SUBCELLULAR ION DISTRIBUTIONS IN ACANTHAMOEBA CASTELLANII

收缩空泡(CV)是一种渗透调节细胞器，发现于 生活在低渗环境中的阿米巴虫。碱性钙调蛋白 磷酸酶和质子泵与血管紧张素转换酶相关。 以及它的小管海绵体。然而，产生的离子梯度 跨CV膜及其在抽水机制中的作用 仍然不为人所知。对CV水分调节的更好理解可能会 与其他系统的生理学有关，如脊椎动物 肾脏。快速冷冻、冷冻、扫描技术 透射电子显微镜、x射线光谱学和电子 能量损失光谱学已被用于测量循环伏安离子。 速冻棘阿米巴冰冻切片中的浓度 卡斯特拉尼。低剂量暗视野STEM提供了一种估计 稀释亚细胞隔间中的离子浓度 第一次。对于标准生长介质中的细胞，初步结果 表示[Na+]：[K+]比约为6：1；低[Cl-]， 表明HCO3-是主要的阴离子；总渗透压为 大约21个摩尔分子。这一新方法使我们能够探索如何 外部低渗和高渗离子环境影响不孕症 液泡离子浓度。

The contractile vacuole (CV) is an osmoregulatory organelle found in amoebae that live in hypotonic environments. Calmodulin, alkaline phosphatase, and a proton pump are known to be associated with the CV and its spongiome of tubules. However, the ion gradients generated across the CV membrane and their role in the water-pumping mechanism remain unknown. An improved understanding of CV water regulation may be relevant to the physiology of other systems, such as the vertebrate kidney. The techniques of rapid freezing, cryosectioning, scanning transmission electron microscopy, x-ray spectroscopy, and electron energy-loss spectroscopy have been adapted to measure CV ion concentrations in cryosections of rapidly frozen Acanthamoeba castellanii. Low-dose dark-field STEM has provided an estimation of the ion concentrations in dilute subcellular compartments for the first time. For cells in standard growth medium, preliminary results indicate a [Na+]:[K+] ratio of approximately 6:1; low [Cl-], suggesting HCO3- as the major anion; and a total osmolality of approximately 21 mosmoles. This new approach allows us to explore how external hypotonic and hypertonic ionic environments affect contracile vacuole ion concentrations.