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 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.

scholarly journals Ultrastructure of mononuclear phagocytes developing in liquid bone marrow cultures. A study on peroxidatic activity

1979 ◽  
Vol 149 (1) ◽  
pp. 17-26 ◽  
Author(s):  
JWM Van Der Meer ◽  
RHJ Beelen ◽  
DM Fluitsma ◽  
R Van Furth
Keyword(s):  
Bone Marrow ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Nuclear Envelope ◽  
Rough Endoplasmic Reticulum ◽  
Precursor Cells ◽  
Mononuclear Phagocytes ◽  
Peroxidatic Activity

Monoblasts, promonocytes, and macrophages in in vitro cultures of murine bone marrow were studied ultrastructurally, with special attention to peroxidatic activity. Monoblasts show peroxidatic activity in the rough endoplasmic reticulum and nuclear envelope as well as in the granules. The presence of peroxidatic activity in the Golgi apparatus could not be determined. Promonocytes have peroxidase-positive rough endoplasmic reticulum, Golgi apparatus, nuclear envelope, and granules, as previously reported. During culture, cells are formed with peroxidatic activity similar to that of monocytes or exudate macrophages (positive granules; negative Golgi apparatus, RER, and nuclear envelope); we call these cells early macrophages. In addition, transitional macrophages with both positive granules and positive RER, nuclear envelope, negative Golgi apparatus (as in exudate- resident macrophages in vivo), and mature macrophages with peroxidatic activity only in the RER and nuclear envelope (as in resident macrophages in vivo) were found. A considerable number of cells without detectable peroxidatic activity were also encountered. Our finding that macrophages with the peroxidatic pattern of monocytes (early macrophages), exudate-resident macrophages (transitional macrophages), and resident macrophages (mature macrophages), develop in vitro from proliferating precursor cells deriving from the bone marrow, demonstrates once again that resident macrophages in tissues originate from precursor cells in the bone marrow. Therefore, this conclusion can no longer be challenged on the basis of a cytochemical difference between monocytes and exudate macrophages on the one hand and resident macrophages on the other.

scholarly journals Polyprenyl phosphate sugars synthesized during slime-polysaccharide production by membranes of the root-cap cells of maize (Zea mays)

1979 ◽  
Vol 178 (3) ◽  
pp. 661-671 ◽  
Author(s):  
J R Green ◽  
D H Northcote
Keyword(s):  
Endoplasmic Reticulum ◽  
Zea Mays ◽  
Neutral Lipids ◽  
Root Tip ◽  
Synthetase Activity ◽  
Root Tips ◽  
Maize Roots ◽  
Glucose Derivatives

Two types of experiments were carried out; either maize roots were incubated in L-[1-3H]fucose or membranes were prepared from root tips and these were incubated with GDP-L-[U-14C]fucose or UDP-D-[U-4C]glucose. The radioactively labelled lipids that were synthesized in vivo and in vitro were extracted and separated into polar and neutral components. The polar lipids had the characteristics of polyprenyl phosphate and diphosphate fucose or glucose derivatives, and the neutral lipids of sterol glycosides (fucose or glucose). A partial separation of the glycolipid synthetase reactions was achieved. Membranes were fractionated into material that sedimented at 20,000g and 100,000g. Most of the polar glycolipid synthetase activity (for the incorporation of both fucose and glucose) was located in the 100,000 g pellet, and this activity was probably located in the endoplasmic reticulum. The neutral lipid, which contained fucose, was synthesized mainly by membranes of the 20,000g pellet, and the activity was probably associated with the dictyosomes, whereas the neutral glucolipids were synthesized by all the membrane fractions. It is suggested that the polar (polyprenyl) lipids labelled with fucose could act as possible intermediates during the synthesis of the glycoproteins and slime in the root tip.

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.

scholarly journals Facilitated transport of Mn2+ in sycamore (Acer pseudoplatanus) cells and excised maize root tips. A comparative 31P n.m.r. study in vivo

1988 ◽  
Vol 252 (2) ◽  
pp. 401-408 ◽  
Author(s):  
C Roby ◽  
R Bligny ◽  
R Douce ◽  
S I Tu ◽  
P E Pfeffer
Keyword(s):  
Metal Ion ◽  
Plasma Membranes ◽  
Maize Root ◽  
Root Tip ◽  
Acer Pseudoplatanus ◽  
Relative Distribution ◽  
Root Tips ◽  
Root Cells ◽  
Hypoxic Conditions

