scholarly journals THE NUCLEAR ENVELOPE

1955 ◽  
Vol 1 (3) ◽  
pp. 257-270 ◽  
Author(s):  
Michael L. Watson
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Particulate Material ◽  
Tangential Section ◽  
Resting Cells ◽  
Thin Sections ◽  
Outer Membranes ◽  
Perinuclear Space ◽  
Interphase Cells ◽  
Embryonic Ectoderm

An electron microscope study of thin sections of interphase cells has revealed the following:— Circular pores are formed in the double nuclear envelope by continuities between the inner and outer membranes which permit contact between the nucleoplasm and the cytoplasm unmediated by a well defined membrane. The pores, seen in sections normal to the nuclear envelope, are profiles of the ring-shaped structures described by others and seen in tangential section. The inner and outer nuclear membranes are continuous with one another and enclose the perinuclear space. The pores contain a diffuse, faintly particulate material. A survey of cells of the rat derived from the embryonic ectoderm, mesoderm, and endoderm, and of a protozoan and an alga has revealed pores in all tissues examined, without exception. It is concluded that pores in the nuclear envelope are a fundamental feature of all resting cells. In certain cells, the outer nuclear membrane is continuous with membranes of the endoplasmic reticulum, hence the perinuclear space is continuous with cavities enclosed by those membranes. There are indications that this is true for all resting cells, at least in a transitory way. On the basis of these observations, the hypothesis is made that two pathways of exchange exist between the nucleus and the cytoplasm; by way of the perinuclear space and cavities of the endoplasmic reticulum and by way of the pores in the nuclear envelope.

scholarly journals Endoplasmic reticulum-to-Golgi transitions upon herpes virus infection

F1000Research ◽  
2018 ◽  
Vol 6 ◽  
pp. 1804 ◽  
Author(s):  
Peter Wild ◽  
Andres Kaech ◽  
Elisabeth M. Schraner ◽  
Ladina Walser ◽  
Mathias Ackermann
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Golgi Complex ◽  
Nuclear Membrane ◽  
Progeny Virus ◽  
Cytoplasmic Matrix ◽  
Outer Nuclear Membrane ◽  
Nuclear Membranes ◽  
Perinuclear Space ◽  
Hsv 1

Background: Herpesvirus capsids are assembled in the nucleus, translocated to the perinuclear space by budding, acquiring tegument and envelope, or released to the cytoplasm via impaired nuclear envelope. One model proposes that envelopment, “de-envelopment” and “re-envelopment” is essential for production of infectious virus. Glycoproteins gB/gH were reported to be essential for de-envelopment, by fusion of the “primary” envelope with the outer nuclear membrane. Yet, a high proportion of enveloped virions generated from genomes with deleted gB/gH were found in the cytoplasm and extracellular space, suggesting the existence of alternative exit routes.Methods: We investigated the relatedness between the nuclear envelope and membranes of the endoplasmic reticulum and Golgi complex, in cells infected with either herpes simplex virus 1 (HSV-1) or a Us3 deletion mutant thereof, or with bovine herpesvirus 1 (BoHV-1) by transmission and scanning electron microscopy, employing freezing technique protocols.Results:  The Golgi complex is a compact entity in a juxtanuclear position covered by a membrane on thecisface. Golgi membranes merge with membranes of the endoplasmic reticulum forming an entity with the perinuclear space. All compartments contained enveloped virions. After treatment with brefeldin A, HSV-1 virions aggregated in the perinuclear space and endoplasmic reticulum, while infectious progeny virus was still produced.Conclusions: The data suggest that virions derived by budding at nuclear membranes are intraluminally transported from the perinuclear space via Golgi -endoplasmic reticulum transitions into Golgi cisternae for packaging. Virions derived by budding at nuclear membranes are infective like Us3 deletion mutants, which  accumulate in the perinuclear space. Therefore, i) de-envelopment followed by re-envelopment is not essential for production of infective progeny virus, ii) the process taking place at the outer nuclear membrane is budding not fusion, and iii) naked capsids gain access to the cytoplasmic matrix via impaired nuclear envelope as reported earlier.

scholarly journals Endoplasmic reticulum-to-Golgi transitions upon herpes virus infection

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1804 ◽  
Author(s):  
Peter Wild ◽  
Andres Kaech ◽  
Elisabeth M. Schraner ◽  
Ladina Walser ◽  
Mathias Ackermann
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Golgi Complex ◽  
Progeny Virus ◽  
Perinuclear Space ◽  
Exit Route ◽  
Scanning Electron ◽  
Hsv 1

