Total Lipid Phosphorus Research Articles

Thyroid control over biomembranes: VI. Lipids in liver mitochondria and microsomes of hypothyroid rats.

The lipids of liver mitochondria prepared from normal rats and from rats made hypothyroid by thyroidectomy and injection with 131 INa contained similar amounts, per mg protein, of total lipids, phospholipids, neutral lipids and lipid phosphorus. Hypothyroidism caused a doubling of the relative amounts of mitochondrial cardiolipins (CL; to 20.5% of the phospholipid P) and an accompanying trend (although statistically not significant) toward decreased amounts of both phosphatidylcholines (PC) and phosphatidylserines (PS), with phosphatidylethanolamines (PE) remaining unchanged. The pattern of elevated 18:2 fatty acyl content and depleted 20:4 acyl groups of the mitochondrial phospholipids of hypothyroid preparations was reflected to varying degrees in the resolved phospholipids, with PC showing greater degrees of abnormality than PE, and CL showing none. Hypothyroidism produced the same abnormal pattern of fatty acyl distributions in liver microsomal total lipids as was found in the mitochondria. Hypothyroid rats, when killed 6 hr after injection of [1-14C] labeled linoleate, showed the following abnormalities: the liver incorporated less label into lipids, and converted 18:2 not exclusively to 20:4 (as normals do) but instead incorporated the label mainly into saturated fatty acids. These data, together with the known decrease in beta-oxidation, suggest that hypothyroidism involves possible defective step(s) in the conversion of 18:2 to 20:4.

Effect of Temperature and BASF 13 338 on the Lipid Composition and Respiration of Wheat Roots

The fatty acid composition of wheat seedling roots changed in response to temperature. As temperature declined, the level of linolenic acid increased and the level of linoleic acid decreased. The distribution of phospholipid classes was not influenced by temperature. Phosphatidyl choline and phosphatidyl ethanolamine were the predominant phospholipids isolated and comprised 85% of the total lipid phosphorus. Smaller quantities of phosphatidyl glycerol, phosphatidyl inositol, phosphatidic acid, and phosphatidyl serine were isolated. The fatty acid composition of phosphatidyl choline and phosphatidyl ethanolamine were the same and temperature affected the fatty acid composition of both phospholipids in the same manner.Growth in the presence of the substituted pyridazinone, BASF 13 338 (4-chloro-5-dimethylamino-2-phenyl-3(2H)pyridazinone), reduced the level of linolenic acid and increased the level of linoleic acid in the phosphatidyl choline, phosphatidyl ethanolamine, and total polar lipid fractions. BASF 13 338 did not affect the levels of palmitate, stearate, and oleate or the distribution of phospholipid classes.Respiration rates of wheat root tips were measured over a range of temperatures. The respiration rate declined as the temperature decreased. Neither the temperature at which the tissue was grown nor BASF 13 338 treatment influenced the ability of root tips to respire at any temperature from 4 to 30 C. The results indicated that the relative proportion of linolenic acid to linoleic acid did not influence the plants ability to grow and respire over the range of temperatures tested.

β-adrenegic receptor-adenylate cyclase alterations during the postnatal development of skeletal muscle

The postnatal development of mammalian skeletal muscle is associated with an increased capacity for glycogenolysis. In the present study rabbit skeletal muscle underwent a 7-fold increase in glycogen synthase and glycogen phosphorylase activity over the postnatal period of 0–8 weeks. An enriched fraction of sarcolemma was prepared from neonatal and adult muscle to examine the development of the β-adrenergic receptor-adenylate cyclase system. Adult membranes possessed a 2-fold greater Na +K +(Mg 2+)-ATPase activity and a 6–8-fold greater sodium fluoride- and epinephrine-stimulated adenylate cyclase activity. The activation ratio (effector activity/basal activity) increased 2–3-fold for epinephrine and sodium fluoride in adult sarcolemma. The activation by catecholamines conformed to the physiological β 2 type response with isoproterenol (1.8 · 10 −8 M) > epinephrine (1.1 · 10 −7 M) > norinephrine (3.2 · 10 −6 M). In contrast, binding studies employing (−)-[ 3H] dihydroalprenolol showed little difference between neonatal and adult membranes with respect to (1) number of binding sites, (2) equilibrium dissociation constant and (3) displacement of (−)-[ 3H]dihydroalprenolol by catecholamine agonists. Protein and lipid components of the sarcolemma were also modified during development. Neonatal membranes possessed two glycopeptides of M r 80 000 and 86 000, whereas in the adult only a single M r 133 000 species was evident. The total lipid phosphorus and phospholipid composition was unchanged during development. The content of linoleic acid increased approx. 3-fold during development in the phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine phospholipids. The cholesterol content of adult membranes was decreased by 29% compared to neonatal membranes.

