Physiological and Molecular Characterization of Ca Pump and Exchanger; an Integrated Approach Modeled on the Freshwater Crayfish Molting Cycle

矿物质钙（简称Ca）具有重要的生物学基础。在动物中，它是骨骼和贝壳等生物矿物质的组成部分。它也是肌肉收缩和从细胞外部向细胞内部传递信息所必需的。由于这些原因，科学家们对钙如何在身体不同部位之间移动，特别是如何跨细胞膜（边界）运输非常感兴趣。由于两个原因，这些过程很容易在甲壳类动物（水生节肢动物）中模拟。首先，它们的碳酸钙骨架在外部，因此比脊椎动物的脊椎骨更容易接近。更重要的是，为了生长，它们经历了蜕皮周期，其中包括钙在动物体内和体外循环。在蜕皮的准备过程中，钙从旧骨架中被重新吸收，然后再循环或丢失（钙叶）。一旦旧骨架脱落，动物必须迅速矿化新骨架（钙进入）。钙通过专门的细胞层（上皮）离开/进入，这些细胞层直接或间接地与外部水交流。钙交换表面包括鳃、肾和肠。钙离子在这些细胞中的移动受到位于细胞膜上的特殊蛋白质的影响。特定蛋白质的制造是由细胞核中的遗传物质（称为DNA）控制的。在这项资助中，PI建议使用甲壳类动物的蜕皮周期来(1)研究钙在囊泡（类似于水球的重新密封的细胞膜斑块）中的运输动力学，(2)分离编码钙泵蛋白的DNA，并评估DNA的丰度是否受到类固醇的调节。这些研究将有助于了解所有细胞中常见的钙转运蛋白的进化。＊＊＊

9603723 Wheatly The mineral calcium (abbreviated Ca) is of fundamental biological importance. In animals it is a component of biominerals such as skeleton and shell. It is also necessary for muscle contraction and for relaying messages from the exterior to the interior of the cell. For these reasons, scientists are very interested in how Ca moves between different parts of the body and specifically how it is transported across cell membranes (boundaries). These processes are easily modeled in crustaceans (aquatic arthropods) for two reasons. First their calcium carbonate skeleton is external and therefore far more accessible than the backbone of vertebrates. More importantly, in order to grow, they undergo the molting cycle which involves Ca cycling out of and into the animal. In preparation for molting, Ca is reabsorbed from the old skeleton and either recycled or lost (Ca leaves). Once the old skeleton is shed, the animal must rapidly mineralize the new skeleton (calcium enters). Calcium leaves/enters via specialized layers of cells (epithelia) that communicate either directly or indirectly with the external water. The calcium exchanging surfaces include gill, kidney and gut. Ca movement across these cells is effected by specialized proteins situated in the cell membrane. Manufacture of specific proteins is under the control of genetic material (termed DNA) in the nucleus of the cell. In this grant, the PI proposes to use the crustacean molting cycle to (1) study the dynamics of Ca transport across vesicles (resealed patches of cell membrane akin to a water balloon) and to (2) isolate the DNA that codes for the Ca pumping proteins and to assess whether abundance of the DNA is regulated by steroids. These studies will enable understanding of the evolution of Ca transporting proteins common to all cells. ***