Gary J. Nelson

Lipid composition of erythrocytes in various mammalian species.

Abstract Lipid distribution in the erythrocyte was investigated in several common mammals, including rat, rabbit, pig, dog, horse, sheep, cow, goat, cat and guinea pig. Lipids were extracted from fresh, thoroughly washed, whole packed cells. The lipids were purified by Sephadex column chromatography and separated by thin-layer chromatography. Infrared spectrophotometry was also used to identify components. The distribution of cholesterol, glycolipids, and the phospholipids is reported. Cholesterol was approx. 26% of total lipid in all species while phospholipids ranged between 50 and 70%. The glycolipids were considerably more variable, accounting for 5.3% of the lipids in the rabbit erythrocyte and 23.5% of the lipids in the horse erythrocyte. The glycolipid fraction was not analyzed in detail. The phospholipids were separated into the various classes, but neither vinyl nor glyceryl ether compounds were separated from diacyl derivatives. The phospholipids common to all species were phosphatidic acid, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, and sphingomyelin. There are, however, marked species variations in the relative abundance of these erythrocyte phospholipids. No lecithin was detected in sheep, cow, or goat. However, an as yet unidentified phospholipid was detected in these species.

Quantitative analysis of brain and spinach leaf lipids employing silicic acid column chromatography and acetone for elution of glycolipids

AbstractsQuantitative elution of acidic and neutral glycolipids of brain and spinach leaves from silicic acid columns with acetone was demonstrated. Cerebrosides and sulfatides of brain and sulfolipid and glycosyl diglycerides of spinach leaves were eluted quantitatively with acetone while prospholipids remained on the column. The observations provide the basis for an analytical procedure employing column and quantitative thin-layer chromatography (TLC). Sephadex column chromatography is utilized for separation of lipids from nonlipids; silicic acid column chromatography for separation into neutral lipid, glycolipid and phospholipid fractions; and quantitative TLC for analysis of lipid classes of each column fraction.

The phospholipid composition of plasma in various mammalian species.

Plasma phospholipids in several common mammalian species, including cat, cow, dog, goat, guinea pig, horse, pig, rabbit, rat, and sheep, were analyzed by using chromatographic and spectrophotometric methods. Lipids were extracted from plasma with chloroform-methanol 2∶1 (v/v) and freed of nonlipid material by passage through a Sephadex column. The phospholipids were separated by two-dimensional thin-layer chromatography (TLC). Spots were identified by spray reagents, also by infrared spectrophotometry. The relative distribution of the phospholipids was determined by phosphorus analysis on the spot scraped off the TLC plate.Lecithin, lysolecithin, and sphingomyelin were found in the plasma of all species and accounted for more than 95% of the phospholipids except in the rodents. Lecithin was without exception the major phospholipid in plasma (56 to 83%). Lysolecithin and sphingomyelin content varied between 8 and 23% and 6 and 15% respectively. Phosphatidyl ethanolamine and phosphatidyl inositol were the only noncholine-containing phospholipids detected (detection limits 0.2%) in the plasma of these species. Together these compounds usually made up less than 5% of the total phospholipid. Rodents were an exception, especially the guinea pig, which had 21.7% phosphatidyl ethanolamine.

Studies on the lipids of sheep red blood cells. IV. The identification of a new phospholipid, N-acyl phosphatidyl serine

Abstract A new phospholipid has been isolated from the erythrocytes of sheep. It has been tentatively identified as N -acyl phosphatidyl serine. It amounts to between 2.0 and 4.0% of the total phospholipids in sheep erythrocytes. This phospholipid has also been detected in the red cells of other ruminants, such as the cow and goat.

Studies on the lipids of sheep red blood cells. I. Lipid composition in low and high potassium red cells.

The lipid composition of whole red blood cells was investigated in five sheep with red cells containing a low concentration of potassium (LK) and in five sheep with red cells containing a high concentration of potassium (HK). No apparent differences within the limit of error of the experiment were detected in the lipid class composition between the HK and LK red cells. Cholesterol, the only nonpolar lipid detected in the tissue, was present in oneto-one molar ratio to the total phospholipids. Phosphatidyl ethanolamine and sphingomyelin accounted for 85% of the total phospholipids; phosphatidyl serine, phosphatidyl inositol, phosphatidic acid, and lysolecithin were present in lesser amounts. No lecithin was detected in any of the animals in this investigation. Plasmalogen compounds were found only in the ethanolamine lipids. The molar ratio of choline to noncholine phospholipids was also approximately one to one. It was concluded that the major lipid class distribution in the two types of red cells cannot be directly responsible for the differences observed in the cation concentrations in these cells in the two species of sheep.

