Showing papers on "Lipid biosynthesis published in 1982"

Phosphatidylglycerol Synthesis in Spinach Chloroplasts: Characterization of the Newly Synthesized Molecule

Abstract: Intact chloroplasts from spinach (Spinacia oleracea L., hybrid 424) readily incorporate [14C]glycerol-3-phosphate and [14C]acetate into diacylglycerol, monoacylglycerol, diacylglycrol, free fatty acids (only when acetate is the precursor), phosphatidic acid, phosphatidylcholine, and most notably phosphatidylglycerol. The fraction of phosphatidylglycerol synthesized is greatly increased by the presence of manganese chloride in the reaction mixture. Glycerol-3-phosphate-labeled phosphatidylglycerol is equally labeled in the two glycerol moieties of the molecule. Acetate-labeled phosphatidylglycerol is equally labeled in both acyl groups. Position one contains primarily oleate, linoleate and small amounts of palmitate. Position two contains primarily palmitate. No radioactive trans-Δ3-hexadecenoate was detected. The labeling patterns indicate that the radioactive phosphatidylglycerol is the product of de novo chloroplast lipid biosynthesis and furthermore, phosphatidylglycerol may be a substrate for fatty acid desaturation.

Jahreszeitliche Dynamik der Fettspeicherung von Loiseleuria procumbens und anderen Ericaceen der alpinen Zwergstrauchheide

Abstract: Das Ausmass der Fettspeicherung und die Zusammensetzung der Fette in Blattern, oberirdischen Sprossachsen, unterirdischen Pflanzenteilen und reproduktiven Organen von Loiseleuria procumbens aus der alpinen Zwergstrauchheide in 2000 m MH wurde zu phanologisch bezeichnenden Terminen histochemisch und nach Extraktion gravimetrisch sowie dunnschicht- und gaschromatographisch bestimmt. An Arcloslaphylos uva-ursi, Vaccinium gaultherioides, V. myrlillus, V. vitis idaea, Calluna vuigaris und Empetrum hermaphroditum erfolgten gravimetrische Bestimmungen des Fettgehalts jeweils im Sommer und im Winter, histochemische Untersuchungen zu verschiedenen Jahreszeiten. Die physiologische und okologische Bedeutung der erheblichen Akkumulation von Fetten durch Loiseleuria und andere Ericaceen der alpinen Zwergstrauchheide ist noch nicht klar. Zwar konnte gezeigt werden, dass Fett wahrend intensiver Wachstumsphasen und auch nach Dunkelstellen im Winter mobilisiert wird, doch weist der hohe Fettgehalt vergilbender Blatter darauf hin, dass Fett moglicherweise auch das Ergebnis einer Verschiebung im Gesamtstoffwechsel der auf kaltebelastete und stickstoffarme Standorte spezialisierten Pflanzen sein konnte. The extent of fat storage and the composition of lipids in the leaves, the propagative organs, the above-ground sterns and the below-ground parts of Loiseleuria procumbens from an alpine dwarf shrub heath at 2,000 m altitude were assayed histochemically, determined gravimetrically, and analyzed by thin layer and gas chromatography throughout the year at different phenological stages. For Arctostaphylos uva-ursi, Calluna vulgaris, Empetrum hermaphroditum, Vaccinium gaultherioides, V. myrtillus and V. vitis idaea the contents of total lipids were determined in summer and in winter, and histochemical assays were made at the various seasons. The physiological and ecological significance of the storage of such considerable amounts of lipids in alpine ericads is not yet clear. Even if part of the lipids is mobilized during phases of intensive extension growth and also during artificial darkness lasting two weeks, the role as a deposit for metabolic consumption seems to be of minor importance. The high density of fat droplets in senescent leaves of Ericaceae suggests that accumulation of lipids represents a specific physiological feature of this plant group. Low temperatures in alpine environments and low nitrogen availability on raw humus soils may further enhance lipid biosynthesis.

Changes in enzyme activities of glycerolipid metabolism of guinea-pig cerebral hemispheres during experimental hypoxia.

Abstract: Hypoxic treatment causes changes of some enzymatic activities involved in the glycerolipid metabolism in subcellular fractions of guinea pig cerebral hemispheres. The activity of lysophosphatidylcholine acyltransferase, choline phosphotransferase, glycerol-3-phosphate acyltransferase(s), as well as the activity of triacylglycerol lipase significantly decreased in the microsomes of cerebral hemispheres of animals intermittently exposed to hypoxic treatment for eighty hours. At the same time, a marked activation of microsomal and mitochondrial phospholipase A2 occurred. The changes of the above-mentioned enzymatic activities after the hypoxic treatment correlated well with the increase in the level of brain and blood free fatty acids. The changes also correlated with the decrease of labeled lipid precursors incorporated into lipids of the cerebral hemispheres, observed during oxygen insufficiency.

