The environmental yeast Nakaseomyces delphensis is, phylogenetically, the closest known species to Candida glabrata, a major fungal pathogen of humans. C. glabrata is haploid and described as asexual, while N. delphensis is also haploid, but has been described as competent for mating and meiosis. Both genomes contain homologues of all the genes necessary for sexual reproduction and also the genes for Ho‐dependent mating‐type switching, like Saccharomyces cerevisiae. We first report the construction of genetically engineered strains of N. delphensis, including by CRISPR‐Cas 9 gene editing. We also report the description of the sexual cycle of N. delphensis. We show that it undergoes Ho‐dependent mating‐type switching in culture and that deletion of the HO gene prevents such switching and allows maintenance of stable, separate, MATa and MATalpha haploid strains. Rare, genetically selected diploids can be obtained through mating of haploid strains, mutated or not for the HO gene. In contrast to HO/HO diploids, which behave as expected, Δho/Δho diploids exhibit unusual profiles in flow cytometry. Both types of diploids can produce recombined haploid cells, which grow like the original haploid‐type strain. Our experiments thus allow the genetic manipulation of N. delphensis and the reconstruction, in the laboratory, of its entire life cycle.

中文翻译：

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酵母 Nakaseomyces delphensis 中的基因组编辑及其完整的性周期描述

环境酵母Nakaseomyces delphensis在系统发育上是与光滑念珠菌（人类的主要真菌病原体）最接近的已知物种。C. glabrata是单倍体并被描述为无性，而N. delphensis也是单倍体，但被描述为能够进行交配和减数分裂。两个基因组都包含有性生殖所需的所有基因的同源物，以及依赖 Ho 的交配类型转换基因，如酿酒酵母。我们首先报告了N. delphensis基因工程菌株的构建，包括 CRISPR-Cas 9 基因编辑。我们还报告了对N的性周期的描述。 德尔芬斯。我们表明它在培养中经历了依赖于 Ho 的交配类型转换，并且HO基因的缺失阻止了这种转换，并允许维持稳定、独立的MATa和MATalpha单倍体菌株。罕见的遗传选择的二倍体可以通过单倍体菌株的交配获得，无论HO基因是否突变。与表现出预期的H2O/H2O二倍体相比，Δho / Δho二倍体在流式细胞术中表现出不寻常的特征。两种类型的二倍体都可以产生重组的单倍体细胞，它们像原始单倍体型菌株一样生长。因此，我们的实验允许对N. delphensis进行基因操作 并在实验室中重建其整个生命周期。