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C Cassagne

Publications and source records attributed to C Cassagne.

At least 91 records · Page 5Linked to original sources
PubMed1989

Partial purification of the acyl-CoA elongase of Allium porrum leaves.

Acyl-CoA elongase has been partially purified from leek (Allium porrum L.) epidermal cells. The microsomal elongase is first solubilized by Triton X-100. The solubilized proteins are then submitted to anion exchange chromatography on DEAE-cellulose and, finally, to gel filtration on Ultrogel 34 AcA. The purification of the elongase activity is accompanied by the enrichment in three major protein bands of 59, 61, and 65 kDa. The partially purified elongase is highly delipidated (about 10 mol lipid/mol of 60- to 65-kDa protein) and phosphatidylserine and phosphatidylethanolamine account respectively for 60 and 40% of the remaining phospholipids. The partially purified elongase retains some activities associated with fatty acid biosynthesis. The overall activity is strongly stimulated by the addition of exogenous lipids. In the presence of a mixture of PS, PE, and PC the C18-CoA elongase activity is increased more than sixfold. The Km value of stearoyl-CoA, in the presence of lipid vesicles, was determined to be 1.7 microM.

Acyl-Carrier Protein S-Malonyltransferase↗
PubMed1989

Phospholipid and fatty acid composition of erythrocytes in type I and type II diabetes.

Different data have been reported concerning modifications of the erythrocyte lipid composition in the different types of diabetes. The heterogeneity of diabetes could be a cause for such differences. Ten type I and ten type II diabetics were carefully selected. The patients were poorly controlled (the mean glycosylated hemoglobin was 12.8% +/- 0.7%); their mean age was 54 +/- 5 years, with a mean duration of diabetes of 18 +/- 4 years. One half of them had severe diabetic complications (nephropathy, retinopathy, and/or polyneuropathy). The diabetics were compared with ten controls. The phospholipid composition was determined by HPTLC analysis, and the fatty acid moieties of the total phospholipids were measured by gas liquid chromatography associated with mass spectrometry. Under well-defined experimental conditions, these results demonstrated a slight, but significant (P less than .05), increase in the phosphatidylethanolamine (PE)/phosphatidylserine (PS) ratio using a Ninhydrin quantitation method; there was also an increase in two minor lipids content (phosphatidylinositol, phosphatidic acid) and the appearance of a lysolipid (lysoPE) in the patients. Whatever the type of diabetes, the red blood cells of diabetics showed no significant differences in their fatty acid contents.

Adolescent↗
PubMed1988

Localization of the synthesis of very-long-chain fatty acid in mitochondria from Saccharomyces cerevisiae.

The localization of the mitochondrial elongation activities ('elongases') from Saccharomyces cerevisiae has been investigated. It was shown, using carboxyatractyloside in the incubation mixture, that synthesis of very-long-chain fatty acids probably occurred outside the matrix and, by fractionation experiments, that elongases are membrane-bound enzymes. The solubilization of the outer membrane by digitonin showed that three elongating activities are correlated with a marker of the outer membrane and not with an inner membrane marker. A further partial purification of the outer membrane showed that elongases are present in the outer membrane of mitochondria.

Acyl-Carrier Protein S-Malonyltransferase↗
PubMed1988

Decrease of lipid extractability of chloroform-methanol upon water addition to human erythrocytes.

The yield of lipids extractable by chloroform-methanol 2:1 from human erythrocytes decreases as a function of the relative amount of water added to--or present in--the erythrocyte pellet prior to the lipid extraction. Only slight modifications are observed as long as the volume of water does not exceed that of the red blood cell pellet. As the volume of added water increases, the phosphatidylserine recovery drops dramatically and tends to zero while the yield of the other phospholipids remains unchanged. This phenomenon is not observed when the lipids are extracted by a mixture of isopropanol-chloroform.

1-Propanol↗
PubMed1988

Demonstration of high specificity antibodies against phosphatidylserine.

Anti-phosphatidylserine antibodies were raised in rabbits immunized with phosphatidylserine-polyacrylamide gels and with phosphatidylserine-cytochrome c vesicles. A solid-phase immunoenzymatic assay (ELISA) was developed to study the immune serum. The optimal conditions were defined and the technique used to obtain quantitative results. The anti-phosphatidylserine serum diluted to 1/1000 was tested against several phospholipids and was found to be highly specific to phosphatidylserine. This represents the first experimental demonstration of the specificity of antibodies raised against phosphatidylserine.

