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Biomedical subjects

K Waku

Publications and source records attributed to K Waku.

At least 127 records · Page 7Linked to original sources

Alkenyl and alkyl ether phospholipids in pig mesenteric lymph node lymphocytes.

Significant amounts of alkenyl and alkyl ether phosphoglycerides were found in pig mesenteric lymph node lymphocytes. The choline phosphoglycerides are composed of 2.6% alkenyl ether and 25.7% alkyl ether compounds besides 71.7% diacyl analogs. The ethanolamine phosphoglycerides consist of 50.2% alkenyl ether, 7.8% alkyl ether and 42.0% diacyl compounds. The fatty acids chain compositions at the 1- and 2-positions of each lipid class were analyzed.

Animals↗

Turnover rates of the molecular species of alkenyl ether phospholipids of Ehrlich ascites tumor cells.

[1-14C]Glycerol was injected into the peritoneal cavity of mice bearing Ehrlich ascites tumor cells and the lipids were extracted from the cells after selected periods. 1-O-Alkenyl-2-acyl-3-acetylglycerols were prepared from the ethanolamine phosphoglycerides and fractionated by AgNO3-impregnated thin-layer chromatography into five molecular species. Bands 1--5 obtained in this way can be designated as saturated, monoene, diene, tetraene and hexaene species, respectively. Band 5, composed mainly of hexaene species was predominant among those derived from alkenyl ether phospholipids. The specific radioactivities of the fractionated species were determined. Hexaene molecular species turned over most rapidly and disaturated and tetraene species turned over at a high rate, while monoene and diene molecular species turned over very slowly.

Animals↗

Incorporation rates of [1-14C]glycerol into the molecular species of alkyl ether phospholipids of Ehrlich ascites tumor cells in vivo.

[1-14C]Glycerol was injected into the peritoneal cavity of mice bearing Ehrlich ascites tumor cells and the lipids were extracted from the cells after selected periods. 1-O-Alkyl-2-acyl-3-acetyl-glycerols and 1,2-diacyl-3-acetylglycerols were prepared from the ethanolamine and choline phosphoglycerides and fractionated by AgNO3-impregnated thin-layer chromatography into seven molecular species. Bands 1--7 obtained in this way can be designed as saturated, monoene, diene (11), diene (02), triene, tetraene and pentaene + hexaene species, respectively. Band 7, composed mainly of hexaene species, was predominant among those derived from ether phospholipids. The predominant species was band 4 (saturated/linoleate) in both diacyl ethanolamine and choline phospholipids. The specific radioactivities of the fractionated species were determined. In diacyl or alkyl ether compounds of ethanolamine and choline phosphoglycerides, disaturated species turned over very rapidly, while in alkyl ether ethanolamine phosphglyceride, hexaene + pentaene molecular species turned over rapidly. In diacyl compounds of the ethanolamine phosphoglyceride, hexaene molecular species also turned over at a high rate. In diacyl ethanolamine or choline phosphoglycerides, dienoic species turned over rather slowly.

Animals↗

Regulation of the fatty acid composition of alkyl ether phospholipid in Ehrlich ascites tumor cells. The substrate specificities of 1-O-alkylglycerol 3-phosphate and 1-O-alkylglycero-3-phosphocholine acyltransferases.

Activity for the acylation of 1-O-alkyl-GP was found in the microsomes of Ehrlich ascites tumor cells. The reaction product was shown to be 1-O-alkyl-2-acyl-GP by identifying the acetolysis product as 1-O-alkyl-2-acyl-3-acetylglycerol. The acyl transfer activity to 1-O-alkyl-GP was significantly lower than that to 1-acyl-GP. The substrate specificity of 1-O-alkyl-GP acyltransferase was rather broad as regards thiol esters. Similar specificity was observed with 1-acyl-GP acyltransferase. In contrast to these acyltransferase systems, the 1-acyl- and 1-O-alkyl-GPC acyltransferases were specific for polyunsaturated fatty acyl-CoA's. Since a high percentage of polyunsaturated fatty acid and a little palmitic acid were located at the 2-position of 1-O-alkyl-2-acyl-GPC(E), the observed specificities for acyl-COA's of these acyltransferase systems can be considered in relation to the fatty acid composition at the 2-position of 1-O-alkyl-2-acyl-GPC(E) in the cells.

Acyltransferases↗

Phospholipid metabolism in Ehrlich ascites tumor cells. I. Turnover rate of phosphatidylinositol.

1. Radioactive precursors, 32 PI, [1-14C]glycerol, and [1-14C]acetate, were individually injected into the peritoneal cavity of mice bearing Ehrlich ascites tumor, and the rates of incorporation into phospholipid fraction of Ehrlich ascites tumor cells were estimated. Although no distinct difference in specific activities was observed between phosphatidylinositol and other phospholipid classes as regards the incorporation of [1-14C]acetate of [1-14C]glycerol, a higher rate of incorporation of 32Pi into phosphatidylinositol was observed. The specific activity of phosphatidylinositol reached more than ten times that of phosphatidylcholine in the first hour. 2. The radioactivities incorporated into the phospholipids of Ehrlich ascites tumor cells and liver were estimated after simultaneous injection 32Pi and [2-3H]inositol. The incorporation of 32Pi into phosphatidylinositol of liver was similar in specific activity to those of other phospholipids. The ratio (3H/32Pi) of phosphatidylinositol only slightly in the ascites tumor cells, while an appreciable decrease of the ratio was observed in the liver during the first 3 hr. 3. These results suggest that phosphatidylinositol synthesis through pathways other than de novo synthesis is rapid in ascites tumor cells.

Acetates↗

Phospholipid metabolism in ehrlich ascites tumor cells. II. Turnover rate of ether phospholipids.

1. Radioactive precursors of phospholipids, i.e., 32Pi, [1-14C]glycerol, [2-3H]glycerol, and [1-14C]acetate, were individually injected into the peritoneal cavity of mice bearing Ehrlich ascites tumor cells and the rates of incorporation were estimated. 2. Although [2-3H]glycerol was not practically incorporated into ether phospholipids, the other three radioactive precursors were incorporated into diacyl, 1-O-alkenyl-2-acryl-, and 1-O-alkyl-2-acryl-GPE (GPC). 3. In the experiments on 32Pi or [1-14C]acetate incorporation, 1-O-alkyl compounds in the ethanolamine phosphoglyceride fraction showed high specific activities in comparison with 1-acyl compounds. In the case of [1-14C]glycerol incorporation, a high rate of incorporation into 1-O-alkyl compounds was not found. In the choline phosphoglyceride fraction, a high rate of incorporation of the above precursors into 1-O-alkyl compounds was not observed. 4. The specific activities of 1-O-alkenyl compounds were fairly low compared with those of 1-acyl- and 1-O-acyl- and 1-O-alkyl compounds throughout the incorporation experiments with [1-14C]glycerol and [1-14C]acetate, but in 32Pi incorporation, 1-O-alkenyl compounds showed higher specific activities than 1-acyl compounds in ethanolamine phosphoglyceride, suggesting an exchange reaction of the phosphorylethanolamine moiety. 5. From the above findings, it appears that alkyl ether phospholipids of ethanolamine from may have a significant role in ascites tumor cells, based on their rapid turnover.

Animals↗