Development and application of an ethically and epidemiologically advantageous assay for the multi-locus microsatellite analysis of Schistosoma mansoni
Development and application of an ethically and epidemiologically advantageous assay for the multi-locus microsatellite analysis of Schistosoma mansoni
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DOI：
10.1017/s0031182006001685
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发表时间：
2007-04-01
期刊：
影响因子：
2.4
通讯作者：
Webster, J. P.
中科院分区：
文献类型：
--
作者：
Gower, C. M.;Shrivastava, J.;Webster, J. P.
无法从活宿主中获得成虫仍然是血吸虫群体遗传学研究的一个关键问题。涉及通过实验动物的间接采样存在重大的伦理和实际缺陷，并可能导致采样偏差，例如瓶颈过程和/或宿主引起的选择压力。本文报道的用于曼氏血吸虫幼虫采样、储存和多位点微卫星分析的新技术，允许对单个幼虫的 7 个微卫星位点进行 Lip 基因分型，从而避免了这些问题。使用从乌干达 Hoima 地区学童收集的 7 个曼氏链球菌种群分离株，通过将相关的现场收集的毛蚴与成虫和从单代实验室小鼠中获得的毛蚴进行比较，评估了这些测定的实用性和实验室传代的潜在问题。对实验室传代材料的分析错误地表明群体中存在地理结构，强调了群体遗传学研究中间接采样的危险。与现场采集的亲本幼虫样本相比，成虫的变异性降低证明了瓶颈和/或其他采样效应。杂合子缺陷的模式在现场采集的样本中很明显，而在实验室来源的样本中并不明显，这可能表明杂合子在实验室宿主内建立的优势。大多数分离株生命周期阶段之间的遗传距离表明，成虫和实验室传代的毛蚴聚集在一起，同时与田间毛蚴分离，从而进一步突出了该测定的实用性。
Non-availability of adult worms from living hosts remains a key problem in population genetic studies of schistosomes. Indirect sampling involving passage through laboratory animals presents significant ethical and practical drawbacks, and may result in sampling biases such as bottlenecking processes and/or host-induced selection pressures. The novel techniques reported here for sampling, storage and multi-locus microsatellite analysis of larval Schistosoma mansoni, allowing genotyping of Lip to 7 microsatellite loci from a single larva, circumvent these problems. The utility of these assays and the potential problems of laboratory passage, were evaluated using 7 S. mansoni population isolates collected from school-children in the Hoima district of Uganda, by comparing the associated field-collected miracidia with adult worms and miracidia obtained from a single generation in laboratory mice. Analyses of laboratory-passaged material erroneously indicated the presence of geographical structuring in the population, emphasizing the dangers of indirect sampling for population genetic studies. Bottlenecking and/or other sampling effects were demonstrated by reduced variability of adult worms compared to their parent field-collected larval samples. Patterns of heterozygote deficiency were apparent in the field-collected samples, which were not evident in laboratory-derived samples, potentially indicative of heterozygote advantage in establishment within laboratory hosts. Genetic distance between life-cycle stages in the majority of isolates revealed that adult worms and laboratory-passaged miracidia clustered together whilst segregating from field miracidia, thereby further highlighting the utility of this assay.