Effect of acute thioacetamide administration on rat brain phospholipid metabolism

Brain phospholipid composition and the [³²P]orthophosphate incorporation into brain phospholipids of control and rats treated for 3 days with thioacetamide were studied. Brain phospholipid content, phosphatidylcholine, phosphatidylethanolamine, lysolecithin and phosphatidic acid did not show any significant change by the effect of thioacetamide. In contrast, thioacetamide induced a significant decrease in the levels of phosphatidylserine, sphingomyelin, phosphatidylinositol and diphosphatidylglycerol. After 75 minutes of intraperitoneal label injection, specific radioactivity of all the above phospholipids with the exception of phosphatidylethanolamine and phosphatidylcholine significantly increased. After 13 hours of isotope administration the specific radioactivity of almost all studied phospholipid classes was elevated, except for phosphatidic acid, the specific radioactivity of which did not change and for diphosphatidylglycerol which showed a decrease in specific radioactivity. These results suggest that under thioacetamide treatment brain phospholipids undergo metabolic transformations that may contribute to the hepatic encephalopathy induced by thioacetamide.     

Role of phospholipids in activation of mitochondrial D(-)-beta-hydroxybutyrate dehydrogenase

Although phosphatidylcholine (PC) has been shown to be the type of phospholipid required for activation of mitochondrial beta-hydroxybutyrate dehydrogenase (BDH), mixtures of phospholipids containing PC are more effective activators. This study shows that apo-BDH, purified from bovine-heart mitochondria, and phospholipid-reconstituted BDH appear to be polydisperse. Upon cross-linking with dimethylpimelimidate and acrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS), the enzyme exhibited molecular weight forms from monomeric to heptameric BDH as well as higher molecular weight aggregates that did not much penetrate the gels. When different phospholipid mixtures containing PC were used to activate apo-BDH, and the reconstituted samples were subjected to cross-linking and SDS-gel electrophoresis, a direct relationship was found between the activating effect of the phospholipids used and BDH monomer concentration in the gels. The effectiveness order of phospholipids used was as follows: a mixture of PC, phosphatidylethanolamine and diphosphatidylglycerol in a molar ratio of 5:4:1 greater than bovine-heart mitochondrial phospholipids greater than Asolectin greater than PC. These results suggest the following. In addition to PC, which is required by BDH, other types of phospholipids play a role in activation of purified apo-BDH, possibly via enzyme disaggregation. The activity exhibited by purified, phospholipid-reconstituted BDH is associated mainly with the lower molecular aggregates of the enzyme, especially monomeric BDH.     

Negatively charged phospholipid requirement of the oligomycin-sensitive mitochondrial ATPase

The highly-purified, oligomycin-sensitive mitochondrial adenosine triphosphatase has been reconstituted with phosphatidylserine. Treatment of the phosphatidylserine-reconstituted ATPase with phosphatidylserine decarboxylase produced a 3-fold decrease in the specific activity of the resulting phosphatidylethanolamine-enriched ATPase complex. Subsequent control experiments indicated that the resulting phosphatidylethanolamine was responsible for the lowered ATPase specific activity. These observations indicate that acidic phospholips do more than facilitate an interaction between the highly-purified, lipid-depleted ATPase and phospholipid. The negatively charged phospholipid appears to be essential for maintaining high levels of oligomycin-sensitive activity even after the initial interaction between phospholipid and the ATPase complex has occurred.     

Phospholipid Dependence of the Reversible,Energy-Linked,Mitochondrial Transhydrogenase in <Emphasis Type="Italic">Manduca sexta</Emphasis>

Midgut mitochondria from fifth larval instar Manduca sexta exhibit a membrane-associated transhydrogenase that catalyzes hydride ion transfer between NADP(H) and NAD(H). The NADPH-forming transhydrogenations occur as nonenergy- and energy-linked activities. The energy-linked activities couple with electron transport-dependent utilization of NADH/succinate, or with Mg²⁺-dependent ATPase. These energy-linked transhydrogenations have been shown to be physiologically and developmentally significant with respect to insect larval/pupal maturation. In the present study, isolated mitochondrial membranes were lyophilized and subjected to organic solvent or phospholipase treatments. Acetone extraction and addition of Phospholipase A₂ proved to be effective inhibitors of the insect transhydrogenase. Liberation of phospholipids was reflected by measured phosphorous release. Addition of phospholipids to organic solvent- and phospholipase-treated membranes was without effect. Employing a partially lipid-depleted preparation, phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine were reintroduced and transhydrogenase activity assessed. Of the phospholipids tested, only phosphatidylcholine significantly stimulated transhydrogenase activity. The results of this study suggest a phospholipid dependence of the M. sexta mitochondrial transhydrogenase.     

