Microsatellite analysis of genetic diversity among clinical and nonclinical Saccharomyces cerevisiae isolates suggests heterozygote advantage in clinical environments
Microsatellite analysis of genetic diversity among clinical and nonclinical Saccharomyces cerevisiae isolates suggests heterozygote advantage in clinical environments
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DOI：
10.1111/j.1365-294x.2009.04234.x
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发表时间：
2009-07-01
影响因子：
4.9
通讯作者：
Mccusker, John H.
中科院分区：
文献类型：
--
作者：
Muller, Ludo A. H.;Mccusker, John H.
利用12个微卫星标记分析了全球170个临床和非临床酿酒酵母分离株的遗传结构。在临床和非临床的酿酒葡萄球菌分离株中都显示出高度的遗传多样性，这两组分离株之间没有明显的差异，因此不太可能是单一来源的致病分离株。这表明酿酒葡萄球菌是一种真正的机会性病原体，具有多种不相关的遗传背景，能够引起人类感染，酿酒葡萄球菌分离物引起感染的能力可能是由于其表型可塑性和暴露个体免疫系统状态的综合作用。正如之前报道的面包、啤酒和葡萄酒菌株以及环境中的酿酒葡萄球菌分离株一样，微卫星基因型显示了临床酿酒葡萄球菌分离株的倍性水平变化，可能从单倍体到四倍体。然而，与单倍体相比，产孢能力和孢子活力数据表明，在所有检测的微卫星位点上，大多数酿酒葡萄球菌分离物都是单等位基因，可能是同源的和自二倍体的。有趣的是，临床分离的杂合子比例明显高于非临床分离的杂合子比例，这表明杂合子酿酒酵母在临床环境中具有选择优势。
The genetic structure of a global sample of 170 clinical and nonclinical Saccharomyces cerevisiae isolates was analysed using 12 microsatellite markers. High levels of genetic diversity were revealed both among the clinical and among the nonclinical S. cerevisiae isolates without significant differentiation between these two groups of isolates, rendering a single origin of pathogenic isolates unlikely. This suggests that S. cerevisiae is a true opportunistic pathogen, with a diversity of unrelated genetic backgrounds able to cause infections in humans, and that the ability of S. cerevisiae isolates to cause infections is likely due to a combination of their phenotypic plasticity and the immune system status of the exposed individuals. As was previously reported for bread, beer and wine strains and for environmental S. cerevisiae isolates, the microsatellite genotypes indicated ploidy level variation, from possibly haploid up to tetraploid, among clinical S. cerevisiae isolates. However, rather than haploid, sporulation proficiency and spore viability data indicated that most S. cerevisiae isolates that were mono-allelic at all examined microsatellite loci were likely homothallic and self-diploidized. Interestingly, the proportion of heterozygous clinical isolates was found to be significantly higher than the proportion of heterozygous nonclinical isolates, suggesting a selective advantage of heterozygous S. cerevisiae yeasts in clinical environments.