Fukui Y, Murray J, Riddelle K S, Soll D R
Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611.
Cell Struct Funct. 1991 Aug;16(4):289-301. doi: 10.1247/csf.16.289.
The behavior of individual Dictyostelium amebae was quantitatively analyzed with the computer-assisted "Dynamic Morphology System" (Soll, Voss, Varnum-Finney and Wessels, (1988) J. Cell. Biochem., 37: 177-192.). The same amoebae were then fixed and analyzed for filamentous (F-) actin and myosin (myosin-II, or "conventional" myosin) by fluorescence microscopy using the "agar-overlay method" (Yumura, and Fukui (1985) Nature, 314: 194-196.). This procedure provides a novel description of the behavior and morphometric changes preceding the static analysis of cytoskeletal organization in the same cell. It is demonstrated that when translocating cells make contact with an etched-smooth glass interface, 14% cross the interface, 20% either reverse direction or migrate along the interface, and the remaining 45% stay at the site. Cells contacting the interface from the smooth or etched side show equivalent behavioral responses. Upon contact with the interface, they project numerous lamellipodia and pseudopodia. While the lamellipodial projections exhibit cycles of spreading and retraction, the pseudopodia show lateral scanning motion, analogous to "substrate exploration" in fibroblasts (Albrecht-Buehler (1976) J. Cell Biol., 69: 275-286.). F-actin is localized in the lamellipodia and pseudopodia of amoebae contacting the interface. There is also discernable cortical F-actin, while conventional myosin appears to be excluded from the cortex and dispersed throughout the cytoplasm. The myosin displays a transient filamentous lattice at the base of newly forming lamellipodia. The ultrastructural study suggests that the new lamellipodia are formed on the dorsal surface and subsequently make contact with the substrate, indicating the dorsoventral sequence of polarity of the motile/sensory cellular organs. The present study demonstrates substrate exploration in Dictyostelium amoebae, and suggests its coupling to dynamic reorganization of the actomyosin cytoskeleton. The possible role of single-headed small myosin(s) (myosin-I, or mini-myosin) is discussed.
利用计算机辅助的“动态形态系统”（索尔、沃斯、瓦纳姆 - 芬尼和韦塞尔，（1988年）《细胞生物化学杂志》，37卷：177 - 192页）对单个盘基网柄菌变形虫的行为进行了定量分析。然后将相同的变形虫固定，使用“琼脂覆盖法”（汤村和福井（1985年）《自然》，314卷：194 - 196页）通过荧光显微镜分析丝状（F -）肌动蛋白和肌球蛋白（肌球蛋白 - II，或“传统”肌球蛋白）。该程序为同一细胞中细胞骨架组织的静态分析之前的行为和形态测量变化提供了一种新颖的描述。结果表明，当迁移的细胞与蚀刻光滑的玻璃界面接触时，14%穿过界面，20%改变方向或沿界面迁移，其余45%停留在原地。从光滑面或蚀刻面接触界面的细胞表现出等效的行为反应。接触界面后，它们会伸出许多片状伪足和伪足。虽然片状伪足的伸出表现出伸展和收缩的循环，但伪足表现出横向扫描运动，类似于成纤维细胞中的“底物探索”（阿尔布雷希特 - 比勒（1976年）《细胞生物学杂志》，69卷：275 - 286页）。F - 肌动蛋白定位于接触界面的变形虫的片状伪足和伪足中。也可辨别出皮质F - 肌动蛋白，而传统肌球蛋白似乎被排除在皮质之外并分散在整个细胞质中。肌球蛋白在新形成的片状伪足基部显示出短暂的丝状晶格。超微结构研究表明，新的片状伪足在背表面形成，随后与底物接触，表明运动/感觉细胞器官极性的背腹顺序。本研究证明了盘基网柄菌变形虫中的底物探索，并表明其与肌动球蛋白细胞骨架的动态重组相关。还讨论了单头小肌球蛋白（肌球蛋白 - I，或微型肌球蛋白）的可能作用。
