title: Comparison of sea turtle thrombocyte aggregation to human platelet aggregation in whole blood.
abstract: The endangered sea turtles are living "fossils" that afford us an opportunity to study the hemostatic process as it likely existed millions of years ago. There are essentially no data about turtle thrombocyte aggregation prior to our studies. Thrombocytes are nucleated cells that serve the same hemostatic functions as the anucleated mammalian platelet. Sea turtle thrombocytes aggregate in response to collagen and beta-thrombin. Ristocetin induces an agglutination/aggregation response indicating the presence of a von Willebrand-like receptor, GPIb, found in all mammalian platelets. Samples treated with alpha-thrombin plus gamma-thrombin followed by ristocetin results in a rapid, stronger response than ristocetin alone. These responses are inhibited by the RGDS peptide that blocks fibrinogen cross-linking of mammalian platelets via the fibrinogen receptor, GPIIb/IIIa. Three platelet-like proteins, GPIb, GPIIb/IIIa and P-selection are detected in sea turtle thrombocytes by fluorescence activated cell sorting. Turtle thrombocytes do not respond to ADP, epinephrine, serotonin, thromboxane A2 mimetic, U46619, trypsin, or alpha-thrombin and gamma-thrombin added alone. Comparison of hemostasis in sea turtles to other vertebrates could provide a framework for understanding the structure/function and evolution of these pathways and their individual components.
authors.affiliation: Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N. 15th Street, MS 344, Philadelphia, PA 19102, USA. gsoslau@drexelmed.edu
authors.forename: Gerald
authors.initials: G
authors.lastname: Soslau
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Prest
authors.forename: Reiner
authors.initials: R
authors.lastname: Class
authors.forename: Robert
authors.initials: R
authors.lastname: George
authors.forename: Frank
authors.initials: F
authors.lastname: Paladino
authors.forename: Gary
authors.initials: G
authors.lastname: Violetta
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002469:Cell Separation; D005260:Female; D006487:Hemostasis / Q000502:physiology; D006801:Humans; D009842:Oligopeptides / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology*; D010979:Platelet Function Tests; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism; D012310:Ristocetin / Q000494:pharmacology; D013917:Thrombin / Q000378:metabolism; D014426:Turtles / Q000502:physiology*
chemical_list: D009842:Oligopeptides; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex; D012310:Ristocetin; C046617:arginyl-glycyl-aspartyl-serine; D013917:Thrombin