scholarly journals Subcellular localization and function of melanogenic enzymes in the ink gland of Sepia officinalis

1997 ◽  
Vol 323 (3) ◽  
pp. 749-756 ◽  
Author(s):  
Anna PALUMBO ◽  
Anna DI COSMO ◽  
Ida GESUALDO ◽  
Vincent J. HEARING
Keyword(s):  
Endoplasmic Reticulum ◽  
Subcellular Localization ◽  
Rough Endoplasmic Reticulum ◽  
Polyclonal Antibodies ◽  
Sepia Officinalis ◽  
Complex Organization ◽  
The Matrix ◽  
And Function ◽  
Golgi Network ◽  
Open Question

The ink gland of the cuttlefish Sepia officinalis has traditionally been regarded as a convenient model system for investigating melanogenesis. This gland has been shown to contain a variety of melanogenic enzymes including tyrosinase, a dopachrome-rearranging enzyme and peroxidase. However, whether and to what extent these enzymes co-localize in the melanogenic compartments and interact is an open question. Using polyclonal antibodies that recognize the corresponding Sepia proteins, we have been able to demonstrate that peroxidase has a different subcellular localization pattern from tyrosinase and dopachrome-rearranging enzyme. Whereas peroxidase is located in the rough endoplasmic reticulum and in the matrix of premelanosomes and melanosomes, tyrosinase and dopachrome-rearranging enzyme are present in the rough endoplasmic reticulum–Golgi transport system, at the level of trans-Golgi cisternae, trans-Golgi network and coated vesicles, and in melanosomes on pigmented granules. These results fill a longstanding gap in our knowledge of the melanin-producing system in Sepia and provide the necessary background for dissection at the molecular level of the complex interaction between melanogenic enzymes. Moreover, the peculiar and complex organization of melanin in an invertebrate such as Sepia officinalis is surprising and could provide the basis for understanding the process in more evolved systems such as that of mammals.

scholarly journals Subcellular localization of complex carbohydrates in rat macrophages and monocytes.

1979 ◽  
Vol 27 (8) ◽  
pp. 1180-1181 ◽  
Author(s):  
P L Sannes ◽  
M Eguchi ◽  
S S Spicer
Keyword(s):  
Bone Marrow ◽  
Endoplasmic Reticulum ◽  
Subcellular Localization ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Peripheral Blood ◽  
Periodic Acid ◽  
High Iron ◽  
Cytoplasmic Vesicles ◽  
Complex Carbohydrates

Methods for visualization of complex carbohydrates ultrastructurally were employed to study specific organelles of the rat monocyte and macrophage. Vicinal glycols of glycoconjugates were demonstrated with the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) postembedding sequence and acid groups were delineated by the dialyzed iron (DI) and high iron diamine (HID) preembedding techniques. Lysosomal bodies were generally found reactive with all three methods, although those of monocytes from the bone marrow and peripheral blood were notably lacking in acidic groups. The Golgi complex was consistently PA-TCH-SP-reactive, as were associated vesicles and occasional cisternal expansions, possibly related to GERL. Numerous cytoplasmic vesicles and small granulated structures and cisternae of the rough endoplasmic reticulum were also PA-TCH-SP-reactive.

The protein translocation machinery of the endoplasmic reticulum

1982 ◽  
Vol 300 (1099) ◽  
pp. 225-228 ◽  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Rough Endoplasmic Reticulum ◽  
Protein Translocation ◽  
Signal Sequence ◽  
Integral Membrane Proteins ◽  
Multiple Copies ◽  
And Function ◽  
Lysosomal Proteins

The rough endoplasmic reticulum (r.e.r.) has been postulated to possess a single translation-coupled translocation system (in multiple copies) that effects signal sequence-mediated translocation of all secretory and lysosomal proteins and integration of all integral membrane proteins whose port of entry is the rough endoplasmic reticulum (G. Blobel 1980 Proc. natn. Acad. Sci. U.S.A. 77, 1496—1500). Two proteins have been isolated that are components of the r.e.r. translocation system. Their properties and function in protein translocation across and integration into membranes are discussed.