Animals↗
PubMed1988

Po, MBP, histone, and DNA levels in sciatic nerve. Postnatal accumulation studies in normal and trembler mice.

We studied the quantitative changes in proteins (total, Po, MBP, and histones) and DNA from sciatic nerves of normal and Trembler mice during postnatal development. Polyacrylamide gel electrophoresis and immunoblotting procedures allowed an accurate characterization of Po, MBP, and histones, as well as the comparison of their respective amounts from d 2 to d 120 after birth. It was found that 1. The immunoblotting procedure ascertains the presence of Po in the sciatic nerve of Trembler. In the 2-d-old mice, Po is detected in essentially similar amounts in Trembler and normal PNS, whereas its level in adult mutant sciatic nerves is never greater than 20% of the control. The sharp increase in Po levels observed during the third week in the normal nerves is not observed in those of the mutant; 2. MBP species are at most 4% of the control in the 10- to 12-d-old Trembler mice, whereas they were not detectable in adult nerves. The distribution of the different MBP species is the same in both mutant and control mice; 3. In normal mice, Po and MBP accumulate at similar rates, but the 14 kDa MBP accumulates faster than the 18.5 kDa MBP; and 4. Histone and DNA contents decrease 3- to 5-fold in normal nerves, whereas they remain constant, or increase slightly, in the mutant.

Animals↗
PubMed1987

Natural seric anti-fatty acid antibodies in multiple sclerosis.

Naturally occurring anti-oleic acid conjugate antibodies were detected in human sera using an adapted direct immunoenzymatic assay. They were present to a higher level in the sera of patients with multiple sclerosis in acute relapse compared to patients with other neurological diseases or healthy subjects and even patients with multiple sclerosis in progressive form.

Adult↗
PubMed1987

Fatty acid synthesis in mitochondria from Saccharomyces cerevisiae.

The ability of purified mitochondria isolated from S. cerevisiae to synthesize fatty acids and especially very long chain fatty acids (VLCFA) has been investigated. The VLCFA synthesis requires malonyl-CoA as the C2 unit donor and NADPH as the reducing agent. Moreover the yeast mitochondrial elongase is able to accept either exogenous long chain fatty acyl-CoAs as substrates or elongate endogenous substrates. In the latter case, ATP is required for full activity. Besides this important VLCFA formation, the mitochondria from S. cerevisiae were also able to synthesize C16 and C18.

Acetyltransferases↗
PubMed1987

A developmental study of fatty acyl group contents in the peripheral nervous system of normal and trembler mice.

We quantitated the content of the fatty acyl groups of sciatic nerves from normal and Trembler mice between the postnatal ages of 5 and 60 d. Palmitoyl, stearoyl, and unsaturated 18-carbon groups increased normally in Trembler nerves during the first 9 d, after which their levels were notably lower than those observed for the normal littermates. In good agreement, the synthesis of palmitic acid by the fatty acid synthetase was normal in the PNS of 9-d-old Trembler mice. "Myelin-specific" saturated very long chain fatty acyl groups (VLCFAG) were deficient at all ages studied, the deficiency increasing from about 2.5-fold at 5 d, to 26-fold at 60 d, compared to the maximal 3- to 4-fold decrease observed for the more ubiquitous shorter chains. The results presented in this paper suggest that the highly abnormal VLCFAG content of the mutant nerves cannot be accounted for by an abnormal fatty acid synthetase activity. For the fatty acyl chains with 18 carbon atoms, however, the deficiency observed after 9 d of age can be almost entirely explained by the diminished levels of palmitic acid. The relatively late occurrence of the palmitic acid deficiency compared with that of the VLCFAG and the normal palmitate synthetase activity observed in young mutant mice indicates that the former is an indirect consequence of the Trembler mutation.

Aging↗
PubMed1986

Membrane labeling of the cortex of 'aging' rats by anti-fatty acid antibodies.