Glucocorticoid effects on lipid metabolism in HeLa cells: inhibition of cholesterol synthesis and increased sphingomyelin synthesis.

Glucocorticoid treatment had a variety of effects on lipid composition of HeLa S3G (HeLa 65) cells. Total cellular cholesterol levels were lower in treated cultures than in controls within 6 h of the addition of glucocorticoids and remained lower for up to 48 h. Total cell protein and total lipid phosphorus levels were also decreased, but only after more prolonged exposure. The major phospholipid components, viz. phosphatidylcholine and phosphatidylethanolamine, representing, respectively, 48% and 29% of the total phospholipids, were not affected by glucocorticoid treatment. Sphingomyelin, however, increased from 4.8 to 8.3% of the total phospholipid content after 48 h of exposure, whereas lysolecithin increased from 0.1 to 1.9%. The incorporation of labeled precursors was also measured after glucocorticoid addition. As related to cellular protein content, only slight increases were found for all major phospholipids. In contrast, sphingomyelin synthesis increased up to 200% after treatment with glucocorticoids. The fatty acid and plasmalogen compositions were unchanged by glucocorticoids.

Effects of chronic consumption of ethanol and low-thiamin, low-protein diets on the lipid composition of rat whole brain and brain membranes

Four groups of rats were used in a nutritionally-controlled study of effects of chronic ethanol consumption on brain membrane lipid composition. Rats chronically consuming ethanol were fed high-nutrient or low-thiamin, low-protein diets. After 4 months, lipid analyses were performed on brains, brain microsomes and myelin from each group and from pair-fed, non-ethanol controls. Among the effects of ethanol was an increase of the relative proportion of cholesterol in microsomal lipids while there was decrease of it in myelin. Ethanol also increased plasmenylethanolamine while decreasing phosphatidylethanolamine proportions in myelin and in whole brain lipids, decreased the total lipid phosphorus of whole brain, and elevated the proportion of phosphatidylserine in microsomal and whole brain lipids. Effects of poor diet generally did not interfere with ethanol effects except in the case of microsomal lipids, where it apparently prevented an ethanol-induced increase in proportion of cholesterol. These changes may be adaptive responses to the fluidizing effect of ethanol on membranes.

Effect of vitamin E on lipid composition of submandibular and lacrimal glands in rats.

SummaryThe effects of different levels of vitamin E on SMSG and lacrimal gland lipids were studied in rats. Feeding of purified diets containing 0, 250, or 2500 IU vitamin E/kg of diet was initiated during gestation and continued throughout lactation and then to the pups until 1 month after weaning. SMSG and lacrimal glands were extracted for lipids and the effects of vitamin E on lipid and fatty acid composition were examined. Total lipid content was not affected by different levels of vitamin E. Total lipid phosphorus was, however, decreased with an increase in dietary vitamin E. Vitamin E content of the SMSG and lacrimal glands was increased by severalfold depending upon the level of dietary vitamin E. The fatty acid composition of total lipids, neutral lipids, and phospholipids showed that the levels of C20:3 ω9 were reduced and those of C20:3 ω6 were increased as the dietary levels of vitamin E were increased. This resulted in a decrease in the ratio of C20:3 ω9 to C20:3 ω6.

Distribution of arachidonic acid and other fatty acids in glycerolipids of the rabbit iris

