scholarly journals Genomic and Biochemical Analysis of Lipid Biosynthesis in the Unicellular Rhodophyte Cyanidioschyzon merolae: Lack of a Plastidic Desaturation Pathway Results in the Coupled Pathway of Galactolipid Synthesis

2007 ◽  
Vol 6 (6) ◽  
pp. 1006-1017 ◽  
Author(s):  
Naoki Sato ◽  
Takashi Moriyama
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Linoleic Acid ◽  
Polyunsaturated Fatty Acids ◽  
Green Algae ◽  
Acyl Carrier Protein ◽  
Genomic Analysis ◽  
Minor Component ◽  
Acid Synthesis ◽  
Cyanidioschyzon Merolae

ABSTRACT The acyl lipids making up the plastid membranes in plants and algae are highly enriched in polyunsaturated fatty acids and are synthesized by two distinct pathways, known as the prokaryotic and eukaryotic pathways, which are located within the plastids and the endoplasmic reticulum, respectively. Here we report the results of biochemical as well as genomic analyses of lipids and fatty acids in the unicellular rhodophyte Cyanidioschyzon merolae. All of the glycerolipids usually found in photosynthetic algae were found, such as mono- and digalactosyl diacylglycerol, sulfolipid, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol. However, the fatty acid composition was extremely simple. Only palmitic, stearic, oleic, and linoleic acids were found as major acids. In addition, 3-trans-hexadecanoic acid was found as a very minor component in phosphatidylglycerol. Unlike the case for most other photosynthetic eukaryotes, polyenoic fatty acids having three or more double bonds were not detected. These results suggest that polyunsaturated fatty acids are not necessary for photosynthesis in eukaryotes. Genomic analysis suggested that C. merolae lacks acyl lipid desaturases of cyanobacterial origin as well as stearoyl acyl carrier protein desaturase, both of which are major desaturases in plants and green algae. The results of labeling experiments with radioactive acetate showed that the desaturation leading to linoleic acid synthesis occurs on phosphatidylcholine located outside the plastids. Monogalactosyl diacylglycerol is therefore synthesized by the coupled pathway, using plastid-derived palmitic acid and endoplasmic reticulum-derived linoleic acid. These results highlight essential differences in lipid biosynthetic pathways between the red algae and the green lineage, which includes plants and green algae.

scholarly journals The role of lipid components of the diet in the regulation of the fatty acid composition of the rat liver endoplasmic reticulum and lipid peroxidation

1978 ◽  
Vol 174 (2) ◽  
pp. 585-593 ◽  
Author(s):  
Catherine T. Hammer ◽  
Eric D. Wills
Keyword(s):  
Lipid Peroxidation ◽  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Polyunsaturated Fatty Acids ◽  
Acid Composition ◽  
Corn Oil ◽  
Lipid Peroxide

The fatty acid compositions of the lipids and the lipid peroxide concentrations and rates of lipid peroxidation were determined in suspensions of liver endoplasmic reticulum isolated from rats fed on synthetic diets in which the fatty acid composition had been varied but the remaining constituents (protein, carbohydrate, vitamins and minerals) kept constant. Stock diet and synthetic diets containing no fat, 10% corn oil, herring oil, coconut oil or lard were used. The fatty acid composition of the liver endoplasmic reticulum lipid was markedly dependent on the fatty acid composition of the dietary lipid. Feeding a herring-oil diet caused incorporation of 8.7% eicosapentaenoic acid (C20:5) and 17% docosahexaenoic acid (C22:6), but only 5.1% linoleic acid (C18:2) and 6.4% arachidonic acid (C20:4), feeding a corn-oil diet caused incorporation of 25.1% C18:2, 17.8% C20:4 and 2.5% C22:6 fatty acids, and feeding a lard diet caused incorporation of 10.3% C18:2, 13.5% C20:4 and 4.3% C22:6 fatty acids into the liver endoplasmic-reticulum lipids. Phenobarbitone injection (100mg/kg) decreased the incorporation of C20:4 and C22:6 fatty acids into the liver endoplasmic reticulum of rats fed on a lard, corn-oil or herring-oil diet. Microsomal lipid peroxide concentrations and rates of peroxidation in the presence of ascorbate depended on the nature and quantity of the polyunsaturated fatty acids in the diet. The lipid peroxide content was 1.82±0.30nmol of malonaldehyde/mg of protein and the rate of peroxidation was 0.60±0.08nmol of malonaldehyde/min per mg of protein after feeding a fat-free diet, and the values were increased to 20.80nmol of malonaldehyde/mg of protein and 3.73nmol of malonaldehyde/min per mg of protein after feeding a 10% herring-oil diet in which polyunsaturated fatty acids formed 24% of the total fatty acids. Addition of α-tocopherol to the diets (120mg/kg of diet) caused a very large decrease in the lipid peroxide concentration and rate of lipid peroxidation in the endoplasmic reticulum, but addition of the synthetic anti-oxidant 2,6-di-t-butyl-4-methylphenol to the diet (100mg/kg of diet) was ineffective. Treatment of the animals with phenobarbitone (1mg/ml of drinking water) caused a sharp fall in the rate of lipid peroxidation. It is concluded that the polyunsaturated fatty acid composition of the diet regulates the fatty acid composition of the liver endoplasmic reticulum, and this in turn is an important factor controlling the rate and extent of lipid peroxidation in vitro and possibly in vivo.

