Nemhauser I, Joseph-Silverstein J, Cohen W D
J Cell Biol. 1983 Apr;96(4):979-89. doi: 10.1083/jcb.96.4.979.
The erythrocytes of blood clams (arcidae) are flattened, elliptical, and nucleated. They contain elliptical marginal bands (MBs) of microtubules, each physically associated with a pair of centrioles marginal bands (MBs) of microtubles, each physically associated with a pair of centrioles (Cohen, W., and I. Nemhauser, 1980, J. Cell Biol., 86:286-291). The MBs were found to be cold labile in living cells, disappearing within 1-2 h at 0 degrees C. After the cells had been rewarmed for 1-2 h, continuous MBs with associated centrioles were once again present. Time-course studies utilizing phase contrast, antitubulin immunofluorescence, and electron microscopy of cytoskeletons prepared during rewarming revealed structural evidence of centriole participation in MB reassembly. At the earliest stage of reassembly, a continuous MB was not present. Instead, relatively short and straight microtubules focused on a pointed centriolar "pole," and none were present elsewhere in the cytoskeleton. Thin continuous MBs then formed, still pointed in the centriolar region. Subsequently, the MBs regained ellipticity, with their thickness gradually increasing but not reaching that of controls even after several hours of rewarming. At these later time points, microtubules still radiated from the centrioles and joined the MBs some distance away. In the presence of 0.1 mM colchicines, MB reassembly was arrested at the pointed stage. Electron microscopic observations indicate that pericentriolar material is involved in microtubule nucleation in this system, rather than the centriolar triplets directly. The results suggest a model in which the centrioles and associated material nucleate assembly and growth of microtubules in diverging directions around the cell periphery. Microtubules of opposite polarity would then pass each other at the end of the cell distal to the centrioles, with continued elongation eventually closing the MB ellipse behind the centriole pair.
蚶科（Arcidae）血蛤的红细胞呈扁平状、椭圆形，且有细胞核。它们含有椭圆形的微管边缘带（MBs），每条微管边缘带都与一对中心粒实际相连（科恩，W.，和I. 内姆豪泽，1980年，《细胞生物学杂志》，86:286 - 291）。研究发现，在活细胞中微管边缘带对低温敏感，在0摄氏度下1 - 2小时内就会消失。细胞复温1 - 2小时后，又会再次出现带有相连中心粒的连续微管边缘带。利用相差显微镜、抗微管蛋白免疫荧光以及复温过程中制备的细胞骨架的电子显微镜进行的时间进程研究，揭示了中心粒参与微管边缘带重新组装的结构证据。在重新组装的最早阶段，不存在连续的微管边缘带。相反，相对短而直的微管集中在一个尖锐的中心粒“极”上，细胞骨架的其他地方都没有。然后形成了细的连续微管边缘带，仍然指向中心粒区域。随后，微管边缘带恢复椭圆形，其厚度逐渐增加，但即使复温几个小时后也未达到对照组的厚度。在这些较晚的时间点，微管仍然从中心粒放射状发出，并在一段距离外与微管边缘带相连。在存在0.1 mM秋水仙碱的情况下，微管边缘带的重新组装在尖锐阶段被阻止。电子显微镜观察表明，在这个系统中，中心粒周围物质参与微管的成核，而不是中心粒三联体直接参与。结果提出了一个模型，即中心粒和相关物质在细胞周边沿着不同方向成核微管的组装和生长。相反极性的微管然后会在细胞远离中心粒的一端相互穿过，随着持续延长最终在中心粒对后面封闭微管边缘带的椭圆形。