Effect of 3-isobutyl-1-methylxanthine on prolactin actions on RNA synthesis, casein synthesis, lipid synthesis and ornithine decarboxylase activity in mouse mammary gland explants.

Abstract: The effect of 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of cyclic nucleotide phosphodiesterase, was tested on several actions of prolactin in cultured mouse mammary tissues At concentrations of 05 mM and above, IBMX abolished the actions of prolactin on RNA and casein synthesis IBMX by itself, stimulated ornithine decarboxylase (ODC) activity in a dose-response fashion; but the IBMX at concentrations up to 1 mM had no effect on the magnitude of the prolactin-stimulated ODC activity IBMX inhibited in a dose-response fashion the rate of [14C]-acetate incorporation into lipids; however, prolactin stimulated lipid biosynthesis in the presence of IBMX concentrations of up to 1 mM

Effects of fowlpox virus infection on lipid metabolism in cultured chicken embryo cells.

Abstract: Lipid biosynthesis was measured in cultured chicken embryo cells after infection with fowlpox virus. Between 24 and 72 h postinfection, fowlpox virus-infected cells incorporated less [14C]acetate and 3H2O into fatty acids and sterols than did mock-infected cells, demonstrating a virus-dependent inhibition of general lipid metabolism. Two specific effects of fowlpox virus infection were an accumulation of C-4 alkylated sterol intermediates and inhibition of monounsaturated fatty acid biosynthesis.

Oral contraceptive and platelet lipid biosynthesis in female rats: Dose-response relationship

Abstract: Female rats were treated with different doses of an oral contraceptive (ethinyl estradiol + lynestrenol) and lipid biosynthesis was studied in blood platelets by acetate incorporation into different fractions separated by thin layer chromatography A marked increase in lipid biosynthesis was observed, especially in the sterol fractions (cholesterol and lanosterol-dihydrolanosterol) It was dose-dependent, observed after a lag-phase, maximal in 3 days and normalized in 8 days Thus, the oral contraceptive studied here appears to modify platelet lipid biosynthesis for the entire life of the platelets

Accumulation of polychlorinated biphenyls by Saccharomyces cerevisiae and their effects on lipid biosynthesis

Abstract: Cultures of S. cerevisiae were routinely grown in fermentable mdeia at 27 +/- 1/sup 0/ C during incubation periods of 5, 15, 22, 28, and 44 hours according to the methods and conditions established in a previous paper (TEJEDOR et al. 1979). Cultures were dosed with the Aroclors 1232, 1242, 1248, and 1260 (Monsanto) to provide initial concentrations of 5, 10, 25, and 50 ppm in the media. Parallel controls were also performed. Cultures designed to determine the uptake and retention of Aroclors were performed following the methods described by MURADO et al. (1976) and VOERMAN and TAMMES (1969). PCB uptake, bioconcentration and retention of the various Aroclor doses stated above were measured at the end of the stationary growth phase and expressed in ppm on the basis of dry biomass weight. PCB quantitation was made by GLC. (JMT)

Exogenous utilization of 14C sugars and 14C proline as carbon source for lipid biosynthesis in the germinating Crotalaria juncea L. pollen

Abstract: Of the 14C labelled sugars (sucrose, glucose and fructose) and 14C proline, the incorporation of label into different lipid types was least from proline while sucrose was the preferred precursor over glucose or fructose. High incorporation into phosphatidyl inositol with 14C sucrose suggested that this phosphatide besides being a membrane component served possibly as the inositol storage component. High incorporation of label into phosphatidyl choline also suggested synthesis of new membranes during pollen tube growth.

