Role of the nuclear membrane in smooth endoplasmic reticulum formation in white rat pinealocytes

1967 ◽  
Vol 23 (6) ◽  
pp. 465-466 ◽  
Author(s):  
H. M. Poletti ◽  
M. A. Castellano
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Smooth Endoplasmic Reticulum

A special pattern of the smooth endoplasmic reticulum in the kidney of the snail Cryptomphalus aspersa

1976 ◽  
Vol 22 (3) ◽  
pp. 617-622
Author(s):  
R. Paniagua ◽  
J.J. Vazquez
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Smooth Endoplasmic Reticulum ◽  
Glycogen Metabolism ◽  
Alpha Particles ◽  
Structural Pattern ◽  
Dark Cells ◽  
Beta Particles ◽  
Special Pattern

A special structural pattern of the smooth endoplasmic reticulum (SER) has been observed in the kidney of the snail Cryptomphalus aspersa. Two types of cells (clear and dark) cover the foldings of the renal sac; the dark cells are by far the most numerous. A cisterna of SER enveloping the nucleus appears invariably in both types of cells, with no disruptions, or small ones (from 50 to 90 nm) along its profile. The layer of cytoplasm lodged between the external nuclear membrane and this cisterna is found invariably to be from 0-20 to 0-25 mum in width. Glycogen is abundant in the cytoplasm as alpha particles, and also in the nucleus, but as beta particles. It is noteworthy that absolutely no glycogen is present in the layer of cytoplasm lodged between the nuclear membrane and the surrounding SER envelope. Long profiles of SER are also observed closely approaching and parallel to the plasma membrane of the dark cells. Considering the role of SER in glycogen metabolism in the kidney of the snail, the possible function of these cisternae as a support system ofr enzymes involved in the metabolism of glucides is discussed.

scholarly journals Role of p97 and Syntaxin 5 in the Assembly of Transitional Endoplasmic Reticulum

2000 ◽  
Vol 11 (8) ◽  
pp. 2529-2542 ◽  
Author(s):  
Line Roy ◽  
John J.M. Bergeron ◽  
Christine Lavoie ◽  
Rob Hendriks ◽  
Jennifer Gushue ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Atp Hydrolysis ◽  
Smooth Endoplasmic Reticulum ◽  
Atp Depletion ◽  
Low Density ◽  
Transitional Endoplasmic Reticulum ◽  
Membrane Compartment ◽  
A Cell

Transitional endoplasmic reticulum (tER) consists of confluent rough and smooth endoplasmic reticulum (ER) domains. In a cell-free incubation system, low-density microsomes (1.17 g cc− 1) isolated from rat liver homogenates reconstitute tER by Mg2+GTP- and Mg2+ATP-hydrolysis–dependent membrane fusion. The ATPases associated with different cellular activities protein p97 has been identified as the relevant ATPase. The ATP depletion by hexokinase or treatment with either N-ethylmaleimide or anti-p97 prevented assembly of the smooth ER domain of tER. High-salt washing of low-density microsomes inhibited assembly of the smooth ER domain of tER, whereas the readdition of purified p97 with associated p47 promoted reconstitution. The t-SNARE syntaxin 5 was observed within the smooth ER domain of tER, and antisyntaxin 5 abrogated formation of this same membrane compartment. Thus, p97 and syntaxin 5 regulate assembly of the smooth ER domain of tER and hence one of the earliest membrane differentiated components of the secretory pathway.

Liver alterations as a result of the 90-day continuous feeding of 2,3,7,8-tetrachlorodibenzo-p-dioxin

1986 ◽  
Vol 44 ◽  
pp. 364-365
Author(s):  
J.N. Turner ◽  
D.N. Collins
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Complex Mixture ◽  
Environmental Toxins ◽  
Bile Canaliculi ◽  
Cytoplasmic Vacuoles ◽  
Continuous Feeding ◽  
Tetrachlorodibenzo P Dioxin ◽  
Dose Levels

Chlorinated hydrocarbons are a highly toxic, ubiquitous class of environmental toxins of which 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) is the most toxic. PCB pyrolysates contain a complex mixture of these chemicals and have been shown to produce extensive alterations in the liver of guinea pig hepatocytes, including proliferated smooth endoplasmic reticulum (SER), concentric membrane arrays (CMA) which are a condensation of proliferated SER, and cytoplasmic vacuoles. A mechanism of membrane excretion into the bile canaliculi and sinusoids has been proposed to account for these alterations and their relationship to each other. This report demonstrates the proposed mechanism for a purified compound (TCDD) fed continuously for 90 days and further elucidates the role of the cytoplasmic vacuoles which are observed for dose levels at which no other alteration is present.

