scholarly journals TcGPXII, a glutathione-dependent Trypanosoma cruzi peroxidase with substrate specificity restricted to fatty acid and phospholipid hydroperoxides, is localized to the endoplasmic reticulum

2002 ◽  
Vol 364 (3) ◽  
pp. 787-794 ◽  
Author(s):  
Shane R. WILKINSON ◽  
Martin C. TAYLOR ◽  
Said TOUITHA ◽  
Isabel L. MAURICIO ◽  
David J. MEYER ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Fatty Acid ◽  
Trypanosoma Cruzi ◽  
Peroxidase Activity ◽  
Fatty Acid Biosynthesis ◽  
Smooth Endoplasmic Reticulum ◽  
Single Copy ◽  
Biochemical Properties ◽  
Rate Limiting Step ◽  
Ping Pong

Until recently, it had been thought that trypanosomes lack glutathione peroxidase activity. Here we report the subcellular localization and biochemical properties of a second glutathione-dependent peroxidase from Trypanosoma cruzi (TcGPXII). TcGPXII is a single-copy gene which encodes a 16kDa protein that appears to be specifically dependent on glutathione as the source of reducing equivalents. Recombinant TcGPXII was purified and shown to have peroxidase activity towards a narrow substrate range, restricted to hydroperoxides of fatty acids and phospholipids. Analysis of the pathway revealed that TcGPXII activity could be readily saturated by glutathione and that the peroxidase functioned by a Ping Pong mechanism. Enzyme reduction was shown to be the rate-limiting step in this pathway. Using immunofluorescence, TcGPXII was shown to co-localize with a homologue of immunoglobulin heavy-chain binding protein (BiP), a protein restricted to the endoplasmic reticulum and Golgi. As the smooth endoplasmic reticulum is the site of phospholipid and fatty acid biosynthesis, this suggests that TcGPXII may play a specific role in the T. cruzi oxidative defence system by protecting newly synthesized lipids from peroxidation.

scholarly journals The distribution of the components of mixed-function oxidase between the rough and the smooth endoplasmic reticulum of liver cells

1968 ◽  
Vol 110 (3) ◽  
pp. 407-412 ◽  
Author(s):  
J. L. Holtzman ◽  
T. E. Gram ◽  
P. L. Gigon ◽  
J. R. Gillette
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Reductase Activity ◽  
Mixed Function Oxidase ◽  
Protein Ratio ◽  
Nadph Cytochrome ◽  
Rate Limiting Step ◽  
Significant Difference ◽  
The Difference ◽  
Cytochrome P 450

Mixed-function oxidase activity, when measured by the N-demethylation of ethylmorphine or the hydroxylation of aniline, is significantly higher in the smooth hepatic endoplasmic reticulum than in the rough. In the rabbit the smooth membrane/rough membrane activity ratios are significantly greater than 1 whether the activities are expressed per g. of liver (ratio 5), per mg. of protein (ratio 3–5), per μg. of phospholipid phosphorus (ratio 2), per unit of cytochrome P-450 (ratio 1·7) or per unit of NADPH–cytochrome c reductase activity (ratio 2). On the other hand, if the activities are normalized to the NADPH–cytochrome P-450 reductase, there is no significant difference between the rough and smooth membranes. These results suggest that, in the rabbit, the rate-limiting step is the reduction of cytochrome P-450. In contrast, in the rat the difference in activities can be explained by differences in the concentration of cytochrome P-450.

scholarly journals A COMPARATIVE CYTOCHEMICAL STUDY OF MICROBODIES (PEROXISOMES) IN GREAT ALVEOLAR CELLS OF RODENTS, RABBIT AND MONKEY

1972 ◽  
Vol 20 (3) ◽  
pp. 180-191 ◽  
Author(s):  
EVELINE E. SCHNEEBERGER
Keyword(s):  
Endoplasmic Reticulum ◽  
Peroxidase Activity ◽  
Guinea Pigs ◽  
Smooth Endoplasmic Reticulum ◽  
Alveolar Cells ◽  
Cytochemical Study ◽  
Peroxidatic Activity ◽  
Endogenous Peroxidase ◽  
Light Staining

