Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

scholarly journals Nonuniform distribution of sodium in the rat hepatocyte.

1976 ◽  
Vol 67 (4) ◽  
pp. 469-474 ◽  
Author(s):  
G Hooper ◽  
D A Dick
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Rat Hepatocytes ◽  
Nonuniform Distribution ◽  
Flame Photometry ◽  
Ground Substance ◽  
Rat Hepatocyte ◽  
Correlation Parameters ◽  
Cytoplasmic Ground Substance

The volume of the nucleus, endoplasmic reticulum (including Golgi complex), mitochondria, and cytoplasmic ground substance was measured in rat hepatocytes by stereological methods. The Na content was also measured by flame photometry. Variations in Na content correlated significantly with variations in volume of nucleus and endoplasmic reticulum. From the correlation parameters, Na concentrations were estimated as follows: nucleus, 108 mM; endoplasmic reticulum (ER) (including Golgie complex) 27 mM; cytoplasm (including and remaining organelles) 16 mM.

scholarly journals OBSERVATIONS ON A SUBMICROSCOPIC BASOPHILIC COMPONENT OF CYTOPLASM

1953 ◽  
Vol 97 (5) ◽  
pp. 727-750 ◽  
Author(s):  
Keith R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Dark Field ◽  
Ground Substance ◽  
Adjacent Cell ◽  
Submicroscopic Structure ◽  
Dark Field Microscopy ◽  
Reticular System ◽  
Living Unit ◽  
Cytoplasmic Ground Substance

The cytoplasmic ground substance of animal tissue cells grown in vitro has been found by electron microscopy to contain, as a part of its submicroscopic structure, a complex reticulum of strands, to be referred to as the endoplasmic reticulum. It has been found in all types of cells extensively studied. The components of this reticular system vary considerably in size and form, apparently in some relation to physiological changes in the cell. Thus in one cell of a culture colony it may be finely divided into strands or canaliculi, 50 to 100 mµ in diameter, whereas in an adjacent cell of the same type the components of the reticulum may be relatively coarse, 600 mµ in diameter, and vesiculated. The membrane, which can be shown to limit the system and separate it from the rest of the ground substance, is similar in thickness to the plasma membrane surrounding the cell. Photomicrographs of living cells taken by phase contrast and dark field microscopy define a structure of similar form and indicate that the reticulum of the electron microscope image has its equivalent in the living unit. Where its component units are sufficiently large, a structure of identical form can be resolved by light microscopy in cells stained with hematoxylin or with toluidine blue. This indicated that the endoplasmic reticulum is to be identified with the basophilic or chromophilic component (the ergastoplasm) of the cytoplasm and that such properties of this component as have been determined by cytochemical methods, such as a high RNA content, may be assigned to this "submicroscopic" system.

The fine structure of RNA-storing archaeocytes from gemmules of fresh-water sponges

1965 ◽  
Vol s3-106 (73) ◽  
pp. 99-114
Author(s):  
AUGUST RUTHMANN
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Fresh Water ◽  
Structural Integrity ◽  
Structural Aspect ◽  
Ground Substance ◽  
Annulate Lamellae ◽  
Golgi Bodies ◽  
High Concentrations ◽  
Cytoplasmic Ground Substance

Gemmules of fresh-water sponges contain about 500 binucleated cells (‘archaeocytes’) which are loaded with reserve substances including ribonucleoprotein, acidophilic proteins, lipids, and polysaccharides. These substances are utilized during the early phase of histogenesis after germination of the gemmules. Apart from the presence of reserve bodies, the basic fine structure of metabolically inactive archaeocytes within the closed system of a gemmule is not fundamentally different from actively metabolizing cells of rapidly growing tissues. In particular, ribosomes, endoplasmic reticulum, mitochondria, Golgi bodies, and RNA-containing nucleoli are present during inactivity as well as after germination and resumption of growth and synthesis. Changes in cellular fine structure after germination include an increased density of the cytoplasmic ground substance, the appearance of small vesicles in the vicinity of the Golgi bodies and of annulate lamellae and a large, cylindrical centriole near the nuclear envelope. Two general conclusions are drawn from these results. Neither the ultra-structural aspect of a cell nor the presence of high concentrations of RNA in cytoplasm and nucleolus is a valid indication of cellular activity or inactivity. The persistence of Golgi bodies and endoplasmic reticulum through long periods of inactivity shows that their structural integrity is not dependent upon continuous energy input, although these intracellular membrane systems are undoubtedly dynamic structures in metabolically active cells.

scholarly journals Immunocytochemical localization of catalase in rat liver.

