Mating is rare within as well as between clades of the human pathogen Candida albicans
Mating is rare within as well as between clades of the human pathogen Candida albicans
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DOI：
10.1016/j.fgb.2007.10.008
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发表时间：
2008-03-01
影响因子：
3
通讯作者：
d'Enfert, Christophe
中科院分区：
文献类型：
--
作者：
Bougnoux, Marie-Elisabeth;Pujol, Claude;d'Enfert, Christophe
白色念珠菌是一种二倍体酵母菌，可以进行交配和副性周期，但显然不能进行减数分裂。对白色念珠菌种群结构的表征表明，繁殖主要是无性繁殖，如果发生交配，则很少或仅限于遗传相关的分离株。由于分子分型已经描绘了白色念珠菌的不同分支，我们已经测试了重组是否在分支内常见，但在分支之间罕见。本文对203株白色念珠菌进行了多位点序列分型（MLST）和杂合型MLST单倍型分析。白色念珠菌分离株分布在9个分支中，其中5个分支与Ca3指纹图谱鉴定的分支相对应。在每一个有10个以上分离株的分支中，位于6个位点中的3到4个位点的多态性核苷酸位置处于Hardy-Weinberg不平衡状态。此外，这些多态位点都含有过多的杂合子。对最近发表的1044株MLST数据集进行的扩展分析证实了这一点。平均而言，单个分支中66%的多态性位点在5个分支中显着超过杂合子。这些数据表明，进化枝内的交配和自我受精都是有限的，白色念珠菌进化枝并不代表一个隐秘物种的集合。在我们的数据集上对杂合位点的单倍型进行的研究表明，由于有丝分裂重组导致的杂合性丢失事件在白色念珠菌的自然群体中是中等常见的。尽管相对频繁的杂合性丢失，但大量杂合性的维持可能是由于杂合性所赋予的选择优势。(c) 2007爱思唯尔公司版权所有。
Candida albicans is a diploid yeast that can undergo mating and a parasexual cycle, but is apparently unable to undergo meiosis. Characterization of the population structure of C albicans has shown that reproduction is largely clonal and that mating, if it occurs, is rare or limited to genetically related isolates. Because molecular typing has delineated distinct clades in C. albicans, we have tested whether recombination was common within clades, but rare between clades. Two hundred and three C. albicans isolates have been subjected to multilocus sequence typing (MLST) and the haplotypes at heterozygous MLST genotypes characterized. The C albicans isolates were distributed among nine clades, of which five corresponded to those previously identified by Ca3 fingerprinting. In each of these clades with more than 10 isolates, polymorphic nucleotide positions located on between 3 and 4 of the six loci were in Hardy-Weinberg disequilibrium. Moreover, each of these polymorphic sites contained excess heterozygotes. This was confirmed by an expanded analysis performed on a recently published MLST dataset for 1044 isolates. On average, 66% of polymorphic positions in the individual clades were in significant excess of heterozygotes over the five clades. These data indicate that mating within clades as well as self-fertilization are both limited and that C albicans clades do not represent a collection of cryptic species. The study of haplotypes at heterozygous loci performed on our dataset indicates that loss of heterozygosity events due to mitotic recombination is moderately common in natural populations of C albicans. The maintenance of substantial heterozygosity despite relatively frequent loss of heterozygosity could result from a selective advantage conferred by heterozygosity. (c) 2007 Elsevier Inc. All rights reserved.