scholarly journals The Endoplasmic Reticulum and the Golgi Structures in Maize Root Cells

1959 ◽  
Vol 5 (3) ◽  
pp. 501-506 ◽  
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.

scholarly journals The amounts and rates of export of polysaccharides found within the membrane system of maize root cells

1974 ◽  
Vol 142 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Dianna J. Bowles ◽  
D. H. Northcote
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Golgi Apparatus ◽  
Cell Surface ◽  
Rough Endoplasmic Reticulum ◽  
Membrane System ◽  
Maize Root ◽  
Wall Material ◽  
Cell Wall Material ◽  
Root Cells

1. Maize seedling roots were incubated in vivo with d-[U-14C]glucose for 2, 5, 10, 15, 30 and 45min. The total incorporation of radioactivity into polysaccharide components in isolated fractions was investigated, and the pattern of incorporation into different polysaccharide components within the rough endoplasmic reticulum, Golgi apparatus and exported material was analysed. 2. The membrane compartments reached a saturation value of radioactivity in polysaccharide components by 30min incubation. Radioactivity in exported polysaccharide continued to increase after that time. The latter was formed and maintained by a steady-state turnover of polysaccharide synthesis and transport from the membrane system. 3. If the only access of the slime polysaccharide to the cell surface is via dictyosome-derived vesicles, the amount of slime components in the Golgi apparatus would have to be displaced every 0.3min in order to maintain the observed rates of increase in slime. This is in contrast with a displacement time of about 2.5min that is necessary for polysaccharide components in the Golgi apparatus to produce the observed increase in cell-wall material. The activity of the membrane system in the production of maize root slime is 8 times as great as that of the membrane system involved in cell-wall synthesis. 4. If the amount of polysaccharide material in the Golgi apparatus is maintained only by inflow of polymeric material from the rough endoplasmic reticulum the total amount of slime components in the rough endoplasmic reticulum would have to be displaced every 7min to maintain a constant amount in the Golgi apparatus. If the endoplasmic reticulum contributed directly to the cell surface in the synthesis of cell-wall material, displacement times necessary to maintain the observed rate of polymer production would be very slow.

Location of fucosyl transferases in the membrane system of maize root cells

1979 ◽  
Vol 40 (1) ◽  
pp. 235-244
Author(s):  
J.R. Green ◽  
D.H. Northcote
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Sucrose Gradient ◽  
Maize Root ◽  
Transferase Activity ◽  
Root Tips ◽  
Root Cells ◽  
Discontinuous Sucrose Gradient

There are two fucosyl transferase activities present within the endomembranes of the cells of maize root-tips. One transfers fucose to polyprenyl phosphate and occurs in the endoplasmic reticulum, the second transfers fucose probably to polysaccharide or glycoprotein. In order to show an association of this second fucosyl transferase activity with the endoplasmic reticulum as well as the Golgi apparatus, a method of fractionating the membranes in a discontinuous sucrose gradient was used. Membranes were prepared in the presence of Mg2+, which maintained the attachment of ribosomes to the endoplasmic reticulum, and also in the presence of EDTA, which removed most of the ribosome complex. This caused a shift in density of these membranes. Two types of experiments were carried out; either maize roots were incubated in L-[1-3H]fucose and then membranes prepared and the amount of polymer synthesized in vivo determined or isolated membranes were incubated with GDP-L-[U-14C]fucose in vitro and the amount of polymer synthesized was found. The results showed that the Golgi apparatus had the highest amount of this fucosyl transferase activity, but there was a significant amount of activity associated with the endoplasmic reticulum and the latter was shifted in the sucrose gradient depending on the conditions used.

scholarly journals THE STRUCTURE OF SOME CYTOPLASMIC COMPONENTS OF PLANT CELLS IN RELATION TO THE BIOCHEMICAL PROPERTIES OF ISOLATED PARTICLES

1957 ◽  
Vol 3 (1) ◽  
pp. 61-70 ◽  
Author(s):  
A. J. Hodge ◽  
E. M. Martin ◽  
R. K. Morton
Keyword(s):  
Endoplasmic Reticulum ◽  
Wheat Root ◽  
Dense Material ◽  
Animal Cells ◽  
Wheat Roots ◽  
Root Cells ◽  
Intact Cells ◽  
Thin Sections ◽  
Isolated Mitochondria ◽  
Silver Beet

1. Electron micrographs of thin sections of material fixed with buffered osmium tetroxide have been used for comparison of the fine structure of isolated cytoplasmic particles from silver beet petioles and roots of germinating wheat with that of the cytoplasm of the intact cells. 2. Mitochondria of wheat roots have an external double membrane and poorly oriented internal double membranes. As compared with the structures seen in situ, the isolated mitochondria showed evidence of some disorganisation of the fine internal structure, probably due to osmotic effects. The possible influence of such changes on the enzymic properties of the isolated mitochondria is discussed. 3. The isolated plant microsomes are mainly spherical vesicular structures consisting of (a) an outer membrane enclosing (b) either an homogeneous slightly dense material (wheat root microsomes) or some granular dense material (silver beet microsomes) and (c) small dense particles, mostly associated with the vesicle membranes. 4. The cytoplasm of the wheat root cells does not contain any structures similar to the isolated microsomes but has a very dense reticular network, consisting of membranes with associated small dense particles, here called the endoplasmic reticulum. The observations indicate that the isolated microsomes arise mainly by rupture and transformation of the membranes of this structure. The effects of such extensive changes in the lipoprotein membranes on the enzymic activities of the endoplasmic reticulum, as studied in isolated microsomes, is discussed. 5. Meristematic wheat root cells contain structures which consist of smooth membranes with associated vacuoles and are similar to the Golgi zones of animal cells. The membranes of these zones probably contribute to the microsomal fraction under the conditions of preparation used for the enzymic and chemical studies previously reported.

