Soslau Gerald, Wallace Bryan, Vicente Catherine, Goldenberg Seth J, Tupis Todd, Spotila James, George Robert, Paladino Frank, Whitaker Brent, Violetta Gary, Piedra Rotney
Department of Biochemistry, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
Comp Biochem Physiol B Biochem Mol Biol. 2004 Aug;138(4):399-406. doi: 10.1016/j.cbpc.2004.05.004.
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 degrees 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 degrees 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.
功能性止血途径对所有脊椎动物的生存至关重要，并且已经进化了超过4亿年。绝大多数关于脊椎动物止血的研究都集中在哺乳动物上，而对爬行动物的关注非常少。实际上，对于其祖先可追溯到侏罗纪时期的海龟的凝血途径几乎没有研究。海龟在潜水期间经常暴露于快速变化的环境条件下。这可能会在长时间的低氧潜水中降低它们的血液pH值。本报告表明，五种海龟仅拥有哺乳动物凝血途径的一个分支，即外源性途径。海龟血浆与人类缺乏因子的血浆的混合研究表明，内源性途径因子VIII和IX存在于海龟血浆中。这两种因子可能通过反馈回路在支持外源性途径中发挥重要作用。未检测到内源性因子XI和XII，这可以解释试剂在体外无法通过内源性途径诱导凝血的原因。对两种海龟因子，即因子II（凝血酶原）和因子X的分析表明，它们在抗原性/功能上与相应的人类因子相似。相对于每种海龟物种以及相对于人类样本，海龟凝血途径对pH和温度的反应有所不同。在37至15摄氏度之间，随着温度降低，凝血时间（凝血酶原时间）增加。增加的时间呈线性关系，蠵龟、肯氏丽龟和玳瑁以及人类样本的斜率相似。棱皮龟样本在23摄氏度以下显示出显著的非线性增加时间，绿海龟样本的反应相似但不太显著。除了三种海龟物种外，所有样本在pH从7.8降至6.4时也显示出凝血酶原时间增加。凝血酶原时间相对于pH降低呈线性下降，变化速率在棱皮龟>绿海龟>>蠵龟中最大。所有研究均使用为人类样本开发的试剂进行，这会影响海龟样本的定量结果，但不太可能改变定性结果。这些对海龟和人类凝血途径的比较研究可以增强我们对凝血因子的结构/功能关系和进化的认识。
