Endoplasmic Reticulum Forms a Dynamic Continuum for Lipid Diffusion between Contiguous Soybean Root Cells

1993 ◽  
Vol 5 (1) ◽  
pp. 25 ◽  
Author(s):  
Sharon Grabski ◽  
Adriaan W. de Feijter ◽  
Melvin Schindler
1959 ◽  
Vol 5 (3) ◽  
pp. 501-506 ◽  
Author(s):  
W. Gordon Whaley ◽  
Hilton H. Mollenhauer ◽  
Joyce E. Kephart

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.


1957 ◽  
Vol 3 (1) ◽  
pp. 61-70 ◽  
Author(s):  
A. J. Hodge ◽  
E. M. Martin ◽  
R. K. Morton

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.


2013 ◽  
Vol 163 (3) ◽  
pp. 1230-1241 ◽  
Author(s):  
Maria Cristina Bonza ◽  
Giovanna Loro ◽  
Smrutisanjita Behera ◽  
Andrea Wong ◽  
Jörg Kudla ◽  
...  

1974 ◽  
Vol 52 (7) ◽  
pp. 1747-1755 ◽  
Author(s):  
P. A. Sargent ◽  
J. King

Cells cultured in sterile, liquid media from a number of Phaseolus spp., soybean cotyledons, shoots, and roots and from rice explants grew, in terms of dry-weight increase, much better in the presence of NH4+ and NO3− as sources of nitrogen than with NO3− alone. Other cultures tested, including other legumes, either did not respond positively to added NH4+ or, as in the case of Haplopappus gracilis cells, grew better in its absence.Earlier it had been shown that soybean (Glycine max. L. cv. Mandarin) root cells grew better in the presence of NH4+ than in its absence and that 'conditioning' substances were produced by cells and excreted into the medium between about the 15th and 35th h of incubation. These observations and those above with other cell cultures led to the initiation of an investigation of why some cells respond to NH4+ while others do not.This investigation has so far taken the form of an analysis of nitrogenous compounds in soybean root cells and in the NH4+-containing medium in which they were grown during 120 h of incubation and especially after 24 h of incubation, the time of maximum production of growth-enhancing ability in both cells and medium.Growth enhancement can be accounted for, apparently, by the occurrence of residual NH4+ in conditioned medium and by the presumed occurrence of NH4+ in cells. However, glutamine and its derivatives are implicated in the conditioning process.


1991 ◽  
Vol 96 (1) ◽  
pp. 192-197 ◽  
Author(s):  
Matthew T. Loper ◽  
Roger M. Spanswick

1974 ◽  
Vol 142 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Dianna J. Bowles ◽  
D. H. Northcote

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.


1980 ◽  
Vol 28 (10) ◽  
pp. 1129-1132 ◽  
Author(s):  
F Marty

Structural interactions between intracellular membranes in root cells of Triticum sativum L. have been investigated with the 3 MeV electron microscope in Toulouse after selective labeling of the membranes with either zinc iodide-osmium tetroxide or phosphotungstate at low pH. Direct membrane continuities between endoplasmic reticulum, Golgi apparatus, and biogenetically derived compartments of the exoplasmic space are more extensive than commonly suggested from conventional electron microscopy. The results are discussed with reference to current concepts suggesting a membrane flow from the endoplasmic reticulum to the terminal components, plasmalemma, and vacuoles.


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