scholarly journals The Decrease of n-3 Fatty Acid Energy Percentage in an Equicaloric Diet Fed to B6C3Fe Mice for Three Generations Elicits Obesity

2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
Ingeborg Hanbauer ◽  
Ignacio Rivero-Covelo ◽  
Ekrem Maloku ◽  
Adam Baca ◽  
Qiaoyan Hu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Polyunsaturated Fatty Acids ◽  
Linolenic Acid ◽  
Liver Lipid ◽  
Liver Steatosis ◽  
Docosapentaenoic Acid ◽  
Carbon Chain ◽  
Standard Diet

Feeding mice, over 3 generations, an equicaloric diet in which α-linolenic acid, the dietary precursor of n-3 polyunsaturated fatty acids, was substituted by linoleic acid, the dietary precursor of n-6 polyunsaturated fatty acids, significantly increased body weight throughout life when compared with standard diet-fed mice. Adipogenesis observed in the low n-3 fatty acid mice was accompanied by a 6-fold upregulation of stearyl-coenzyme A desaturase 1 (Scd1), whose activity is correlated to plasma triglyceride levels. In total liver lipid and phospholipid extracts, the sum of n-3 fatty acids and the individual longer carbon chain acids, eicosapentaenoic acid (20:5n3), docosapentaenoic acid (22:5n3), and docosahexaenoic acid (22:6n3) were significantly decreased whereas arachidonic acid (20:4n6) was significantly increased. In addition, low n-3 fatty acid-fed mice had liver steatosis, heart, and kidney hypertrophy. Hence, reducing dietary α-linolenic acid, from 1.02 energy% to 0.16 energy% combined with raising linoleic acid intake resulted in obesity and had detrimental consequences on organ function.

scholarly journals Poultry meat production as a functional food with a voluntary n-6 and n-3 polyunsaturated fatty acids ratio

2008 ◽  
Vol 52 (No. 7) ◽  
pp. 203-213 ◽  
Author(s):  
D. Schneideroá ◽  
J. Zelenka ◽  
E. Mrkvicová
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Polyunsaturated Fatty Acids ◽  
Linolenic Acid ◽  
Functional Food ◽  
The Other ◽  
Poultry Meat ◽  
Meat Production ◽  
Alpha Linolenic Acid

