scholarly journals The incorporation of 3H-palmitic acid into Ornithogalum umbellatum lipotubuloids, which are a cytoplasmic domain rich in lipid bodies and microtubules. Light and EM autoradiography

2011 ◽  
Vol 73 (3) ◽  
pp. 181-186 ◽  
Author(s):  
Maria Kwiatkowska
Keyword(s):  
Palmitic Acid ◽  
Active Site ◽  
Lipid Synthesis ◽  
Cytoplasmic Domain ◽  
Lipid Bodies ◽  
Free Medium ◽  
Whole Cells ◽  
Ultrastructural Studies ◽  
Lipid Solvent ◽  
Em Autoradiography

<p>In the ovary epidermis of <em>Ornithogalum umbellatum </em>L. lipotubuloids were found, i.e. distinguished cytoplasmic domain with an agglomeration of half unit membrane-surrounded lipid bodies, entwined and held together by a system of microtubules (Protoplasma 75: 345-357; 77: 473-476).</p><p>Using light and EM-autoradiography with <sup>3</sup>H-palmitic acid (25 μCi/ml) it was found that lipotubuloids were the site of intense incorporation of this isotope. After extraction of lipids with lipid solvent the lipotubuloids were not labeled. Localization of autoradiographic grains after 15-h postincubation with isotope-free medium indicated a migration of the labeled substances from the lipotubuloids to the whole cells. Ultrastructural studies demonstrated that most autoradiographic grains after 2-h incubation were localized over the site of the microtubules adjoining closely the half unit membranes of lipid bodies. These observations suggest, that the surface of lipid bodies may be the active site in lipid synthesis and involvement of the microtubules in these processes is possible.</p>

scholarly journals The Platelet Dense Tubular System: Its Relationship of Prostaglandin Synthesis and Calcium Flux

1977 ◽  
Author(s):  
Jonathan M. Gerrard ◽  
James G. White
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Divalent Cations ◽  
Lipid Synthesis ◽  
Prostaglandin Synthesis ◽  
Calcium Flux ◽  
Secretory Cells ◽  
Ultrastructural Studies ◽  
Tubular System ◽  
Relationship Of ◽  
Columnar Cells

Evidence that the dense tubular system (DTS) is the site of platelet prostaglandin synthesis derives from several observations. First platelet peroxidase is localized in the DTS. Aminotriazole which inhibits the platelet peroxidase, inhibits prostaglandin biosynthesis at the same concentration. Secondly, a similar peroxidase occurs in the secretory cells of the sheep vesicular gland (SVG) and other cells known to be involved in prostaglandin synthesis. Third, the DTS is smooth endoplasmic reticulum (SER) and SER, which is abundant in the prostaglandin synthesizing columnar cells of the SVG secretory units, is known to be involved in lipid synthesis and metabolism in other tissues. Evidence that calcium is stored in the DTS derives from ultrastructural studies showing that the DTS is analagous to the sarcotubules of skeletal muscle, and that the DTS has the capacity to bind divalent cations. Evidence that calcium flux and prostaglandin synthesis are closely linked comes from several observations which suggest 1) that movement of calcium ions to the site where arachidonic acid (AA) is released from the precursor phospholipids to be used for synthesis of prostaglandins, stimulates the AA release and 2) that synthesized prostaglandin G2, prostaglandin H2, and/or thromboxane A2 initiate platelet contraction by moving calcium from the site of synthesis to the vicinity of the contractile actin and myosin. The results suggest that the DTS, prostaglandin and thromboxane synthesis, and calcium flux are integral parts of the system modulating platelet activation.

Histochemical and Morphological Studies of the Lipids in Oogenesis. I. Periplaneta americana

1958 ◽  
Vol s3-99 (47) ◽  
pp. 315-332
Author(s):  
VISHWA NATH ◽  
BRIJ L. GUPTA ◽  
BACHAN LAL
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Periplaneta Americana ◽  
Lipid Synthesis ◽  
Active Role ◽  
Lipid Bodies ◽  
Acetone Extraction ◽  
Morphological Studies ◽  
Carbohydrate Complex

