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.

scholarly journals The sites of synthesis and transport of extracellular polysaccharides in the root tissues of maize

1972 ◽  
Vol 130 (4) ◽  
pp. 1133-1145 ◽  
Author(s):  
Dianna J. Bowles ◽  
D. H. Northcote
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Secondary Wall ◽  
Extracellular Polysaccharide ◽  
Membrane System ◽  
Maize Root ◽  
Extracellular Polysaccharides ◽  
Root Tip ◽  
Root Cells

1. Subcellular fractionation of maize roots resulted in the isolation of the following enriched fractions: cell wall, dictyosome, smooth-membrane and rough-microsomal fractions. In addition, extracellular polysaccharide of the root slime was isolated. 2. Maizeseedling roots were incubated in vivo with d-[U-14C]glucose, and the pattern of incorporation of radioactivity into the polysaccharides of each fraction was investigated. 3. The differentiation of maize-root cells with respect to the synthesis of specific extracellular polysaccharide directly relates to the polysaccharide synthesized and transported within the membrane system of the cell. A fucose-containing polysaccharide, characteristic only of root slime, was present only in the membrane system of the root-tip region of the root. Regions of typical secondary wall development within the root were characterized by an increased incorporation of radioactivity into xylose of polysaccharide within the membrane system. 4. The incorporation of radioactivity into glucan polymers in the membrane fractions was very low in all regions of the root. Since in regions of secondary wall development greater than 60% of all radioactive incorporation was into a glucan polymer, it can be inferred that this polymer, most probably cellulose, is not synthesized or transported within the compartments of the membrane system. It is suggested that synthesis of cellulose occurs at the surface of the plasmalemma. 5. Maize-root cells contained 40 times more rough endoplasmic reticulum than dictyosome membrane. The relative specific radioactivities of each fraction indicated that polysaccharide was concentrated in the region of the Golgi apparatus, which showed a 100% increase in specific radioactivity compared with the rough endoplasmic reticulum. The Golgi apparatus can thus be regarded as a localized focal point on the synthetic and transport system of polysaccharide by the intracellular membrane compartments.

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.

Altered labelling of the cell surface and intracellular organelles with [3H]mannose in enucleated amoebae

1984 ◽  
Vol 68 (1) ◽  
pp. 83-94
Author(s):  
C.J. Flickinger
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Cell Surface ◽  
Rough Endoplasmic Reticulum ◽  
Intracellular Transport ◽  
Cell Organelles ◽  
Intracellular Organelles ◽  
And Control ◽  
Kinetics Of ◽  
Heavy Labelling

The production, transport, and disposition of material labelled with [3H]mannose were studied in microsurgically enucleated and control amoebae. Cells were injected with the precursor and samples were prepared for electron-microscope radioautography at intervals, up to 24 h later. Control cells showed heavy labelling of the rough endoplasmic reticulum and the Golgi apparatus at early intervals after injection. Later, labelling of groups of small vesicles increased, and the percentage of grains over the cell surface peaked 12 h after administration of the precursor. Two major changes were detected in enucleate amoebae. First, the kinetics of labelling of cell organelles with [3H]mannose were altered in the absence of the nucleus. The Golgi apparatus and cell surface both displayed maximal labelling at later intervals in enucleates, and the percentage of grains over the rough endoplasmic reticulum varied less with time in enucleated than in control cells. Second, the distribution of radioactivity was altered. A greater percentage of grains was associated with lysosomes in enucleates than in control cells. The change in the kinetics of labelling of the endoplasmic reticulum, Golgi apparatus and cell surface indicates that intracellular transport of surface material was slower in the absence of the nucleus. It is suggested that this is related to the decreased motility of enucleate cells.

Effects of Cytochalasin B on the Golgi Apparatus of Maize Root Cells

1975 ◽  
Vol 33 ◽  
pp. 576-577
Author(s):  
H. H. Mollenhauer ◽  
D. J. Morrè
Keyword(s):  
Golgi Apparatus ◽  
Cell Surface ◽  
Cytochalasin B ◽  
Zea Mays L ◽  
Distribution Patterns ◽  
Maize Root ◽  
Secretory Vesicles ◽  
Root Tips ◽  
Root Cells ◽  
M 14

Seedlings of maize (Zea mays L.) var. WF-9 X M-14 were exposed to cytochalasin B for 1/2, 1, and 2 hr at concentrations of 0, 10, and 100 ppm. The root tips were then fixed for electron microscopy and the epidermal and outer cap cells examined for changes in dictyosome form, intercisternal fibers or secretory vesicles.Cytochalasin B did not cause significant changes in dictyosome form (Fig. 1) or intercisternal fibers. However, it did induce alterations in the distribution patterns of Golgi apparatus-derived secretory vesicles.In epidermal and outer cap cells of the maize root, following cytochalasin B treatment, secretory vesicles accumulated within the central portions of the cytoplasm in those regions occupied by Golgi apparatus (Fig. 2, 3). Cytoplasmic regions along the cell surface were devoid of secretory vesicles, and very few vesicles were found at the cell surface (Fig. 2, 3). We interpret these findings to mean that secretory vesicles formed by the Golgi apparatus did not move to the cell surface, but accumulated at or near their sites of origin following treatment with cytochalasin B.

