Faculty Opinions recommendation of Nuclear envelope formation by chromatin-mediated reorganization of the endoplasmic reticulum.

2007 ◽  
Author(s):  
Thorsten Hoppe
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Nuclear Envelope Formation

scholarly journals Reshaping of the endoplasmic reticulum limits the rate for nuclear envelope formation

2008 ◽  
Vol 182 (5) ◽  
pp. 911-924 ◽  
Author(s):  
Daniel J. Anderson ◽  
Martin W. Hetzer
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Mammalian Cells ◽  
Time Lapse ◽  
Principal Mechanism ◽  
Nuclear Assembly ◽  
Nuclear Envelope Formation ◽  
Rate Limiting

During mitosis in metazoans, segregated chromosomes become enclosed by the nuclear envelope (NE), a double membrane that is continuous with the endoplasmic reticulum (ER). Recent in vitro data suggest that NE formation occurs by chromatin-mediated reorganization of the tubular ER; however, the basic principles of such a membrane-reshaping process remain uncharacterized. Here, we present a quantitative analysis of nuclear membrane assembly in mammalian cells using time-lapse microscopy. From the initial recruitment of ER tubules to chromatin, the formation of a membrane-enclosed, transport-competent nucleus occurs within ∼12 min. Overexpression of the ER tubule-forming proteins reticulon 3, reticulon 4, and DP1 inhibits NE formation and nuclear expansion, whereas their knockdown accelerates nuclear assembly. This suggests that the transition from membrane tubules to sheets is rate-limiting for nuclear assembly. Our results provide evidence that ER-shaping proteins are directly involved in the reconstruction of the nuclear compartment and that morphological restructuring of the ER is the principal mechanism of NE formation in vivo.

scholarly journals Endoplasmic reticulum hypertrophy and nuclear envelope formation - a. postulate

2015 ◽  
Vol 48 (3) ◽  
pp. 381-389
Author(s):  
J. A. Tarkowska
Keyword(s):  
Aqueous Solution ◽  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Nerium Oleander ◽  
Membrane Structures ◽  
Nuclear Envelope Formation

Dividing endosperm cells of <i>Haemanthus katherinae</i> Bak., treated with 0.025 per cent aqueous solution of a mixture of glycosides from <i>Nerium oleander</i> were examined in vitro in the light and in the electron microscope. A high hypertrophy of endoplasmic reticulum was noted. In prometaphase and metaphase, after treatment for about l h 45 min there appeared very narrow cisternae forming various configurations, frequently in parallel and concentric arrangement. On the membranes of these cisternae there are formed dark areas interpreted as pores characteristic for nuclear envelopes, this indicating that at least part of the two-membrane structures transforms to the nuclear envelope. The formation of the new nuclear envelope pre-maturely and apparently in excess is discussed.

Phosphatidylinositol metabolism and membrane fusion

2009 ◽  
Vol 418 (2) ◽  
pp. 233-246 ◽  
Author(s):  
Dominic Poccia ◽  
Banafshé Larijani
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Membrane Fusion ◽  
Membrane Lipids ◽  
Structure And Dynamics ◽  
Cellular Events ◽  
Recognition Sites ◽  
Nuclear Envelope Formation ◽  
Membrane Recognition ◽  
Regulatory Functions

Membrane fusion underlies many cellular events, including secretion, exocytosis, endocytosis, organelle reconstitution, transport from endoplasmic reticulum to Golgi and nuclear envelope formation. A large number of investigations into membrane fusion indicate various roles for individual members of the phosphoinositide class of membrane lipids. We first review the phosphoinositides as membrane recognition sites and their regulatory functions in membrane fusion. We then consider how modulation of phosphoinositides and their products may affect the structure and dynamics of natural membranes facilitating fusion. These diverse roles underscore the importance of these phospholipids in the fusion of biological membranes.

Distinct egg membrane vesicles differing in binding and fusion properties contribute to sea urchin male pronuclear envelopes formed in vitro

1996 ◽  
Vol 109 (6) ◽  
pp. 1275-1283 ◽  
Author(s):  
P. Collas ◽  
D. Poccia
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Sea Urchin ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Critical Element ◽  
Marker Enzyme ◽  
Sea Urchin Egg ◽  
Nuclear Envelope Formation

We have identified three distinct membrane vesicle populations from sea urchin egg cytoplasm that cooperate in assembling the male pronuclear envelope in vitro. Membranes from sea urchin egg homogenates were separated by buoyant density into five vesicle fractions, three of which bind to demembranated sperm nuclei. Each requires a membranous element (lipophilic structure) derived from the sperm nuclear envelope at the tip and base (poles) of the nucleus in order to bind. Binding is differentially sensitive to protease, high salt and N-ethyl maleimide treatment of the membrane vesicles. MV1 binds at the poles and is required for fusion of the membrane vesicle fractions to each other and to the lipophilic structures. MV2 beta binds over the entire chromatin surface and is enriched in an endoplasmic reticulum marker enzyme. MV2 alpha binds at the nuclear poles, is enriched in a Golgi enzyme marker and is required for fusion of MV2 beta. All three fractions are required for nuclear envelope formation in vitro. The results suggest a multistep process for nuclear envelope formation involving contributions from both sperm and egg, roles for both endoplasmic reticulum and non-endoplasmic reticulum-derived vesicles, and the localization of a critical element of the fusion machinery in MV1.

Compound Symbiosis in Peridinium Balticum

1973 ◽  
Vol 31 ◽  
pp. 500-501
Author(s):  
R. N. Tomas
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
The Other ◽  
Exact Nature ◽  
Symbiotic Relationship

Peridinium balticum appears to be unusual among the dinoflagellates in that it possesses two DNA-containing structures as determined by histochemical techniques. Ultrastructurally, the two dissimilar nuclei are contained within different protoplasts; one of the nuclei is characteristically dinophycean in nature, while the other is characteristically eucaryotic. The chloroplasts observed within P. balticum are intrinsic to an eucaryotic photosynthetic endosymbiont and not to the dinoflagellate. These organelles are surrounded by outpocketings of endoplasmic reticulum which are continuous with the eucaryotic nuclear envelope and are characterized by thylakoids composed of three apposed lamellae. Girdle lamellae and membranebounded interlamellar pyrenoids are also present. Only the plasmalemma of the endosymbiont segregates its protoplast from that of the dinophycean cytoplasm. The exact nature of this symbiotic relationship is at present not known.

Temporal and spatial interrelationships of confronting cisternae to nuclear envelope

1992 ◽  
Vol 50 (1) ◽  
pp. 930-931
Author(s):  
John R. Palisano
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Tumor Cells ◽  
Hela Cells ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Serial Sections ◽  
Electron Microscopic ◽  
Fetal Rat ◽  
Temporal And Spatial

Although confronting cistemae (CC) have been observed in a variety of tumor cells and normal fetal rat, mouse, and human epithelial tissues, little is known about their origin or role in mitotic cells. While several investigators have suggested that CC arise from nuclear envelope (NE) folding back on itself during prophase, others have suggested that CC arise when fragments of NE pair with endoplasmic reticulum. An electron microscopic investigation of 0.25 um thick serial sections was undertaken to examine the origin of CC in HeLa cells.

Sign in / Sign up

Export Citation Format

Share Document