Electron microscopic studies of mitosis in amebae. II. The giant ameba Pelomyxa carolinensis.
Electron microscopic studies of mitosis in amebae. II. The giant ameba Pelomyxa carolinensis.
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DOI：
10.1083/jcb.12.1.57
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发表时间：
1962-01
期刊：
影响因子：
--
通讯作者：
DANIELS EW
中科院分区：
文献类型：
--
作者：
ROTH LE;DANIELS EW
将巨型变形虫Pelmyxa carolinensis分离的细胞核固定在四氧化三铯溶液中，该溶液以韦罗纳醋酸酯为缓冲溶液至pH 8.0。如果在固定液中加入二价阳离子(0.002 M钙、镁或锶作为氯化物)，则在纺锤体中可观察到直径14m微米、皮质致密的纤维。如果省略二价离子，则存在较小尺寸的定向粒子，纤维不明显。观察有丝分裂的不同阶段，比较纺锤体成分。在钙离子存在下固定的纤维在中期早期不像后期那样清晰，但在中期晚期、后期和末期早期具有相同的直径。除了末期早期，原纤维被细小的物质云包围着，这时它们形成紧密的束状，躺在细胞质中，与细胞核无关。没有钙离子固定的中期和后期纤维不那么清晰，彼此之间没有明显的差异。这些观察结果与纺锤体纤维是由聚合的、定向的蛋白质分子组成的概念是一致的，这些分子与相同蛋白质的非定向分子保持平衡并沐浴在其中。当核膜仅有小的不连续时，在混合质中可观察到部分形成的纺锤体纤维和核糖体样颗粒。包膜的残留物在整个分裂过程中都是可见的，很可能在末期并入新的包膜。核糖体样颗粒在中期和后期纺锤体中大量存在，但在末期核、被膜重建后或间期核中看不到。
Dividing nuclei from the giant ameba Pelomyxa carolinensis were fixed in osmium tetroxide solutions buffered with veronal acetate to pH 8.0. If divalent cations (0.002 M calcium, magnesium, or strontium as chlorides) were added to the fixation solution, fibrils that are 14 mµ in diameter and have a dense cortex are observed in the spindle. If the divalent ions were omitted, oriented particles of smaller size are present and fibrils are not obvious. The stages of mitosis were observed and spindle components compared. Fibrils fixed in the presence of calcium ions are not so well defined in early metaphase as later, but otherwise have the same diameter in the late metaphase, anaphase, and early telophase. Fibrils are surrounded by clouds of fine material except in early telophase, when they are formed into tight bundles lying in the cytoplasm unattached to nuclei. Metaphase and anaphase fibrils fixed without calcium ions are less well defined and are not observably different from each other. The observations are consistent with the concept that spindle fibrils are composed of polymerized, oriented protein molecules that are in equilibrium with and bathed in non-oriented molecules of the same protein. Partially formed spindle fibrils and ribosome-like particles were observed in the mixoplasm when the nuclear envelope had only small discontinuities. Remnants of the envelope are visible throughout division and are probably incorporated into the new envelope in the telophase. Ribosome-like particles are numerous in the metaphase and anaphase spindle but are not seen in the telophase nucleus, once the envelope is reestablished, or in the interphase nucleus.