediating this complex phenotype and the third part will aim to establish whether there is a causative relationship between chromosomal rearrangement and switching.