Leclerc M C, Durand P, Gauthier C, Patot S, Billotte N, Menegon M, Severini C, Ayala F J, Renaud F
Unité Mixte de Recherche 2724, Institut de Recherche pour le Développement et Centre National de la Recherche Scientifique, 911 Avenue Agropolis, 34394 Montpellier Cedex 5, France.
Proc Natl Acad Sci U S A. 2004 Oct 5;101(40):14455-60. doi: 10.1073/pnas.0405186101. Epub 2004 Aug 24.
Malaria is a major human parasitic disease caused by four species of Plasmodium protozoa. Plasmodium vivax, the most widespread, affects millions of people across Africa, Asia, the Middle East, and Central and South America. We have studied the genetic variability of 13 microsatellite loci in 108 samples from 8 localities in Asia, Africa, South America, and New Guinea. Only one locus is polymorphic; nine are completely monomorphic, and the remaining three are monomorphic in all but one or two populations, which have a rare second allele. In contrast, Plasmodium falciparum displays extensive microsatellite polymorphism within and among populations. We further have analyzed, in 96 samples from the same 8 localities, 8 tandem repeats (TRs) located on a 100-kb contiguous chromosome segment described as highly polymorphic. Each locus exhibits 2-10 alleles in the whole sample but little intrapopulation polymorphism (1-5 alleles with a prevailing allele in most cases). Eight microsatellite loci monomorphic in P. vivax are polymorphic in three of five Plasmodium species related to P. vivax (two to seven individuals sampled). Plasmodium simium, a parasite of New World monkeys, is genetically indistinguishable from P. vivax. At 13 microsatellite loci and at 7 of the 8 TRs, both species share the same (or most common) allele. Scarce microsatellite polymorphism may reflect selective sweeps or population bottlenecks in recent evolutionary history of P. vivax; the differential variability of the TRs may reflect selective processes acting on particular regions of the genome. We infer that the world expansion of P. vivax as a human parasite occurred recently, perhaps <10,000 years ago.
疟疾是由四种疟原虫引起的主要人类寄生虫病。间日疟原虫分布最为广泛，影响着非洲、亚洲、中东以及中南美洲的数百万人。我们研究了来自亚洲、非洲、南美洲和新几内亚8个地区的108个样本中13个微卫星位点的遗传变异性。只有一个位点是多态性的；九个位点完全是单态性的，其余三个位点在除一两个群体外的所有群体中都是单态性的，这一两个群体有罕见的第二个等位基因。相比之下，恶性疟原虫在群体内部和群体之间表现出广泛的微卫星多态性。我们还在来自相同8个地区的96个样本中分析了位于一个100 kb连续染色体片段上的8个串联重复序列（TRs），该片段被描述为高度多态性。每个位点在整个样本中表现出2至10个等位基因，但群体内多态性很少（在大多数情况下有1至5个等位基因，其中一个等位基因占主导）。间日疟原虫中8个单态性的微卫星位点在与间日疟原虫相关的五种疟原虫中的三种（每种采样两到七个个体）中是多态性的。新世界猴的寄生虫——西氏疟原虫在基因上与间日疟原虫无法区分。在13个微卫星位点和8个TRs中的7个位点上，这两个物种共享相同（或最常见）的等位基因。稀少的微卫星多态性可能反映了间日疟原虫近期进化历史中的选择性清除或群体瓶颈；TRs的差异变异性可能反映了作用于基因组特定区域的选择过程。我们推断，间日疟原虫作为人类寄生虫在全球范围内的扩张是最近发生的，可能在<10,000年前。