Background: Herpesvirus capsids are assembled in the nucleus before they are translocated to the perinuclear space by budding, acquiring tegument and envelope, or releasing to the cytoplasm in a “naked” state via impaired nuclear envelope. One model proposes that envelopment, “de-envelopment” and “re-envelopment” are essential steps for production of infectious virus. Glycoproteins gB/gH were reported to be essential for de-envelopment, by fusion of the “primary” envelope with the outer nuclear membrane. Yet, a high proportion of enveloped virions generated from genomes with deleted gB/gH were found in the cytoplasm and extracellular space, suggesting the existence of an alternative exit route.Methods: We investigated the relatedness between the nuclear envelope and membranes of the endoplasmic reticulum and Golgi complex, in cells infected with either herpes simplex virus 1 (HSV-1) or a Us3 deletion mutant thereof, or with bovine herpesvirus 1 (BoHV-1) by transmission and scanning electron microscopy, employing freezing technique protocols that lead to improved spatial and temporal resolution.Results: Scanning electron microscopy showed the Golgi complex as a compact entity in a juxtanuclear position covered by a membrane on thecisface. Transmission electron microscopy revealed that Golgi membranes merge with membranes of the endoplasmic reticulum forming an entity with the perinuclear space. All compartments contained enveloped virions. After treatment with brefeldin A, HSV-1 virions aggregated in the perinuclear space and endoplasmic reticulum, while infectious progeny virus was still produced.Conclusions: The data strongly suggest that virions are intraluminally transported from the perinuclear space via Golgi complex-endoplasmic reticulum transitions into Golgi cisternae for packaging into transport vacuoles. Furthermore, virions derived by budding at nuclear membranes are infective as has been shown for HSV-1 Us3 deletion mutants, which almost entirely accumulate in the perinuclear space. Therefore, de-envelopment followed by re-envelopment is not essential for production of infective progeny virus.

scholarly journals Studies on the Endoplasmic Reticulum

1960 ◽  
Vol 7 (1) ◽  
pp. 167-180 ◽  
Author(s):  
Keith R. Porter ◽  
Raul D. Machado
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Phase Contrast ◽  
Cell Plate ◽  
Middle Zone ◽  
Root Tips ◽  
Late Prophase ◽  
Polar Caps ◽  
Interphase Cells ◽  
And Behavior

Cells of onion and garlic root tips were examined under the electron and phase contrast microscopes after fixation in KMnO4. Special attention was focused on the distribution and behavior of the endoplasmic reticulum (ER) during the several phases of mitosis. Slender profiles, recognized as sections through thin lamellar units of the ER (most prominent in KMnO4-fixed material), are distributed more or less uniformly in the cytoplasm of interphase cells and show occasional continuity with the nuclear envelope. In late prophase the nuclear envelope breaks down and its remnants plus cytoplasmic elements of the ER, which are morphologically identical, surround the spindle in a zone from which mitochondria, etc., are excluded. During metaphase these ER elements persist and concentrate as two separate systems in the polar caps or zones of the spindle. At about this same time they begin to proliferate and to invade the ends of the spindle. The invading lamellar units form drape-like partitions between the anaphase chromosomes. In late anaphase, their advancing margins reach the middle zone of the spindle and begin to fray out. Finally, in telophase, while elements of the ER in the poles of the spindle coalesce around the chromosomes to form the new envelope, the advancing edges of those in the middle zone reticulate at the level of the equator to form a close lattice of tubular elements. Within this, which is identified as the phragmoplast, the earliest signs of the cell plate appear in the form of small vesicles. These subsequently grow and fuse to complete the separation of the two protoplasts. Other morphological units apparently participating in mitosis are described. Speculation is provided on the equal division or not of the nuclear envelope and the contribution the envelope fragments make to the ER of the new cell.

scholarly journals Synthesis, transport and incorporation into the nuclear envelope of A-type lamins and inner nuclear membrane proteins

2011 ◽  
Vol 39 (6) ◽  
pp. 1758-1763 ◽  
Author(s):  
Jose M. González ◽  
Vicente Andrés
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Complex Structure ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Inner Nuclear Membrane ◽  
Perinuclear Space ◽  
Interphase Cells ◽  
Pore Complexes

The mammalian NE (nuclear envelope), which separates the nucleus from the cytoplasm, is a complex structure composed of nuclear pore complexes, the outer and inner nuclear membranes, the perinuclear space and the nuclear lamina (A- and B-type lamins). The NE is completely disassembled and reassembled at each cell division. In the present paper, we review recent advances in the understanding of the mechanisms implicated in the transport of inner nuclear membrane and nuclear lamina proteins from the endoplasmic reticulum to the nucleus in interphase cells and mitosis, with special attention to A-type lamins.

scholarly journals THE FINE STRUCTURAL ORGANISATION OF ROUS TUMOUR CELLS

1957 ◽  
Vol 3 (6) ◽  
pp. 851-858 ◽  
Author(s):  
M. A. Epstein
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cell Membrane ◽  
Nuclear Membrane ◽  
Tumour Cells ◽  
Thin Sections ◽  
Outer Nuclear Membrane ◽  
Structural Organisation ◽  
Perinuclear Space

The fibroblast-like tumour cells of Rous sarcomata have been studied in thin sections with the electron microscope. A description is given of the fine structure of the cells which includes some features not hitherto recorded. The tightly packed piles of smooth cisternae usually found only in the centrosome region have been observed, in individual Rous cells, in two separate areas of cytoplasm at opposite poles of the nucleus. Continuity between the perinuclear space and the lumen of rough surfaced cisternae of the endoplasmic reticulum has frequently been found; a similar continuity between the cisternae and the exterior of the cell has also been seen. In some cases, the cell membrane has been shown to have an unbroken connection with the outer nuclear membrane through continuity with the limiting membranes of elements of the endoplasmic reticulum. These findings are discussed.

