Positional distribution of fatty acids in the phospholipids of regenerating rat liver]

The fatty acid composition and positioning in the glycerophospholipids from regenerating rat liver were investigated at different stages of the regeneration process. In the lecithins and phosphatidylethanolamines of the regenerating liver the content of arachidonic acid is lower and that of linoleic acid is higher than in the corresponding lipid fractions of normal rat liver. These deviations are maximal at 24 hours after hepatectomy i.e. at the onset of the mitosis. At any stage of the regeneration the high specifity of the fatty acid positioning characteristical for the normal liver is retained completely. The fatty acid composition of cardiolipin is not changed during the regeneration process.     

Positional distribution of fatty acids in glycerophosphatides of bovine gray matter

Glycerophosphatides were isolated from ox brain gray matter by column chromatography. The fatty acid compositions of ethanolamine glycerophosphatides (EGP), serine glycerophosphatides (SGP), and choline glycerophosphatides (CGP) were determined by gas-liquid chromatography. The positional distribution of fatty acids in these glycerophosphatides were determined by phospholipase A hydrolysis (Habu habu venom). C(20) and C(22) polyunsaturated acids were confined almost exclusively to the 2-position of these lipids, where they comprised the majority of 2-substituents in EGP and SGP (oleic acid predominated in this position in CGP). In the 1-position, palmitoyl was the major substituent in CGP, stearoyl in SGP, and stearoyl or the corresponding alk-1-enyl group in EGP.     

Positional distribution of isomers of monoenoic fatty acids in animal glycerolipids

The distributions of the following monoenoic acids were determined [notation: (position of double bond)-(chain length): (no. of double bonds)]: 7-, 9-, and 11-16:1; 7-, 9-, 11-, and 13-18:1; 9-, 11-, and 13-20:1; 9 + 11-22:1 and 13-22:1. As a rule, all isomers of a group show different distribution patterns. In the phospholipids of fish and mammals, the 7- and 13-isomers of 18:1 accumulate in position 1. In triglycerides of mammals fed on fish they accumulate in positions 1 plus 3, and this distribution is shared by 7-16:1 and 11-16:1 and by the groups 20:1 and 22:1. The positional distribution of the acids seems to depend on their structure, the 9-isomers in general accumulating in position 2; but in triglycerides, at least, the origin of the acid also seems to play a directing role, the exogenous acids being incorporated into positions 1 and 3. The variability of the distribution patterns of 9-16:1, 9-18:1, and 11:18:1, which contrasts with the regularity of the patterns for saturated and polyenoic acids, may be connected with the ability of the endogenous monoenoic acids to balance fluctuations in the supply of the exogenous polyenoic acids, and with the role of the fatty acid 9,10-dehydrogenation mechanism in the maintenance of structural and physical properties of phospholipids and triglycerides.     

The positional distribution of fatty acids in phospholipids ofFusarium oxysporum

Fusarium oxysporum, when cultured in the basal synthetic medium, synthesized as much as 26.4 % lipids. TLC analysis of total lipid shows the presence of two main classes of lipids,viz. glycerophospholipids and triacylglycerols, the latter being predominant. The major glycerophospholipid is phosphatidylcholine, the others being phosphatidylethanolamine and phosphatidylinositol.     

Positional distribution of fatty acids in the glycerophospholipids of Tetrahymena pyriformis.

The positional distributions of the fatty acids in the major glycerophospholipids of Tetrahymena pyriformis W were analyzed. A comparison was made of the acyl distributions in normal and ergosterol-grown cells. It was assumed that the positional arrangement of fatty acids would serve as an indicator of acyltransferase enzyme specificity. The acyltransferases in this protozoan have substrate specificities that direct unsaturated groups, particularly polyunsaturates, to the 2-carbon of the glycerophospholipids. An exception is gamma-linolenic acid, which represents a substantial proportion of the total acids at both carbons. Saturated and iso-acids are esterified primarily at the 1-carbon. The qualitative pattern of the fatty acyl distribution is the same in both normal and ergosterol-grown organisms. Sterol substitution produces quantitative differences in the acyl components at both the 1- and 2-carbons of the glycerophospholipids. These differences include a shortening of the average chain length and a decrease in total unsaturation at both the 1- and 2-positions. In addition, there is a modification at the 2-carbon in the relative amounts of the products of two pathways involved in the biosynthesis of fatty acids. The data are interpreted to indicate that the fatty acid transformations in the glycerophospholipids of organisms that contain ergosterol are not the result of altered acyltransferase specificities.     

Transfer of phospholipids between mesosomes and protoplasts from Bacillus subtilis

1. Phospholipids were more intensively labelled from ammonium [1-14C]glycerophosphate in mesosomes than in protoplasts isolated from Bacillus subtilis. 2. When mesosomes, containing phospholipids labelled from sodium-[32P] phosphate were incubated with non radioactive protoplasts, labelled phospholipids were recovered in protoplasts after incubation. 3. This transfer of phospholipids from mesosomes toward protoplasts is time-dependent. 4. Soluble proteins obtained from Bacillus subtilis after ammonium sulphate precipitation were separated on a Sephadex G-100 column. 5. The two main fractions were able to accelerate the transfer of phospholipids from mesosomes toward protoplasts. 6. The first peak stimulated more actively the transfer of phosphatidylethanolamine whereas the second one preferentially accelerated the transfer of phosphatidylglycerol and diphosphatidylglycerol.     

Positional distribution of fatty acids in lipids of the marine diatom Phaeodactylum tricornutum

The composition of fatty acids and lipids in the marine diatom, Phaeodactylum tricornutum was determined. The Lipids consisted of monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulphoquinovosyldiacylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphtidylinositol, triacylglycerol and minor unidentified ones. At the early stationary phase of growth, the total fatty acids were mainly 20:5, 16:1, 16:0 and 16:3. 20:5 was distributed in polar lipids, particularly in monogalactosyldiacylglycerol, phosphatidylcholine and phosphatidylglycerol. This fatty acid was exclusively located at the sn-1 position of the glycerol moiety in all polar lipids except for phosphatidylcholine. In phosphatidylcholine 20:5 was distributed at both the sn-1 and sn-2 positions. 16:3 was concentrated at the sn2 position of monogalactosyldiacylglycerol and trans-16:1 (n-13) was dominant at the sn-2 position of phosphatidylglycerol. C₁₈ fatty acids, the minor fatty acids in P. tricornutum, were confined to the sn-2 position of phosphatidylcholine.     

Positional distribution of constituent fatty acids in phosphatidylethanolamine during early development in Rana nigromaculata

Qualitative and quantitative changes in phosphatidylethanolamine (PE) were analyzed in the eggs, embryos and tadpoles of the Japanese pond frog, Rana nigromaculata, at various stages of development. The weight percentage of PE to total phospholipid and to total lipid was about 15-18% and about 3-4%, respectively, during embryonic life. At all stages from the unfertilized egg to the feeding tadpole, the major fatty acids at the 1-position of PE were palmitic, stearic and oleic acids. At the 2-position, arachidonic, oleic, palmitic, stearic and linoleic acids were present during embryonic life. The most abundant fatty acid at the 2-position was arachidonic acid at the unfertilized egg and hatching embryo stages. However, palmitic acid was the most prevalent 2-fatty acid at the posthatching tadpole and the feeding tadpole stages. Thus, there were marked changes in the positional distribution of the constituent fatty acids in PE during development.