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Biomedical subjects

M G Rumsby

Publications and source records attributed to M G Rumsby.

At least 91 records · Page 5Linked to original sources
PubMed1976

The lecithin: cholesterol acyltransferase reaction, lysolecithin and red cell ageing in blood stored under normal transfusion service conditions.

The lecithin:cholesterol acyltransferase (LCAT) activity and lysolecithin content of human blood stored under standard blood transfusion service conditions at 4 degrees C for 6 weeks has been investigated. Cooling the blood to 4 degrees C rapidly inactivates the LCAT reaction, but the enzyme is not denatured during storage under these conditions. Citrate in the anticoagulant did not activate the LCAT reaction in freshly-taken whole blood. The total phospholipid and total lysolecithin content of whole blood decreased during storage at 4 degrees C for 6 weeks. The lysolecithin content of fresh red cells (2.0-3.0 mumol lysolecithin x 10(-11) per cell) showed no significant change during the storage period.

Acyltransferases↗
PubMed1974

Lipid biosynthesis in green leaves of developing maize.

Successive leaf sections from the base to the tip of rapidly developing leaves of 7-day-old maize (Zea mays var. Kelvedon Glory), grown in the light, utilized acetate for fatty acid biosynthesis in a very divergent manner. Basal regions of the leaf containing proplastids synthesized insignificant proportions of unsaturated fatty acids and appreciable proportions of fatty acids with 20 or more carbon atoms. An increase in the light intensity during incubations with acetate-1-(14)C resulted in very little enhancement of either total or polyunsaturated fatty acid biosynthesis in this tissue.When the distal leaf sections, containing mesophyll chloroplasts with well developed grana and bundle sheath chloroplasts without grana, were incubated with acetate at 150 ft-c and 30 C, approximately 30% of the newly synthesized fatty acids were unsaturated (mainly 18: 1 and 18: 2). At 2800 ft-c and 20 C, 60% of the fatty acids were unsaturated and the total synthesis of fatty acids increased 4-fold. No detectable amount of fatty acids with 20 or more carbon atoms were synthesized in this morphologically mature tissue, and the proportions of newly synthesized fatty acids more closely resembled the endogenous fatty acids in the immature tissue.Only 4% of the newly synthesized fatty acids were 18: 3 but most of this was incorporated into monogalactolipid. In the distal sections, 20 to 25% of the newly synthesized fatty acids in monogalactolipid were 18: 3 compared with the endogenous proportions of 85%. The differences in the composition of the newly synthesized fatty acids and the endogenous fatty acids appear to be related very largely to the low rate of 18: 3 biosynthesis from 18: 1 and 18: 2. Phosphatidyl choline and phosphatidyl ethanolamine, with lower proportions of 18: 3, contained radioactive fatty acids which resembled the endogenous composition more closely.Phosphatidyl choline was quantitatively the most important acyl lipid synthesized under both light conditions. In addition, there was considerable stimulation of acetate incorporation into phosphatidyl glycerol and monogalactolipid, especially in the morphologically most mature regions of the tissue at the higher light intensity.

Journal Article↗
PubMed1973

Plastid differentiation, acyl lipid, and Fatty Acid changes in developing green maize leaves.

Plastid differentiation, acyl lipid, and fatty acid composition have been followed in successive 2-cm sections from the base (youngest tissue) to the tip (oldest tissue) of green Zea mays (maize) leaves grown under a normal diurnal light regime. Although the youngest cells (0-4 cm from the leaf base) had only proplastids with one or two grana, they contained chlorophylls a and b, monogalactosyldiglyceride, digalactosyldiglyceride, sulfolipid, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol. In the more mature sections, the plastids increased in size 5-fold, and differentiation into mesophyll and bundle-shealth chloroplasts had occurred. Concomitantly, the levels of all the lipids increased with the exception of phosphatidylcholine and phosphatidylethanolamine which decreased. With increasing cell maturity, the percentage of linolenic acid increased in all the individual acyl lipids, but palmitic acid remained constant in phosphatidylcholine, phosphatidylethanolamine, and sulfolipid. The Delta(3t)-hexadecenoic acid was only detectable in the phosphatidylglycerol of the most mature maize tissue.

Journal Article↗