Stohler R A, Curtis J, Minchella D J
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
Int J Parasitol. 2004 Apr;34(5):595-601. doi: 10.1016/j.ijpara.2003.11.026.
The genetic diversity of a field population (recently collected in Melquiades, Brazil) and two laboratory strains (LE and NMRI) of a human blood fluke, Schistosoma mansoni, were analysed using microsatellite markers. Data from the three groups showed an extreme and consistent discrepancy in the level of polymorphism at all microsatellite loci between the field population and laboratory populations. The numbers of alleles detected in LE and NMRI populations averaged only 14 and 10% of those found in the field population, respectively. Especially apparent was the abundance of rare alleles in the Melquiades population when compared with the laboratory strains. The reduction in allelic diversity in the laboratory strains is most likely due to the founder effect and potential bottlenecks that may have occurred during decades of laboratory maintenance. Surprisingly, a much less drastic difference was found when comparing the average heterozygosity of the field population with the laboratory strains. This apparent anomaly may be explained by observed population substructuring (and a potential resultant Wahlund effect) in the natural population. Our comparison of genetic diversity between laboratory and field populations of S. mansoni emphasizes the need for studies of representative populations in schistosome vaccine development.
利用微卫星标记分析了人体血吸虫曼氏血吸虫一个野外种群（最近在巴西梅尔基阿德斯采集）以及两个实验室品系（LE和NMRI）的遗传多样性。三组数据显示，在所有微卫星位点上，野外种群和实验室种群之间的多态性水平存在极端且一致的差异。在LE和NMRI种群中检测到的等位基因数量分别仅为野外种群中发现的等位基因数量的14%和10%。与实验室品系相比，梅尔基阿德斯种群中稀有等位基因的丰富程度尤为明显。实验室品系中等位基因多样性的降低很可能是由于奠基者效应以及在数十年实验室维持过程中可能出现的潜在瓶颈。令人惊讶的是，在比较野外种群与实验室品系的平均杂合度时，发现差异要小得多。这种明显的异常现象可能是由自然种群中观察到的种群亚结构（以及潜在的由此产生的瓦伦德效应）所解释。我们对曼氏血吸虫实验室种群和野外种群遗传多样性的比较强调了在血吸虫疫苗开发中研究代表性种群的必要性。
