Isolates of Cryptococcus neoformans from Infected Animals Reveal Genetic Exchange in Unisexual, α Mating Type Populations
Isolates of Cryptococcus neoformans from Infected Animals Reveal Genetic Exchange in Unisexual, α Mating Type Populations
复制标题
DOI：
10.1128/ec.00097-08
复制
发表时间：
2008-10-01
期刊：
影响因子：
--
通讯作者：
Carter, Dee
中科院分区：
文献类型：
--
作者：
Bui, Tien;Lin, Xiaorong;Carter, Dee
有性繁殖和遗传交换对于真菌病原体的进化和产生潜在的感染性孢子是重要的。确定致病酵母新生隐球菌变种是否发生性行为的研究。然而，Grubii产生了令人费解的结果：担孢子是最有可能的感染性繁殖体，临床分离株具有生育能力和遗传多样性，与有性物种一致，但几乎所有研究的种群都由单一交配型组成，几乎没有证据表明基因重组。在寻找重组的时候，种群的选择是至关重要的，特别是当很可能发生显著的无性繁殖时，以及当潜伏期可能使评估分离株的起源复杂化时。因此，我们从生活在澳大利亚悉尼地区的受感染动物中选择了分离株，假设动物宿主相对较短的寿命和有限的旅行将提供一个非常明确的种群。所有分离株均为交配型α，均为VNI或VNII分子基因型。两个基因座之间缺乏连锁不平衡，表明两个基因组间存在遗传交换。四个二倍体VNII分离株在与交配型菌株接近培养时产生细丝和类似担子的结构。最近的研究表明，在新生葡萄球菌变种中可以发生相容的α-α结合。新生杆菌种群和近缘种隐球菌属的种群。作为一株交配型新生隐翅虫变种。Grubii在澳大利亚从未被发现，或者在全球的VNII分子类型中从未被发现，α-α结合的可能性是α-α单性交配维持这种病原体的有性重组和多样性并可能产生传染性繁殖的证据。
Sexual reproduction and genetic exchange are important for the evolution of fungal pathogens and for producing potentially infective spores. Studies to determine whether sex occurs in the pathogenic yeast Cryptococcus neoformans var. grubii have produced enigmatic results, however: basidiospores are the most likely infective propagules, and clinical isolates are fertile and genetically diverse, consistent with a sexual species, but almost all populations examined consist of a single mating type and have little evidence for genetic recombination. The choice of population is critical when looking for recombination, particularly when significant asexual propagation is likely and when latency may complicate assessing the origin of an isolate. We therefore selected isolates from infected animals living in the region of Sydney, Australia, with the assumption that the relatively short life spans and limited travels of the animal hosts would provide a very defined population. All isolates were mating type alpha and were of molecular genotype VNI or VNII. A lack of linkage disequilibrium among loci suggested that genetic exchange occurred within both genotype groups. Four diploid VNII isolates that produced filaments and basidium-like structures when cultured in proximity to an a mating type strain were found. Recent studies suggest that compatible alpha-alpha unions can occur in C. neoformans var. neoformans populations and in populations of the sibling species Cryptococcus gattii. As a mating type strains of C. neoformans var. grubii have never been found in Australia, or in the VNII molecular type globally, the potential for alpha-alpha unions is evidence that alpha-alpha unisexual mating maintains sexual recombination and diversity in this pathogen and may produce infectious propagules.