Establishment of a Genetic System in Candida albicans

超出所提供的空间。 白色念珠菌是一种二倍体真菌，随着医疗水平的提高，高度虚弱和免疫抑制患者的生命得以保全，白色念珠菌已成为一种常见的病原体。近年来，在利用分子遗传学来探索这种生物体的毒力机制方面取得了很大的进展，但它的二倍体性质和明显缺乏性周期严重阻碍了对这种重要病原体的了解，因为在酿酒酵母中进行的那种优雅的实验是不可能的。我们最近构建了个能够交配的白色念珠菌菌株，我们还发现相当一部分临床分离株在MIL基因座上是纯合的（a或a），因此可能能够在体内交配。在这个建议中，我们有三个具体的目标：1）我们将描述交配反应，检查其遗传基础，以最大限度地提高其有用性的研究人员以及了解其在念珠菌生物学的作用。（2）寻找交配产物发生减数分裂的条件，使性周期得以完成。如果我们在交配产物中没有发现减数分裂，我们将利用我们对链球菌减数分裂的了解来构建应该能够进行减数分裂的菌株。3)我们将询问交配和减数分裂是否可以在非实验室菌株中发生，我们将检查MTLa、MTLa和MIL a/a（二倍体和四倍体）菌株在体内的行为，以了解性周期的部分或全部组成部分是否在动物中发生。这项资助中提出的实验将开启白色念珠菌生物学的新纪元，并使研究人员能够提出关于这种生物体发病机制的新的重要问题。如果我们能找到或设计出将四倍体交配产物恢复为二倍体的方法，白色念珠菌将对酿酒酵母中开发的所有重要技术开放，这些技术使该真菌成为首选的模型系统。但是对于念珠菌，我们将研究的不是一个模型系统，而是病原体本身。性能现场=

EXCEED THE SPACE PROVIDED. Candida albicans is a diploid fungus which has becomeamajornosocomialpathogen as improved medical carehas preserved the live; of highly debilitated and immunosuppressed patients. In recent yearsgreatadvanceshavebeen madein the use of molecular genetics to probe the mechanisms of virulence in this organism, but its diploid nature and apparent lack of a sexualcyclehave seriously hampered advances in understanding this important pathogen, since elegant experiments of the sort carried out inS. cerevisiae havebeen impossible. Wehaverecently constructedstrains of C.albicans that will mate, and we havealso found that a significant fraction of clinical isolates are homozygous(aor a)at the MIL locus andthus maybe able to matein vivo. In this proposal we havethree specific aims: 1)Wewill characterize the mating reaction, examining its genetic basis in order to maximize its usefulness to investigators aswell asto understand its role in the biology of Candida. 2)We will search for conditions which will give rise to meiosis in the mating products so that the sexualcycle will becompleted. If wefail to find meiosis in our mating products, wewill useour understanding of meiosis in S.cerevisiaeto construct strains which ought to be capable of meiosis. 3) Wewill ask whether mating and meiosis can occur amongnon-laboratory strains and wewill examine the behavior of MTLa, MTLa, and MIL a/a(both diploid andtetraploid) strains in vivo, to seewhether some or all of the components of the sexualcycle occur in the animal. Theexperiments proposed in this grant will open a newera in Candidaalbicans biology and will allow investigators to formulate newand important questions about the pathogenesis of this organism. If we canfind or devise away to return the tetraploid mating products to diploidy, C.albicans will beopen to all the important technology developed in S.cerevisiae,technology which hasmadethat fungus the model systemof choice. But with Candida, we will be studying not a model systembut the pathogen itself. PERFORMANCE SITE ========================================Section End===========================================