Ultrastructural changes in nuclear membranes and organelle associations during mitosis of the aquatic fungus Entophlyctis sp.

1975 ◽  
Vol 53 (7) ◽  
pp. 627-646 ◽  
Author(s):  
Martha J. Powell
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Nuclear Division ◽  
Ultrastructural Changes ◽  
Aquatic Fungus ◽  
Electron Microscopic ◽  
Mitotic Apparatus ◽  
Inner Membrane ◽  
Nuclear Membranes ◽  
Spindle Microtubules

Electron microscopic observations on an endobiotic chytrid, Entophlyctis sp., have revealed a mitotic apparatus which is presently unique among fungi. Daughter nuclear envelopes are reconstituted from cisternae apparently proliferated by the inner membrane of the nuclear envelope. Before nuclear division, centrioles replicate and migrate to the poles of the nucleus. Large pores appear at this time in a depression of the nuclear envelope opposite the paired centrioles. This region of the envelope fragments and leaves polar fenestrae as spindle microtubules appear in the nucleus. The inner membrane of the nuclear envelope then invaginates and proliferates cisternae until a layer of inner membrane cisternae lines the original nuclear envelope at late metaphase. Connections between the inner membrane of the original nuclear envelope and the cisternae persist until telophase. As the spindle elongates and the inner membrane cisternae fuse centripetally to form a reticulum around the chromatin mass, the original nuclear envelope opens more at the poles. The reticulum becomes the nuclear envelope of the new daughter nuclei. When the original envelope finally disperses, it is distinguishable from the endoplasmic reticulum only by the presence of pores. Microbodies are consistently associated with the original nuclear envelope and appear adjacent to the new daughter envelopes at the end of telophase. Densely staining arms project from the sides of the primary centrioles toward the polar mitochondria.

Cell and nucleomorph division in the alga Cryptomonas

1982 ◽  
Vol 60 (11) ◽  
pp. 2440-2452 ◽  
Author(s):  
Lisa McKerracher ◽  
Sarah P. Gibbs
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Outer Membrane ◽  
Basal Body ◽  
Nuclear Division ◽  
Residual Nucleus ◽  
Inner Membrane ◽  
Double Membrane ◽  
Ultrastructural Investigation ◽  
Periplastidal Compartment

An ultrastructural investigation of cell and nuclear division in Cryptomonas sp. (θ) was made with particular emphasis on the mode of division of the chloroplast and nucleomorph. Mitosis is similar to that in other cryptomonads except that the nuclear envelope remains mostly intact. Division of the single chloroplast occurs in preprophase by constriction through the dorsal bridge. Frequently there is a lag between the division of the chloroplast and the division of its envelope of chloroplast endoplasmic reticulum. In addition, the inner membrane of the chloroplast endoplasmic reticulum may infold well in advance of the outer membrane.The nucleomorph is a unique double membrane limited organelle which is found in the periplastidal compartment of cryptomonads. It divides in preprophase following basal body replication but before division of the chloroplast and its chloroplast endoplasmic reticulum is complete. The inner membrane of the nucleomorph envelope invaginates first forming a double membraned baffle. The outer membrane invaginates next and completes division. Microtubules are not involved in nucleomorph division. None were observed and colchicine, which inhibited nuclear division, did not inhibit nucleomorph division. The theory that the nucleomorph is the residual nucleus of a former eukaryotic endosymbiont is reevaluated in light of these new observations.

Mitosis in Phlyctochytrium irregulare

1973 ◽  
Vol 51 (11) ◽  
pp. 2065-2074 ◽  
Author(s):  
Rand McNitt
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Green Algae ◽  
Light Microscope ◽  
Equatorial Plate ◽  
Metaphase Chromosomes ◽  
Mitotic Apparatus ◽  
Initial Separation ◽  
Spindle Microtubules

Mitosis in zoosporangia of the chytrid Phlyctochytrium irregulare is described from electron microscope observations and also from light microscope observations of both living and haematoxylin-stained thalli. At the onset of prophase the centriole complex replicates, and the complexes migrate to polar positions. The semi-persistent nucleolus is appressed to the nuclear envelope as the nuclear pockets invaginate, finally rupturing to create polar fenestrae, through which spindle microtubules penetrate the nucleus from the region of the centrioles at prometaphase. Metaphase chromosomes form an equatorial plate. Initial separation at anaphase seems to be accomplished mainly by shortening of chromosome-to-pole microtubules; additional anaphase and telophase separation is accomplished by elongation of the nucleus. A system of perinuclear endoplasmic reticulum is formed during prophase and is completed by metaphase. It persists during all division stages after its formation. Features of this mitotic apparatus are discussed with reference to earlier light microscope studies of chytrid mitosis. The ultrastructure of P. irregulare's mitotic apparatus is similar to that of certain unicellular green algae.

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.

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.

