Showing papers on "Lipid biosynthesis published in 1972"
TL;DR: A screening test for hypolipidemic agents in which compounds are administered orally to fasted rats after a single intravenous injection of 225 mg Triton WR-1339/kg and serum cholesterol and triglycerides are measured 43 hr post-Triton is described.
Abstract: We describe a screening test for hypolipidemic agents in which compounds are administered orally to fasted rats after a single intravenous injection of 225 mg Triton WR-1339/kg and serum cholesterol and triglycerides are measured 43 hr post-Triton. Conditions for the screen were established by studying interrelationships between serum cholesterol, triglycerides and Triton levels during the post-Triton period and the effects of Triton dose, route of administration and fasting on serum lipid levels and drug hypocholesterolemic activity. The test detects compounds which inhibit lipid biosynthesis or stimulate lipid catabolism. Several drugs with different mechanisms of action which are hypolipidemic in man, including nicotinic acid,D-thyroxine, triparanol, nafoxidine HCl and clofibrate are active in this system. Results with standard hypolipidemic agents are reproducible and conform well to performance levels of the screen predicted from statistical analysis.
201 citations
TL;DR: This chapter attempts to outline their differences, to describe the biosynthetic systems—the presence or absence of which lead to the observed compositions, and to assess the significance of these differcnces.
Abstract: Publisher Summary This chapter deals with the comparative aspects of bacterial lipids The chapter attempts to outline their differences, to describe the biosynthetic systems—the presence or absence of which lead to the observed compositions, and to assess the significance of these differcnces Bacterial lipids have been discussed extensively in monographs Research on bacterial lipids focuses on such questions as their location in functional membrane units, the relationship of individual lipid species to vitrous enzymes, multi-enzyme complexes, and transport systems The regulation of membrane–lipid biosynthesis at the enzyme level is receiving more attention in bacteria, and the isolation of a variety of mutants with lesions in the synthesis of lipids promises to lead to a better understanding of the genetics and control of lipid biosynthesis It has long been recognized that cell diversity among the bacteria tends to increase toward the periphery of the cell, and the membrane lipids clearly offer a fertile ground for the study of comparitive biochemistry
189 citations
TL;DR: The results indicate that in Euglena gracilis there are a light independent and a light and ammonium dependent pathway of fatty acid biosynthesis and both pathways seem to be in association with specific lipids.
Abstract: When Euglena gracilis was grown under white (fluorescent) light in media containing high concentrations of ammonium chloride (more than 0.005%), the main lipids synthesized were monogalactosyl diglyceride, digalactosyl diglyceride, phosphatidyl glycerol, sulfolipid and the all cis △7,10-16:2, △7,10,13-16:3, △4,7,10,13-16:4, △9,12-18:2 and △9,12,15-18:3 fatty acids. At low levels of ammonium (less than 0.002%) these compounds were produced only in small amounts, while neutral lipids, phosphatidyl choline, phosphatidyl ethanolamine and the 14:0, 16:0 and 16:1 fatty acids predominated. When Euglena gracilis was grown in white light in the presence of dichlorophenyldimethylurea (DCMU) or in the dark, fatty acid and lipid biosyntheses followed the same pattern as in white light at low levels of ammonium. Similar results were obtained when nitrate served as the only nitrogen source in the light and in the dark. The results indicate that in Euglena gracilis there are a light independent and a light and ammonium dependent pathway of fatty acid biosynthesis. Both pathways seem to be in association with specific lipids.
46 citations
TL;DR: Both mercuric chloride and methyl mercurIC chloride strongly inhibited the galactosyl transferase activity for the galactsolipid biosynthesis in the chloroplasts isolated from Euglena cells and spinach leaves.
Abstract: Mercuric chloride and methyl mercuric chloride inhibited the biosynthesis of lipids, especially galactolipids and chlorophylls in photosynthetically grown freshwater algae, Ankistrodesmus braunii and Euglena gracilis. Three and one-half parts per million of mercuric chloride gave 50% inhibition of galactolipid biosynthesis, 98% inhibition of chlorophyll synthesis in A. braunii, and a slightly smaller degree of inhibition in E. gracilis. Also, 2 ppm of methyl mercuric chloride caused 85% inhibition of galactolipid biosynthesis and 98% inhibition of chlorophyll biosynthesis in A. braunii. Both mercuric chloride and methyl mercuric chloride strongly inhibited the galactosyl transferase activity for the galactolipid biosynthesis in the chloroplasts isolated from Euglena cells and spinach leaves. 12 references, 2 figures, 2 tables.
26 citations
TL;DR: The neuronal-enriched fraction incorporated 14 C-label into gangliosides to a greater extent than the glial-en enriched fractions, substantiating previous indications that the neurons are the principal site of gangliosiside biosynthesis in the brain.