We studied the effect of different levels of linseed oils made either of the flax cultivar Atalante with a high content of &alpha;-linolenic acid (612 g/kg) or of the cultivar Lola with a predominating content of linoleic acid (708 g/kg) in a chicken diet upon the fatty acid pattern in meat. Cockerels Ross 308 were fed the diets containing 1, 3, 5 or 7 per cent of oil in the last 15 days of fattening. Breast meat (BM) and thigh meat (TM) without skin of 8 chickens from each dietary group were used for analyses. The relative proportions of fatty acids were expressed as percentages of total determined fatty acids. When feeding Atalante oil, the proportions of n-6 fatty acids were highly significantly lower while those of n-3 fatty acids were higher; the ratio of n-6/n-3 polyunsaturated fatty acids in meat was narrower (<i>P</i> < 0.001) than in chickens fed oil with a low content of &alpha;-linolenic acid. In BM and TM, the relative proportions of &alpha;-linolenic and &gamma;-linolenic acids were nearly the same, the proportion of linoleic acid in BM was lower, and the proportions of the other polyunsaturated fatty acids in BM were higher than in TM. In BM, the ratio of n-6/n-3 polyunsaturated fatty acids was significantly (<i>P</i> < 0.001) more favourable than that found in TM. The relative proportions of total saturated and monounsaturated fatty acids in meat decreased and those of polyunsaturated fatty acids increased significantly (<i>P</i> < 0.01) in dependence on the increasing level of dietary oils. When feeding Atalante oil, a significant increase in the proportion of linoleic acid in BM but not in TM was observed. The proportions of the other n-6 fatty acids decreased and those of all determined n-3 fatty acids, with the exception of docosahexaenoic acid, significantly increased with the increasing level of oil in the diet. When feeding Lola oil, its increasing content in the diet increased the relative proportion of linoleic acid as well as its elongation to &gamma;-linolenic acid; however, the proportions of arachidonic and adrenic acid did not change significantly (<i>P</i> > 0.05). The proportion of &alpha;-linolenic acid increased in both BM and TM. The proportion of eicosapentaenoic and clupanodonic acids in BM significantly decreased. The ratio of n-6 to n-3 polyunsaturated fatty acids ranged from 0.9 to 13.6 and from 1.0 to 17.2 in BM and TM, respectively. An increase in the level of Lola oil in the diet by 1% caused that the n-6/n-3 polyunsaturated fatty acid ratio extended by 1.00 and 1.19 units in BM and TM, respectively. Dependences of n-6/n-3 ratio on the level of Atalante oil were expressed by equations of convex parabolas with minima at the level of oil 5.8 and 5.9% for BM and TM, respectively. By means of the inclusion of linseed oil with a high content of &alpha;-linolenic acid in the feed mixture it would be possible to produce poultry meat as a functional food with a very narrow ratio of n-6/n-3 polyunsaturated fatty acids.

scholarly journals Identification of Polyunsaturated Fatty Acids Synthesis Pathways in the Toxic Dinophyte Alexandrium minutum Using 13C-Labelling

Biomolecules ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1428
Author(s):  
Marine Remize ◽  
Frédéric Planchon ◽  
Ai Ning Loh ◽  
Fabienne Le Grand ◽  
Christophe Lambert ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Polyunsaturated Fatty Acids ◽  
Polyketide Synthase ◽  
Neutral Lipids ◽  
Acid Synthesis ◽  
Exponential Growth Phase ◽  
Lag Phase ◽  
Alexandrium Minutum ◽  
The One

The synthetic pathways responsible for the production of the polyunsaturated fatty acids 22:6n-3 and 20:5n-3 were studied in the Dinophyte Alexandrium minutum. The purpose of this work was to follow the progressive incorporation of an isotopic label (13CO2) into 11 fatty acids to better understand the fatty acid synthesis pathways in A. minutum. The Dinophyte growth was monitored for 54 h using high-frequency sampling. A. minutum presented a growth in two phases. A lag phase was observed during the first 30 h of development and had been associated with the probable temporary encystment of Dinophyte cells. An exponential growth phase was then observed after t30. A. minutum rapidly incorporated 13C into 22:6n-3, which ended up being the most 13C-enriched polyunsaturated fatty acid (PUFA) in this experiment, with a higher 13C atomic enrichment than 18:4n-3, 18:5n-3, 20:5n-3, and 22:5n-3. Overall, the 13C atomic enrichment (AE) was inversely proportional to number of carbons in n-3 PUFA. C18 PUFAs, 18:4n-3, and 18:5n-3, were indeed among the least 13C-enriched FAs during this experiment. They were assumed to be produced by the n-3 PUFA pathway. However, they could not be further elongated or desaturated to produce n-3 C20-C22 PUFA, because the AEs of the n-3 C18 PUFAs were lower than those of the n-3 C20-C22 PUFAs. Thus, the especially high atomic enrichment of 22:6n-3 (55.8% and 54.9% in neutral lipids (NLs) and polar lipids (PLs), respectively) led us to hypothesize that this major PUFA was synthesized by an O2-independent Polyketide Synthase (PKS) pathway. Another parallel PKS, independent of the one leading to 22:6n-3, was also supposed to produce 20:5n-3. The inverse order of the 13C atomic enrichment for n-3 PUFAs was also suspected to be related to the possible β-oxidation of long-chain n-3 PUFAs occurring during A. minutum encystment.

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