Nuclear division in the marine dinoflagellate Oxyrrhis marina

1986 ◽  
Vol 85 (1) ◽  
pp. 161-175
Author(s):  
X.P. Gao ◽  
J.Y. Li
Keyword(s):  
Nuclear Envelope ◽  
Phylogenetic Relationships ◽  
Nuclear Division ◽  
Metaphase Plate ◽  
Active Role ◽  
Ultrastructural Changes ◽  
Interphase Nuclei ◽  
Oxyrrhis Marina ◽  
Two Stages ◽  
Anaphase B

The nuclear division of Oxyrrhis marina is a very distinct one among the mitoses of dinoflagellates that have been studies. Using synchronized populations, we have investigated the ultrastructural changes in this nuclear division. In interphase, nuclei can be classified into two groups on the basis of the shapes of the chromosomes. Y- and U-shaped chromosomes have been observed in both types of interphase nuclei. By prophase the nucleus becomes oval, many nuclear plaques appear on the nuclear envelope, and many microtubules radiate from these nuclear plaques within the nucleus. Metaphase can be identified by the characteristic arrangement of the chromosomes; an equatorial metaphase plate is absent. As in many higher organisms, anaphase includes two stages: anaphase A and anaphase B. During anaphase A the nucleus does not apparently elongate and the chromosomes migrate towards the poles by a combination of the shortening of the chromosome-associated microtubules and the elongation of those located between daughter chromosomes. During anaphase B the nucleus elongates to about twice its former length. This elongation may result from growth of the interzonal nuclear envelope. Dividing nucleoli are associated with microtubules, which suggests that microtubules may play an active role in the division of the nucleolus. The evolution of mitosis and the phylogenetic relationships between Oxyrrhis, typical dinoflagellates and Syndinium are discussed.

scholarly journals Relationship between peroxisomes and endoplasmic reticulum investigated by combined catalase and glucose-6-phosphatase cytochemistry.

1981 ◽  
Vol 29 (11) ◽  
pp. 1263-1272 ◽  
Author(s):  
H Shio ◽  
P B Lazarow
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Rat Liver ◽  
Reaction Products ◽  
Lead Phosphate ◽  
Electron Microscopic ◽  
Phosphatase Cytochemistry ◽  
Electron Microscopic Cytochemistry ◽  
Cellular Compartments

The theoretical advantages of electron microscopic cytochemistry were utilized to look for evidence of possible connections between peroxisomes and the endoplasmic reticulum in rat liver. Established cytochemical procedures for catalase (peroxisomes) and glucose-6-phosphatase (endoplasmic reticulum) were carried out, and evidence was sought of diffusion of reaction products between the organelles. No such diffusion was observed: lead phosphate was found in the endoplasmic reticulum and in the nuclear envelope but not in peroxisomes; oxidized diaminobenzidine (DAB) was seen only in peroxisomes. In addition, both types of cytochemistry were carried out on the same tissue. The two kinds of reaction product could be distinguished by virtue of their different electron opacities. No mixing of the two reaction products was observed. These results do not support the hypothesis that peroxisomes and endoplasmic reticulum may be connected; rather, they support the idea that the two organelles exist as separate cellular compartments.

scholarly journals Nuclear Envelope Proteins Modulating the Heterochromatin Formation and Functions in Fission Yeast

Cells ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1908 ◽  
Author(s):  
Yasuhiro Hirano ◽  
Haruhiko Asakawa ◽  
Takeshi Sakuno ◽  
Tokuko Haraguchi ◽  
Yasushi Hiraoka
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Fission Yeast ◽  
Histone Deacetylase ◽  
Nuclear Pore Complex ◽  
Molecular Mechanisms ◽  
Nuclear Pore ◽  
Double Membrane ◽  
Heterochromatin Formation ◽  
Nuclear Membranes

The nuclear envelope (NE) consists of the inner and outer nuclear membranes (INM and ONM), and the nuclear pore complex (NPC), which penetrates the double membrane. ONM continues with the endoplasmic reticulum (ER). INM and NPC can interact with chromatin to regulate the genetic activities of the chromosome. Studies in the fission yeast Schizosaccharomyces pombe have contributed to understanding the molecular mechanisms underlying heterochromatin formation by the RNAi-mediated and histone deacetylase machineries. Recent studies have demonstrated that NE proteins modulate heterochromatin formation and functions through interactions with heterochromatic regions, including the pericentromeric and the sub-telomeric regions. In this review, we first introduce the molecular mechanisms underlying the heterochromatin formation and functions in fission yeast, and then summarize the NE proteins that play a role in anchoring heterochromatic regions and in modulating heterochromatin formation and functions, highlighting roles for a conserved INM protein, Lem2.

