Jeon K W, Jeon M S
J Cell Biol. 1975 Oct;67(1):243-9. doi: 10.1083/jcb.67.1.243.
The flexibility and self-healing properties of animal cell surface membranes are well known. These properties have been best exploited in various micrurgical studies on living cells (2, 3), especially in amoebae (7, 20). During nuclear transplantation in amoebae, the hole in the membrane through which a nucleus passes can have a diameter of 20-30 mum, and yet such holes are quickly sealed, although some cytoplasm usually escapes during the transfer. While enucleating amoebae in previous studies, we found that if a very small portion of a nucleus was pushed through the membrane and exposed to the external medium, the amoeba expelled such a nucleus on its own accord. When this happened, a new membrane appeared to form around the embedded portion of the nucleus and no visible loss of cytoplasm occurred during nuclear extrusion. In the present study, we examined amoebae that were at different stages of expelling partially exposed nuclei, to follow the sequence of events during the apparent new membrane formation. Unexpectedly, we found that a new membrane is not formed around the nucleus from inside but a hole is sealed primarily by a constriction of the existing membrane, and that cytoplasmic filaments are responsible for the prevention of the loss of cytoplasm.
动物细胞表面膜的柔韧性和自我修复特性是众所周知的。这些特性在对活细胞进行的各种显微手术研究中得到了最充分的利用(2,3)，尤其是在变形虫中(7,20)。在变形虫的核移植过程中，细胞核穿过的细胞膜上的孔直径可达20-30微米，然而，尽管在转移过程中通常会有一些细胞质逸出，但这些孔会很快被封闭。在之前的去核变形虫研究中，我们发现，如果将细胞核的一小部分推过细胞膜并暴露于外部介质中，变形虫会自行排出这样的细胞核。当这种情况发生时，新的膜似乎会在细胞核的嵌入部分周围形成，并且在核挤出过程中没有明显的细胞质损失。在本研究中，我们检查了处于排出部分暴露细胞核不同阶段的变形虫，以跟踪明显的新膜形成过程中的一系列事件。出乎意料的是，我们发现新膜不是从内部围绕细胞核形成，而是一个孔主要通过现有膜的收缩来封闭，并且细胞质细丝负责防止细胞质流失。