The cortex of 'aging' rat brain exhibits no significant difference in the lipid and fatty acid composition in comparison with that of control rat brain, except for a lowered value of the cholesterol/phospholipids ratio. However, an antiserum raised against oleic acid, specifically labels neurones of the cortex of the 'aging' rat mainly within layers IV and V. An electron microscopical study revealed that immunoreactivity was associated with cytoplasmic vesicular inclusions (lipofuscin) and with membranes. Thus, these anti-fatty acid antibodies may help in the evaluation of local modifications of membranes which are not predictable on the basis of biochemical analysis of lipids.

Aging↗
PubMed1986

Technique for injection into the sciatic nerve of the mouse for quantitative in vivo metabolic studies.

In this paper we describe a technique for intraneural injections, applicable to mouse peripheral nerves, which, compared with previous techniques, reduces trauma to the nerves and increases the level and reduces the variability of label recovery. Our technique employs glass needles (tip diameter, 50 micron) linked to a peristaltic pump by polyethylene tubing to inject small volumes (in the microliter range) of radiolabeled substrate solutions into mouse sciatic nerves, and allows the recovery of 20.9 +/- 1.9% (mean +/- standard deviation) and 30.5 +/- 4.8% of the injected radioactivity for 2 microliter [3H]acetate and 0.5 microliter of [3H]stearate, respectively.

Animals↗
PubMed1986

Fatty acid biosynthesis in the peripheral nervous system of normal and Trembler mice.

De novo fatty acid biosynthesis was demonstrated in a particle-free supernatant from normal and Trembler mouse sciatic nerves. In both systems, it required acetyl-CoA and malonyl-CoA, and led chiefly to the formation of free palmitic acid. No palmitoyl-CoA formation was detected. The ability of the cell-free extract of the mutant to form palmitic acid in vitro was greater than that of the control extracts when the results were expressed as the total activity per 100 mg of freshly excised sciatic nerves.

Acetyl Coenzyme A↗
PubMed1986

Biochemical and physicochemical determinations in a premyelin fraction obtained by zonal centrifugation in normal mouse and in dysmyelinating mutants (quaking, shiverer, and myelin-deficient).

Myelin and premyelin material denser than myelin were obtained from quaking (Qk), shiverer (Shi), and myelin-deficient (mld) mutant and control mice, using zonal centrifugation on zonal rotor. On these fractions, we performed biochemical analysis (lipids and fatty acid), and, in parallel, we determined the physical structure of membranes by the spin-label method. The hyperfine splitting constant (2 Tll) was used to determine the order of membranes and their rigidity, and frequency of rotation (Vc) was used to measure fluidity. In control mice, the premyelin material contained a lesser amount of sphingolipids than pure myelin, but the relative proportions between hydroxy- and nonhydroxy-cerebroside and sulfatides were similar in the premyelin material and in pure myelin. The premyelin material contained half the alkanes found in the pure myelin and much less very-long-chain fatty acids. The (2 Tll) was lower in the premyelin material, but the (Vc) was similar in myelin and premyelin material. In mutants, the amount of material recovered in the premyelin fraction was reduced in qk, and increased in both shi and mld. The relative amount of sphingolipids were normal in mld, but not in shi mutants, especially in cerebrosides formed with alpha-hydroxylated fatty acids and sulfatides formed with unsubstituted fatty acids. The absolute amounts of sphingolipids were nearly normal in both shi and mld. In the premyelin fraction from qk mutants, both relative and absolute amounts of sphingolipids were drastically altered. In percentage, cerebrosides and sulfatides formed with nonhydroxyfatty acids were dramatically reduced, and, conversely, cerebrosides and sulfatides formed with hydroxyfatty acids were increased. In terms of absolute amount, only cerebrosides and sulfatides formed with nonhydroxyfatty acids were dramatically reduced. In the premyelin fraction, polyunsaturated fatty acids were increased in shi and mld, but decreased in qk. In this mutant, lignoceric (24:0) and nervonic (24:1) acids were drastically reduced. The amount of alkanes in the premylin material from qk and mld was reduced by 50%. The shi fraction was nearly free of alkanes. The maximal apparent coupling constant (hyperfine splitting constant, 2 Tll) was not affected in the mld and qk mutant, but was reduced in the shi mutant premyelin fraction. The Vc was dramatically increased in the qk, slightly decreased in the shi, and close to control in the mld. This work provides additional data on premyelin material prepared in various neurological mutants using continuous gradients in zonal rotor.(ABSTRACT TRUNCATED AT 400 WORDS)

Alkanes↗
PubMed1986

Correlation between the morphology and the lipid and protein compositions in the peripheral nervous system of individual 8-day-old normal and trembler mice.