The submicrosomal distribution of dolichol and dolichol phosphokinase activity in rat liver

1982 ◽  
Vol 60 (1) ◽  
pp. 36-41 ◽  
Author(s):  
Jack W. Rip ◽  
Kenneth K. Carroll
Keyword(s):  
High Pressure ◽  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Smooth Endoplasmic Reticulum ◽  
Glycoprotein Synthesis ◽  
Dolichyl Phosphate ◽  
Glycoprotein Processing ◽  
Specific Activities ◽  
High Concentrations

Microsomes were isolated from rat liver and fractionated into Golgi, smooth endoplasmic reticulum (SER), and rough endoplasmic reticulum (RER) components, and the purity of these fractions was determined. The dolichol content of each of the three fractions was estimated, using high-pressure liquid chromatography. Although highest concentrations (1940 ng/mg protein) were found in Golgi, the RER contained the largest absolute amounts. The presence of large quantities of dolichol in RER is consistent with the role of dolichol as an intermediate in asparagine-linked glycoprotein synthesis. RER and SER fractions contained high specific activities for dolichol phosphokinase, while the activity in Golgi was quite low. High concentrations of dolichol in Golgi and high dolichol phosphokinase activity in SER suggest that dolichol (and dolichyl phosphate) may be utilized in Golgi for glycoprotein processing and in the transmembrane movement of sugars such as galactose.

scholarly journals FINE STRUCTURAL LOCALIZATION OF ACYLTRANSFERASE ACTIVITY IN RAT HEPATOCYTES

1972 ◽  
Vol 20 (12) ◽  
pp. 1031-1040 ◽  
Author(s):  
FRANCINE M. BENES ◽  
JOAN A. HIGGINS ◽  
RUSSELL J. BARRNETT
Keyword(s):  
Heavy Metal ◽  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Rat Hepatocytes ◽  
Potassium Ferricyanide ◽  
Potassium Ferrocyanide ◽  
Significant Extent ◽  
Acyltransferase Activity ◽  
Structural Localization

A method for the fine structural localization of acyltransferases catalyzing the transfer of acyl groups from palmityl-coenzyme A (CoA) to α-glycerophosphate based on the formation of a heavy metal precipitate at the site of CoA release is described. In this method CoA released through the action of the enzyme is oxidized by potassium ferricyanide, which is reduced to potassium ferrocyanide and precipitates in the presence of cupric ions. Acyltransferase activity was found to survive both fixation in glutaraldehyde and incubation in the presence of the capture reagent system used for cytochemistry. Reaction product marking the enzyme activity was located within the cisternae of the rough endoplasmic reticulum and to lesser, but significant extent, within the membranous envelope of the smooth endoplasmic reticulum. Reaction product was not associated to any significant extent with other membranous organelles. The significance of these observations in terms of the role of acyltransferases in liver function is discussed.

scholarly journals Macroautophagy Involved in Testosterone Synthesis in Leydig Cells of Male Dairy Goats (Capra Hircus)

2021 ◽  
Author(s):  
Hong Chen ◽  
Kexin Chen ◽  
Fange Zhao ◽  
Yihan Guo ◽  
Yue Liang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Leydig Cells ◽  
Smooth Endoplasmic Reticulum ◽  
Capra Hircus ◽  
Dairy Goats ◽  
Serum Luteinizing Hormone ◽  
Ultrastructural Characteristics ◽  
Autophagy Activity ◽  
Testosterone Synthesis

Abstract Background Testosterone is an important steroid hormone that is indispensable for male sexual development and the reproductive system. Leydig cells (LCs), where autophagy extremely active, reside in the testicular interstitium and are the major sites of testosterone production. However, the ultrastructural characteristics and the functional role of autophagy in LCs of livestock remain unknown. This study was to investigate the role of autophagy in LCs testosterone synthesis of dairy goats at juvenile, pubertal, and adult stages. Results In the present study, morphological results showed that the steroidogenic activity and ultrastructure of the LCs were altered with increasing age. Serum luteinizing hormone and testosterone levels were significantly elevated with sexual maturation. Organelles involved in testosterone synthesis, e.g., smooth endoplasmic reticulum, mitochondria, and lipid droplets, were abundantly distributed within the cytoplasm of LCs in adult testes. However, further studies demonstrated that selective autophagy (including lipophagy and mitophagy) did not participate in the synthesis of testosterone in LCs. In contrast, the autophagy activity was enhanced in the testes at puberty and adulthood compared to that at the juvenile stage. Moreover, a number of different autophagosomes, including phagophores and autolysosomes, were observed within the cytoplasm of LCs. Conclusions Together, our results reveal that macroautophagy is involved in testosterone synthesis mainly through degrading mitochondria and endoplasmic reticulum in the LCs of dairy goats.

