Molecular Biology and Evolution 19:1695-1705 (2002)
© 2002 Society for Molecular Biology and Evolution
Evolution of Hematophagy in Ticks: Common Origins for Blood Coagulation and Platelet Aggregation Inhibitors from Soft Ticks of the Genus Ornithodoros
Department of Biochemistry, University of Pretoria
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 
-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 nonsynonymous-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.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  Y. Decrem, G. Rath, V. Blasioli, P. Cauchie, S. Robert, J. Beaufays, J.-M. Frere, O. Feron, J.-M. Dogne, C. Dessy, et al. Ir-CPI, a coagulation contact phase inhibitor from the tick Ixodes ricinus, inhibits thrombus formation without impairing hemostasis J. Exp. Med., October 26, 2009; 206(11): 2381 - 2395. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. J. Mans, J. M. C. Ribeiro, and J. F. Andersen Structure, Function, and Evolution of Biogenic Amine-binding Proteins in Soft Ticks J. Biol. Chem., July 4, 2008; 283(27): 18721 - 18733. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Kuno and G.-J. J. Chang Biological Transmission of Arboviruses: Reexamination of and New Insights into Components, Mechanisms, and Unique Traits as Well as Their Evolutionary Trends Clin. Microbiol. Rev., October 1, 2005; 18(4): 608 - 637. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. S. Khokhlova, M. Spinu, B. R. Krasnov, and A. A. Degen Immune response to fleas in a wild desert rodent: effect of parasite species, parasite burden, sex of host and host parasitological experience J. Exp. Biol., July 15, 2004; 207(16): 2725 - 2733. [Abstract] [Full Text] [PDF]
|
|