Ultrastructure of the Parotid Gland of the Nine-Banded Armadillo

1977 ◽  
Vol 35 ◽  
pp. 640-641
Author(s):  
J. R. Ruby
Keyword(s):  
Endoplasmic Reticulum ◽  
Parotid Gland ◽  
Periodic Acid ◽  
Acinar Cells ◽  
Duct System ◽  
Parotid Glands ◽  
Dasypus Novemcinctus ◽  
Anterior Portion ◽  
Periodic Acid Schiff ◽  
Thin Sections

Parotid glands were obtained from five adult (four male and one female) armadillos (Dasypus novemcinctus) which were perfusion-fixed. The glands were located in a position similar to that of most mammals. They extended interiorly to the anterior portion of the submandibular gland.In the light microscope, it was noted that the acini were relatively small and stained strongly positive with the periodic acid-Schiff (PAS) and alcian blue techniques, confirming the earlier results of Shackleford (1). Based on these qualities and other structural criteria, these cells have been classified as seromucous (2). The duct system was well developed. There were numerous intercalated ducts and intralobular striated ducts. The striated duct cells contained large amounts of PAS-positive substance.Thin sections revealed that the acinar cells were pyramidal in shape and contained a basally placed, slightly flattened nucleus (Fig. 1). The rough endoplasmic reticulum was also at the base of the cell.

Membranous alterations in the cytoplasm and nucleus in a primitive neuroectodermal tumor of the brain

1978 ◽  
Vol 36 (2) ◽  
pp. 628-629
Author(s):  
C. N. Sun ◽  
C. Araoz ◽  
H. J. White
Keyword(s):  
Nuclear Envelope ◽  
Tumor Cells ◽  
Osmium Tetroxide ◽  
Primitive Neuroectodermal Tumor ◽  
Uranyl Acetate ◽  
Neuroectodermal Tumor ◽  
Annulate Lamellae ◽  
Lead Citrate ◽  
Thin Sections ◽  
The Brain

The ultrastructure of a cerebral primitive neuroectodermal tumor has been reported previously. In the present case, we will present some unusual previously unreported membranous structures and alterations in the cytoplasm and nucleus of the tumor cells.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4% glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1% buffered osmium tetroxide for one hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate.In the cytoplasm of the tumor cells, we found paired cisternae (Fig. 1) and annulate lamellae (Fig. 2) noting that the annulate lamellae were sometimes associated with the outer nuclear envelope (Fig. 3). These membranous structures have been reported in other tumor cells. In our case, mitochondrial to nuclear envelope fusions were often noted (Fig. 4). Although this phenomenon was reported in an oncocytoma, their frequency in the present study is quite striking.

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.

The ultrastructure of the double membrane-bound bodies and endoplasmic reticulum in serial sections of wheat spot mosaic-affected wheat plants

1990 ◽  
Vol 48 (3) ◽  
pp. 694-695
Author(s):  
M. H. Chen ◽  
C. Hiruki
Keyword(s):  
Endoplasmic Reticulum ◽  
High Resolution ◽  
Membrane Structure ◽  
Mosaic Disease ◽  
Serial Sections ◽  
Thin Sections ◽  
Double Membrane ◽  
Southern Alberta ◽  
Membrane Bound ◽  
Scanning Em

Wheat spot mosaic disease was first discovered in southern Alberta, Canada, in 1956. A hitherto unidentified disease-causing agent, transmitted by the eriophyid mite, caused chlorosis, stunting and finally severe necrosis resulting in the death of the affected plants. Double membrane-bound bodies (DMBB), 0.1-0.2 μm in diameter were found to be associated with the disease.Young tissues of leaf and root from 4-wk-old infected wheat plants were fixed, dehydrated, and embedded in Spurr’s resin. Serial sections were collected on slot copper grids and stained. The thin sections were then examined with a Hitachi H-7000 TEM at 75 kV. The membrane structure of the DMBBs was studied by numbering them individually and tracing along the sections to see any physical connection with endoplasmic reticulum (ER) membranes. For high resolution scanning EM, a modification of Tanaka’s method was used. The specimens were examined with a Hitachi Model S-570 SEM in its high resolution mode at 20 kV.

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