The secretion of collagen by insects: uptake of [3H]proline by collagen-synthesizing cells in Locusta migratoria and Galleria mellonella

1976 ◽  
Vol 20 (2) ◽  
pp. 377-403
Author(s):  
D.E. Ashhurst ◽  
N.M. Costin
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Galleria Mellonella ◽  
Unit Area ◽  
Locusta Migratoria ◽  
Relative Number ◽  
Collagen Secretion ◽  
The Matrix ◽  
Intracellular Pathway ◽  
Wax Moth

The uptake of [H3]proline by collagen-secreting cells of the locust, Locusta migratoria, and wax-moth, Galleria mellonella, has been investigated by electron autoradiography. The locust cells are around the ejaculatory duct and they secrete collagen in the young adult male, while the wax-moth cells are those which produce the dorsal mass of connective tissue on the abdominal nerve cord during the late pupal stage. The cells were exposed to [H3]proline either by injection of the [3H]proline into the insect, or as a pulse while the tissue was maintained in a culture medium. The tissues were fixed at differeing experimental times after exposure to the [3H]proline. The resulting electron autoradiographs were subjected to quantitative analysis, and the silver grain distribution was determined as the relative number of grains per unit area over a series of tissue compartments. When the results of this analysis for the matrix, rough endoplasmic reticulum and Golgi complexes of the two tissues were plotted against experimental time, it was seen that the relative number of grains per unit area over the rough endoplasmic reticulum decreases while that over the matrix increases; statistical analysis has shown that these changes are significant. For the Golgi complexes, however, the theoretical variances are much greater, due to the small relative area occupied by this organelle. There is little evidence for anything other than random sampling fluctuations in the relative numbers of grains per unit area, and hence it is unlikely that the time course of the label over the Golgi complexes follows that over the rough endoplasmic reticulum. The conclusions drawn from these experiments are firstly that a large portion of the labelled protein passes straight from the rough endoplasmic reticulum to the matrix, but that a smaller portion of the labelled material might pass from the rough endoplasmic reticulum to the Golgi complexes and thence to the matrix. It is assumed that collagen comprises most of the protein which passes straight from the rough endoplasmic reticulum to the matrix, and while there is no evidence to exclude collagen from the material passing through the Golgi complexes, it is probable that other proteins and glycosaminoglycans are also present in this labelled material. These conclusions about the intracellular pathway for collagen secretion are similar to those derived from recent studies of some vertebrate fibroblasts. There is, however, conflicting opinion about the intracellular pathway of collagen and it is pointed out that there is diversity in collagen-synthesizing cells, which may account for the differences in the intracellular pathways for collagen secretion which have been proposed.

Ultrastructure of Solitary Enchondromas

1984 ◽  
Vol 9 (1) ◽  
pp. 95-97 ◽  
Author(s):  
MARILYN L. ZIMNY ◽  
I. REDLER
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Cell Types ◽  
Transmission Electron ◽  
The Matrix ◽  
Small Bones ◽  
Dying Cells ◽  
Myelin Figures

Solitary enchondromas obtained from the small bones of the hand were studied with transmission electron microscopy. Three cell types were seen as follows: (1) young looking, active cells with extensive dilated rough endoplasmic reticulum and well defined Golgi and mitochondria; (2) older looking, degenerating cells with dilated rough endoplasmic reticulum, well defined Golgi, glycogen masses, vacuoles containing tropocollagen, lipid and myelin figures; and (3) dying cells showing loss of cell membrane and lysosomal-like bodies. A young chondroblastic cell may try to mature, become a normal chondrocyte that produces normal matrix but it does not succeed and dies. Enchondromal cells are not capable of forming tropocollagen or synthesizing proteoglycans for the matrix.

scholarly journals Subcellular localization of the enzyme that forms mannosyl retinyl phosphate from guanosine diphosphate [14C]mannose and retinyl phosphate

1979 ◽  
Vol 180 (3) ◽  
pp. 449-453 ◽  
Author(s):  
M J Smith ◽  
J B Schreiber ◽  
G Wolf
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Subcellular Localization ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Subcellular Distribution ◽  
Smooth Endoplasmic Reticulum ◽  
Marker Enzymes ◽  
Guanosine Diphosphate

The subcellular distribution of the enzyme catalysing the conversion of retinyl phosphate and GDP-[14C]mannose into [14C]mannosyl retinyl phosphate was determined by using subcellular fractions of rat liver. Purity of fractions, as determined by marker enzymes, was 80% or better. The amount of mannosyl retinyl phosphate formed (pmol/min per mg of protein) for each fraction was: rough endoplasmic reticulum 0.48 +/- 0.09 (mean +/- S.D.); smooth membranes (consisting of 60% smooth endoplasmic reticulum and 40% Golgi apparatus), 0.18 +/- 0.03; Golgi apparatus, 0.13 +/- 0.03; and plasma membrane 0.02.

scholarly journals Anterograde and retrograde traffic between the rough endoplasmic reticulum and the Golgi complex.