Eiution characteristics of fatty acid methyl esters on capillary columns

The elution characteristics of fatty acid methyl esters on support-coated and open tubular capillary columns were investigated using reference standards and natural mixtures of fatty acid methyl esters. Over an extended range of fatty acid methyl esters chain lengths (C-11–C-26), the plot of the log of the adjusted retention time, t′R, vs. number of carbon atoms in the fatty acid chain was not linear, as has been previously assumed by many investigators. With support-coated open tubular columns and with diethylene glycol succinate as the stationary phase, the relationship between the log of the retention time and carbon number was best approximated by a second-order equation: log (t′R)x=α+β(CNx)+γ(CNx)2 where α, β, and γ are the virial coefficients of the equation. In addition, for the longer fatty acid methyl esters, the plots all tended to converge. Hence, for data from capillary columns, especially over a wide range of carbon numbers, all tentative indications based upon linear log plots and parallel lines for different homologous series of fatty acid isomers should be viewed with caution. A method is presented for identifying peaks from capillary columns; it uses quadratic equations and three reference fatty acid methyl ester standards for each homologous series being studied.

Studies on the lipids of sheep red blood cells: III. The fatty acid composition of phospholipids in HK and LK cells

The fatty acid composition of the erythrocyte phospholipids was studied in samples from five high potassium (HK) and five low potassium (LK) sheep. The total fatty acid composition, including the composition from the individual phospholipids in the erythrocytes of these animals is reported. There were no significant differences between either the total fatty acid composition or that of the individual phospholipids in the HK or LK cells. Sheep red cells had very little polyunsaturated fatty acids in their phospholipids. Palmitic, stearic and oleic acids were the major components of glyceryl phospholipids, while nervonic acid accounted for 50% of the fatty acids in the sphingomyelin fraction. The similarity between the fatty acid composition of HK and LK red cells indicates that quantitative differences in the lipids of the membrane are not the primary reason for the observed differences in the cation levels in the two types of cells. This agrees with conclusions drawn from previous studies.

The lipid composition of plasma lipoprotein density classes of sheep Ovis aries.

Abstract 1. 1. The lipoproteins of sheep plasma were separated by preparative ultracentrifugation into five different classes based on hydrated density. 2. 2. Agarose gel electrophoresis patterns of the sheep lipoprotein classes and whole plasma were obtained. 3. 3. No pre-beta band (VLDL) was found in sheep plasma; beta (LDL) was present along with two alpha (HDL) bands. 4. 4. The lipids associated with the various lipoprotein classes did not vary appreciably with density except that the fraction with ρ>1·20 g/ml contained most of the free fatty acids and lysophosphatidyl choline present in sheep plasma. 5. 5. Cholesterol ester was the major neutral lipid in the LDL and HDL fractions, while phosphatidyl choline was the major phospholipid in the HDL, and equal amounts of sphingomyelin and phosphatidyl choline were present in the LDL fraction. 6. 6. The absence of VLDL and chylomicrons in sheep plasma suggest that sheep absorb dietary fat differently than do humans.

Studies on the lipids of sheep red blood cells. II. The incorporation of phosphorus into phospholipids of HK and LK cells.

The incorporation of inorganic phosphate (as NaH2PO4) into the phospholipids of sheep red blood cells was studied in vitro in blood samples from five highpotassium (HK) and five low-potassium (LK) sheep. The erythrocytes from HK sheep incorporated more activity in 4 hr than those from the LK sheep. However no activity was incorporated into the major phospholipids of the cells (phosphatidyl ethanolamine, phosphatidyl serine, and sphingomyelin) of either group. The phosphatidic acid fraction was labeled in both groups and to a significantly greater extent in the HK samples. However the highest activity in the phospholipid of sheep red-cells was located in three unknown compounds not previously detected. Their specific activities were the same in the HK and the LK samples although they were present in slightly larger amounts in the HK samples. In general, incorporation was at a rather low level, and from stoichiometric considerations it was concluded that the metabolism in the red-cell phospholipids could not be directly involved in the active transport of ions across the cell membrane. This work also confirmed a previous report that no quantitative differences exist among the major phospholipid classes in the two types of cells.

The lipid composition of the blood of marine mammals—II. Atlantic bottlenose dolphins, Tursiops truncatus and two species of seals, Halichoerus grypus and Phoca vitulina

Abstract 1. 1. The blood lipids of four mature Atlantic bottlenose dolphins, two young grey seals and one harbor seals were analyzed. 2. 2. Cholesterol esters constituted the major lipid in the plasma of both dolphins and seals. 3. 3. The plasma phospholipid compositions were similar in both species of seal while the plasma phospholipid compositions in the dolphin had reduced amounts of phosphatidyl choline and elevated sphingomyelin compared to the seal samples. 4. 4. The erythrocyte lipid consisted of cholesterol, glycosphingolipids and phospholipids. 5. 5. In the red cells of both the seals and dolphins the major components present were sphingomyelin, phosphatidyl choline, phosphatidyl serine and phosphatidyl ethanolamine, although in somewhat different proportions.