Tibayrenc Michel, Ayala Francisco J
Centre ORSTOM, 2051 Avenue du Val de Montferrand, BP 5045, 34032, Montpellier Cedex, FRANCE.
Department of Genetics, University of California, Davis, CA, 95616.
Evolution. 1988 Mar;42(2):277-292. doi: 10.1111/j.1558-5646.1988.tb04132.x.
A genetic interpretation of the zymograms of 524 Trypanosoma cruzi stocks from various hosts and representing a broad geographical range (United States to Southern Brazil) reveals high genetic variability (only one monomorphic locus out of 15) and suggests that this parasite has a diploid structure. The data do not give any indication of Mendelian sexuality, although many opportunities are present for genetic exchange between extremely different genotypes. The population structure of T. cruzi appears to be multiclonal and complex. The natural clones evidenced by isozyme analysis are numerous (43 different ones are recorded among 121 stocks assayed at 15 gene loci) and exhibit a large range of genotypes, in a nonhierarchical structure; it is not possible to cluster them into a few strictly delimited groups which could represent natural taxa. The available data suggest that the genetic variability of T. cruzi reflects the long separate evolution of multiple clones. It is suggested that long clonal evolution may explain the present biological and medical variability of the causative agent of Chagas' disease.
对来自不同宿主、代表广泛地理范围（从美国到巴西南部）的524株克氏锥虫菌株的酶谱进行的遗传学解释显示出高度的遗传变异性（15个位点中只有1个单态位点），并表明这种寄生虫具有二倍体结构。尽管存在许多机会让极其不同的基因型之间进行基因交换，但数据并未显示出孟德尔式的有性生殖迹象。克氏锥虫的种群结构似乎是多克隆且复杂的。通过同工酶分析证明的天然克隆数量众多（在15个基因位点检测的121株菌株中记录到43种不同的克隆），并呈现出大范围的基因型，呈非层级结构；无法将它们聚类为几个严格界定的组，这些组可能代表自然分类群。现有数据表明，克氏锥虫的遗传变异性反映了多个克隆的长期独立进化。有人提出，长期的克隆进化可能解释了恰加斯病病原体目前的生物学和医学变异性。
