scholarly journals STRUCTURE AND DEVELOPMENT OF THE CHLOROPLAST IN CHLAMYDOMONAS

1957 ◽  
Vol 3 (3) ◽  
pp. 463-488 ◽  
Author(s):  
Ruth Sager ◽  
George E. Palade
Keyword(s):  
Endoplasmic Reticulum ◽  
Higher Plants ◽  
Matrix Material ◽  
Starch Synthesis ◽  
Animal Cells ◽  
Thin Sections ◽  
Green Strain ◽  
Normal Green ◽  
Lamellar Region ◽  
Cytoplasmic Organization

The cytoplasmic organization of a normal green strain of the alga Chlamydomonas reinhardi has been investigated with the electron microscope using thin sections of OsO4 fixed material. The detailed organization of the chloroplast has been of special interest. The chloroplast, a cup-shaped organelle, surrounded by a double membrane, consists of: (1) discs about 1 micron in diameter, considered to represent the basic structural unit of the chloroplast, and each composed of a pair of membranes joined at their ends to form a flat closed vesicle; the discs are grouped into stacks resembling the grana of higher plants; (2) matrix material of low density in which the discs are embedded; (3) starch grains; (4) the pyrenoid, a non-lamellar region associated with starch synthesis, and containing tubules which connect with the lamellae; (5) the eyespot, a differentiated region containing two or three plates of hexagonally packed, carotenoid-containing granules, located between discs, and associated with phototaxis. In addition to the chloroplast, the cytoplasm contains various membranous and granular components, including mitochondria, endoplasmic reticulum, and dictyosomes, identified on the basis of morphological comparability with structures seen in animal cells. The nucleus, not investigated in detail in this study, contains a large, granular nucleolus and is surrounded by a nuclear envelope which is provided with pores and exhibits instances of continuity with the endoplasmic reticulum of the cytoplasm.

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.

scholarly journals CHROMATOPHORE DEVELOPMENT, PITS, AND OTHER FINE STRUCTURE IN THE RED ALGA, LOMENTARIA BAILEYANA (HARV.) FARLOW

1962 ◽  
Vol 12 (3) ◽  
pp. 553-569 ◽  
Author(s):  
G. Benjamin Bouck
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Higher Plants ◽  
Red Alga ◽  
Cellular Structures ◽  
Secretory Function ◽  
Thin Sections ◽  
Floridean Starch ◽  
Oriented Parallel

Thin sections of the red alga, Lomentaria baileyana, a tubular member of the Rhodymeniales, were examined after permanganate fixation and Araldite embedding. Many of the cellular structures in Lomentaria were found to be similar to analogous structures in animals and higher plants. However, in the walls between cells are modified areas generally known as pits which are unique to the higher orders of red algae (Florideae). In this study the pits were found to consist of a plug-like structure surrounded by an uninterrupted membrane apparently continuous with the plasma membrane. Examination of the chromatophore revealed a characteristic limiting membrane, a relatively sparse distribution of plates, no grana, and a single disc apparently oriented parallel to the limiting membrane. In addition to their origin from non-lamellate proplastids, chromatophores were found capable of division by simple constriction. Floridean starch grains were observed outside the chromatophore and the possibility of an association of the first formed grains with portions of the endoplasmic reticulum is considered. Gland cells seem to have a high proportion of Golgi components (dictyosomes), and are believed to have some kind of secretory function. Many of the Golgi vesicles seem to open on the wall and presumably discharge their contents.

Ultrastructure of the Parotid Gland of the Nine-Banded Armadillo

1977 ◽  
Vol 35 ◽  
pp. 640-641
Author(s):  
J. R. Ruby
Keyword(s):  
Endoplasmic Reticulum ◽  
Parotid Gland ◽  
Periodic Acid ◽  
Acinar Cells ◽  
Duct System ◽  
Parotid Glands ◽  
Dasypus Novemcinctus ◽  
Anterior Portion ◽  
Periodic Acid Schiff ◽  
Thin Sections

Parotid glands were obtained from five adult (four male and one female) armadillos (Dasypus novemcinctus) which were perfusion-fixed. The glands were located in a position similar to that of most mammals. They extended interiorly to the anterior portion of the submandibular gland.In the light microscope, it was noted that the acini were relatively small and stained strongly positive with the periodic acid-Schiff (PAS) and alcian blue techniques, confirming the earlier results of Shackleford (1). Based on these qualities and other structural criteria, these cells have been classified as seromucous (2). The duct system was well developed. There were numerous intercalated ducts and intralobular striated ducts. The striated duct cells contained large amounts of PAS-positive substance.Thin sections revealed that the acinar cells were pyramidal in shape and contained a basally placed, slightly flattened nucleus (Fig. 1). The rough endoplasmic reticulum was also at the base of the cell.