1981 ◽  
Vol 29 (7) ◽  
pp. 805-812 ◽  
Author(s):  
S Yokota ◽  
H D Fahimi
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Golgi Complex ◽  
Intracellular Localization ◽  
Sodium Dodecyl ◽  
Specific Staining ◽  
Simple Method ◽  
Fab Fragments ◽  
The Matrix ◽  
A Cell

The intracellular localization of catalase has been studied using monospecific Fab fragments against rat liver catalase (RLC) and preembedding immunoelectron microscopy. Purified RLC, exhibiting a single band on sodium dodecyl sulfate gel electrophoresis, was used for the immunization of rabbits. The anti-RLC IgG was purified by affinity chromatography. Fab fragments were obtained by papain digestion and were labeled with horseradish peroxidase (HRP) using a modified two-step procedure and glutaraldehyde as coupling agents. Livers were perfused with 4% depolymerized paraformaldehyde and chopper sections were incubated with HRP-labeled Fab fragments against RLC. Because of the limited penetration of labeled Fab fragments into chopper sections a simple method for preparation of a cell suspension from aldehyde-fixed livers was devised. Adequate staining of more than 90% of cell was obtained by incubation of cell suspensions for 12--18 hr with the labeled antibody. By light microscopy specific staining was present in fine granules in the cytoplasm of hepatocytes. By electron microscopy the electron-dense reaction product was localized in the matrix of peroxisomes with no reaction in the endoplasmic reticulum and the Golgi complex. In some hepatocytes, positively reacted peroxisomes were seen side by side with unstained particles. Although focal diffusion was noted around a few peroxisomes, no evidence of cytoplasmic catalase independent of peroxisomes was found. These observations indicate that in rat liver peroxisomes are the only organelle containing substantial amounts of catalase antigen and rule out any involvement of the endoplasmic reticulum and the Golgi complex in the sequestration of this protein.

scholarly journals Prohibitin: A Novel Molecular Player in KDEL Receptor Signalling

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Monica Giannotta ◽  
Giorgia Fragassi ◽  
Antonio Tamburro ◽  
Capone Vanessa ◽  
Alberto Luini ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Membrane Trafficking ◽  
Transmembrane Domain ◽  
Cell Cycle Control ◽  
Retrograde Transport ◽  
Multifunctional Protein ◽  
G Protein Coupled ◽  
Kdel Receptor ◽  
Prohibitin 1

The KDEL receptor (KDELR) is a seven-transmembrane-domain protein involved in retrograde transport of protein chaperones from the Golgi complex to the endoplasmic reticulum. Our recent findings have shown that the Golgi-localised KDELR acts as a functional G-protein-coupled receptor by binding to and activating Gs and Gq. These G proteins induce activation of PKA and Src and regulate retrograde and anterograde Golgi trafficking. Here we used an integrated coimmunoprecipitation and mass spectrometry approach to identify prohibitin-1 (PHB) as a KDELR interactor. PHB is a multifunctional protein that is involved in signal transduction, cell-cycle control, and stabilisation of mitochondrial proteins. We provide evidence that depletion of PHB induces intense membrane-trafficking activity at the ER–Golgi interface, as revealed by formation of GM130-positive Golgi tubules, and recruitment of p115,β-COP, and GBF1 to the Golgi complex. There is also massive recruitment of SEC31 to endoplasmic-reticulum exit sites. Furthermore, absence of PHB decreases the levels of the Golgi-localised KDELR, thus preventing KDELR-dependent activation of Golgi-Src and inhibiting Golgi-to-plasma-membrane transport of VSVG. We propose a model whereby in analogy to previous findings (e.g., the RAS-RAF signalling pathway), PHB can act as a signalling scaffold protein to assist in KDELR-dependent Src activation.

scholarly journals The Lamellar Systems of Cytoplasmic Membranes in Dividing Spermatogenic Cells of Drosophila virilis

1960 ◽  
Vol 7 (3) ◽  
pp. 433-441 ◽  
Author(s):  
Susumu Ito
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Light And Electron Microscopy ◽  
Primary Spermatocyte ◽  
Drosophila Virilis ◽  
Spermatogenic Cells ◽  
Membrane Systems ◽  
Cytoplasmic Membranes ◽  
Pas Reaction ◽  
Staining Methods

Spermatogenic cells of Drosophila virilis were studied by light and electron microscopy. The persistence of a "nuclear wall" during the meiotic divisions has been reported by a number of early cytologists, but this interpretation has been a subject of debate. Electron micrographs of dividing spermatocytes reveal the presence of multiple layers of paired membranes surrounding the nuclear region. These lamellar membrane systems are not typical of the nuclear envelope, but were interpreted as such by light microscopists. The membranes constituting a pair are separated by an interspace of ∼ 100 A and successive pairs are 200 to 400 A apart. These spacings are similar but not identical to those found in the lamellar systems of the Golgi complex. The cisternae of the endoplasmic reticulum in this material are devoid of attached ribonucleoprotein particles, are more precisely ordered than in vertebrate cells, and show a uniform, narrow intracisternal space of ∼ 100 A. The conspicuous asters appear to be made up of similar paired membranes radiating from the centriolar region. The primary spermatocyte has numerous dictyosomes and a well developed endoplasmic reticulum in cisternal form, but no typical Golgi complex or endoplasmic reticulum is found during the meiotic division stages of metaphase to telophase. Evidence is presented that these cytoplasmic organelles contribute to the formation of the extensive lamellar systems that appear during meiosis. The results of the Golgi silver staining methods and staining tests for phospholipids, basophilia, and the PAS reaction, indicate that the lamellar arrays of membranes present during meiosis are indistinguishable from the Golgi complex in their tinctorial properties.