1. Three kinds of lipid bodies have been described in the oogenesis of the cockroach, Periplaneta americana (i) L1 bodies, present in the earliest oocyte, which persist till the oocyte measures approximately mm and contain phoapholipids only, possibly having more lecithint than cephalins; (ii) L2bodies, which first arise in the oocyte measuring 0.4 mm and have a complete or incomplete sheath of phoapholipida surrounding a medulla of triglycerides (rather highly saturated); (iii) L3 bodies, which are the only type of lipids present in the oocytea measuring more than 0.65 mm and consist of triglycerides only (rather highly saturated). 2. Some of the larger L3 bodies give a ‘ringed’ or ‘crescentic’ appearance in Sudan black when used at room temperatures (12° C to 40° C) but appear mostly solid when this colouring agent is used at 6o° C. 3. Mitochondria, which remain as fine granules throughout the course of oogenesis, contain proteins and phospholipids. They seem to have some lipids which are masked normally but are unmasked after acetone extraction, with a resulting increase in sudanophilia. 4. Yolk globules appear in the oocytes meaauring approximately 0.5 mm. They contain a protein-carbohydrate complex. 5.The bacterioid objects described by earlier workers have been shown to contain phospholipids and free fatty acids. They possibly play an active role in the lipid synthesis of the cell.

Effect of aging on lipid composition and metabolism in the adipose tissues of the rat

1961 ◽  
Vol 201 (3) ◽  
pp. 540-546 ◽  
Author(s):  
William Benjamin ◽  
Alfred Gellhorn ◽  
Mary Wagner ◽  
Harold Kundel
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Palmitic Acid ◽  
Subcutaneous Fat ◽  
Lipid Synthesis ◽  
Pentose Phosphate ◽  
Acid Oxidation ◽  
Acetate Incorporation ◽  
Adipose Tissues

Lipid metabolism and chemistry was studied in adipose tissues of the rat from the age of 38 days to 647 days. Aging process was characterized by a marked decrease in lipid synthesis from acetate, a reduction in the proportion of glucose metabolized by the pentose phosphate pathway, and a lower rate of palmitate incorporation into the mixed lipids. Oxidation of palmitic acid to CO2 and release of free fatty acid by epididymal fat was the same in young and old tissues under control conditions; when, however, glucose was absent from the medium or when epinephrine was added, there was a significantly greater rate of palmitic acid oxidation and free fatty acid release by young compared to old adipose tissue. Rate of acetate incorporation into mixed lipids by multiple adipose tissue sites was determined at different ages. Consistently greater rates of lipid biosynthesis were found in the epididymal, perirenal, mesenteric and interscapular adipose tissues than in subcutaneous fat at all ages. Rate of lipid synthesis by the interscapular fat (unlike any of the other depots) remained high at all ages studied. A greater proportion of short chain fatty acids was found in adipose tissues from young rats than in the old. This was related to fatty acid composition of rat milk.

Some aspects of the nitrogen metabolism of Nodularia spumigena (Cyanophyceae)

1974 ◽  
Vol 52 (4) ◽  
pp. 719-726 ◽  
Author(s):  
E. L. Camm ◽  
J. R. Stein
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Growth Inhibition ◽  
Glutamic Acid ◽  
Nitrogen Metabolism ◽  
Free Medium ◽  
Nodularia Spumigena ◽  
Whole Cells ◽  
Acid Dehydrogenase ◽  
Reducing Ability

Nitrate-reducing ability, NO2−-reducing ability, and glutamic acid dehydrogenase levels were measured in two clones of Nodularia spumigena Mertens. Measurements with whole cells of both clones show that NO3− reduction is stimulated by NO3−, and that NO2− reduction is probably stimulated by NO2−. The NO3−-reducing system is stimulated by light and inhibited by NH4+. These controls and possible control over NH4+ incorporation into amino acids are compared to systems operative in other organisms.Differences in growth and physiology of the clones in growth rate on N-free medium, growth inhibition by urea, and NO2− accumulation in the medium are discussed.

scholarly journals Diosgenin ameliorates palmitic acid-induced lipid accumulation via AMPK/ACC/CPT-1A and SREBP-1c/FAS signaling pathways in LO2 cells

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Ke Fang ◽  
Fan Wu ◽  
Guang Chen ◽  
Hui Dong ◽  
Jingbin Li ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Fatty Acid ◽  
Liver Disease ◽  
Fatty Liver ◽  
Palmitic Acid ◽  
Mitochondrial Function ◽  
Lipid Accumulation ◽  
Lipid Synthesis ◽  
Underlying Mechanism ◽  
Intracellular Lipid