Localization of Adenosine Triphosphatase Activity in the Phleom of Nicotiana Tabacum

1972 ◽  
Vol 30 ◽  
pp. 230-231
Author(s):  
James Cronshaw ◽  
Jamison E. Gilder
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Higher Plants ◽  
High Surface ◽  
Root Tip ◽  
Animal Cells ◽  
Physiological Processes ◽  
Tip Cells ◽  
Atpase Localization

Adenosine triphosphatase (ATPase) activity has been shown to be associated with numerous physiological processes in both plants and animal cells. Biochemical studies have shown that in higher plants ATPase activity is high in cell wall preparations and is associated with the plasma membrane, nuclei, mitochondria, chloroplasts and lysosomes. However, there have been only a few ATPase localization studies of higher plants at the electron microscope level. Poux (1967) demonstrated ATPase activity associated with most cellular organelles in the protoderm cells of Cucumis roots. Hall (1971) has demonstrated ATPase activity in root tip cells of Zea mays. There was high surface activity largely associated with the plasma membrane and plasmodesmata. ATPase activity was also demonstrated in mitochondria, dictyosomes, endoplasmic reticulum and plastids.

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

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.

Immunoprobe localization in mammalian embryos

1990 ◽  
Vol 48 (3) ◽  
pp. 32-33
Author(s):  
Patricia G. Calarco ◽  
Margaret C. Siebert
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Thin Sections ◽  
Relative Lack ◽  
Large Size ◽  
Mammalian Embryos ◽  
Antigen Localization ◽  
Difficult Challenge ◽  
Lowicryl K4m ◽  
Fertilized Egg

Visualization of preimplantation mammalian embryos by electron microscopy is difficult due to the large size of the ircells, their relative lack of internal structure, and their highly hydrated cytoplasm. For example, the fertilized egg of the mouse is a single cell of approximately 75μ in diameter with little organized cytoskelet on and apaucity ofor ganelles such as endoplasmic reticulum (ER) and Golgi material. Thus, techniques that work well on tissues or cell lines are often not adaptable to embryos at either the LM or EM level.Over several years we have perfected techniques for visualization of mammalian embryos by LM and TEM, SEM and for the pre-embedding localization of antigens. Post-embedding antigenlocalization in thin sections of mouse oocytes and embryos has presented a more difficult challenge and has been explored in LR White, LR Gold, soft EPON (after etching of sections), and Lowicryl K4M. To date, antigen localization has only been achieved in Lowicryl-embedded material, although even with polymerization at-40°C, the small ER vesicles characteristic of embryos are unrecognizable.

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 Three-dimensional electron microscopy of ribosomal chromatin in two higher plants: a cytochemical, immunocytochemical, and in situ hybridization approach.

1991 ◽  
Vol 39 (11) ◽  
pp. 1495-1506 ◽  
Author(s):  
P M Motte ◽  
R Loppes ◽  
M Menager ◽  
R Deltour
Keyword(s):  
Electron Microscopy ◽  
In Situ Hybridization ◽  
Spatial Organization ◽  
Higher Plants ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Thin Sections ◽  
Cytoplasmic Dna ◽  
Immunocytochemical Techniques