The hereditary, hypertrophic interstitial neuropathy which afflicts the trembler mouse manifests itself about two weeks after birth. Consequently, the identification of these mutant mice was not possible before this age, except when double mutants were available. We show that the trembler mice can be easily distinguished from their normal littermates before the clinical symptoms appear by using an HPTLC/densitometry technique that allows the simple and rapid analysis of the polar lipids extracted from one sciatic nerve. The results presented in this paper demonstrate important differences between the polar lipid compositions of sciatic nerves from 8-day-old normal and trembler littermates, whose phenotypes were confirmed by the morphological analysis of the contralateral sciatic nerves. The small amount of material that is needed for this identification makes it possible to use the remaining nerve material for other studies. Furthermore, important differences between the sciatic nerve protein compositions of normal and trembler mice, identified according to their polar lipid composition, were also observed and these differences can, therefore, also be employed for the identification of the mutants before the manifestation of the clinical symptoms of the trembler neuropathy.

Animals↗
PubMed1986

A quantitative developmental study of the peripheral nerve lipid composition during myelinogenesis in normal and trembler mice.

The quantitative evolution of 10 polar lipids was examined in the sciatic nerves of normal and trembler mice between the ages of 3 days and 60 days. In normal nerves, the polar lipids accumulated slowly until the age of 9 days. A period of rapid accumulation then took place until 18 days of age, after which the phospholipids plateaued, while the glycolipid content continued to increase at a slower rate. The results obtained for the sciatic nerves of trembler mice show that the accumulation of all the polar lipids studied, except phosphatidylcholine and hydroxysulfatides, is abnormal from the earliest stages of postnatal development, and strongly support the view that the primary disorder in the trembler peripheral nervous system is one of dysmyelination. With the exception of cardiolipin, all the lipids in the trembler nerves stopped accumulating at the age of 18 days. The cerebrosides were the lipids the most affected severely at all ages.

Aging↗
PubMed1986

A quantitative developmental study of neutral lipids during myelinogenesis in the peripheral nervous system of normal and trembler mice.

The quantitative accumulation of neutral lipids during the period of myelination in the peripheral nervous system was studied in normal and trembler mouse sciatic nerves, between the ages of 5 and 27 days. Neutral lipids were resolved by high-performance thin-layer chromatography, using the solvent mixture hexane/diethyl ether/acetic acid (90:15:2, v/v/v). The lipids were quantitated, after copper acetate/phosphoric acid charring, by densitometric scanning, using an external standard technique. Cholesterol and triacylglycerols accumulated in normal nerves throughout the period studied, while cholesteryl esters were not observed at any age. In trembler nerves, the accumulation of cholesterol took place at a much lower rate than in normal nerves and this lipid was deficient from the earliest stages of development. Triacylglycerols were not significantly deficient in trembler nerves during the first 2-3 weeks, but, after the age of 18 days, their quantity diminished significantly. Cholesteryl esters were first detected in the mutant nerves at the age of 18 days. These results, in agreement with those of a previous developmental study of the polar lipids, are strongly in favour of the view that the trembler mutation directly induces a process of dysmyelination and that demyelination is a secondary event.

Aging↗
PubMed1985

Nature of the reaction product of [1-14C]stearoyl-CoA elongation by etiolated leek seeding microsomes.

The elongation of [1-14C]stearoyl-CoA by microsomes from etiolated leek seedlings, in the presence of malonyl-CoA and NADPH, has been studied at different substrate and enzyme concentrations. The HPTLC analysis of the whole reaction mixture, followed by the analysis of the label in the fatty acid methyl esters of long-chain acyl-CoAs, phosphatidylcholine (PC), and neutral lipids, showed that the acyl-CoA fraction contained most of the labeled very-long-chain fatty acids. The very-long-chain fatty acids were rapidly formed and released from the elongase(s) as acyl-CoAs. The label of long-chain acyl-CoAs increased for 20 min and then decreased, whereas it increased in PC. Labeled very-long-chain fatty acids appeared in the neutral lipid + free fatty acid fraction after a 20-min lag.

Acetyltransferases↗