Abstract Background Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is characterized by excessive hepatic lipid accumulation. Many studies have suggested that lipid overload is the key initial factor that contributes to hepatic steatosis. Our previous study indicated that diosgenin (DSG) has a beneficial effect on energy metabolism, but the underlying mechanism remains unclear. Methods Human normal hepatocytes (LO2 cells) were incubated with palmitic acid to establish the cell model of nonalcoholic fatty liver. The effects of DSG on lipid metabolism, glucose uptake and mitochondrial function were evaluated. Furthermore, the mechanism of DSG on oxidative stress, lipid consumption and lipid synthesis in LO2 cells was investigated. Results The results indicated that palmitic acid induced obvious lipid accumulation in LO2 cells and that DSG treatment significantly reduced the intracellular lipid content. DSG treatment upregulated expression of lipolysis proteins, including phospho-AMP activated protein kinase (p-AMPK), phospho-acetyl-coA carboxylase (p-ACC) and carnitine acyl transferase 1A (CPT-1A), and inhibited expression of lipid synthesis-related proteins, including sterol regulatory element-binding protein 1c (SREBP-1c) and fatty acid synthase (FAS). Additionally, DSG-treated cells displayed a marked improvement in mitochondrial function, with less production of reactive oxygen species and a higher mitochondrial membrane potential compared with the model group. Conclusion This study suggests that DSG can reduce intracellular lipid accumulation in LO2 cells and that the underlying mechanism may be related to the improving oxidative stress, increasing fatty acid β-oxidation and decreasing lipid synthesis. The above changes might be mediated by the activation of the AMPK/ACC/CPT-1A pathway and inhibition of the SREBP-1c/FAS pathway.

The Influence of the Glycerol-3-Phosphate Level in the Stroma Space on Lipid Synthesis of Intact Chloroplasts

1983 ◽  
Vol 38 (5-6) ◽  
pp. 399-404 ◽  
Author(s):  
Andreas Sauer ◽  
Klaus-Peter Heise
Keyword(s):  
Fatty Acid ◽  
Palmitic Acid ◽  
Silicone Oil ◽  
Lipid Synthesis ◽  
Fatty Acid Fraction ◽  
Chain Elongation ◽  
Acyl Acceptor ◽  
Chloroplast Stroma ◽  
Elongation Step ◽  
Coa Thioesters

The G3P level in chloroplasts, rapidly isolated from spinach leaves during a light-dark cycle, oscillated between 2.5 and 4 nmol · mg-1 Chi, which corresponds to a concentration of nearly 0.1 -0.2 mᴍ. In order to study the role of the stromal G3P level on chloroplast lipid biosynthesis, G3P uptake, measured by silicone oil centrifugation, has been correlated with the lipid synthesizing capacity of intact spinach chloroplasts. The level of G3P in the chloroplast stroma was decreased by high orthophosphate (Pi) concentrations in the medium. This decrease was caused by a strong Pi transport into the stroma, which is counterbalanced by a release of phosphorylated metabolites including G3P, mediated by the translocator. But because the reduced stromal G3P concentration exceeded about 3 times that for half saturation of the primary G3P acylation with oleoyl-ACP as preferred fatty acid donor, glycerolipid synthesis was not eliminated. Instead, the lowered G3P level in the stroma space limited the secondary acyla­tion step, indicated by the reduced incorporation of palmitic acid into the diglyceride fraction, and led to an accumulation of free oleic acid. Thus, beside its function as primary acyl acceptor, the stromal G3P level apparently controls the pool size of ACP bound palmitic acid by limitation of the chain elongation step from palmitoyl- to stearoyl-ACP in order to induce the specific palmitic acid channeling into the C-2-position of chloroplast lipids by the secondary G3P acylation. A similar function may be due to fatty acid consuming reactions from outside the chloroplast like acyl-CoA thioester formation in the outer envelope membrane, stimulated by exogenous CoA and ATP. In contradiction to earlier findings intact Percoll chloroplasts showed a measurable glycerolipid labelling (3-4%) from exogenous [14C]oleoyl-CoA in the presence of G3P (0.5 mᴍ), although most of the radioactivity was found in the free fatty acid fraction (7-10%). Incorporation into diglycerides was increased two-fold under fatty acid synthesizing conditions in the medium and the resulting diglycerides were further galactosylated by UDP- galactose addition. The latter observations suggest, that even in spite of the envelope imperme­ability for physiological concentrations of long-chain acyl-CoA thioesters, fatty acid transfer from these substrates to typical chloroplast lipids cannot be totally excluded.