1995 ◽  
Vol 131 (6) ◽  
pp. 1387-1401 ◽  
Author(s):  
J C Stinchcombe ◽  
H Nomoto ◽  
D F Cutler ◽  
C R Hopkins
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Temperature Shift ◽  
Golgi Stack ◽  
Retrograde Traffic ◽  
Almost All ◽  
Golgi Network ◽  
In Cells

The transfer of newly synthesized membrane proteins moving from the rough endoplasmic reticulum (RER) to the Golgi complex has been studied by electron microscopy in HEp-2 cells transfected with cDNAs for chimeric proteins. These proteins consist of a reporter enzyme, horseradish peroxidase (HRP), anchored to the transmembrane domains of two integral membrane proteins, the transferrin receptor and sialyl-transferase. The chimeras are distributed throughout the nuclear envelope, RER, vesicular tubular clusters (VTCs) and a network of tubules in the cis-Golgi area. At 20 degrees C tubules containing chimera connect the RER to the VTCs and to the cis-Golgi network. On transfer to 37 degrees C in the presence of dithiothreitol (DTT), the chimeras are seen to move from the RER and through the Golgi stack. With this temperature shift the direct connections with the RER are lost and free vesicles form; some of these vesicles contain HRP reaction product which is much more concentrated than in the adjacent RER while others lack reaction product entirely. In cells expressing SSHRPKDEL, DAB reaction product remains distributed throughout the RER, the VTCs, and the cis-Golgi network for prolonged periods in the presence of DTT and almost all of the vesicles which form at 37 degrees C are DAB-positive. Together these observations demonstrate that all three chimeras are transported from the RER to the cis-Golgi in free, 40-60-nm vesicles at 37 degrees C. They also suggest that the retrograde traffic which carries SSHRPKDEL back to the RER is probably mediated by vesicles with a similar morphology but which, in cells expressing membrane-anchored chimeras, lack detectable reaction product.

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).

Modification of Pineal Ultrastructure by Exogenous Hormones

1967 ◽  
Vol 25 ◽  
pp. 170-171
Author(s):  
R. A. Turner ◽  
A. E. Rodin ◽  
D. K. Roberts
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Estradiol Benzoate ◽  
Female Rats ◽  
List Type ◽  
Type Number ◽  
Pregnant Rats ◽  
Gonadal Atrophy ◽  
Pineal Ultrastructure

There have been many reports which establish a relationship between the pineal and sexual structures, including gonadal hypertrophy after pinealectomy, and gonadal atrophy after injection of pineal homogenates or of melatonin. In order to further delineate this relationship the pineals from 5 groups of female rats were studied by electron microscopy:ControlsPregnant ratsAfter 4 weekly injections of 0.1 mg. estradiol benzoate.After 8 daily injections of 150 mcgm. melatonin (pineal hormone).After 8 daily injections of 3 mg. serotonin (melatonin precursor).No ultrastructural differences were evident between the control, and the pregnancy and melatonin groups. However, the estradiol injected animals exhibited a marked increase in the amount and size of rough endoplasmic reticulum within the pineal cells.

Membrane-associated microtubular areays induced in proximal myelinated processes of dorsal root ganglia by large doses of vitamin B6

1986 ◽  
Vol 44 ◽  
pp. 368-369
Author(s):  
V.J. Montpetit ◽  
S. Dancea ◽  
L. Tryphonas ◽  
D.F. Clapin
Keyword(s):  
Animal Model ◽  
Endoplasmic Reticulum ◽  
Dorsal Root Ganglia ◽  
Rough Endoplasmic Reticulum ◽  
Dorsal Root ◽  
Vitamin B6 ◽  
Morphological Changes ◽  
Model System ◽  
Sensory Nerves ◽  
Peripheral Sensory

Very large doses of pyridoxine (vitamin B6) are neurotoxic in humans, selectively affecting the peripheral sensory nerves. We have undertaken a study of the morphological and biochemical aspects of pyridoxine neurotoxicity in an animal model system. Early morphological changes in dorsal root ganglia (DRG) associated with pyridoxine megadoses include proliferation of neurofilaments, ribosomes, rough endoplasmic reticulum, and Golgi complexes. We present in this report evidence of the formation of unique aggregates of microtubules and membranes in the proximal processes of DRG which are induced by high levels of pyridoxine.

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