DNA sequence characterisation and phylogeography of Lymnaea cousini and related species, vectors of fascioliasis in northern Andean countries, with description of L. meridensis n. sp (Gastropoda: Lymnaeidae)
DNA sequence characterisation and phylogeography of Lymnaea cousini and related species, vectors of fascioliasis in northern Andean countries, with description of L. meridensis n. sp (Gastropoda: Lymnaeidae)
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DOI：
10.1186/1756-3305-4-132
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发表时间：
2011-07-12
影响因子：
3.2
通讯作者：
Mas-Coma, Santiago
中科院分区：
文献类型：
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作者：
Dolores Bargues, M.;Artigas, Patricio;Mas-Coma, Santiago
背景：家畜肝片吸虫病在厄瓜多尔、哥伦比亚和委内瑞拉是一个问题，主要是在安第斯地区，该疾病似乎也影响人类。肝吸虫感染的传播模式和流行病学情景已显示出根据所涉及的淋巴媒介钉螺种类的不同而不同。这些安第斯国家提供了在拉丁美洲其他地区未知的传病媒介Lymneea cousini、L.bogotensis和L.ubaquens。通过核糖体18S RNA基因、ITS-2和ITS-1以及线粒体DNA cox1基因的DNA测序，对这些物种进行了详尽的组合单倍型研究。结果：通过比较不同的伯氏乳杆菌种群，保守的5.8S rDNA序列证实了在ITS-2和ITS-1序列之间出现的大量非微卫星/小卫星相关的内含子中没有假基因参与。序列分析和系统发育重建方法，包括其他淋巴载体物种表明：(1)伯氏钩端螺旋体是冠状钩端螺旋体的异名，(2)乌巴库钩端螺旋体是柱状拟钩端螺旋藻的异名，(3)委内瑞拉高地迄今已知的钩端螺旋体种群确实属于一个新种，其名称为L.merdensis n.SP。是提议的。结论：ITS-2、ITS-1和Cox1是病区形态相似的淋巴组织标本分类和单倍型鉴定的良好标记。对18S基因的分析和系统发育重建结果表明，库西尼乳杆菌和小球藻均为链球菌属。聚在一个不同的进化线上，尽管它们的外部相似之处。这表明进化表型趋同与相似的环境有关，并已导致频繁的标本错误分类。斑节对虾的体型大小和系统发育关系与著名的媒介如莱姆奈亚·库里尼和柱状P.以及Galba/Fossaria物种的研究表明，在每年气温高于肝片吸虫最低发育阈值的窗口期间，新物种可能参与了疾病对动物和人类的传播。分析了库欣尼和柱状螺旋体在这些安第斯国家的肝片吸虫病传播和地理/海拔分布中的作用。
Background: Livestock fascioliasis is a problem throughout Ecuador, Colombia and Venezuela, mainly in Andean areas where the disease also appears to affect humans. Transmission patterns and epidemiological scenarios of liver fluke infection have shown to differ according to the lymnaeid vector snail species involved. These Andean countries present the vectors Lymnaea cousini, L. bogotensis and L. ubaquensis, unknown in the rest of Latin America. An exhaustive combined haplotype study of these species is performed by means of DNA sequencing of the nuclear ribosomal 18S RNA gene, ITS-2 and ITS-1, and mitochondrial DNA cox1 gene.Results: The conserved 5.8S rDNA sequence corroborated that no pseudogenes are involved in the numerous non-microsatellite/minisatellite-related indels appearing between the ITS-2 and ITS-1 sequences when comparing different L. cousini - L. bogotensis populations. Sequence analyses and phylogenetic reconstruction methods including other lymnaeid vector species show that (i) L. bogotensis is a synonym of L. cousini, (ii) L. ubaquensis is a synonym of Pseudosuccinea columella, and (iii) populations of L. cousini hitherto known from Venezuelan highlands indeed belong to a new species for which the name L. meridensis n. sp. is proposed. This new species is described and a complete phenotypic differentiation provided.Conclusions: ITS-2, ITS-1 and cox1 prove to be good markers for specimen classification and haplotype characterisation of these morphologically similar lymnaeids in endemic areas. Analysis of the 18S gene and phylogenetic reconstructions indicate that L. cousini and L. meridensis n. sp. cluster in an evolutionary line different from the one of P. columella, despite their external resemblance. This suggests an evolutionary phenotypic convergence related to similar environments and which has given rise to frequent specimen misclassification. Body size and phylogenetic relationships of L. meridensis n. sp. with well-known vectors as Lymnaea cousini and P. columella, as well as with Galba/Fossaria species, suggest that the new species may participate in disease transmission to both animals and humans in altitude areas during the yearly window in which temperatures are higher than the F. hepatica minimum development threshold. The involvement of L. cousini and P. columella in the transmission and geographical/altitudinal distribution of fascioliasis in these Andean countries is analysed.