scholarly journals THE ROLE OF CYTOCHROME P450 ISOFORMS OF HEPATOCYTE ENDOPLASMIC RETICULUM IN ETHANOL METABOLISM

2021 ◽  
Vol 5 (2) ◽  
pp. 132-137
Author(s):  
I. P. Sutsko ◽  
◽  
I. N. Semenenya ◽  
A. G. Shlyahtun ◽  
◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cytochrome P450 ◽  
Ethanol Oxidation ◽  
Smooth Endoplasmic Reticulum ◽  
Ethanol Metabolism ◽  
Primary Role ◽  
Liver Alcohol Dehydrogenase ◽  
Cyp Isoforms ◽  
Main Components

Background. Three metabolic pathways that can function simultaneously are known to be involved in ethanol oxidation in the liver: alcohol dehydrogenase pathway, microsomal ethanol-oxidizing system, and catalase pathway. Though the cytochrome P450-dependent microsomal ethanol-oxidizing system plays an insignificant role in metabolism of small amounts of ethanol, it is induced in case of ethanol excess and becomes essential when ethanol is abused. The main components of this system are cytochrome P450 (CYP) isoforms of smooth endoplasmic reticulum. Objective. To characterize the role of the key isoforms of cytochrome P450 in ethanol oxidation. Material and methods. We carried out an analysis of modern literature data on the role of the main isoforms of cytochrome P450 in liver metabolism of ethanol. Results. Data on the primary role of cytochrome CYP2E1 in ethanol metabolism, as well as on the contribution of isoforms CYP1A2, CYP2B1/2, CYP2C, CYP3A4, CYP4B1 to ethanol oxidation are presented. Conclusions. Ethanol is metabolized by many CYPs of endoplasmic reticulum of hepatocytes. The importance of CYP in biotransformation processes in the liver necessitates the study of the role of individual CYP isoforms in ethanol metabolism for predicting changes in the pharmacokinetics of drugs and metabolism of endogenous compounds under the influence of ethanol.

In Vitro Induction of Crystals of MT Protein by Vinblastine-Colcemid in Mouse Spermatids

1974 ◽  
Vol 32 ◽  
pp. 132-133
Author(s):  
John J. Wolosewick ◽  
John H. D. Bryan
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Nuclear Ring ◽  
Rough Er ◽  
Distal Direction ◽  
In Vitro Induction

Early in spermiogenesis the manchette is rapidly assembled in a distal direction from the nuclear-ring-densities. The association of vesicles of smooth endoplasmic reticulum (SER) and the manchette microtubules (MTS) has been reported. In the mouse, osmophilic densities at the distal ends of the manchette are the organizing centers (MTOCS), and are associated with the SER. Rapid MT assembly and the lack of rough ER suggests that there is an existing pool of MT protein. Colcemid potentiates the reaction of vinblastine with tubulin and was used in this investigation to detect this protein.

Hepatic Ultrastructure Changes Induced by Lithocholic Acid

1967 ◽  
Vol 25 ◽  
pp. 162-163 ◽  
Author(s):  
F. G. Zaki
Keyword(s):  
Endoplasmic Reticulum ◽  
Lithocholic Acid ◽  
Smooth Endoplasmic Reticulum ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Electron Microscopic ◽  
Hydropic Degeneration ◽  
Hepatic Cells ◽  
Low Protein ◽  
Microscopic Studies

Addition of lithocholic acid (LCA), a naturally occurring bile acid in mammals, to a low protein diet fed to rats induced marked inflammatory reaction in the hepatic cells followed by hydropic degeneration and ductular cell proliferation. These changes were accompanied by dilatation and hyperplasia of the common bile duct and formation of “gallstones”. All these changes were reversible when LCA was withdrawn from the low protein diet except for the hardened gallstones which persisted.Electron microscopic studies revealed marked alterations in the hepatic cells. Early changes included disorganization, fragmentation of the rough endoplasmic reticulum and detachment of its ribosomes. Free ribosomes, either singly or arranged in small clusters were frequently seen in most of the hepatic cells. Vesiculation of the smooth endoplasmic reticulum was often encountered as early as one week after the administration of LCA (Fig. 1).

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