Characterization of gastric mucosal membranes: lipid composition of purified gastric microsomes from pig, rabbit, and frog

The lipid compositions of the gradient-purified gastric microsomal membranes from the fundic mucosa of pig, rabbit, and frog were determined. The total lipid content varied widely. Compared to the rabbit (21.6 ± 0.6 mg/100 mg protein), the pig had about twice as much and the frog about three times as much lipid. The levels of cholesterol were higher in both mammalian species (about 32% of the lipid) compared to frog (23%). Phospholipids accounted for about 45, 54, and 52% of the total microsomal lipids from pig, rabbit, and frog and the molar ratios of cholesterol to phospholipid in the three species were 1.95, 1.6, and 1.17, respectively. Phosphatidyl choline and phosphatidyl ethanolamine together constituted about 75% of the total phospholipids in pig and frog and 93% in rabbit gastric microsomes. Sphingomyelin comprised 19.3, 3.2, and 1.5% in pig, rabbit, and frog, respectively. Phosphatidyl inositol constituted 5, 2.7, and 23.6% in pig, rabbit, and frog, respectively. The ratios of phosphatidyl ethanolamine to phosphatidyl choline were 1.17, 1.1, and 0.85 in pig, rabbit, and frog, respectively. The saturated fatty acids 16:0 and 18:0 and the unsaturated fatty acid 18:1 and 18:2 were the predominant fatty acids in all phospholipids. The ratios of saturated to unsaturated fatty acids were between 0.8 and 0.9 in phosphatidyl choline and 0.27 and 0.5 in phosphatidyl ethanolamine from all three species. The contributions by saturated fatty acids were much more in phosphatidyl inositol and sphingomyelin than in phosphatidyl choline and phosphatidyl ethanolamine from all species. Position 1 of phosphatidyl choline had 63% saturated and 37% unsaturated fatty acids; while the reverse was true for position 2. Phosphatidyl ethanolamine, however, had 85% saturated fatty acids in position 1 compared to only 25% in position 2. Arachidonic acid (20:4) was present in significant amounts in all species located exclusively at position 2 of both phosphatidyl choline and phosphatidyl ethanolamine.     

Phospholipids and phospholipid-bound fatty acids and aldehydes of spermatozoa and seminal plasma of rhesus monkeys.

The major components of the phospholipids of rhesus monkey spermatozoa are phosphatidyl choline (33%), phosphatidyl ethanolamine (25%), ethanolamine plasmalogen (16-1%), sphingomyelin (8-1%), choline plasmalogen (6-9%) and cardiolipin (4-5%). The major phospholipid-bound fatty acids are 16:0, 18:0, 18:1 and 22:6; the major fatty aldehydes are 15:0, 16:0 and 18:2. The same phospholipids are also present in the seminal plasma.     

Peripheral Nerve Phospholipid Composition: Development in Normal Nerve and Age-Dependent Changes in Wallerian Degenerated Nerve

Abstract: The phospholipid composition of normal peripheral nerve as a function of developmental age as well as that of Wallerian-degenerated nerve as a function of age at nerve transection and duration of Wallerian degeneration have been quantitated in rabbit sciatic nerve. During development, increases in the proportions of ethanolamine plasmalogen, sphingomyelin, and combined phosphatidyl serine plus phosphatidyl inositol and decreases in the proportions of phosphatidyl choline and phosphatidyl ethanolamine correlated well with the concurrent myelin accretion. During Wallerian degeneration, age-dependent changes in phospholipid composition were observed. The large and statistically significant increase in the proportion of phosphatidyl choline and decrease in the proportion of ethanolamine plasmalogen were manifest promptly in nerves transected at 2 weeks of age but in a delayed manner in nerves transected at 8, 12, and 20 weeks of age. The rate of loss of individual phospholipids was greater in nerves transected at younger ages. The findings from normal developing peripheral nerve may well serve as baseline data for subsequent studies of phospholipid composition in pathological peripheral nerve. The Findings from Wallerian-degenerated peripheral nerve provide additional evidence for age-dependent chemical changes occurring in Wallerian-degenerated peripheral nerve that may be of significance in explaining the superior functional recovery from peripheral nerve injury observed in younger compared with older subjects.     

Temperature adaptation of biological membranes. Compensation of the molar activity of cytochrome c oxidase in the mitochondrial energy-transducing membrane during thermal acclimation of the carp (cyprinus carpio L.)