Redistribution of material labelled with [3H]mannose in amoebae induced to undergo pinocytosis

1982 ◽  
Vol 58 (1) ◽  
pp. 79-93
Author(s):  
C.J. Flickinger
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Cell Surface ◽  
Rough Endoplasmic Reticulum ◽  
Lysosomal Enzymes ◽  
Surface Material ◽  
Albumin Solution ◽  
Electron Microscopic ◽  
Normal Medium ◽  
Electron Microscopic Radioautography

The synthesis, transport, and disposition of material labelled with [3H]mannose were studied by electron microscopic radioautography in normal amoebae and in cells that had internalized cell surface as a result of being induced to undergo pinocytosis. Control amoebae were injected with the precursor and placed in normal medium. The Golgi apparatus and rough endoplasmic reticulum were heavily labelled at the earliest intervals, while radioactivity of the cell surface peaked 12 h after injection of precursor. The experimental cells were injected, placed in bovine serum albumin solution from 15 to 60 min after injection, and then removed to normal medium until fixation. Incorporation of the precursor into the rough endoplasmic reticulum was near normal, but the proportions of grains associated with the Golgi apparatus and the cell surface were greatly reduced. The percentage of grains overlying vacuoles increased 12 h after injection, notably in the case of polymorphous vacuoles and dense vacuoles, both of which were identified as lysosomes with the acid phosphatase reaction. The results suggest that addition to the surface of components labelled with [3H]mannose was diminished following induction of pinocytosis. Incorporation of the precursor appeared to be shifted from cell surface material to lysosomal contents, possibly lysosomal enzymes. It is thought that this shift occurred in response to the need for the cell to digest unusually large amounts of endocytosed protein. Recycling of cell surface under these conditions is considered possible.

Aerial root cap structure of an orchid, Epidendrum

1981 ◽  
Vol 59 (9) ◽  
pp. 1702-1708 ◽  
Author(s):  
Susan J. Blackman ◽  
Edward C. Yeung
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Cell Walls ◽  
Root Cap ◽  
Wall Material ◽  
Wall Thickening ◽  
Cell Wall Material ◽  
Random Orientation ◽  
Mitotic Figures ◽  
Distal Cell

The root cap of Epidendrum ibaguense has a rounded profile with a root cap junction present between the cap and meristem. A distinct columella region is lacking. Mitotic figures are infrequent in the root cap initial cells. The root cap initials and their immediate derivatives show few dictyosomes, little endoplasmic reticulum, plastids lacking starch, and few vacuoles. As the cells age they increase in size and show increasing vacuolation. Plastids increase by division and accumulate large starch grains. Throughout the root cap, amyloplasts maintain a random orientation in the cell. Endoplasmic reticulum also becomes more abundant as the cells age. In older cells, hypertrophied dictyosomes are evident and cell wall material begins accumulating between the distal cell wall and the plasmalemma. Wall thickening progresses with age though radial walls remain largely unthickened. Vacuolation progresses and is followed by complete senescence leaving only the cell walls.

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 Changes in the ultrastructure of meristematic root cells of Allium sativum L. treated with selenium

2014 ◽  
Vol 69 (2) ◽  
pp. 93-100 ◽  
Author(s):  
Sława Glińska ◽  
Barbara Gabara
Keyword(s):  
Cell Wall ◽  
Allium Sativum ◽  
Stress Factors ◽  
Ultrastructural Changes ◽  
Wall Material ◽  
Sodium Selenate ◽  
Cell Wall Material ◽  
Root Cells ◽  
Selenium Compounds ◽  
Material Deposition

Ultrastructure of meristematic cells of garlic (<em>Allium sativum</em> L.) roots treated with sodium selenate and sodium selenite was assessed using transmission electron microscopy. Both selenium compounds applied at the concentrations: 80, 160 and 320 µM caused many malformations in the ultrastructure of mitochondria, plastids, endoplasmic reticulum and Golgi apparatus such as deformation in shape and size, disturbances in inner membranes organization, appearance of concentric or parallel arrangement of ER cisternae. Moreover, in the presence of selenium, beside uneven thickening of cell wall, many vacuoles of different dimensions filled with wall-like material even in the vicinity of nucleus were visible. The latter results suggest that selenium not only intensified the synthesis of cell wall material but also inhibited the process of cell wall material deposition. The similarity of all observed ultrastructural changes in garlic root cells after selenium treatment with those appearing after action of other stress factors are discussed.

Development of a cellular body during differentiation of conidial chlamydospores in Fusarium

1974 ◽  
Vol 20 (9) ◽  
pp. 1205-1208 ◽  
Author(s):  
Edward F. Schneider ◽  
W. L. Seaman
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Late Stage ◽  
Cell Structure ◽  
The Body ◽  
Wall Material ◽  
Cell Wall Material ◽  
Single Membrane ◽  
Fusarium Poae ◽  
Similar Body

The development of cellular bodies during the conversion of conidial cells to chlamydospores in Fusarium sulphureum (F. sambucinum f.6) is described. Development of the bodies from dilated cisternae within the endoplasmic reticulum begins before there are other recognizable changes in cell structure and is completed before new cell wall material is laid down. Each body is bounded by a single membrane derived from the endoplasmic reticulum and contains electron-dense particles, vesicular structures, and usually a microbody. These components remain intact within the body until a late stage in chlamydospore development. At that time the contents become granular, the vesicles and microbodies disappear, and the body becomes vacuole-like. A similar body was found in cells of Fusarium poae at comparable stages of chlamydospore development.

Sign in / Sign up

Export Citation Format

Share Document