Lungs from rodents, lagomorphs and primates were briefly fixed in purified glutaraldehyde and incubated with diaminobenzidene and peroxide at pH 7.6 for the demonstration of peroxidase activity and at pH 9.0 for the demonstration of peroxidatic activity of catalase. Great alveolar cells of all animals except the rabbit contained round to elongated microbodies that stained at pH 9.0. In mice, rough and smooth endoplasmic reticulum and the perinuclear cisternae of these cells were also stained. At pH 7.6 there was no staining of great alveolar cells in any species, except in mice, where a light staining of the endoplasmic reticulum, perinuclear cisternae and microbodies persisted. In rodents, microbodies ranged in diameter from 0.13 µ in mice to 0.22 µ in guinea pigs. In monkeys they measured approximately 0.15 µ. Microbodies were not identified with certainty in rabbit great alveolar cells. In rodents the ratio of microbodies to mitochondria was roughly 1:1, whereas in primates it was roughly 1:2. Using appropriate inhibitors it was concluded that staining at pH 9.0 was due to peroxidatic activity of catalase within peroxisomes. Extraperoxisomal staining in mice was attributed to endogenous peroxidase.

scholarly journals Evolution and Functional Characteristics of the Novel Elovl8 That Play Pivotal Roles in Fatty Acid Biosynthesis

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1287
Author(s):  
Shouxiang Sun ◽  
Yumei Wang ◽  
Pei-Tian Goh ◽  
Mónica Lopes-Marques ◽  
L. Filipe C. Castro ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
The Novel ◽  
Acid Biosynthesis ◽  
Long Chain Fatty Acid ◽  
Rate Limiting Step ◽  
Gene Expression Quantification ◽  
Rate Limiting ◽  
Zebrafish Liver

Elongation of very long-chain fatty acid (Elovl) proteins are key enzymes that catalyze the rate-limiting step in the fatty acid elongation pathway. The most recently discovered member of the Elovl family, Elovl8, has been proposed to be a fish-specific elongase with two gene paralogs described in teleosts. However, the biological functions of Elovl8 are still to be elucidated. In this study, we showed that in contrast to previous findings, elovl8 is not unique to teleosts, but displays a rather unique and ample phylogenetic distribution. For functional determination, we generated elovl8a (elovl8a−/−) and elovl8b (elovl8b−/−) zebrafish using CRISPR/Cas9 technology. Fatty acid composition in vivo and zebrafish liver cell experiments suggest that the substrate preference of Elovl8 overlapped with other existing Elovl enzymes. Zebrafish Elovl8a could elongate the polyunsaturated fatty acids (PUFAs) C18:2n-6 and C18:3n-3 to C20:2n-6 and C20:3n-3, respectively. Along with PUFA, zebrafish Elovl8b also showed the capacity to elongate C18:0 and C20:1. Gene expression quantification suggests that Elovl8a and Elovl8b may play a potentially important role in fatty acid biosynthesis. Overall, our results provide novel insights into the function of Elovl8a and Elovl8b, representing additional fatty acid elongases not previously described in chordates.

scholarly journals Apicoplast and Endoplasmic Reticulum Cooperate in Fatty Acid Biosynthesis in Apicomplexan ParasiteToxoplasma gondii

2011 ◽  
Vol 287 (7) ◽  
pp. 4957-4971 ◽  
Author(s):  
Srinivasan Ramakrishnan ◽  
Melissa D. Docampo ◽  
James I. MacRae ◽  
François M. Pujol ◽  
Carrie F. Brooks ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
Acid Biosynthesis

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).