The phospholipid composition, fatty acid pattern and cholesterol content are studied in mitochondria of red lateral muscle of carp acclimated to high and low environmental temperatures.The results of the experiments are: mitochondria from cold-acclimated carp contain higher proportions of ethanolamine phosphatides than mitochondria from warm-acclimated fish, the opposite is true for the choline phosphatides. Thus, at constant pH, the membrane phospholipids are slightly more negatively charged at low acclimation temperature. The total plasmalogen content is reduced in the cold; this reduction is caused by a decrease in the proportion of the choline plasmalogens. The ethanolamine phosphoglycerides contain approx. 20% of the alk-1-enyl acyl type, irrespective of the acclimation temperature. There is no temperature-dependent difference in the low proportion of cholesterol.The fatty acids of total mitochondrial phospholipids are characterized by large amounts of the n-3 and n-6 families. The ratio of unsaturated to saturated fatty acids and the unsaturation index are remarkably higher than those reported for comparable mammalian phospholipids. Cold acclimation of carp does not significantly increase the unsaturation of total phospholipids. A fatty acid analysis of the main isolated phospholipids, however, shows that cold acclimation considerably increases unsaturation of the neutral phosphatidylcholine, whereas it dramatically decreases unsaturation of the negatively charged cardiolipin. It is suggested that the observed fatty acid substitution in phosphatidylcholine indicates a temperature-induced fluidity adaptation within the mitochondrial lipid bilayer, whereas the inverse acclimation pattern of cardiolipin provides a suitable lipid to accommodate the temperature-dependent modifications in the dynamic surface shape of integral membrane proteins.     

THE ISOLATION AND LIPID COMPOSITION OF MYELIN-FREE AXONS FROM RAT CNS1

—Myelin-free axons were isolated from rat CNS using a modification of the method of De Vries et al. (1972). On a dry weight basis, the axons contained 15·2% lipid composed of 19·4% cholesterol, 56·9% phospholipid and 23·7% galactolipid with a weight ratio of cerebroside to sulfatide of 3·6-1. The phospholipid was composed of 11·0% ethanolamine phosphatides (44·4% in the plasmalogen form), 21·0% choline phosphatides (9·3% in the plasmalogen form), 4·5% sphingomyelin, 4·5% phosphatidyl serine, 4·3% phosphatidyl inositol, 3·0% diphosphatidyl glycerol and 8·5% unidentified phospholipid. The rat axons contained 0·18 μg ganglioside NeuNAc/mg dry wt. In addition to the 4 major brain gangliosides, the rat axons contained gangliosides G_D2 and G_D3. The axonal galactolipid could not be accounted for by myelin contamination as revealed by electron microscopy, absence of the characteristic ratio of myelin specific proteins in the axonal protein profile as shown by polyacrylamide gel electrophoresis, and the axonal level of the myelin marker enzyme 2′,3′-cyclic nucleotide-3′-phosphohydrolase. The relationship between lipids of axons isolated from rat and bovine CNS, and rat whole brain and CNS myelin is discussed.     

The molecular organization of nerve membranes

Summary The lipid content and composition from an axolemma-rich preparation isolated from squid retinal axons was analyzed.The lipids, which accounted for 45.5% of the dry weight of this membrane, were composed of 22% cholesterol, 66.7% phospholipids and 5.2% free fatty acids. The negatively charged species phosphatidyl ethanolamine (37%), phosphatidyl serine (10%) and lysophosphatidyl ethanolamine (4%) made up 51% of the phospholipids. The amphoteric phosphatidyl choline and sphingomyelin accounted for 39% and 4%, respectively.The relative distribution of fatty acids in each of the isolated phospholipids was studied. The most remarkable feature of these phospholipids was the large proportion of long-chain polyunsaturated fatty acids. The 226 acyl chain accounted for 37% in phosphatidyl ethanolamine, 21.7% in phosphatidyl choline, 17.5% on phosphatidyl serine and 20.3% in sphingomyelin (all expressed as area %).The molar fraction of unsaturated fatty acids reached 65% in phosphatidyl ethanolamine and 42.0 and 44.8% in phosphatidyl choline and phosphatidyl serine, respectively. The double bond index in these species varied between 1.0 and 2.6.The lipid composition of the axolemma-rich preparation isolated from squid retinal axons appears to be similar to other excitable plasma membranes in two important features: (a) a low cholesterol/phospholipid molar ratio of 0.61; and (b) the polyunsaturated nature of the fatty acid of their phospholipids.This particular chemical composition may contribute a great deal to the molecular unstability of excitable membranes.The preceding papers of this series were published inArchives of Biochemistry and Biophysics.     

