Evidence for a more recently evolved clade within a Candida albicans North American population
Evidence for a more recently evolved clade within a Candida albicans North American population
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DOI：
10.1099/00221287-147-6-1687
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发表时间：
2001-06-01
期刊：
影响因子：
2.8
通讯作者：
Effat, MM
中科院分区：
文献类型：
--
作者：
Lott, TJ;Effat, MM
白念珠菌为二倍体，主要以克隆方式繁殖。然而，有减数分裂的证据，这种减数分裂在自然界中发生的程度尚不清楚。尽管随机交配会模糊克隆谱系，但之前的研究表明，北美分离株的集合显示出三个主要的分区，没有地理聚集性的证据。为了更好地了解该物种的性征程度及其在系统发育中的作用，利用1个小卫星、5个微卫星(MSS)和15个核多态(NP)对代表这一三部分划分的50个分离物的参考子集进行了分析。21个座位共检测到87个等位基因，其中12个信息座位偏离Hardy-Weinberg预期(G(2)小于或等于0.05)。我们没有观察到MSS和NP之间的绝对相关性，尽管具有相同NP基因的分离株与先前定义的主要类别(假定的I组)相关。使用更多的标记并没有增加对人口三方结构的支持。然而，(9/19)I组分离株被发现高度相关，只有一个或几个等位基因不同，命名为A亚组，解释是这些分离株通过血统联系在一起，它们是较新的进化起源，与I克隆的祖先组不同。它们在种群中相对丰富的原因尚不清楚；一种可能性是它们可能处于正向选择之下。
Candida albicans is diploid and displays a primarily clonal mode of reproduction. There is, however, evidence for meiosis and the degree to which this occurs in nature is unknown. Although random mating would act to obscure clonal lineages, previous studies have demonstrated that collections of North American isolates display three major partitions with no evidence of geographic clustering. To better understand the extent of sexuality and its role in the phylogeny of the species, a reference subset of 50 isolates representing this tripartite division was analysed using 1 minisatellite, 5 microsatellites (MSs) and 15 nuclear polymorphisms (NP). A total of 87 alleles were observed for 21 loci and 12/16 informative loci exhibited a departure from Hardy-Weinberg expectations (G(2) less than or equal to 0.05). We did not observe an absolute correlation between MSs and NP, although isolates with identical NP genotypes were correlated with a previously defined, predominant class (putative group I). The use of additional markers did not give increased support for the tripartite structure of the population. However, (9/19) group I isolates were found to be highly related, differing by only one or a few alleles, Designated subgroup A, the interpretation is that these isolates are related by descent and that they are of a more recent evolutionary origin, diverging from an ancestral group I clone. The reason for their relative abundance in the population is unknown; one possibility is that they may be under positive selection.