Roles and regulation of aqua/glyceroporins in a freeze tolerant amphibian

通过冷冻保存生物组织在从生殖技术到濒危物种保护的各个领域都有应用。然而，尽管科学家可以成功地超低温保存卵子和胚胎等小型活结构，但将这些策略应用于更大的结构仍然具有挑战性。自然界可以为克服这些挑战提供洞察力。许多“冷血”动物在它们的自然环境中遇到了零度以下的温度，在脊椎动物中，有几个物种已经进化出了在寒冷中生存的生理和生化策略。本项目将研究其中的一个物种，科普？S灰色树蛙。冷冻给动物带来了艰巨的挑战，包括冰对身体的潜在损害，血液冻结和解冻时组织氧合的波动，以及液态水冻结和体液浓度变化对分子和细胞结构的破坏。在这些挑战中生存下来的一个关键是对水和溶解溶质的分布进行调控。结冰必须限制在细胞外的液体中，因此当冰冻开始时，水必须能够迅速离开细胞。此外，一些溶质，如甘油，具有低温保护作用，有助于在冷冻过程中保持分子和生理的完整性。灰色树蛙为解开这些能力背后的机制提供了一个自然的模型。在凉爽的秋季，它们会积累甘油。它们还调节促进水和甘油跨细胞膜移动的蛋白质(“水通道蛋白”)的表达。这个项目将评估这些分子机制是如何调节的，对细胞特性的结果是什么影响，以及这如何有助于整个动物的耐冻性。这种综合的方法为从高中到博士水平的学生提供了一个很好的框架，培训他们分子生理调节的方法和思想，并将对保持组织冷冻存活的挑战产生新的见解。

Preservation of biological tissues by freezing has application in fields ranging from reproductive technology to conservation of endangered species. However, while scientists can successfully cryopreserve small living structures like eggs and embryos, application of those strategies to larger structures remains challenging. The natural world can provide insights into overcoming those challenges. Many "cold-blooded" animals encounter sub-freezing temperatures in their natural environment and, among the vertebrates, a few species have evolved physiological and biochemical strategies to survive freezing. This project will study one of those species, Cope?s gray treefrog. Freezing imposes daunting challenges for an animal, including potential physical damage from ice, fluctuating tissue oxygenation as the blood freezes and thaws, and disruption of molecular and cellular structures as liquid water freezes and body fluid concentrations change. A key to surviving these challenges is regulation of the distribution of water and dissolved solutes. Ice formation must be restricted to fluids outside of cells, and so water must be able to leave cells rapidly when freezing begins. In addition, some solutes, such as glycerol are cryoprotective and help to preserve molecular and physiological integrity during freezing. Gray treefrogs present a natural model for unraveling the mechanisms behind these capabilities. During the cooling autumn months they accumulate glycerol. They also regulate the expression of proteins ("aquaporins") that facilitate movement of water and glycerol across cell membranes. This project will evaluate how these molecular mechanisms are regulated, what is the resulting impact on cellular properties, and how this contributes to freeze tolerance of the whole animal. This integrative approach provides an excellent framework for training students from high school through PhD level in methods and ideas of molecular physiological regulation, and it will yield novel insights into the challenge of keeping tissues frozen alive.