The Ecological Physiology of a Supercooled Vertebrate

过冷脊椎动物的生态生理学

• 批准号: 0112283
• 负责人: Gary Packard
• 金额: $ 33.01万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0112283&HistoricalAwards=false
• 关键词: Ecological; Physiology; Supercooled; Vertebrate

This is a proposal to investigate the ecological physiology of overwintering hatchlings of the North American painted turtle (Chrysemys picta). This widely-distributed and abundant species has become a model organism for studies on the ecology and evolution of freshwater chelonians. The natural history of painted turtles differs from that of most other species in an important respect, however. Whereas neonates of other aquatic turtles usually emerge from their nest in late summer or autumn and move to a nearby marsh, lake, or stream to spend their first winter, hatchling painted turtles typically remain inside their shallow, subterranean nest throughout their first winter and do not come above ground until the following spring. This behavior commonly causes neonatal painted turtles at northern localities to be exposed during winter to ice and cold with temperatures in some nests going below -10oC. Many hatchlings withstand such exposure and emerge from their nest when the ground finally thaws in the spring.Hatchlings tolerate the cold of mid-winter by becoming supercooled (i.e., they remain unfrozen at temperatures below the equilibrium freezing point for their bodily fluids). Although this "adaptive strategy" has many benefits for neonatal turtles, the strategy also has important consequences one of the more important of which is a shutdown of the circulation at temperatures near -10oC. The proposed investigation will focus on the use of energy reserves by liver, heart, and brain in animals subjected to the stagnant anoxia that results from shutdown of the circulation, and on the patterns of accumulation by different organs of the lactic acid that is produced in anaerobic respiration. The work will yield important new insights concerning the physiology of neonatal turtles and also may identify new methods for storing transplantable organs for use in human and/or veterinary medicine.

本文旨在探讨北美彩龟越冬幼体的生态生理。 这种分布广泛且数量丰富的物种已成为研究淡水龟类生态和进化的模式生物。 然而，彩龟的自然历史在一个重要方面与大多数其他物种不同。 其他水龟的新生儿通常在夏末或秋季从巢中出来，搬到附近的沼泽、湖泊或溪流度过他们的第一个冬天，而孵化的彩龟通常在他们的第一个冬天呆在他们的浅的地下巢中，直到第二年春天才出现在地面上。 这种行为通常导致北方地区的新生彩龟在冬季暴露在冰冷的环境中，一些巢穴的温度低于-10 ° C。 许多幼龟经受住了这样的暴露，并在春季地面最终解冻时从巢中出来。幼龟通过变得过冷来忍受仲冬的寒冷（即，它们在低于其体液的平衡凝固点的温度下保持不冻结）。 虽然这种“适应性策略”对新生海龟有许多好处，但这种策略也有重要的后果，其中一个更重要的后果是在接近-10 ° C的温度下关闭循环。 拟议的调查将集中在使用能量储备的肝脏，心脏和大脑在动物受到停滞缺氧，导致关闭的循环，并在模式的积累由不同器官的乳酸产生的无氧呼吸。 这项工作将产生关于新生海龟生理学的重要新见解，也可能确定用于人类和/或兽医学的可移植器官储存的新方法。