scholarly journals Biosynthesis of the insulin receptor in rat adipose cells. Intracellular processing of the Mr-190 000 pro-receptor

1985 ◽  
Vol 232 (1) ◽  
pp. 71-78 ◽  
Author(s):  
J A Hedo ◽  
I A Simpson
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Insulin Receptor ◽  
Golgi Complex ◽  
Microsomal Fraction ◽  
Primary Cultures ◽  
Sodium Dodecyl ◽  
High Density ◽  
Low Density ◽  
Adipose Cells

We investigated the biosynthesis of the insulin receptor in primary cultures of isolated rat adipose cells. Cells were pulse-chase-labelled with [3H]mannose, and at intervals samples were homogenized. Three subcellular membrane fractions were prepared by differential centrifugation: high-density microsomal (endoplasmic-reticulum-enriched), low-density microsomal (Golgi-enriched), and plasma membranes. After detergent solubilization, the insulin receptors were immunoprecipitated with anti-receptor antibodies and analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and autoradiography. After a 30 min pulse-label [3H]mannose first appeared in a band of Mr 190 000. More than 80% of the Mr-190 000 component was recovered in the microsomal fractions. Its intensity reached a maximum at 1 h in the high-density microsomal fraction and at 2 h in the low-density microsomal fraction, and thereafter declined rapidly (t 1/2 approx. 3 h) in both fractions. In the plasma-membrane fraction, the radioactivity in the major receptor subunits, of Mr 135 000 (alpha) and 95 000 (beta), rose steadily during the chase and reached a maximum at 6 h. The Mr-190 000 precursor could also be detected in the high-density microsomal fraction by affinity cross-linking to 125I-insulin. In the presence of monensin, a cationic ionophore that interferes with intracellular transport within the Golgi complex, the processing of the Mr-190 000 precursor into the alpha and beta subunits was completely inhibited. Our results suggest that the Mr-190 000 pro-receptor originates in the endoplasmic reticulum and is subsequently transferred to the Golgi complex. Maturation of the pro-receptor does not seem to be necessary for the expression of the insulin-binding site. Processing of the precursor into the mature receptor subunits appears to occur during the transfer of the pro-receptor from the Golgi complex to the plasma membrane.

scholarly journals Myosin Motors and Not Actin Comets Are Mediators of the Actin-based Golgi-to-Endoplasmic Reticulum Protein Transport

2003 ◽  
Vol 14 (2) ◽  
pp. 445-459 ◽  
Author(s):  
Juan M. Durán ◽  
Ferran Valderrama ◽  
Susana Castel ◽  
Juana Magdalena ◽  
Mónica Tomás ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Light Chain ◽  
Shiga Toxin ◽  
Actin Filaments ◽  
Protein Transport ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii ◽  
Myosin Motors

We have previously reported that actin filaments are involved in protein transport from the Golgi complex to the endoplasmic reticulum. Herein, we examined whether myosin motors or actin comets mediate this transport. To address this issue we have used, on one hand, a combination of specific inhibitors such as 2,3-butanedione monoxime (BDM) and 1-[5-isoquinoline sulfonyl]-2-methyl piperazine (ML7), which inhibit myosin and the phosphorylation of myosin II by the myosin light chain kinase, respectively; and a mutant of the nonmuscle myosin II regulatory light chain, which cannot be phosphorylated (MRLC2AA). On the other hand, actin comet tails were induced by the overexpression of phosphatidylinositol phosphate 5-kinase. Cells treated with BDM/ML7 or those that express the MRLC2AA mutant revealed a significant reduction in the brefeldin A (BFA)-induced fusion of Golgi enzymes with the endoplasmic reticulum (ER). This delay was not caused by an alteration in the formation of the BFA-induced tubules from the Golgi complex. In addition, the Shiga toxin fragment B transport from the Golgi complex to the ER was also altered. This impairment in the retrograde protein transport was not due to depletion of intracellular calcium stores or to the activation of Rho kinase. Neither the reassembly of the Golgi complex after BFA removal nor VSV-G transport from ER to the Golgi was altered in cells treated with BDM/ML7 or expressing MRLC2AA. Finally, transport carriers containing Shiga toxin did not move into the cytosol at the tips of comet tails of polymerizing actin. Collectively, the results indicate that 1) myosin motors move to transport carriers from the Golgi complex to the ER along actin filaments; 2) nonmuscle myosin II mediates in this process; and 3) actin comets are not involved in retrograde transport.

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