Evolution of hematophagy in ticks:: Common origins for blood coagulation and platelet aggregation inhibitors from soft ticks of the genus Ornithodoros
Evolution of hematophagy in ticks:: Common origins for blood coagulation and platelet aggregation inhibitors from soft ticks of the genus Ornithodoros
复制标题
DOI：
10.1093/oxfordjournals.molbev.a003992
复制
发表时间：
2002-10-01
影响因子：
10.7
通讯作者：
Neitz, AWH
中科院分区：
文献类型：
--
作者：
Mans, BJ;Louw, AI;Neitz, AWH
鉴定和鉴定噬血生物中的抗止血成分，有助于阐明与高度复杂的宿主止血系统相适应的进化机制。虽然已经描述了许多参与调节宿主止血系统的生物活性成分，但节肢动物如何适应觅血环境的进化机制尚未阐明。这项研究描述了凝血抑制物和血小板聚集抑制物(PAI)的共同来源，这些物质来自鸟形纲动物属的软蜱。邻接分析表明，FXA、凝血酶和PAI具有共同的祖先。最大简约分析和基于α-碳主干结构均方根值的系统发育分析表明，通过一系列类似的基因复制事件，不同的止血功能进化出了一条新的进化途径。在这种情况下，凝血酶抑制剂先于FXA和PAI。这一进化模型解释了为什么壁虱丝氨酸蛋白酶抑制剂具有不同于经典的牛胰腺胰蛋白酶抑制剂(BPTI)样抑制剂的抑制机制。较高的非同义到同义替换率表明对FXA和PAI的达尔文选择是积极的。与硬蜱的止血抑制剂的比较表明，两个主要的硬蜱家族独立地进化出了新的抗止血机制。这些机制在扁虱中的独立进化表明，扁虱家族之间的快速分化可以追溯到120到92年间。这与目前关于白垩纪晚期现代鸟类和胎盘哺乳动物早期分化的分子系统学观点不谋而合，这表明这一事件可能是扁虱噬血进化的驱动力。
Identification and characterization of antihemostatic components from hematophagous organisms are useful for the elucidation of the evolutionary mechanisms involved in adaptation to a highly complex host hemostatic system. Although many bioactive components involved in the regulation of the host's hemostatic system have been described, the evolutionary mechanisms of how arthropods adapted to a blood-feeding environment have not been elucidated. This study describes common origins of both blood coagulation inhibitors and platelet aggregation inhibitors (PAIs) from soft ticks of the genus Ornithodoros. Neighbor-joining analysis indicates that fXa, thrombin, and PAIs share a common ancestor. Maximum parsimony analysis and a phylogeny based on root mean square deviation values of alpha-carbon backbone structures suggest a novel evolutionary pathway by which different antihemostatic functions have evolved through a series of paralogous gene duplication events. In this scenario, the thrombin inhibitors preceded the fXa and PAIs. This evolutionary model explains why the tick serine protease inhibitors have inhibition mechanisms that differ from that of the canonical bovine pancreatic trypsin inhibitor (BPTI)-like inhibitors. Higher non synonymous-to-synonymous substitution rates indicate positive Darwinian selection for the fXa and PAIs. Comparison with hemostatic inhibitors of hard ticks suggests that the two main tick families have independently evolved novel antihemostatic mechanisms. Independent evolution of these mechanisms in ticks points to a rapid divergence between tick families that could be dated between 120 and 92 MYA. This coincides with current molecular phylogeny views on the early divergence of modern birds and placental mammals in the Late Cretaceous, which suggests that this event might have been a driving force in the evolution of hematophagy in ticks.