Abstract
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 μm, 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.
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Selected References
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- Diacumakos E. G., Holland S., Pecora P. Microsurgical studies on human cells and cloning of HeLa cells. Nature. 1971 Jul 2;232(5305):28–32. doi: 10.1038/232028a0. [DOI] [PubMed] [Google Scholar]
- Gingell D. Contractile responses at the surface of an amphibian egg. J Embryol Exp Morphol. 1970 Jun;23(3):583–609. [PubMed] [Google Scholar]
- Jeon K. W., Danielli J. F. Micrurgical studies with large free-living amebas. Int Rev Cytol. 1971;30:49–89. doi: 10.1016/s0074-7696(08)60046-7. [DOI] [PubMed] [Google Scholar]
- Jeon K. W., Lorch I. J. New simple method of micrurgy on living cells. Nature. 1968 Feb 3;217(5127):463–463. doi: 10.1038/217463a0. [DOI] [PubMed] [Google Scholar]
- Jeon K. W. Simple method for staining and preserving epoxy resin-embedded animal tissue sections for light microscopy. Life Sci. 1965 Oct;4(19):1839–1841. doi: 10.1016/0024-3205(65)90064-0. [DOI] [PubMed] [Google Scholar]
- Luckenbill L. M. Dense material associated with wound closure in the axolotl egg (A. mexicanum). Exp Cell Res. 1971 May;66(1):263–267. doi: 10.1016/s0014-4827(71)80039-3. [DOI] [PubMed] [Google Scholar]
- NACHMIAS V. T. FIBRILLAR STRUCTURES IN THE CYTOPLASM OF CHAOS CHAOS. J Cell Biol. 1964 Oct;23:183–188. doi: 10.1083/jcb.23.1.183. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nachmias V. T., Huxley H. E. Electron microscope observations on actomyosin and actin preparations from Physarum polycephalum, and on their interaction with heavy meromyosin subfragment I from muscle myosin. J Mol Biol. 1970 May 28;50(1):83–90. doi: 10.1016/0022-2836(70)90105-1. [DOI] [PubMed] [Google Scholar]
- Pollard T. D., Ito S. Cytoplasmic filaments of Amoeba proteus. I. The role of filaments in consistency changes and movement. J Cell Biol. 1970 Aug;46(2):267–289. doi: 10.1083/jcb.46.2.267. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pollard T. D., Korn E. D. Filaments of Amoeba proteus. II. Binding of heavy meromyosin by thin filaments in motile cytoplasmic extracts. J Cell Biol. 1971 Jan;48(1):216–219. doi: 10.1083/jcb.48.1.216. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schäfer-Danneel S. Strukturelle und funktionelle Voraussetzungen für die Bewegung von Amoeba proteus. Z Zellforsch Mikrosk Anat. 1967;78(4):441–462. [PubMed] [Google Scholar]
- Spudich J. A., Clarke M. The contractile proteins of Dictyostelium discoideum. J Supramol Struct. 1974;2(2-4):150–162. doi: 10.1002/jss.400020209. [DOI] [PubMed] [Google Scholar]
- Szubinska B. "New membrane" formation in Amoeba proteus upon injury of individual cells. Electron microscope observations. J Cell Biol. 1971 Jun;49(3):747–772. doi: 10.1083/jcb.49.3.747. [DOI] [PMC free article] [PubMed] [Google Scholar]