Comparison of functional aspects of the coagulation cascade in human and sea turtle plasmas |
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Authors: | Soslau Gerald Wallace Bryan Vicente Catherine Goldenberg Seth J Tupis Todd Spotila James George Robert Paladino Frank Whitaker Brent Violetta Gary Piedra Rotney |
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Affiliation: | a Department of Biochemistry, Drexel University College of Medicine, Philadelphia, PA, USA;b Medical Science Programs, Drexel University College of Medicine, Philadelphia, PA 19102, USA;c Department of Bioscience, Drexel University, Philadelphia, PA, USA;d Virginia Institute of Marine Sciences, Gloucester Point, VA, USA;e Department of Biology, Purdue University, Fort Wayne, IN, USA;f National Aquarium, Baltimore, MD, USA;g Sea World, Orlando, FL, USA;h Parque Nacional Marino Las Baulas, Costa Rica |
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Abstract: | Functional hemostatic pathways are critical for the survival of all vertebrates and have been evolving for more than 400 million years. The overwhelming majority of studies of hemostasis in vertebrates have focused on mammals with very sparse attention paid to reptiles. There have been virtually no studies of the coagulation pathway in sea turtles whose ancestors date back to the Jurassic period. Sea turtles are often exposed to rapidly altered environmental conditions during diving periods. This may reduce their blood pH during prolonged hypoxic dives. This report demonstrates that five species of turtles possess only one branch of the mammalian coagulation pathway, the extrinsic pathway. Mixing studies of turtle plasmas with human factor-deficient plasmas indicate that the intrinsic pathway factors VIII and IX are present in turtle plasma. These two factors may play a significant role in supporting the extrinsic pathway by feedback loops. The intrinsic factors, XI and XII are not detected which would account for the inability of reagents to induce coagulation via the intrinsic pathway in vitro. The analysis of two turtle factors, factor II (prothrombin) and factor X, demonstrates that they are antigenically/functionally similar to the corresponding human factors. The turtle coagulation pathway responds differentially to both pH and temperature relative to each turtle species and relative to human samples. The coagulation time (prothrombin time) increases as the temperature decreases between 37 and 15 °C. The increased time follows a linear relationship, with similar slopes for loggerhead, Kemps ridley and hawksbill turtles as well as for human samples. Leatherback turtle samples show a dramatic nonlinear increased time below 23 °C, and green turtle sample responses were similar but less dramatic. All samples also showed increased prothrombin times as the pH decreased from 7.8 to 6.4, except for three turtle species. The prothrombin times decreased, to varying extents, in a linear fashion relative to reduced pH with the rate of change greatest in leatherbacks>green loggerhead turtles. All studies were conducted with reagents developed for human samples which would impact on the quantitative results with the turtle samples, but are not likely to alter the qualitative results. These comparative studies of the coagulation pathway in sea turtles and humans could enhance our knowledge of structure/function relationships and evolution of coagulation factors. |
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Keywords: | Prothrombin Coagulation cascade Hemostasis |
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