Lipid bodies in coral-dinoflagellate endosymbiosis: Proteomic and ultrastructural studies

PROTEOMICS ◽  
2011 ◽  
Vol 11 (17) ◽  
pp. 3540-3555 ◽  
Author(s):  
Shao-En Peng ◽  
Wan-Nan U. Chen ◽  
Hung-Kai Chen ◽  
Chi-Yu Lu ◽  
Anderson B. Mayfield ◽  
...  
Keyword(s):  
Lipid Bodies ◽  
Ultrastructural Studies

Studies of the powdery-mildew fungus, Leveillula taurica, on green pepper. II. Light and electron microscopic observation of the infection process

1979 ◽  
Vol 57 (22) ◽  
pp. 2501-2508 ◽  
Author(s):  
Hitoshi Kunoh ◽  
Mitsuru Kohno ◽  
Sadayoshi Tashiro ◽  
Hiroshi Ishizaki
Keyword(s):  
Powdery Mildew ◽  
Light And Electron Microscopy ◽  
Host Cells ◽  
Outer Cell ◽  
Lipid Bodies ◽  
Powdery Mildew Fungus ◽  
Green Pepper ◽  
Ultrastructural Studies ◽  
Leveillula Taurica ◽  
Powdery Mildew Fungi

Almost all ultrastructural studies of powdery-mildew fungi have been focused on the epiparasitic fungi. In this paper, one of the endoparasitic powdery-mildew fungi, Leveillula taurica (Lev.) Arn., on green pepper (Capsicum annuum L. var. angulosum Mill.) leaves was investigated by light and electron microscopy. Most germinated conidia formed a lobed adhesion body (similar to the appressorium in morphology but different in function) before stomatal invasion. The track of the adhesion body on the leaf epidermis was depressed, and no cuticular perforations were observed in it. After stomatal invasion, infection hyphae grew extensively into the intercellular spaces of the leaves and formed haustoria in the spongy- and palisade-parenchyma cells. The haustorium was flask shaped with a neck arising from the intercellular hypha. The overall profiles of the haustorium resembled those of epiphytic powdery-mildew fungi of other authors; the haustorium was composed of a nucleate central body and many anucleate lobes, and the entire structure was bounded by an extrahaustorial membrane. Papillae consisting of three distinct regions formed against the outer cell walls at the site of penetration. The most obvious alteration in infected host cells was a marked increase in the number of large lipid bodies. Lipid bodies increased in number with time after haustorial formation. They appeared first in the host cytoplasm near the extrahaustorial membrane, then in the extrahaustorial matrix and haustorial body.

scholarly journals Roles and origins of leukocyte lipid bodies: proteomic and ultrastructural studies

2006 ◽  
Vol 21 (1) ◽  
pp. 167-178 ◽  
Author(s):  
Hsiao‐Ching Wan ◽  
Rossana C. N. Melo ◽  
Zhoung Jin ◽  
Ann M. Dvorak ◽  
Peter F. Weller
Keyword(s):  
Lipid Bodies ◽  
Ultrastructural Studies

scholarly journals Mmp10 is required for post-translational methylation of arginine at the active site of methyl-coenzyme M reductase

2017 ◽  
Author(s):  
Zhe Lyu ◽  
Chau-wen Chou ◽  
Hao Shi ◽  
Ricky Patel ◽  
Evert C. Duin ◽  
...  
Keyword(s):  
Active Site ◽  
Methane Formation ◽  
Wild Type ◽  
Coenzyme M ◽  
Methane Cycle ◽  
Gene Encoding ◽  
Post Translational Modifications ◽  
Whole Cells ◽  
Type Gene ◽  
Methyl Coenzyme M Reductase

AbstractCatalyzing the key step for anaerobic methane production and oxidation, methyl-coenzyme M reductase or Mcr plays a key role in the global methane cycle. The McrA subunit possesses up to five post-translational modifications (PTM) at its active site. Bioinformatic analyses had previously suggested that methanogenesis marker protein 10 (Mmp10) could play an important role in methanogenesis. To examine its role, MMP1554, the gene encoding Mmp10 inMethanococcus maripaludis, was deleted with a new genetic tool, resulting in the specific loss of the 5-(S)-methylarginine PTM of residue 275 in the McrA subunit and a 40~60 % reduction in the maximal rates of methane formation by whole cells. Methylation was restored by complementations with the wild-type gene. However, the rates of methane formation of the complemented strains were not always restored to the wild type level. This study demonstrates the importance of Mmp10 and the methyl-Arg PTM on Mcr activity.

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