Lipid biosynthesis by chloroplasts from olive tree leaves

Abstract: In vitro incubation of isolated chloroplasts from young olive tree leaves (Olea europaea L. cv. Marteno) in acetate-1-14C showed a high labelling of saturated fatty acids (palmitic + stearic) and, above all, of the monounsatured ones (oleic); the low biosynthetic rate of α-linolenic acid being noteworthy. These fatty acids are mainly found as free ones, or incorporated in mono-and diglyceride molecules. Phosphoand galactolipids, the most abundant acyl-lipid components of chloroplast lamellae, showed low incorporation rates. The fatty acid synthesis by isolated chloroplasts depends on exogenous CoA, ATP, NADPH and, especially, on added ACP (acyl carrier protein) preparation from Escherichia coli, whereas it was strongly inhibited by Triton X-100. In vivo experiments with acetate-1-14C infiltration into young excised leaves showed a high labelling of chloroplast phospholipids, but a low 14C incorporation into galactolipids, a remarkable feature because these latter are main components of chloroplast lamellae. The high biosynthetic rate of α-linolenic acid is noteworthy and appears mainly linked to monogalactosyldiglycerides. Also the low incorporation of saturated fatty acids to neutral lipids is remarkable. The low in vitro synthesis of α-linolenic acid in comparison with that of the in vivo conditions, suggests the existence of a cooperation between chloroplasts and other parts of the cell to carry out the synthesis of this compound.

The effects of clofibrate ingestion on alveolar macrophage peroxisome content and oxygen metabolism.

Abstract: Respiratory burst activity in alveolar macrophages in response to particulate and soluble challenges, such as zymosan particles and phorbol myristate acetate (PMA), is not nearly as dependent upon membrane stimulation as in neutrophils Microperoxisomes are subcellular organelles containing catalase and are present in lung macrophages and cells of other organs Evidence from liver cells indicates that peroxisomes are intimately involved with hydrogen peroxide and lipid metabolism Clofibrate (2-(p-chlorophenoxy)-2-methylpropionic acid ethyl ester, Atromid-S-®), a hypolipidemic drug known to cause peroxisomal proliferation in liver cells, was studied with respect to its ability to cause increases in the microperoxisome content and to alter the cellular metabolism of alveolar macrophages Liver weight increased over a 2-week drug treatment period while lung weight remained unchanged Plasma triglyceride levels were decreased by the treatment, indicating the effectiveness of the drug Unlike the effect on liver cells, however, clofibrate did not cause a proliferation of microperoxisomes, as determined by morphometric analysis Oxygen concumption and hydrogen peroxide generation by alveolar macrophages in response to either stimulant (zymosan or PMA) was no greater in clofibrate-treated rats than in controls Superoxide release, when expressed as the change in response to PMA, appeared elevated in the drug group; statistical significance, however, was not demonstrated The hexose monophosphate shunt (HMP), which produces reducing equivalents for lipid biosynthesis, was elevated in macrophages from clofibrate-treated rats when expressed similarly The significance of these results is discussed in relation to the known effects of the drug on liver cells

The effect of corticosteroid therapy lysosomal enzymes and protein lipid metabolism in rabbit lung administration of Freund's

Abstract: Summary The effect of corticosteroid therapy on the broncho­ alveolar cell response, the changes in activity of some lysosomal enzymes and the protein and lipid biosynthesis rates in lung tissue of normal rabbits and of rabbits after induction of an acute inflamma­ tion by the intravenous injection of complete Freund's adjuvant (CFA) 0,2 ml/kg body weight was investigated. Three intramuscular injections of methylpredni­ solone acetate (Depo-Medrol) 1,2 mg/kg over a period of 8 days reduced the mean total broncho­ alveolar free cell yields significantly. The percen­ tages of Iymphocytes and granulocytes were decreased.'The increase in the macrophage percen­ tage was associated with a significant increase in theacid phosphataseactivity of the broncho-alveolar cells. The B-glucuronidase activity, on the other hand, was lowered in alveolar cells and even signifi­ cantly suppressed in lung tissue. Protein and lipid biosynthesis was significantly retarded in lung tissue 8 days after the start of therapy. Administration of a single dose of CFA 0,2 ml/kg evoked an acute lung inflammation and a significant increase in total alveolar free cell yields. The mac­ rophage percentage was reduced and the Iympho­ cyte numbers doubled, whereas the granulocyte percentage increased more than sevenfold. The change in the percentage distribution of granulo­ cytes may be associated with the marked increase in B-glucuronidase activity of the cells as well as of the lung tissue, In the inflammatory phase, protein bio­ synthesis was significantly increased but lipid syn­ thesis was not affected. Corticosteroid therapy in animals treated with adjuvant reversed all the effects of CFA. It has very pronounced anti-inflammatory action and a cata­ bolic effect on protein and lipid metabolism. S AIr Med J 1982; 62: 648-651.