Lipid composition of brain myelin from normal and hyperphenylalaninemic chick embryos

The influence of hyperphenylalaninemia on the lipid composition of brain myelin has been investigated in 19-day-old chick embryos. CNP-ase activity was used as myelin marker enzyme for myelin isolation. CNP-ase activity was significantly lower in hyperphenylalaninemic myelin when compared with control. No significant differences were observed after experimental treatment in the total lipid content of myelin as well as in the proportion of cholesterol:phospholipid:galactolipid. Nevertheless, a clear increase in the percentage of esterified cholesterol was found. No appreciable alterations were observed in the phospholipid composition of brain myelin from both control and hyperphenylalaninemic chick embryos. However, the ratio of unsaturated to saturated fatty acids in serine plasmalogen and sphingomyelin was considerably increased by this treatment. This ratio in choline and ethanolamine phosphatides from treated embryos did not differ from that of controls.     

Heart fatty acid uptake is decreased in heart fatty acid-binding protein gene-ablated mice

Cell culture systems have demonstrated a role for cytoplasmic fatty acid-binding proteins (FABP) in lipid metabolism, although a similar function in intact animals is unknown. We addressed this issue using heart fatty acid-binding protein (H-FABP) gene-ablated mice. H-FABP gene ablation reduced total heart fatty acid uptake 40 and 52% for [1-(14)C]16:0 and [1-(14)C]20:4n-6 compared with controls, respectively. Similarly, the amount of fatty acid found in the aqueous fraction was reduced 40 and 52% for [1-(14)C]16:0 and [1-(14)C]20:4n-6, respectively. Less [1-(14)C]16:0 entered the triacylglycerol pool, with significant redistribution of fatty acid between the triacylglycerol pool and the total phospholipid pool. Less [1-(14)C]20:4n-6 entered each lipid pool measured, but these changes did not alter the distribution of tracer among these pools. In gene-ablated mice, significantly more [1-(14)C]16:0 was targeted to choline and ethanolamine glycerophospholipids, whereas more [1-(14)C]20:4n-6 was targeted to the phosphatidylinositol (PtdIns) pool. H-FABP gene ablation significantly increased PtdIns mass 1.4-fold but reduced PtdIns 20:4n-6 mass 30%. Consistent with a reported effect of FABP on plasmalogen mass, ethanolamine plasmalogen mass was reduced 30% in gene-ablated mice. Further, 20:4n-6 mass was reduced in each of the three other major phospholipid classes, suggesting H-FABP has a role in maintaining steady-state 20:4n-6 mass in heart. In summary, H-FABP was important for heart fatty acid uptake and targeting of fatty acids to specific heart lipid pools as well as for maintenance of phospholipid pool mass and acyl chain composition.     

Temperature adaptation of biological membranes. The effects of acclimation temperature on the unsaturation of the main neutral and charged phospholipids in mitochondrial membranes of the carp (cyprinus carpio L.)

The phospholipid composition, fatty acid pattern and cholesterol content are studied in mitochondria of red lateral muscle of carp acclimated to high and low environmental temperatures.The results of the experiments are: mitochondria from cold-acclimated carp contain higher proportions of ethanolamine phosphatides than mitochondria from warm-acclimated fish, the opposite is true for the choline phosphatides. Thus, at constant pH, the membrane phospholipids are slightly more negatively charged at low acclimation temperature. The total plasmalogen content is reduced in the cold; this reduction is caused by a decrease in the proportion of the choline plasmalogens. The ethanolamine phosphoglycerides contain approx. 20% of the alk-1-enyl acyl type, irrespective of the acclimation temperature. There is no temperature-dependent difference in the low proportion of cholesterol.The fatty acids of total mitochondrial phospholipids are characterized by large amounts of the $\text{n-3}\text{and}\text{n-6}$ families. The ratio of unsaturated to saturated fatty acids and the unsaturation index are remarkably higher than those reported for comparable mammalian phospholipids. Cold acclimation of carp does not significantly increase the unsaturation of total phospholipids. A fatty acid analysis of the main isolated phospholipids, however, shows that cold acclimation considerably increases unsaturation of the neutral phosphatidylcholine, whereas it dramatically decreases unsaturation of the negatively charged cardiolipin. It is suggested that the observed fatty acid substitution in phosphatidylcholine indicates a temperature-induced fluidity adaptation within the mitochondrial lipid bilayer, whereas the inverse acclimation pattern of cardiolipin provides a suitable lipid to accommodate the temperature-dependent modifications in the dynamic surface shape of integral membrane proteins.     

