阿米巴样运动的收缩基础。II. 运动提取物和质膜-外质体幽灵的结构与收缩性

The contractile basis of ameboid movement. II. Structure and contractility of motile extracts and plasmalemma-ectoplasm ghosts.

作者信息

Taylor D L, Rhodes J A, Hammond S A

出版信息

J Cell Biol. 1976 Jul;70(1):123-43. doi: 10.1083/jcb.70.1.123.

DOI:10.1083/jcb.70.1.123

PMID:6480

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC2109811/

Abstract

The role of calcium and magnesium-ATP on the structure and contractility in motile extracts of Amoeba proteus and plasmalemma-ectoplasm "ghosts" of Chaos carolinensis has been investigated by correlating light and electron microscope observations with turbidity and birefringence measurements. The extract is nonmotile and contains very few F-actin filaments and myosin aggregates when prepared in the presence of both low calcium ion and ATP concentrations at an ionic strength of I = 0.05, pH 6.8. The addition of 1.0 mM magnesium chloride, 1.0 mM ATP, in the presence of a low calcium ion concentration (relaxation solution) induced the formation of some fibrous bundles of actin without contracting, whereas the addition of a micromolar concentration of calcium in addition to 1.0 mM magnesium-ATP (contraction solution) (Taylor, D. L., J. S. Condeelis, P. L. Moore, and R. D. Allen. 1973. J. Cell Biol. 59:378-394) initiated the formation of large arrays of F-actin filaments followed by contractions. Furthermore, plasmalemma-ectoplasm ghosts prepared in the relaxation solution exhibited very few straight F-actin filaments and myosin aggregates. In contrast, plasmalemmaectoplasm ghosts treated with the contraction solution contained many straight F-actin filaments and myosin aggregates. The increase in the structure of ameba cytoplasm at the endoplasm-ectoplasm interface can be explained by a combination of the transformation of actin from a less filamentous to a more structured filamentous state possibly involving the cross-linking of actin to form fibrillar arrays (see above-mentioned reference) followed by contractions of the actin and myosin along an undetermined distance of the endoplasm and/or ectoplasm.

摘要

通过将光学显微镜和电子显微镜观察结果与浊度和双折射测量结果相关联，研究了钙和镁 - ATP对变形虫（Amoeba proteus）活动提取物以及卡罗林海怪（Chaos carolinensis）质膜 - 外质“幽灵”的结构和收缩性的作用。当在离子强度I = 0.05、pH 6.8的低钙离子和ATP浓度存在下制备提取物时，该提取物不具有运动性，并且包含极少的F - 肌动蛋白丝和肌球蛋白聚集体。在低钙离子浓度（松弛溶液）存在下添加1.0 mM氯化镁、1.0 mM ATP会诱导形成一些不收缩的肌动蛋白纤维束，而除了1.0 mM镁 - ATP（收缩溶液）之外添加微摩尔浓度的钙（Taylor, D. L., J. S. Condeelis, P. L. Moore, and R. D. Allen. 1973. J. Cell Biol. 59:378 - 394）会引发大量F - 肌动蛋白丝阵列的形成，随后发生收缩。此外，在松弛溶液中制备的质膜 - 外质幽灵显示出极少的直F - 肌动蛋白丝和肌球蛋白聚集体。相比之下，用收缩溶液处理的质膜 - 外质幽灵含有许多直F - 肌动蛋白丝和肌球蛋白聚集体。内质 - 外质界面处变形虫细胞质结构的增加可以通过肌动蛋白从较少丝状状态转变为更结构化的丝状状态（可能涉及肌动蛋白交联形成纤维状阵列，见上述参考文献），随后肌动蛋白和肌球蛋白在内质和/或外质的不确定距离上收缩来解释。