The phospholipid composition, inclusive of higher inositides, fatty acid composition, and in vivo and in vitro incorporation of [ 14C]arachidonate into the rabbit iris glycerolipids were determined. (1) The total phospholipid phosphorus was found to range between 13–14 μmol/g of iris. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and sphingomyelin constituted about 85% of the total lipid phosphorus. Ethanolamine plasmalogen, choline plasmalogen and inositol-containing phospholipids constituted about 11,4 and 7% of total lipid phosphorus respectively. (2) Analysis of the fatty acids of the various glycerolipids of the iris revealed the major saturates to be 16 : 0 and 18 : 0 and the major unsaturates to be 18 : 1, 18 : 2 and 20 : 4. Ethanolamine-containing phospholipids contained the highest percentage of 20 : 4 followed by choline-containing phospholipids, diacylglycerol and phosphatidylinositol respectively. Sphingomyelin contained only trace amounts of 20 : 4. (3) It was found that the iris can incorporate, both in vivo and in vitro, [ 14C]arachidonate into its own glycerolipids. In general glycerolipids isolated from the in vitro experiment contained significantly higher radioactivities than those obtained from the in vivo experiment. In vitro about 41% of the [ 14C]radioactivity was recovered in the neutral lipids and phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol contained only 10,2 and 2·8% of the total radioactivity respectively; and in vivo about 25% of the total radioactivity was found in each of phosphatidylcholine and the neutral lipids and 8·4% in phosphatidylethanolamine. (4) No intraocular signs of an inflammatory response were observed 0·5, 1 and 7 hr after intracameral injection of [ 14C]arachidonic acid (2 μg) -bound albumin (0·1 mg).

Generation of phospholipid artefacts during extraction of developing soybean seeds with methanolic solvents

AbstractThe major phospholipids of soybean cotyledons during development were phosphatidylcholine (45–55%), phosphatidylethanolamine (24–28%), and phosphatidylinositol (15–18%) when the tissue was steam‐killed prior to extraction of the lipids. The only other phospholipids of any significance (4–6%) was identified as phosphatidylglycerol. Phosphatidic acid was a minor constituent (<1%), and neither N‐acyl phosphatidylethanolamine norbis‐phosphatidic acid were detected in appreciable (>0.1% of the total lipid phosphorus) quantities. When fresh cotyledons were rapidly homogenized in mixtures of chloroform and methanol or in methanol alone, phosphatidylmethanol was formed in variable amounts (0–20% of the total phospholipid), and when cotyledons were soaked in methanol prior to homogenizing, phosphatidylmethanol became the major phospholipid, accounting for up to 75% of the total lipid phosphorus. Phosphatidylmethanol was formed by the phospholipase D‐catalyzed transphosphatidylation of phosphatidylcholine and phosphatidylethanolamine during extraction.

Alterations in the phospholipid composition ofNocardia polychromogenes during growth

The major phospholipid classes of Nocardia polychromogenes were quantitated at different stages of the growth cycle. Significant differences were observed both in the total lipid phosphorus per g (dry weight) of cells, and in the relative percentages of individual phospholipids. The total amount of lipid-phosphorus increased throughout the growth cycle. Cardiolipin and phosphoinositides contents increased with significant decrease in phosphatidyl ethanolamine and unknown phospholipids.

Concentration and composition of the lipoprotein classes in human umbilical cord serum

The concentration and composition of the lipoprotein density classes d< 1.006 (VLDL), d = 1.006–1.064 (LDL), and d = 1.064–1.21 (HDL) of human umbilical cord serum were investigated by means of preparative ultracentrifugation. The concentrations of all the density classes, in particular that of the VLDL, are lower than in adults; the values correspond to 8.1 (VLDL), 59.2 (LDL), and 77.4 (HDL) mg/100 ml. About 15% of the total cholesterol and roughly 40% of the total lipid phosphorus did not float at the highest density of 1.21. The composition of the LDL and the HDL was principally in agreement with the pattern obtained in adults. The VLDL of the cord serum, however, showed a lower amount of triglycerides (45%) and a higher content of proteins (22%) than the VLDL from serum of adults. In cord serum only 25% of the total triglycerides are associated with the VLDL fraction, while more than 50% of the triglycerides circulate as a constituent of the LDL.

Lipid composition of rat sciatic nerve

In the course of our study on the lipids of the rat sciatic nerve, the analysis of the neutral lipids allowed us to detect and characterize cholesteryl esters present at a relatively high level (5%). Among the phospholipids, ethanolamine phosphoglyceride is the most abundant fraction and contains neraly all the plasmalogens (20% of total lipid phosphorus). The glycolipids consist of five different fractions; the cerebrosides with hydroxy fatty acids account for 38% of total glycolipids. Monogalactosyl diglyceride represents 7% of total glycolipids.

Phosphatidylserine synthetase mutants of Escherichia coli. Genetic mapping and membrane phospholipid composition.