Quantitative electron microscopic study of the hepatic endoplasmic reticulum in Reye’s syndrome

1983 ◽  
Vol 41 ◽  
pp. 644-645
Author(s):  
J. M. Sturgess ◽  
F. A. de la Iglesia
Keyword(s):  
Endoplasmic Reticulum ◽  
Critical Evaluation ◽  
Ultrastructural Changes ◽  
Reye's Syndrome ◽  
Cellular Mechanisms ◽  
Electron Microscopic ◽  
Biochemical Alterations ◽  
Clinical Onset ◽  
Tissue Changes ◽  
Liver Biopsies

Reye’s syndrome represents a serious clinical condition in children with symptoms of liver involvement, acute encephalopathy and biochemical alterations. This condition, for which the etiology is not yet known, has been linked to mycotoxin poisoning, viral infection, or simulated by drug toxicity, particularly salicylates. However, basic cellular mechanisms and early ultrastructural changes have not been well defined. The liver endoplasmic reticulum (ER) plays a fundamental role in detoxification. Our understanding of ER changes in this syndrome would clarify the processes leading to liver damage.Quantitative electron microscopic aspects of hepatocytes were evaluated to characterize numerically the tissue changes in liver biopsies from patients with Reye's syndrome and compared with data available from age-matched controls. Liver biopsies were evaluated from three patients, 1.5, 6.5 and 13.5 years of age, having clinical and pathological evidence of Reye's syndrome. All biopsies were obtained within 24 hours of clinical onset. Preservation of architecture of hepatocytes was adequate for critical evaluation of ultrastructure.

An Electron Microscopic Study of the Human Gastric Epithelia with Special Reference to the Cardinal Morphological Changes of the Chief Cells Induced by Insulin Stimulus

1972 ◽  
Vol 30 ◽  
pp. 344-345
Author(s):  
Hiroshi Saito ◽  
Goro Asano ◽  
Kaoru Aihara ◽  
Katsunari Fukushi ◽  
Minoru Yoshida ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Morphological Changes ◽  
Regular Insulin ◽  
Endoscopic Biopsy ◽  
Granular Endoplasmic Reticulum ◽  
Ultrastructural Changes ◽  
Electron Microscopic ◽  
Chief Cells ◽  
Microscopic Studies ◽  
The One

This short communication is dealt with the ultrastructural changes of the chief cells in insulin stimulus in chronic gastritic condition. The bio gastro-endoscopic biopsy was obtained and pepsin activity of the gastric juice was measured in respective cases. Regular insulin of 0.15U/kg was administrated intra-muscularly and in pre-administration of insulin, 10 minutes, 20 minutes and 30 minutes after administration, biopsied specimens were subjected for electron microscopic studies.In the pre-treated chief cells, extensive development of the cysternal structures of the granular endoplasmic reticulum in basal aspect of the cytoplasm and spherical or oval shaped, light homogeneous zymogen granules in supranuclear region and especially apical aspect of the cytoplasm were featured. Moreover, other type of the chief cells as the one characterized by their fragmented and saccular dilated granular endoplasmic reticulum in basal aspect of the cytoplasm, also exist.

The Role of Endoplasmic Reticulum in the Repair of Amoeba Nuclear Envelopes Damaged Microsurgically

1974 ◽  
Vol 14 (2) ◽  
pp. 421-437
Author(s):  
C. J. FLICKINGER
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Rough Endoplasmic Reticulum ◽  
Repair Process ◽  
Nuclear Membranes ◽  
Normal Configuration ◽  
Layer Characteristic ◽  
The Relationship ◽  
Coated Slide

The nuclear envelopes of amoebae were damaged microsurgically, and the fate of the lesions was studied with the electron microscope. Amoebae were placed on the surface of an agar-coated slide. Using a glass probe, the nucleus was pushed from an amoeba, damaged with a chopping motion of the probe, and reinserted into the amoeba. Cells were prepared for electron microscopy at intervals of between 10 min and 4 days after the manipulation. Nuclear envelopes studied between 10 min and 1 h after the injury displayed extensive damage, including numerous holes in the nuclear membranes. Beginning 15 min after the manipulation, pieces of rough endoplasmic reticulum intruded into the holes in the nuclear membranes. These pieces of rough endoplasmic reticulum subsequently appeared to become connected to the nuclear membranes at the margins of the holes. By 1 day following the injury, many cells had died, but the nuclear membranes were intact in those cells that survived. The elaborate fibrous lamina or honeycomb layer characteristic of the amoeba nuclear envelope was resistant to early changes after the manipulation. Patches of disorganization of the fibrous lamina were present 5 h to 1 day after injury, but the altered parts showed evidence of progress toward a return to normal configuration by 4 days after the injury. It is proposed that the rough endoplasmic reticulum participates in the repair of injury to the nuclear membranes. The similarity of this repair process to reconstitution of the nuclear envelope in telophase of mitosis is noted, and the relationship between the nuclear envelope and the rough endoplasmic reticulum is discussed.

Sign in / Sign up

Export Citation Format

Share Document