SOME OBSERVATIONS ON THE NUCLEAR ENVELOPE

In maize root meristem cells, fixed in KMnO4, embedded in epoxy resin, ultrathin sectioned, and studied with an electron microscope, the nuclear envelope is demonstrated to be a double membrane structure. In the nuclear envelope there are: pores of the sort reported in many species of animals and plants; different types of openings associated with extensions of both nuclear membranes into the cytoplasm; and also, often, large discontinuities. The nuclear envelope is a component of the general vesicular reticulum. The reticula of neighboring cells including the nuclear envelopes make up, at certain stages at least, a "systemic" structure. The status of the nuclear envelope as a component of the general cellular reticulum is recognized to change during differentiation. The existence of several types of discontinuities in the nuclear envelope and the extent of nuclear-cytoplasmic surface relationships indicated suggests alteration in concepts of transport and exchanges between nucleus and cytoplasm.

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Ultrastructure of cell division in Cladophora. Pregametangial cell division in the haploid generation of Cladophora flexuosa

Canadian Journal of Botany ◽

10.1139/b76-169 ◽

1976 ◽

Vol 54 (13) ◽

pp. 1546-1560 ◽

Cited By ~ 21

Author(s):

J. L. Scott ◽

K. W. Bullock

Keyword(s):

Life History ◽

Electron Microscope ◽

Cell Division ◽

Nuclear Envelope ◽

Double Membrane ◽

Cell Divisions ◽

Gamete Formation ◽

Reproductive Differentiation ◽

Different Types ◽

Vacuolar System

Cell division preceding gamete formation in the haploid generation of Cladophora flexuosa was studied with the electron microscope. Numerous, asynchronous mitotic nuclear divisions are concurrent with the progressive cleavage of the cytoplasm by invaginations of a central and peripheral vacuolar system. The spindle is enclosed by the nuclear envelope during all stages of mitosis and is associated with polar centriole pairs. The cytokinetic process is not associated with microtubules and is basically similar to that observed in other macroscopic, multinucleate green algae. Unusual mitochondria, characterized by specialized double-membrane-enclosed, presumptive DNA regions, were found during the later stages of reproductive differentiation. It is emphasized that the different types of cell divisions which can occur in plants possessing a haplodiplontic type of life history should all be thoroughly examined before the establishment of a particular mitotic sequence for any given species.

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The Endoplasmic Reticulum and the Golgi Structures in Maize Root Cells

The Journal of Cell Biology ◽

10.1083/jcb.5.3.501 ◽

1959 ◽

Vol 5 (3) ◽

pp. 501-506 ◽

Cited By ~ 59

Author(s):

W. Gordon Whaley ◽

Hilton H. Mollenhauer ◽

Joyce E. Kephart

Keyword(s):

Endoplasmic Reticulum ◽

Cell Wall ◽

Electron Microscope ◽

Nuclear Envelope ◽

Epoxy Resin ◽

Maize Root ◽

Root Tips ◽

Animal Cells ◽

Root Cells ◽

Vesicular Structure

Maize root tips were fixed in potassium permanganate, embedded in epoxy resin, sectioned to show silver interference color, and studied with the electron microscope. All the cells were seen to contain an endoplasmic reticulum and apparently independent Golgi structures. The endoplasmic reticulum is demonstrated as a membrane-bounded, vesicular structure comparable in many aspects to that of several types of animal cells. With the treatment used here the membranes appear smooth surfaced. The endoplasmic reticulum is continuous with the nuclear envelope and, by contact at least, with structures passing through the cell wall. The nuclear envelope is characterized by discontinuities, as previously reported for animal cells. The reticula of adjacent cells seem to be in contact at or through the plasmodesmata. Because of these contacts the endoplasmic reticulum of a given cell appears to be part of an intercellular system. The Golgi structures appear as stacks of platelet-vesicles which apparently may, under certain conditions, produce small vesicles around their edges. Their form changes markedly with development of the cell.

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

Cells ◽

10.3390/cells9081908 ◽

2020 ◽

Vol 9 (8) ◽

pp. 1908 ◽

Cited By ~ 1

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.

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Ultrastructure of Plant Leaf Tissue Infected with Mite-Borne Viral-Like Pathogens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067881 ◽

1970 ◽

Vol 28 ◽

pp. 178-179 ◽

Cited By ~ 2

Author(s):

O. E. Bradfute ◽

R. E. Whitmoyer ◽

L. R. Nault

Keyword(s):

Triticum Aestivum ◽

Zea Mays ◽

Electron Microscope ◽

Hordeum Vulgare ◽

Microscope Study ◽

Electron Microscope Study ◽

Leaf Tissue ◽

Leaf Ultrastructure ◽

Double Membrane ◽

Aceria Tulipae

A pathogen transmitted by the eriophyid mite, Aceria tulipae, infects a number of Gramineae producing symptoms similar to wheat spot mosaic virus (1). An electron microscope study of leaf ultrastructure from systemically infected Zea mays, Hordeum vulgare, and Triticum aestivum showed the presence of ovoid, double membrane bodies (0.1 - 0.2 microns) in the cytoplasm of parenchyma, phloem and epidermis cells (Fig. 1 ).

