Attachment of muscle filaments to the outer membrane of the nuclear envelope

1970 ◽  
Vol 111 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Werner W. Franke
Keyword(s):  
Nuclear Envelope ◽  
Outer Membrane ◽  
Muscle Filaments

The route of entry of cytoplasmically synthesized proteins into chloroplasts of algae possessing chloroplast ER

1979 ◽  
Vol 35 (1) ◽  
pp. 253-266
Author(s):  
S.P. Gibbs
Keyword(s):  
Protein Synthesis ◽  
Nuclear Envelope ◽  
Outer Membrane ◽  
Chloroplast Envelope ◽  
Inhibit Protein Synthesis ◽  
Ochromonas Danica ◽  
Plastid Proteins ◽  
Regular Network ◽  
Cytoplasmic Ribosomes ◽  
Plastid Ribosomes

In 8 classes of algae, namely the Cryptophyceae, Raphidophyceae, Haptophyceae, Chrysophyceae, Bacillariophyceae, Xanthophyceae, Eustigmatophyceae and Phaeophyceae, the chloroplasts, in addition to being surrounded by a double-membraned chloroplast envelope, are also enclosed by a cisterna of endoplasmic reticulum called the chloroplast ER. Often this ER cisterna is continuous with the outher membrane of the nuclear envelope in such a manner that the nuclear envelope forms a part of the ER sac enclosing the chloroplast. In all these classes of algae except the Cryptophyceae, a regular network of tubules and vesicles, named the periplastidal reticulum, is present at a specific location between the chloroplast envelope and the chloroplast ER. In the Cryptophyceae, scattered vesicles are found between the chloroplast envelope and the chloroplast ER. Ribosomes which have been shown to be arranged to polysomes are found on the outer membrane of the chloroplast ER. It is proposed that nuclear-coded proteins which are destined for the chloroplast are synthesized on these polysomes, passing during synthesis into the lumen of the ER cisterna. Vesicles containing these proteins then pinch off the chloroplast ER and form the periplastidal reticulum. Vesicles containing these proteins then pinch off the chloroplast ER and form the periplastidal reticulum. Vesicles then fuse with the outer membrane of the chloroplast envelope thereby delivering their contents to the lumen of the chloroplast envelope. Proteins then cross the inner membrane of the chloroplast envelope in an as yet unknown manner. Experimental evidence for this hypothesis comes from studies on Ochromonas danica using chloramphenicol and spectinomycin, which inhibit protein synthesis on plastid ribosomes, and cycloheximide, which inhibits protein synthesis on cytoplasmic ribosomes. In cells of Ochromonas exposed to chloramphenicol or spectinomycin, the periplastidal reticulum proliferates markedly becoming several layers thick. Presumably this build up of periplastidal reticulum occurs because the transport of cytoplasmically synthesized plastid proteins is slowed down when protein synthesis in the chloroplast is inhibited. Conversely, when cells of Ochromonas are treated with cycloheximide, there is a reduction in the amount of periplastidal reticulum presumably because there are no cytoplasmically synthesized proteins to be transported into the chloroplast.

scholarly journals NUCLEAR ENVELOPE-CHLOROPLAST RELATIONSHIPS IN ALGAE

1962 ◽  
Vol 14 (3) ◽  
pp. 433-444 ◽  
Author(s):  
Sarah P. Gibbs
Keyword(s):  
Nuclear Envelope ◽  
Outer Membrane ◽  
Related Species ◽  
The Other ◽  
Chloroplast Envelope ◽  
Outer Envelope ◽  
Starch Grains ◽  
Ochromonas Danica ◽  
Narrow Space

In Ochromonas danica and two related species (Chrysophyceae) and in Rhodomonas lens and Cryptomonas sp. (Cryptophyceae), the chloroplast is surrounded by an outer double-membraned envelope which lies outside the usual double-membraned chloroplast envelope. At the borders of the area where the chloroplast lies adjacent to the nucleus, this outer envelope is continuous with the outer membrane of the nuclear envelope as a double-membraned outfolding, so that the entire chloroplast in these species lies within a double-membraned sac, one wall of which is the nuclear envelope. In Olisthodiscus sp. (Chrysophyceae ?), each of the small peripheral chloroplasts is surrounded by a similar double-membraned outer envelope, but in this species no connections with the nuclear envelope were observed. In the Ochromonadaceae, a characteristic array of tubules is present within the sac in the narrow space which separates the chloroplast from the nucleus. In the other species studied, tubules are present at places between the chloroplast envelope and the outer envelope. In the Cryptophyceae, the starch grains lie outside the chloroplast envelope, but within the outer double-membraned sac. A double-membraned outer envelope appears to be present outside the chloroplasts of the Phaeophyta and Euglenophyta, but seems to be absent in the other groups of algae.

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.

scholarly journals Distribution and induction of cytochrome P-450 in rat liver nuclear envelope.