We report the 3-D arrangement of DNA within the nucleolar subcomponents from two evolutionary distant higher plants, Zea mays and Sinapis alba. These species are particularly convenient to study the spatial organization of plant intranucleolar DNA, since their nucleoli have been previously reconstructed in 3-D from serial ultra-thin sections. We used the osmium ammine-B complex (a specific DNA stain) on thick sections of Lowicryl-embedded root fragments. Immunocytochemical techniques using anti-DNA antibodies and rDNA/rDNA in situ hybridization were also applied on ultra-thin sections. We showed on tilted images that the OA-B stains DNA throughout the whole thickness of the section. In addition, very low quantities of cytoplasmic DNA were stained by this complex, which is now the best DNA stain used in electron microscopy. Within the nucleoli the DNA was localized in the fibrillar centers, where large clumps of dense chromatin were also visible. In the two plant species intranucleolar chromatin forms a complex network with strands partially linked to chromosomal nucleolar-organizing regions identified by in situ hybridization. This study describes for the first time the spatial arrangement of the intranucleolar chromatin in nucleoli of higher plants using high-resolution techniques.

scholarly journals Microtubule-based Endoplasmic Reticulum Motility in Xenopus laevis: Activation of Membrane-associated Kinesin during Development

1999 ◽  
Vol 10 (6) ◽  
pp. 1909-1922 ◽  
Author(s):  
Jon D. Lane ◽  
Victoria J. Allan
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Types ◽  
Cytoplasmic Dynein ◽  
Culture Cell ◽  
Tissue Culture Cell ◽  
Differential Interference Contrast Microscopy ◽  
Animal Cells ◽  
Microtubule Motor ◽  
Directed Motility ◽  
Conventional Kinesin

The endoplasmic reticulum (ER) in animal cells uses microtubule motor proteins to adopt and maintain its extended, reticular organization. Although the orientation of microtubules in many somatic cell types predicts that the ER should move toward microtubule plus ends, motor-dependent ER motility reconstituted in extracts ofXenopus laevis eggs is exclusively a minus end-directed, cytoplasmic dynein-driven process. We have used Xenopusegg, embryo, and somatic Xenopus tissue culture cell (XTC) extracts to study ER motility during embryonic development inXenopus by video-enhanced differential interference contrast microscopy. Our results demonstrate that cytoplasmic dynein is the sole motor for microtubule-based ER motility throughout the early stages of development (up to at least the fifth embryonic interphase). When egg-derived ER membranes were incubated in somatic XTC cytosol, however, ER tubules moved in both directions along microtubules. Data from directionality assays suggest that plus end-directed ER tubule extensions contribute ∼19% of the total microtubule-based ER motility under these conditions. In XTC extracts, the rate of ER tubule extensions toward microtubule plus ends is lower (∼0.4 μm/s) than minus end-directed motility (∼1.3 μm/s), and plus end-directed motility is eliminated by a function-blocking anti-conventional kinesin heavy chain antibody (SUK4). In addition, we provide evidence that the initiation of plus end-directed ER motility in somatic cytosol is likely to occur via activation of membrane-associated kinesin.

Polymorphous endocytotic organelles in the receptor-mediated endocytosis of gold-labelled alpha 2-macroglobulin complexes by human fibroblasts

1985 ◽  
Vol 75 (1) ◽  
pp. 411-421
Author(s):  
B. Van der Schueren ◽  
D. Gasser ◽  
P. Marynen ◽  
F. Van Leuven ◽  
G. David ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Human Fibroblasts ◽  
Cellular Structures ◽  
Multivesicular Bodies ◽  
Staining Reaction ◽  
Human Skin Fibroblasts ◽  
Thin Sections ◽  
Receptor Mediated Endocytosis ◽  
Gold Label

The receptor-mediated endocytosis of gold-labelled alpha 2-macroglobulin complexes with trypsin or methylamine (alpha 2M-T-Au or alpha 2M-MA-Au) was studied by electron microscopy in human skin fibroblasts. The gold label was found in coated structures and very small tubules as well as in tubulovesicular structures and in multivesicular bodies/lysosomes. Thick sections (200 nm), but especially serial thin sections, clearly showed the polymorphic character of the cellular structures involved in endocytosis. Numerous intercommunications were particularly obvious between the tubulovesicular structures, the larger vesicles and the multivesicular bodies (MVB). Continuities between MVBs and endoplasmic reticulum and interconnections between MVBs were also observed. The specificity of the staining reaction was confirmed by indirect labelling of intracellular alpha 2M by polyclonal and by monoclonal antibodies on ultracryosections. These findings are discussed in relation to observations made on epithelial cells with other ligands.

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