Lipids of the Spirochaetales: Comparison of the Lipids of Several Members of the Genera Spirochaeta, Treponema, and Leptospira

The lipid compositions of 17 spirochetes belonging to the genera Spirochaeta and Treponema were investigated and compared with data previously derived from 11 strains of Leptospira. The lipid compositions and lipid metabolism of any of these genera is sufficiently different to be characteristic of that genus and to differentiate it from the other two genera. Members of the genus Leptospira are characterized by their ability to beta-oxidize long chain fatty acids as their major carbon and energy source. With few exceptions, they are incapable of synthesizing fatty acids de novo. The major phospholipid found was phosphatidyl ethanolamine. No glycolipid or phosphatidyl choline was found in these organisms. Members of the genus Treponema studied were incapable of beta-oxidation as well as de novo synthesis of fatty acids. Phosphatidyl choline is the major phospholipid of this genus. The glycolipid, monogalactosyl diglyceride, is a major component of the Treponema. Members of the Spirochaeta did synthesize fatty acids de novo. Although these spirochetes contain a monoglycosyl diglyceride, the hexose content of the glycolipid varied from species to species. Neither phosphatidyl ethanolamine nor phosphatidyl choline was found in the Spirochaeta.     

Phospholipids from the hepatopancreas of Indian horseshoe crab Carcinoscropius rotundicauda

Total phospholipids were extracted from the heart, hepatopancreas, and hemolymph of the Indian horseshoe crab Carcinoscorpius rotundicauda by the conventional method. Characteristic group reaction and 2-dimensional thin-layer chromatography on silica gel were used for identification of different phospholipids. The phospholipid profile obtained from hemolymph and 2 major organs are comparable and show phosphatidyl choline (PC) and phosphatidyl ethanolamine to be the major phospholipids. A phospholipid has been consistently detected migrating immediately below the PC in the thin-layer chromatogram of lipids extracted from the hepatopancreas. When mixed methyl esters of this slower moving PC are resolved on a silica gel plate ran in hexane ether:acetic acid 80:20:1, with appropriate controls, an additional spot is seen just below the normal methyl ester, indicating a difference between the fatty acid compositions of 2 PC (e.g., regular and slower). The slower mixed methyl esters were found to comprise mainly the 4 saturated fatty acids: lauric, myristic, palmitic, and stearic. The slow moving PC seems to consist mainly of molecular species with the above-mentioned saturated fatty acids at both Sn 1 and Sn 2 positions.     

Phospholipids from the hepatopancreas of Indian horseshoe crab Carcinoscorpius rotundicauda

Total phospholipids were extracted from the heart, hepatopancreas, and hemolymph of the Indian horseshoe crab Carcinoscorpius rotundicauda by the conventional method. Characteristic group reaction and 2-dimensional thin-layer chromatography on silica gel were used for identification of different phospholipids. The phospholipid profile obtained from hemolymph and 2 major organs are comparable and show phosphatidyl choline (PC) and phosphatidyl ethanolamine to be the major phospholipids. A phospholipid has been consistently detected migrating immediately below the PC in the thin-layer chromatogram of lipids extracted from the hepatopancreas. When mixed methyl esters of this slower moving PC are resolved on a silica gel plate ran in hexane ether:acetic acid 80:20:1, with appropriate controls, an additional spot is seen just below the normal methyl ester, indicating a difference between the fatty acid compositions of 2 PC (e.g., regular and slower). The slower mixed methyl esters were found to comprise mainly the 4 saturated fatty acids: lauric, myristic, palmitic, and stearic. The slow moving PC seems to consist mainly of molecular species with the above-mentioned saturated fatty acids at both Sn 1 and Sn 2 positions.     

Age-related changes of the endogenous cardiolipin and plasmalogens of guinea pig kidney and their in vitro hydrolysis by endogenous phospholipases: a thin layer chromatographic analysis in conjunction with densitometric measurement

The phosphoglycerides profile of guinea pig kidney, fetal, young adult, and aged, and their in vitro response to the endogenous lipolytic enzymes, mainly in the phospholipase group were determined by TLC technology in conjunction with densitometric measurement. Changes in phosphoglycerides profile subsequent to in vitro incubation of these tissues at pH 7.4, and 38 degrees C for 45 min and prior to phospholipid extraction has provided evidence relating to their respective lipolytic enzymes capabilities and age. These changes are mainly related to endogenous cardiolipin (CL), alkenyl phospholipids (phosphatidyl ethanolamine and phosphatidyl choline) and their endogenous deacylation to their respective lyso derivatives monolysocardiolipin (MLCL), lyso alkenyl phosphatidyl ethanolamine (LPE), and lyso alkenyl phosphatidyl choline (LPC) by endogenous phospholipases. The hydrolysis of the plasmalogen confirms the action of endogenous PLA(2) on sn-2 fatty acids of these compounds.     