25 citations
TL;DR: The heating of Salmonella typhimurium 7136 at 48C produced a sublethal injury and the decreased concentrations of cyclopropane fatty acids with concomitant increases in their parent monoenoic acids gave presumptive evidence for infection.
Abstract: The heating of Salmonella typhimurium 7136 at 48C produced a sublethal injury. When injured cells were placed in fresh growth medium, they recovered within 3 h their normal tolerance to Levine Eosi...
24 citations
TL;DR: Findings indicate that subnormal amino acid accumulation by pantothenate-deficient cells is caused by a curtailment in lipid biosynthesis which prevents the formation of a membrane having normal retentive properties, and that the membrane lipid content can be increased subsequently in non-growing cells with the restoration of normal permeability properties.
15 citations
TL;DR: In all experiments most of the radioactivity of the liver was transformed to cholesterol and the conversion of squalene to cholesterol proceeded more slowly in the kidneys and 30 min after the administration of the mevalonate substantial amounts of radioactivity was recovered as labelledsqualene and lanosterol.
Abstract: DL-mevalonate-2-14C was administered parenterally to 2 rabbits and 5 groups of mice. In the rabbits the amount of labelled material recovered in the non-saponifiable lipids of the kidneys exceeded that of the liver. Most of the renal radioactivity was found in the squalene, lanosterol and methostenol fractions whereas the major part of the labelled material in the liver was present as radioactive cholesterol. The distribution of radioactivity within the kidney and the liver in the mice varied with the size of the administered dose. The smaller the dose, the larger the proportion of label recovered in the kidneys. In all experiments most of the radioactivity of the liver was transformed to cholesterol. The conversion of squalene to cholesterol proceeded more slowly in the kidneys and 30 min after the administration of the mevalonate substantial amounts of radioactivity was recovered as labelled squalene and lanosterol. The importance of circulating mevalonate as substrate in the cholesterol synthesis of the kidney will be discussed.
14 citations
TL;DR: Dog aortas and coronary arteries were perfused with dog's own serum to study lipid biosynthesis from [2-14C]acetate under the influence of nicotine in vitro, and a modification of the arterial lipid pattern by nicotine was demonstrated.
7 citations
TL;DR: It is suggested that another phenomenon of potential significance may have inadvertently been overlooked in Arenicola and some of the other species mentioned by Hoffman and Mangum.
Abstract: sufficient selective advantage to lead us to expect that a species whose habits meet the physical requirements will capitalize on passive ventilation. Furthermore, demonstration that active pumping can be adequate to meet an animal's respiratory needs does not constitute evidence that the animal cannot benefit from passive ventilation. All of the studies cited by Hoffman and Mangum were carried out under experimental conditions which completely precluded passive ventilation. Even Kruger (1) employed a bell jar over one end of the Arenicola burrow. We do not question any of these results but merely suggest that another phenomenon of potential significance may have inadvertently been overlooked. Does Arenicola plug its burrow between bursts of pumping? Wells (2), commenting on 'his observation of a worm in a glass tube beneath still water, stated only: \"In the relatively quiet intervals between outbursts, the worm was lying in the curved part of the U, with its head toward the float and its body rather short and thick.\" He further noted that \"worms appear to be more active between the bursts when in sand than they are in glass Lubes.\" For worms that make singleended burrows, however, passive ventilation can be disadvantageous; viscous entrainment at the aperture will reduce the pressure in the burrow and may draw water from anoxic sediments into it. Thus plugging of burrows might be expected in some of the other species mentioned by Hoffman and Mangum. STEVEN VOGEL WILLIAM L. BRETZ Department of Zoology, Duke University, Durham, North Carolina 27706
4 citations
TL;DR: The data suggest that biosynthesis of the hepatic triacylglycerols occurs primarily via the Kennedy-Weiss pathway, rather than via acylation of 2- acylglycerol.
Abstract: 1. 1. (1- 14 C) Palmitic acid was administered to dogfish ( Squalus acanthias ) via intrahepatic injection and the uptake of radioactivity into acyl chains on positions 2 and 1,3 of the hepatic triacylglycerols was determined; the metabolic data were evaluated in terms of the fatty acid composition of theacyl chains. 2. 2. A distinct preference for incorporation of radioactivity into acyl chains of position 2 of triacylglycerols was found indicating that these chains are actively metabolized. 3. 3. The data suggest that biosynthesis of the hepatic triacylglycerols occurs primarily via the Kennedy-Weiss pathway, rather than via acylation of 2- acylglycerols.
TL;DR: Lactating mammary cells incorporated [1- 14 C]butyrate into various lipid classes when cultured in vitro and Radiogaschromatography showed that butyrate was used in the synthesis of fatty acids C 4 -C 16 inclusive.
TL;DR: Cal varia from Rattus norvegicus, at birth, 7 days and 14 days of age, were found to differ with regard to lipid synthetic activity from [14C]acetate under in vitro conditions, which constituted the most heavily labelled lipid class.