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100161023 ◽

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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ELECTRON MICROSCOPY OF THE NUCLEAR MEMBRANE OF AMOEBA PROTEUS

The Journal of Cell Biology ◽

10.1083/jcb.2.4.445 ◽

1956 ◽

Vol 2 (4) ◽

pp. 445-448 ◽

Cited By ~ 60

Author(s):

Marie H. Greider ◽

Wencel J. Kostir ◽

Walter J. Frajola

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Nuclear Membrane ◽

Outer Layer ◽

Microscope Study ◽

Electron Microscope Study ◽

Cell Types ◽

Amoeba Proteus ◽

Nuclear Membranes ◽

Thin Sectioning

An electron microscope study of the nuclear membrane of Amoeba proteus by thin sectioning techniques has revealed an ultrastructure in the outer layer of the membrane that is homologous to the pores and annuli observed in the nuclear membranes of many other cell types studied by these techniques. An inner honeycombed layer apparently unique to Amoeba proteus is also described.

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Effect of Kaolin Particle Size Towards Preparation of Kaolin Ceramic Membrane

Emerging Advances in Integrated Technology ◽

10.30880/emait.2021.02.01.005 ◽

2021 ◽

Vol 02 (01) ◽

Author(s):

Siti Khadijah Hubadillah ◽

◽

Norsiah Hami ◽

Nurul Azita Salleh ◽

Mohd Riduan Jamalludin ◽

...

Keyword(s):

Particle Size ◽

Electron Microscope ◽

Scanning Electron Microscope ◽

Field Emission ◽

Preliminary Data ◽

Membrane Structure ◽

Ceramic Membrane ◽

Low Cost ◽

Dense Structure ◽

Scanning Electron

The purpose of this work is to study the effect of kaolin particle size for the preparation of low cost ceramic membrane suspension and ceramic membrane structure. Kaolin particle size is categorized into two categories; i) ≤ 1µm and ii) ≥ 1 µm. The suspension is prepared via stirring technique under 1000 rpm at 60°C. The particle size of kaolin is characterized using field emission scanning electron microscope (FESEM) and the prepared suspension is characterized in term of its viscosity. Results indicate that the particle size gave significant effect to the viscosity of ceramic membrane suspension. Preliminary data showed that kaolin with particle size ≤ 1µm resulted ceramic membrane with dense structure.

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An unusual cell surface modification: a double plasma membrane

Journal of Cell Science ◽

10.1242/jcs.39.1.355 ◽

1979 ◽

Vol 39 (1) ◽

pp. 355-372

Author(s):

N.J. Lane ◽

J.B. Harrison

Keyword(s):

Plasma Membrane ◽

Membrane Structure ◽

Cell Layer ◽

Peritrophic Membrane ◽

Thin Sections ◽

Double Membrane ◽

Freeze Fracturing ◽

Blood Sucking ◽

Great Pressure ◽

Insertion Sites

The occurrence of an unusual double plasma membrane structure is reported; it has been studied in conventional thin sections, after lanthanum-impregnation and with freeze-fracturing. This modification of the plasmalemma is found where the luminal cell membrane (I membrane) of gut microvilli in the haematophagous insect, Rhodnius prolixus, is surrounded by a second, outer membrane (O membrane), the 2 separated from one another by a highly regular I-O space of about 10 nm. Lanthanum impregnation reveals the presence of columns inclined at an angle, within this I-O space; as in the continuous junctions which link the lateral borders of these cells, these columns may maintain the very precise I-O distance. From the outer microvillar membranes radiate short spoke-like fibrils or sheets which encounter another more extensive system of myelin-like sheets. Freeze-fracturing reveals that the spoke-like sheets and the other ones which lie like a tube, around and parallel to the microvilli, contain linear ridges composed of particles, lying at random within layers of the myelin-like material which also extends into the lumen of the gut. The microvillar membanes, both O and I, fracture into faces containing rows of either PF particles or EF pits arranged as spiral ridges or grooves around the sides and across the tip of each microbillus. These could be the insertion sites of one or both of the I-O columns and spoke-like sheets while the sheets could represent a variant of peritrophic membrane. The double membrane may be a cellular device to increase the strength of the microvillar layer in these blood-sucking animals, since the cell layer must withstand great pressure owing to a sudden massive extension of the gut during a blood meal.

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