Differential turnover of polyunsaturated fatty acids in plasmalogen and diacyl glycerophospholipids of isolated cardiac myocytes

To investigate the relative turnover of esterified polyunsaturated fatty acids in diacylglycerophospholipids and plasmalogens in isolated cardiac myocytes, we characterized the phospholipid composition and distribution of radiolabel in different phospholipid classes and in individual molecular species of diradyl choline (CGP) and ethanolamine (EGP) glycerophospholipids after incubation of isolated cardiac myocytes with [3H]arachidonate or [14C]linoleate. Plasmalogens in CGP (55%) and EGP (42%) quantitatively accounted for the total plasmalogen content (39%) of cardiac myocyte phospholipids. Plasmalogens comprised 86% and 51% of total arachidonylated CGP and EGP mass, respectively, and [3H]arachidonate was primarily incorporated into plasmalogens in both CGP (65%) and EGP (61%) classes. The specificity activity of [3H]arachidonylated diacyl-CGP was approximately 2- to 5-fold greater than that of [3H]arachidonylated choline plasmalogen, whereas comparable specific activities were found in the [3H]arachidonate-labeled ethanolamine plasmalogen and diacyl-EGP pools. Of the total linoleate-containing CGP and EGP mass, 54% and 57%, respectively, was esterified to plasmalogen molecular species. However, [14C]linoleate was almost exclusively incorporated into diacyl-CGP (96%) and diacyl-EGP (86%). The specific activities of [14C]linoleate-labeled diacyl-CGP and diacyl-EGP were 5- to 20-fold greater than that of the [14C]linoleate-labeled plasmalogen pools. The differential incorporation of polyunsaturated fatty acids in plasmalogens and diacylglycerophospholipids demonstrates that the metabolism of the sn-2 fatty acyl moiety in these phospholipid subclasses is differentially regulated, possibly fulfilling separate and distinct physiologic roles.     

EFFECT OF 1-AMINOCYCLOPENTANE-1-CARBOXYLIC ACID (CYCLOLEUCINE) ON DEVELOPING RAT CENTRAL NERVOUS SYSTEM PHOSPHOLIPIDS

Treatment of developing rats with 1-amino-cyclopentane carboxylic acid (cycloleucine) resulted in changes in brain and spinal cord phospholipid content and fatty acid composition. General findings were a decrease in ethanolamine phospholipid content, and relative increase in the saturated fatty acid content of ethanolamine phospholipid. In all the different cycloleucine experiments conducted, there was consistently less fatty aldehyde present in the methylated ethanolamine phospholipid fatty acid-fatty aldehyde fractions than in corresponding controls. In some experiments fatty aldehyde was almost completely absent, suggesting the presence of little plasmalogen. Changes in fatty acids of phosphatidyl choline, the other phospholipid examined in this manner, were generally minor. Administration of massive amounts of sodium propionate in addition to cycloleucine did not result in an appreciable odd-chain fatty acid increase in the CNS. Examination of the spinal cords by electron microscopy demonstrated considerable myelin splitting in one set of animals. No other ultrastructural changes were evident. The suitability of this drug to produce a neurological condition and pathological state similar to that seen in B₁₂-deficient subacute combined degeneration is discussed.     

