SUBCELLULAR ION DISTRIBUTIONS IN ACANTHAMOEBA CASTELLANII

收缩泡（CV）是一种可调节的细胞器， 生活在低渗环境中的变形虫。 钙调素，碱性 磷酸酶和质子泵已知与CV相关 和它的小管海绵体。 然而，产生的离子梯度 以及它们在水泵送机制中的作用 仍然未知。 提高对CV水调节的理解， 与其他系统的生理学相关，例如脊椎动物 肾 快速冷冻、冰冻切片、扫描等技术 透射电子显微镜、X射线光谱和电子显微镜 能量损失谱已被用于测量CV离子 快速冷冻阿米巴的冷冻切片中的浓度 castellanii。 低剂量暗场STEM提供了 稀释的亚细胞室中的离子浓度 首次 对于标准生长培养基中的细胞，初步结果 表明[Na+]：[K+]比率约为6：1;低[Cl-]， 表明HCO 3-为主要阴离子;总渗透压为 大约21摩尔。 这种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收缩 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.