Movement of paramagnetic Mn2+ into sycamore (Acer pseudoplatanus) cells has been indirectly examined by observing the line broadening exhibited in its 31P n.m.r. spectra. Mn2+ was observed to pass into the vacuole, while exhibiting a very minor accumulation in the cytoplasm. With time, gradual leakage of phosphate from the vacuole to the cytoplasm was observed along with an increase in glucose-6-phosphate. Anoxia did not appear to affect the relative distribution of Mn2+ in the cytoplasm and vacuole. Under hypoxic conditions restriction of almost all movement of Mn2+ across the plasmalemma as well as the tonoplast was observed. In contrast, maize root tips showed entry and complete complexation of nucleotide triphosphate by Mn2+ during hypoxia. The rate of passage of Mn2+ across the tonoplast in both sycamore and maize root cells is approximately the same. However, the rates of facilitated movement across the respective plasma membranes appear to differ. More rapid movement of Mn2+ across the plasmalemma in maize root tip cells allows a gradual build-up of metal ion in the cytoplasm prior to its diffusion across the tonoplast. Sycamore cells undergo a slower uptake of Mn2+ into their cytoplasms (comparable with the rate of diffusion through the tonoplast), so little or no observable accumulation of Mn2+ is observed in this compartment.

scholarly journals ON THE SITE OF SULFATION IN COLONIC GOBLET CELLS

1964 ◽  
Vol 21 (3) ◽  
pp. 339-351 ◽  
Author(s):  
Nathan Lane ◽  
Lucien Caro ◽  
Luis R. Otero-Vilardebó ◽  
Gabriel C. Godman
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Goblet Cell ◽  
Sodium Sulfate ◽  
Goblet Cells ◽  
Rat Colon ◽  
Time Points

The location of bound S35 in the goblet cell of the rat colon at time points from 2 to 60 minutes after administration of S35 as sodium sulfate has been observed in vivo and in vitro by radioautographic techniques. Grains were first observed by electron microscopy over the stacked lamellae of the paranuclear part of the Golgi apparatus. The label was subsequently found associated with the supranuclear Golgi lamellae and was then seen associated with the smooth membranes limiting the mucin granules in the goblet. Finally, between ½ and 1 hour, the secreted mucus product in the crypts became radioactive. Neither mitochondria nor the endoplasmic reticulum was labeled. It is concluded that the Golgi apparatus is the organelle in which sulfation occurs.

scholarly journals Measurement and characteristics of fusion of isolated membrane fractions from maize root tips

1980 ◽  
Vol 45 (1) ◽  
pp. 169-186
Author(s):  
E.A. Baydoun ◽  
D.H. Northcote
Keyword(s):  
Plasma Membrane ◽  
Membrane Fusion ◽  
Gel Electrophoresis ◽  
Divalent Cations ◽  
Polyacrylamide Gel Electrophoresis ◽  
Maize Root ◽  
Root Tips ◽  
Sulphydryl Group

Maize root tips were incubated in vivo with radioactive glucose, choline or diazotized sulphanilic acid. Membrane fractions were prepared from radioactive and non-radioactive roots. The transfer of radioactivity between mixed membrane fractions has enabled a quantitative system to be developed to study in vitro membrane fusion between Golgi apparatus and plasma membrane-rich fractions. Membrane fusion was found to be dependent on time, temperature, Mn2+ and Ca2+. Mn2+ was as effective as Ca2+, other divalent cations had a moderate or no effect. The effect of various substances, including inhibitors of microtubular and microfilament assembly and blocking reagents for sulphydryl group on membrane fusion has been investigated. The process appears to be dependent on the membrane proteins or glycoproteins; trypsinization of mixed membranes prior to the addition of Ca2+ inhibited significantly the fusion process. SDS-polyacrylamide gel electrophoresis of trypsin-treated membranes revealed the selective loss of one particular polypeptide which could play a role in membrane fusion.

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 Arabinan synthase and xylan synthase activities of Phaseolus vulgaris. Subcellular localization and possible mechanism of action

1983 ◽  
Vol 210 (2) ◽  
pp. 497-507 ◽  
Author(s):  
G P Bolwell ◽  
D H Northcote
Keyword(s):  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Phaseolus Vulgaris ◽  
Golgi Apparatus ◽  
Suspension Culture ◽  
Subcellular Fractionation ◽  
Culture Cells ◽  
Bean Hypocotyl

Membrane fractions from bean hypocotyl or suspension cultures incorporated arabinose from UDP-beta-L-arabinose into arabinan and xylose from UDP-alpha-D-xylose in vitro; the level of each activity was dependent on the state of differentiation of the cells. These activities may be due to single transglycosylases, since no lipid or proteinaceous intermediate acceptors were found in either case. Subcellular fractionation studies showed that enzyme activity in vitro was localized in both Golgi-derived membranes and endoplasmic reticulum in similar amounts. However, incorporation into the polymers in vivo in suspension culture cells incubated with [1-3H]arabinose was considerably greater in the Golgi-derived membranes. Thus, although these enzymes may be translated and inserted at the level of the endoplasmic reticulum, their activities are under other levels of control, so that most of the activity in vivo is confined to the Golgi apparatus. Initiation of glycosylation in the endoplasmic activity may, however, occur.

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