Lipid composition and metabolism in testicular and ejaculated ram spermatozoa

1. Spermatozoa collected directly from the testis of the conscious ram contain 25% more phospholipid than ejaculated spermatozoa. The concentration of lecithin, phosphatidylethanolamine and ethanolamine plasmalogen was greater in testicular spermatozoa; little difference was observed in choline plasmalogen. Both types of spermatozoa had significant amounts of cardiolipin and alkyl ether phospholipid. 2. The fatty acids in the phospholipid extracted from testicular spermatozoa have a very high content of palmitic acid. The phospholipids of ejaculated spermatozoa contained less palmitic acid, but more myristic acid. 3. Ejaculated spermatozoa contained less acyl ester and cholesterol. It is suggested that lipids are a source of substrate for spermatozoa during their passage through the epididymis. 4. Testicular spermatozoa when incubated with [U-¹⁴C]glucose incorporated more radioactivity into the glycerol part of the phospholipid and neutral lipid fractions than did ejaculated cells. The distribution of radioactivity in the individual phospholipids and neutral lipids was similar for both cell types. No radioactivity was detected in choline plasmalogen, which accounted for approx. 40% of the total phospholipid. 5. Testicular spermatozoa incorporated more radioactivity from glucose into formate than into acetate, whereas a higher proportion of radioactivity was found in acetate in ejaculated cells. 6. The implications of these lipid changes in the process of spermatozoal maturation are discussed.     

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.     

High plasmalogen and arachidonic acid content of canine myocardial sarcolemma: a fast atom bombardment mass spectroscopic and gas chromatography-mass spectroscopic characterization

Canine myocardial sarcolemma was purified, and its phospholipid constituents were determined by gas chromatography-mass spectrometry, fast atom bombardment mass spectrometry, and conventional techniques. Canine myocardial sarcolemma contained 2.7 mumol of lipid Pi/mg of protein which was comprised predominantly of choline glycerophospholipids (47%), ethanolamine glycerophospholipids (28%), and sphingomyelin (11%). Sarcolemmal phospholipids contained 40% plasmalogen which was quantitatively accounted for by choline (57% of choline glycerophospholipid) and ethanolamine (64% of ethanolamine glycerophospholipid) plasmalogens. Choline plasmalogens contained predominantly the vinyl ether of palmitic aldehyde though ethanolamine plasmalogens were composed predominantly of the vinyl ethers of stearic and oleic aldehydes. The majority of sarcolemmal ethanolamine glycerophospholipids (75%) contained arachidonic acid esterified to the sn-2 carbon. Sphingomyelin was composed predominantly of long-chain saturated fatty acids (stearic and arachidic) as well as substantial amounts (8%) of odd chain length saturated fatty acids. The possible functional role of these unusual phospholipid constituents is discussed.     

Effect of cryopreservation on lipids and some physiological features of spermatozoa from rams pastured in highlands and in valleys

The effect of low temperature preservation on the motility and morphology of acrosomes, acrosomal proteolytic activity, phospholipid and fatty acid composition of phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE), and the cholesterol/phospholipid molar ratio in sperm from rams housed in the highlands or in the valleys, were studied. The indices of motility and morphological integrity of sperm from highland rams were much greater compared with those of valley rams. Phosphatidyl choline (PC) of the highland rams was more unsaturated, while PE was more saturated compared with those of valley rams. Cryopreservation of the sperm from highland rams significantly increased the content of choline plasmalogen, accompanied by a slight rise in the levels of lysophosphatidyl choline (LPC) and phosphatidyl inositol (PI) in their sperm. The fatty acid composition altered following cryopreservation. These variations were mainly due to a decrease in the amount of docosahexaenic acid and an increase in the amounts of linoleic and palmitic fatty acids. The results may be indicative of the fact that the alterations in the sperm of the valley rams were more pronounced and they may be attributed to the structural features of the sperm, as well as a reduced concentration of oxygen in the organs and tissues of the highland rams.     

The utilisation of yolk phosphoglycerides by the alligator during embryonic development

Summary A study was made of the concentrations and fatty acid compositions of the major phosphoglycerides in the yolk of the alligator egg on the 8th and 75th days of incubation. The major phosphoglycerides were phosphatidyl choline and phosphatidyl ethanolamine which at the start of incubation accounted for 72 and 18%, respectively, of total phosphoglyceride. Phosphoglycerides were characterised by low levels of linoleic acid but extremely high levels of C20 and C22 polyunsaturates. The extensive absorption of phosphoglyceride over the incubation period was accompanied by a reduction in percentage of phosphoglyceride within the residual yolk lipid, a reduction in the proportion of phosphatidyl choline within the total phosphoglyceride, and increases in the proportions of phosphatidyl ethanolamine and lyso-phosphatidyl choline. There were small but wide-spread changes in the fatty acid composition of the phosphatidyl choline during incubation. Within the phosphatidyl ethanolamine and phosphatidyl serine fractions there were very large reductions in the C20 and C22 polyunsaturated fatty acid levels. The phosphoglyceride changes are discussed with respect to the unique role of yolk lipid absorption in the nutrition of the developing embryo.