Ultrastructural Changes of Smoooth Endoplasmic Reticulum in the Retinal Pigment Epithelium by Choline Chloride

1972 ◽  
Vol 30 ◽  
pp. 58-59
Author(s):  
Kazushige Hirosawa ◽  
Eichi Yamada
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cell ◽  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Choline Chloride ◽  
Retinal Pigment ◽  
Ultrastructural Changes ◽  
Lower Vertebrate ◽  
Visual Cells ◽  
Pigment Epithelial

The pigment epithelium is located between the choriocapillary and the visual cells. The pigment epithelial cell is characterized by a large amount of the smooth endoplasmic reticulum (SER) in its cytoplasm. In addition, the pigment epithelial cell of some lower vertebrate has myeloid body as a specialized form of the SER. Generally, SER is supposed to work in the lipid metabolism. However, the functions of abundant SER and myeloid body in the pigment epithelial cell are still in question. This paper reports an attempt, to depict the functions of these organelles in the frog retina by administering one of phospholipid precursors.

Morphological and biochemical analyses of changes in rat hepatocytes related to wine and ethanol consumption

1984 ◽  
Vol 42 ◽  
pp. 232-233
Author(s):  
S.M. Geyer ◽  
C.L. Mendenhall ◽  
J.T. Hung ◽  
E.L. Cardell ◽  
R.L. Drake ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Malic Enzyme ◽  
Smooth Endoplasmic Reticulum ◽  
Rat Hepatocytes ◽  
Mature Male ◽  
Treatment Groups ◽  
Malic Enzyme Activity ◽  
Biochemical Analyses

Thirty-three mature male Holtzman rats were randomly placed in 3 treatment groups: Controls (C); Ethanolics (E); and Wine drinkers (W). The animals were fed synthetic diets (Lieber type) with ethanol or wine substituted isocalorically for carbohydrates in the diet of E and W groups, respectively. W received a volume of wine which provided the same gram quantity of alcohol consumed by E. The animals were sacrificed by decapitation after 6 weeks and the livers processed for quantitative triglycerides (T3), proteins, malic enzyme activity (MEA), light microscopy (LM) and electron microscopy (EM). Morphometric analysis of randomly selected LM and EM micrographs was performed to determine organellar changes in centrilobular (CV) and periportal (PV) regions of the liver. This analysis (Table 1) showed that hepatocytes from E were larger than those in C and W groups. Smooth endoplasmic reticulum decreased in E and increased in W compared to C values.

A Comparison of the Ultrastructural Morphology of Hepatic Necrosis in BDF1 Mice

1981 ◽  
Vol 39 ◽  
pp. 586-587
Author(s):  
Becky Jackson
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Preliminary Investigation ◽  
Hepatic Necrosis ◽  
Hepatic Tissue ◽  
Pronounced Increase ◽  
Glycogen Store ◽  
Ultrastructural Morphology ◽  
Mitochondrial Integrity ◽  
Glycogen Stores

Preliminary investigation has indicated similarity in hepatic ultrastructural morphology in nutritional deprivation, and cyanide induced hepatic necrosis. Analysis of hepatic tissue has indicated disruption of intracellular membranes, specifically, reduction in rough endoplasmic reticulum (RER) mitochondrial integrity, and glycogen stores. An increase in smooth endoplasmic reticulum (SER) portion was observed.To further investigate the apparent equivalence of necrotic morphology, ultrastructura1ly, BDF1 mice were subjected to senescence, nutritional deprevation, potassium cyanide (KCN) induced toxemia, and acetaminophen induced toxemia. Controls were utilized to ellucidate non-necrotic hepatocellular normals. U1trastructura1 investigation of controls (Fig. 1) shows densely granular RER, abundant glycogen stores, and morphologically normal mitochondria. Subjects with acetaminophen induced necrosis exhibit reduced normal RER with increased levels of dialated, vesicular RER in apparent conversion to SER (Fig. 2), loss of mitochondrial integrity, and glycogen store reduction. Senescent subjects exhibit a pronounced increase in SER and loss of glycogen store. (Fig. 3). Investigation of the senescent SER at high magnification (Fig. 5) indicates that the SER is arising from degranulating and vesiculating RER.

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