Mutants of Escherichia coli K-12 defective in CDP-diglyceride:L-serine phosphatidyltransferase (phosphatidylserine synthetase) can be isolated by a rapid autoradiographic screening assay described previously (Raetz, C. R. H. (1975) Proc. Natl. Acad. Sci. U. S. A. 72, 2274-2278). Four organisms of this kind have now been characterized. The gene (designated pss) which is altered in these mutants is closely linked to the nadB locus near minute 49 on the E. coli chromosome. Strains carrying the pss-8 mutation do not grow at elevated temperatures and have low levels of an altered synthetase in cell extracts. An analysis of several hundred transductants and temperature-resistant revertants reveals that the pss-8 mutation is responsible both for the enzyme defect and for the phenotype. When a pss-8 mutant is shifted to the nonpermissive temperature, the cells stop dividing and form long filaments. After 3 hours at 44 degrees the level of phosphatidylethanolamine drops from 66 to 32% (percentage of the total lipid phosphorus), while the combined levels of phosphatidylglycerol and cardiolipin rise from 34 to 68%.

Permeability of the blood-brain barrier to long-chain alcohols from plasma.

Cis-9-octadecenyl alcohol was fed as a dietary supplement to adult male rats for 7 and 14 days. At the end of these feeding intervals, lipids were extracted from brain and liver. The neutral lipids were analyzed for free and esterified long-chain alcohols and alkyl and alk-1-enyl glycerols. Total lipid phosphorus, alkyl acyl and alk-1-enyl acyl phosphoglycerides were determined in the phospholipid fraction. A marked change was observed in these lipid types in the liver, but not in the brain. In liver the free and esterified long-chain alcohols increased threefold following feeding of the dietary supplement. Feeding cis-9-octadecenyl alcohol had no effect on the neutral alkoxy lipids of liver but resulted in an approximately three- to eightfold increase in the ionic alkoxy lipids.

Isolation and characterisation of bis-phosphatidic acid and its partially deacylated derivatives from cultured BHK-cells

Bis-phosphatidic acid, semi-lyso-bis-phosphatidic acid and lyso-bis-phosphatidic acid were isolated from cultured baby hamster kidney fibroblasts (BHK-cells). They constituted about 0.02%, 0.1% and 1.6% respectively of total lipid phosphorus of fresh BHK-cell monolayers. These three phospholipids were also prepared by partial synthesis. The natural lipids were identical with the synthetic samples as determined by thin-layer chromatography and by partial degradation by controlled alkaline methanolysis, acetic acid hydrolysis and acetolysis. The three derivatives of bis-phosphatidic acid contained 60–80% of octadecenoic acid; in this respect they were different from other BHK-cell phospholipids.

Convulsant activity of Naja Naja venom and its phospholipase A component.

Abstract Naja naja (hooded cobra) venom and its purified components were injected intraventricularly into rats. Purified cobrotoxin (50 μg) and cardiotoxin (125 μg) caused piloerection, lacrimation and death but no convulsive activity. Crude cobra venom (5 μg) and a partially purified phospholipase A (2·5 μg) isolated from Naja naja venom induced convulsions. Analysis of brain phospholipids after injection of 330 μg phospholipase A demonstrated an increase in lysophosphatides. Hydrolysis of phospholipids was greater at the onset of convulsions than 1 2 hr before onset. Lysolecithin (100 μg) and stearic acid (500 μg), hydrolysis products of phospholipase A action, did not induce convulsions after intraventricular injection. Phospholipase C in doses as low as 1 μg caused convulsions when injected intraventricularly. Examination of brain phospholipids at the onset of convulsant activity after injection of 250 μg of the enzyme showed a reduction in total lipid phosphorus and a corresponding increase in total aqueous phosphorus and diglyceride as a result of the enzyme's action. The possible involvement of phospholipase A in convulsant activity is discussed.

