Wong G K, Allen P G, Begg D A
Department of Anatomy and Cell Biology, University of Alberta, Edmonton, Canada.
Cell Motil Cytoskeleton. 1997;36(1):30-42. doi: 10.1002/(SICI)1097-0169(1997)36:1<30::AID-CM3>3.0.CO;2-L.
We have used confocal laser scanning microscopy in conjunction with BODIPY-phallacidin staining of filamentous actin to investigate changes in the quantity and organization of cortical actin during the first two cell cycles following fertilization in eggs of the sea urchin Strongylocentrotus purpuratus. Quantification of fluorescent phallacidin staining reveals that the amount of filamentous actin (F-actin) in the cortex undergoes cyclical increases and decreases during early cleavage divisions, peaking near the beginning of the cell cycle and decreasing to a minimum at cytokinesis. Changes in the content of cortical F-actin are accompanied by the growth and disappearance of rootlet-like bundles of actin filaments which extend from the bases of microvilli that cover the surface of the egg. Actin rootlets reach their maximum degree of development by 20 min postfertilization, and then gradually decrease in number and length over the next 40 min. Small actin rootlets persist until cleavage, disappear during cytokinesis, and reform following division. The formation of actin rootlets requires cytoplasmic alkalization and is inhibited by cytochalasin D. Cytochalasin D washout experiments demonstrate that assembly of the cortical actin cytoskeleton can be blocked until 5 min before the onset of cleavage and still allow normal cytokinesis. These results illustrate the dynamic nature of cortical actin organization during early development and demonstrate that cytokinesis occurs at the point of minimum cortical F-actin content. They further demonstrate that cytokinesis can occur in embryos in which the normal developmental sequence of changes in cortical actin organization has been blocked by treatment with cytochalasin D, suggesting that these changes do not function in the establishment of the contractile apparatus for cytokinesis, but rather serve other developmental functions. Cell Motil. Cytoskeleton 36:30-42, 1997.
我们运用共聚焦激光扫描显微镜，结合丝状肌动蛋白的BODIPY - 鬼笔环肽染色，来研究紫海胆（Strongylocentrotus purpuratus）卵受精后的前两个细胞周期中皮质肌动蛋白的数量和组织变化。荧光鬼笔环肽染色的定量分析显示，在早期卵裂过程中，皮质中丝状肌动蛋白（F - 肌动蛋白）的量呈周期性增减，在细胞周期开始时达到峰值，在胞质分裂时降至最低。皮质F - 肌动蛋白含量的变化伴随着从覆盖卵表面的微绒毛基部延伸出的根状肌动蛋白丝束的生长和消失。肌动蛋白根在受精后20分钟达到最大发育程度，然后在接下来的40分钟内数量和长度逐渐减少。小的肌动蛋白根持续到卵裂，在胞质分裂时消失，并在分裂后重新形成。肌动蛋白根的形成需要细胞质碱化，并受到细胞松弛素D的抑制。细胞松弛素D洗脱实验表明，皮质肌动蛋白细胞骨架的组装可以被阻断至卵裂开始前5分钟，且仍能允许正常的胞质分裂。这些结果说明了早期发育过程中皮质肌动蛋白组织的动态性质，并证明胞质分裂发生在皮质F - 肌动蛋白含量最低的时刻。它们进一步证明，在经细胞松弛素D处理而使皮质肌动蛋白组织正常发育序列变化受阻的胚胎中仍可发生胞质分裂，这表明这些变化在胞质分裂收缩装置的建立中不起作用，而是发挥其他发育功能。《细胞运动与细胞骨架》36:30 - 42, 1997年。