Mitosis in Mougeotia sp.

1972 ◽  
Vol 50 (9) ◽  
pp. 1811-1816 ◽  
Author(s):  
Carla W. Bech-Hansen ◽  
Larry C. Fowke
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Short Distance ◽  
Late Anaphase ◽  
New Information ◽  
Early Anaphase

Combined light and electron microscope observations have provided new information concerning mitosis in Mougeotia. The distribution of microtubules during division suggests that intact wall microtubules moved at preprophase to form the spindle and returned to the cell wall at telophase. During metaphase and early anaphase, chromosomal microtubules were attached to distinct kinetochores; few interzonal microtubules were evident. The subsequent elongation of the spindle at late anaphase was accompanied by the appearance of numerous interzonal microtubules and the loss of the original nuclear envelope. The nucleoli dispersed during prophase and reformed at telophase. The wall septum appeared at prophase but extended only a short distance into the cell by telophase; microtubules were not associated with the developing septum.

scholarly journals SOME OBSERVATIONS ON THE NUCLEAR ENVELOPE

1960 ◽  
Vol 8 (1) ◽  
pp. 233-245 ◽  
Author(s):  
W. Gordon Whaley ◽  
Hilton H. Mollenhauer ◽  
James H. Leech
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Epoxy Resin ◽  
Membrane Structure ◽  
Root Meristem ◽  
Double Membrane ◽  
Nuclear Membranes ◽  
Cytoplasmic Surface ◽  
Different Types ◽  
The Status

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.

The fine structure and development of chlamydospores of Fusarium oxysporum

1972 ◽  
Vol 18 (7) ◽  
pp. 997-1002 ◽  
Author(s):  
I. L. Stevenson ◽  
S. A. W. E. Becker
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cell Surface ◽  
Outer Layer ◽  
Outer Wall ◽  
Wall Layer ◽  
Thin Sections ◽  
Hyphal Wall

Methods have been developed for the rapid, reproducible induction of high-density populations of F. oxysporum chlamydospores. On transferring washed pregerminated conidia to a simple two-salts medium, chlamydospore morphogenesis was evident by 12 h and masses of mature spores could be harvested at the end of 4 days. Electron-microscope studies of thin sections of mature chlamydospores reveal a thick triple-layered cell wall. The cytoplasm contains, in addition to large lipid deposits, a nucleus, mitochondria, and endoplasmic reticulum all typical of fungal cells. Chlamydospores of F. oxysporum exhibit two distinct types of cell surface in thin section. The outer wall layer of two of the isolates studied was smooth-surfaced while the outer layer of the two other isolates was distinctly fibrillose. Some evidence is presented suggesting that the fibrillose material arises through the partial breakdown of the original hyphal wall.

scholarly journals POLYRIBOSOMES AND CISTERNAL ACCUMULATIONS IN ROOT CELLS OF RADISH

1965 ◽  
Vol 27 (2) ◽  
pp. 423-432 ◽  
Author(s):  
Howard T. Bonnett ◽  
Eldon H. Newcomb
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Raphanus Sativus ◽  
Phase Contrast ◽  
Animal Cells ◽  
Root Cells ◽  
Common Component ◽  
Raphanus Sativus L ◽  
Root Hair Formation ◽  
Hair Formation

The zone of root hair formation of seedling radish roots, Raphanus sativus L., was studied by phase-contrast and electron microscopy. Localized dilations of the endoplasmic reticulum, which contained a moderately dense proteinaceous material, were found to be a common component of the cytoplasm in cells of the epidermis and cortex. The surfaces of these dilations were covered with polyribosomes in discrete coils commonly composed of 15 to 17 ribosomes. The function of these structures and the fate of the material accumulated in them are unknown. Their similarity to structures described in some types of animal cells is discussed.

scholarly journals Cisternal Organization of the Endoplasmic Reticulum during Mitosis

2009 ◽  
Vol 20 (15) ◽  
pp. 3471-3480 ◽  
Author(s):  
Lei Lu ◽  
Mark S. Ladinsky ◽  
Tom Kirchhausen
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Mammalian Cells ◽  
Three Dimensional ◽  
Freeze Substitution ◽  
High Resolution Electron Microscopy ◽  
Animal Cells ◽  
Resolution Electron ◽  
Major Transformation ◽  
Membrane Bound

The endoplasmic reticulum (ER) of animal cells is a single, dynamic, and continuous membrane network of interconnected cisternae and tubules spread out throughout the cytosol in direct contact with the nuclear envelope. During mitosis, the nuclear envelope undergoes a major rearrangement, as it rapidly partitions its membrane-bound contents into the ER. It is therefore of great interest to determine whether any major transformation in the architecture of the ER also occurs during cell division. We present structural evidence, from rapid, live-cell, three-dimensional imaging with confirmation from high-resolution electron microscopy tomography of samples preserved by high-pressure freezing and freeze substitution, unambiguously showing that from prometaphase to telophase of mammalian cells, most of the ER is organized as extended cisternae, with a very small fraction remaining organized as tubules. In contrast, during interphase, the ER displays the familiar reticular network of convolved cisternae linked to tubules.

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.

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