Membrane lipids of rat liver lysosomes prepared by freeflow electrophoresis

Rat liver lysosomes were isolated by free-flow electrophoresis and were examined morphologically and enzymatically for purity. Their membrane fraction was prepared by osmotic shock and analyzed for cholesterol, phospholipids and fatty acids. The results were compared with the membrane fraction of Triton WR 1339-filled lysosomes and with mitochondria. The cholesterol content (0.269 M cholesterol per M lipid phosphorus), the sphingomyelin concentration (7.9% of total lipid phosphorus) and the degree of unsaturation of fatty acids (38–45%) were found to be intermediate between those of membranes of Triton WR 1339-filled lysosomes (“plasma membrane-like”) and mitochondria (“endoplasmic reticulum-like”). The similarity of these results with corresponding data for the Golgi apparatus support the present view concerning the formation of primary lysosomes via the Golgi apparatus. The drastic changes in the lipid composition found after overloading with Triton WR 1339 confirm that the plasma membrane participates in the formation of the secondary lysosomal membrane. The data presented here underline the significance of the analysis of membrane lipids in evaluating correlations between morphologically different but functionally closely related membrane types.

Comparison of Four Indexes to Fetal Pulmonary Maturity

Abstract With use of the same amniotic fluid specimens, lecithin concentration was compared with nonchromatographically determined glycerophospholipid, total lipid phosphorus, and the bubble-stability test as indexes of fetal lung maturation. The lecithin analysis was performed by thin-layer chromatography, with use of a semiautomated method of spotting and nondigestive release of phosphorus from the separated spots. We conclude that, next to the chromatographic analysis, the best tests are glycerophosphatide P, the bubble-stability test, and total lipid P, in that descending order. Lecithin determination as compared with densitometric evaluation of the lecithin/sphingomyelin ratio is discussed.

Isolation and characterization of luminal membranes from urinary bladder.

A method is reported for the isolation of a highly purified fraction of urinary bladder membranes containing hexagonal plaques. The method uses zonal centrifugation as the final step of fractionation. The purified fraction was characterized by its electron microscopic morphology, by its enzymatic profile, by quantitative and qualitative analysis of lipids and by the protein pattern obtained by electrophoresis in polyacrylamide sodium dodecyl sulfate gels. The fraction contains 65% lipids and 35% proteins. The major protein component has a molecular weight of 27,000 daltons. Phospholipids are more than the 54% of the total lipid weight. Phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol are the major phospholipids with 50%, 30%, and 7% of the total lipid phosphorus, respectively. The glycolipid fraction is 10% of the total lipid weight and is formed by only two components, both sulfatides. Total cholesterol makes up 36% of the total neutral lipid fraction of which cholesterol esters constitute 6%. Glycoproteins are also found to be present in the fraction.

Skeletal muscle lipids. II. Changes in phospholipid composition in man from fetal to middle age

Phospholipid compositions were determined in samples of gastrocnemius muscles of individuals from fetal stage to the age of 55 yr. The lipids were separated by thin-layer chromatography. In order to enable characterization of the individual phospholipids, a lipid extract was prepared from pooled samples of gastrocnemius muscles from adult males and separated by ion-exchange chromatography on TEAE-cellulose. The individual phosphoglycerides were purified by thin-layer chromatography and then characterized according to their content of fatty acids, aldehydes, phosphorus, and the identity of the bases. The relative amounts of the major phospholipids, choline and ethanolamine phosphoglycerides, changed little with age, and in adult males they constituted 47% and 24%, respectively. Cardiolipin increased from 3% in the fetal stage to 9% by the end of the first year of life. Sphingomyelin and serine phosphoglyceride decreased with increasing age, while inositol phosphoglyceride increased. In adult males, cardiolipin constituted 10% of total lipid phosphorus, inositol phosphoglyceride constituted 9%, serine phosphoglyceride 3%, and sphingomyelin 7%.

ABNORMALITIES OF TISSUE LIPIDS: AORTA FATTY ACIDS IN THE NEWBORN PERIO

The phosphoglyceride fatty acids of the aorta were studied in a group of 18 newborn infants with different gestational ages. All the infants had died during the earliest hours of life, before feeding. The total lipids, free cholesterol and lipid phosphorus were quantified in the lipid extract of the homogenized aorta, and no changes in their concentration were found throughout the period studied. As for the fatty acids, the following findings contrasting with those previously reported in brain tissue were observed as the gestational age went up: an increase of the w6 fatty acids, specially of the 20:4w6 with a slowing down of its elongation, and a decrease of the 18:0 in ethanolamine phosphoglycerides. In choline phosphoglycerides the 18:2w6 increased as the gestational age progressed, whereas the 18:0 and 18:lw9 did not vary. The 22:4w6/22:5w6 index increased in both phosphoglycerides but more significantly in lecithin. The w3/w6 ratio only increased clearly in choline phosphoglycerides.