1981 ◽  
Vol 91 (1) ◽  
pp. 212-220 ◽  
Author(s):  
S Matsuura ◽  
R Masuda ◽  
K Omori ◽  
M Negishi ◽  
Y Tashiro
Keyword(s):  
Nuclear Envelope ◽  
Outer Membrane ◽  
Rat Liver ◽  
Molecular Species ◽  
Transmembrane Protein ◽  
Microscopic Analysis ◽  
Inner Membrane ◽  
Cytoplasmic Face ◽  
Biochemical Analyses ◽  
Cytochrome P 450

Induction of cytochrome P-450s by 3-methylcholanthrene (MC) and phenobarbital (PB) and distribution of P-450s in the rat liver nuclear envelope were investigated by biochemical analyses and ferritin immunoelectron microscopy using specific antibodies against the major molecular species of MC- and PB-induced cytochrome P-450. It was found, in agreement with Kasper (J. Biol. Chem., 1971, 246: 577-581), that the total amount of cytochrome P-450s determined by biochemical analysis was markedly increased by MC, but not by PB, treatment. Immunoelectron microscopic analysis, however, showed marked and slight increases in ferritin labeling by MC and PB treatment, respectively. The latter finding was interpreted as resulting from the induction of a particular molecular species of PB-induced cytochrome P-450s. Ferritin immunoelectron microscopic analysis of intact isolated nuclei, naked nuclei from which the outer membrane of the nuclear envelope was partially detached (mechanically), and isolated nuclear envelopes have shown that the ferritin particles are found exclusively on the cytoplasmic face of the outer nuclear envelopes. Neither the nucleoplasmic face of the inner membrane of the nuclear envelope nor the cisternal face of both membranes of the nuclear envelope showed any labeling with ferritin. This indicates that cytochrome P-450 is located only on the outer membrane of the nuclear envelope and does not diffuse laterally into the domain of the inner membrane of the nuclear envelope across the nuclear pores. Our results suggest that a marked heterogeneity exists in the enzyme distribution between the outer and inner membrane of the nuclear envelope and that microsomal marker enzymes such as cytochrome P-450 exist exclusively in the outer membrane. In addition, it appears that cytochrome P-450 is probably not a transmembrane protein but an intrinsic protein located on the cytoplasmic face of the outer membrane of the nuclear envelope.

scholarly journals Visualization of inositol 1,4,5-trisphosphate receptors on the nuclear envelope outer membrane by freeze-drying and rotary shadowing for electron microscopy

2010 ◽  
Vol 171 (3) ◽  
pp. 372-381 ◽  
Author(s):  
Cesar Cárdenas ◽  
Matias Escobar ◽  
Alejandra García ◽  
Maria Osorio-Reich ◽  
Steffen Härtel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Outer Membrane ◽  
Freeze Drying ◽  
Inositol 1,4,5 Trisphosphate ◽  
Rotary Shadowing

Nucleoli in differentiated germ tubes of wheat rust uredospores

1970 ◽  
Vol 48 (9) ◽  
pp. 1693-1695 ◽  
Author(s):  
Larry D. Dunkle ◽  
William P. Wergin ◽  
Paul J. Allen
Keyword(s):  
Electron Microscopy ◽  
Heat Shock ◽  
Nuclear Envelope ◽  
Outer Membrane ◽  
Ribosomal Rna ◽  
Stem Rust ◽  
Wheat Stem Rust ◽  
Cytoplasmic Structures ◽  
Germ Tubes ◽  
Wheat Rust

Nucleoli observed by electron microscopy are illustrated in germ tubes of wheat stem rust uredospores which have been induced by heat shock to differentiate infection structures. The presence of nucleoli in these structures suggests that this obligate parasite may possess the capacity of synthesizing ribosomal RNA independently of its host. In addition to nucleoli, heterochromatin is characteristically observed appressed to the inner membrane of the nuclear envelope. This material is associated with distinct cytoplasmic structures which are appressed to the outer membrane of the nuclear envelope and resemble developing centrioles in other fungi.

The Ultrastructure of the Nuclear Events of Binary Fission in Paramecium bursaria and the Effects of Colchicine on Cell Division

1974 ◽  
Vol 32 ◽  
pp. 276-277
Author(s):  
L. M. Lewis
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Condensed Chromatin ◽  
Binary Fission ◽  
Paramecium Bursaria ◽  
Nuclear Events ◽  
Division Axis

The effects of colchicine on extranuclear microtubules associated with the macronucleus of Paramecium bursaria were studied to determine the possible role that these microtubules play in controlling the shape of the macronucleus. In the course of this study, the ultrastructure of the nuclear events of binary fission in control cells was also studied.During interphase in control cells, the micronucleus contains randomly distributed clumps of condensed chromatin and microtubular fragments. Throughout mitosis the nuclear envelope remains intact. During micronuclear prophase, cup-shaped microfilamentous structures appear that are filled with condensing chromatin. Microtubules are also present and are parallel to the division axis.

Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers

1977 ◽  
Vol 35 ◽  
pp. 576-577
Author(s):  
Joachim R. Sommer ◽  
Nancy R. Wallace
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Granular Material ◽  
Nuclear Envelope ◽  
Intracellular Calcium ◽  
Ruthenium Red ◽  
Threshold Concentration ◽  
Rapid Freezing ◽  
Frog Skeletal Muscle ◽  
Electrical Isolation

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.

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.

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