Maupin P, Pollard T D
J Ultrastruct Mol Struct Res. 1986 Jan;94(1):92-103. doi: 10.1016/0889-1605(86)90055-8.
We used a glutaraldehyde-tannic acid-saponin fixative to improve the preservation of actin filaments in dividing HeLa cells during preparation for thin sectioning. The contractile ring in the cleavage furrow is composed of a parallel array of actin filaments that circle the equator. We show that many of these actin filaments are arranged in small bundles. These bundles consist of about 25 filaments throughout cytokinesis. For comparison, filopodia on these cells have about 23 actin filaments packed at a higher density than the filaments in the contractile ring bundles. Some of the contractile ring actin filaments appear to radiate out from electron-dense sites on the plasma membrane. The contractile ring also has a large number of short filaments 13 nm in diameter that closely resemble filaments formed from purified human cytoplasmic myosin. These thick filaments are aligned circumferentially and interdigitate with the actin filaments, as expected for a sliding filament mechanism of tension generation. There are no long actin filaments in the mitotic spindle, but there are a large number (400 to 1000 per micron 3) of very short filaments identical in appearance to actin filaments in other parts of these cells. These short filaments may account for the reported staining of the mitotic spindle with fluorescent antibodies to actin and with fluorescent myosin fragments.
我们使用戊二醛-单宁酸-皂苷固定剂，以在制备用于超薄切片的分裂期海拉细胞时更好地保存肌动蛋白丝。分裂沟中的收缩环由围绕赤道平行排列的肌动蛋白丝组成。我们发现这些肌动蛋白丝中有许多排列成小束。在整个胞质分裂过程中，这些束由约25条丝组成。作为比较，这些细胞上的丝状伪足有大约23条肌动蛋白丝，其排列密度高于收缩环束中的丝。一些收缩环肌动蛋白丝似乎从质膜上的电子致密位点辐射出来。收缩环还有大量直径为13nm的短丝，与由纯化的人细胞质肌球蛋白形成的丝非常相似。这些粗丝沿圆周排列，并与肌动蛋白丝相互交错，这符合产生张力的滑动丝机制的预期。有丝分裂纺锤体中没有长的肌动蛋白丝，但有大量（每立方微米400至1000条）外观与这些细胞其他部位的肌动蛋白丝相同的非常短的丝。这些短丝可能解释了用抗肌动蛋白荧光抗体和荧光肌球蛋白片段对有丝分裂纺锤体进行染色的报道。
