Collaborative Project: Calcium in the Early Development of Hydrozoans

里奇韦和弗里曼博士最近发现，几种水生动物的卵和胚胎含有类似于Aequorin的内源性钙指示剂。由于钙指示剂是天然的，存在于高浓度下，并且在钙存在的情况下特别发光，这些制剂为研究钙在早期发育中的作用提供了独特的机会。他们建议研究在这些生物体中控制膜上钙通道出现的第一次分裂的机制。这些通道可能在建立发育中的胚胎的前后轴方面发挥作用。他们将通过使用图像增强和图像增强技术，并结合异时细胞质的显微注射，来确定这些通道出现的位置和原因。他们发现，卵裂期胚胎的钾去极化会导致明亮的闪光，这在一定程度上是由于内部储存的钙释放。他们将研究通过钙通道进入钙和内部钙释放的耦合机制。他们将研究四种钙波的传播：1.由于IP3在未受精卵中扩散的钙波，2.可能发生在受精时的钙波，3.由于卵裂期胚胎去极化的钙波，以及4.伴随变态的钙波。钙作为许多细胞过程的调节器的重要性已经确定。问题仍然是钙的水平是如何控制的。里奇韦博士和弗里曼博士开发了一个强大的模型系统来解决这个问题。它利用了在水生动物胚胎中发现的一种自然产生的发光蛋白，这种蛋白在钙存在的情况下会发光。

Drs. Ridgway and Freeman have recently discovered that the eggs and embryos of several species of hydrozoans contain endogenous calcium indicators similar to aequorin. Because the calcium indicators are natural, exist in high concentration, and emit light specifically in the presence of calcium, these preparations offer unique opportunities for studying the role of calcium in early development. They propose to investigate the mechanism that controls the appearance of calcium channels in the membrane at first cleavage in these organisms. These channels could play a role in establishing the anterior-posterior axis of the developing embryo. They will determine where and why these channels appear by using image intensification and image enhancement techniques in conjunction with microinjection of heterochronic cytoplasm. They have discovered that potassium depolarization of cleavage stage embryos leads to a bright flash which is due in part to calcium release from an internal store. They will investigate the mechanism that couples the calcium entry through the calcium channels to the calcium release internally. They will study the propagation of four sorts of calcium waves: 1. those due to IP3 diffusion in unfertilized eggs, 2. those that may occur at fertilization, 3. those due to depolarization of cleavage stage embryos, and 4. those accompanying metamorphosis. %%% The importance of calcium as a regulator of a number of cellular processes has been established. The question remains as to how is the level of calcium itself controlled. Drs. Ridgway and Freeman have developed a powerful model system in which to address this question. It exploits a naturally occurring luminescent protein found in hydrozoan embryos which emits light in the presence of calcium.