Membrane lipids composition and metabolism during early embryonic development. Phospholipid subcellular distribution and 32P labeling

Phospholipid composition and 32P metabolism were studied in oocytes and early developing embryos of the toad, Bufo arenarum, Hensel. The content and distribution of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidic acid, sphingomyelin, phosphatidylserine, and diphosphatidylglycerol in embryos, whole oocytes, and the subcellular fractions of both were determined. Phosphatidylcholine and phosphatidylethanolamine were the major constituents of yolk platelet. Diphosphatidylglycerol was confined to the mitochondrial fraction, where it represented about 7% of the total phosphoacylglycerols. Relatively large amounts of sphingomyelin were found in microsomal and postmicrosomal supernatants. After in vivo labeling with 32P, the early development of individual phospholipids in subcellular fractions and in whole eggs was followed. The greatest uptake was found in mitochondrial and yolk platelet fractions. A steady increase in the amount of 32P present in phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol was seen in the whole embryo from oocyte to late gastrula stage and in all subcellular fractions. Phosphatidic acid exhibited a slight decrease in specific activity, except in the yolk platelet fraction. This high 32P incorporation would indicate a rapid and uneven polar headgroup turnover determined by phospholipid class and subcellular fraction. At the same time, the phospholipid content of the subcellular fractions studied remained unchanged during early embryogenesis. Moreover, 32P was actively incorporated into the individual phospholipids in the absence of measurable net synthesis.     

Distribution of phospholipids around gramicidin and D-beta-hydroxybutyrate dehydrogenase as measured by resonance energy transfer

A resonance energy transfer method was developed to study the distribution of phospholipids around integral membrane proteins. The method involved measuring the extent of energy transfer from tryptophan residues of the proteins to different phospholipids labeled with a dansyl moiety in the fatty acid chain. No specific interactions were observed between gramicidin and dansyl-labeled phosphatidylcholine, phosphatidylethanolamine, or phosphatidic acid. The results were consistent with a random distribution of each phospholipid in the bilayer in the presence of gramicidin. However, a redistribution of both gramicidin and dansyl-labeled phospholipids was easily observed when a phase separation was induced by adding Ca2+ to vesicles made up of phosphatidylcholine and phosphatidic acid. Polarization measurements showed that in the presence of Ca2+ a rigid phosphatidic acid rich region and a more fluid phosphatidylcholine-rich region were formed. Energy-transfer measurements from gramicidin to either dansylphosphatidylcholine or dansylphosphatidic acid showed gramicidin preferentially partitioned into the phosphatidylcholine-rich regions. Energy-transfer measurements were also carried out with D-beta-hydroxybutyrate dehydrogenase reconstituted in a vesicle composed of phosphatidylcholine, phosphatidylethanolamine, and phosphatidic acid. Although the enzyme has a specific requirement for phosphatidylcholine for activity, the extent of energy transfer decreased in the order dansylphosphatidic acid, dansylphosphatidylcholine, dansylphosphatidylethanolamine. Thus, the enzyme reorganized the phospholipids in the vesicle into a nonrandom distribution.     

The phospholipid headgroup specificity of an ATP-dependent calcium pump.

We have replaced the lipid associated with a purified calcium transport protein with a series of defined synthetic dioleoyl phospholipids in order to determine the effect of phospholipid headgroup structure on the ATPase activity of the protein. At 37 degrees C the zwitterionic phospholipids (dioleoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine) support the highest activity, while a phospholipid with two negative charges (dioleoyl phosphatidic acid) supports an activity which is at least twenty times lower. Dioleoyl phospholipids with a single net negative charge support at intermediate ATPase activity which is not affected by the precise chemical structure of the phospholipid headgroup. The protocol used to determine the phospholipid headgroup specificity of calcium transport protein is novel because it establishes the composition of the lipid in contact with the protein without the need to isolate defined lipid-protein complexes. This allows the lipid specificity to be determined using only very small quantities of test lipids. We also determined the ability of the same phospholipids to support calcium accumulation in reconstituted membranes. Two requirements had to be met. The phospholipid had to support the ATPase activity of the pump protein and it had to form sealed vesicles as determined by electron microscopy. Since a number of phospholipids met those requirements it is clear that in vitro the lipid specificity of the calcium-accumulating system is rather broad.     

Diabetes affects phospholipid content in the nuclei of the rat liver.

The aim of the present study was to examine the effect of acute streptozotocin diabetes on the content of different phospholipids and the incorporation of blood-borne 14C-palmitic acid into the phospholipid moieties in the rat liver nuclei. Diabetes was produced by intravenous administration of streptozotocin, and determinations were carried out two and seven days thereafter. Phospholipids were extracted from isolated nuclei and separated into the following fractions: sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine and cardiolipin. Following that, they were quantified and radioactivity was measured. It was found that, in comparison to non-diabetic controls, two-day diabetes reduced the total content of phospholipids in the nuclei by 9.6%. The content of phospholipids in the nuclei by 9.6%. The content of phosphatidylcholine and phosphatidylserine was reduced and the content of the remaining phospholipids was stable. The specific activity of phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and cardiolipin, based on radioactivity incorporated from 14C-palmitic acid, was elevated. Seven-day diabetes resulted in a reduction of the total phospholipid content in the nuclei by 39.4%. This was accounted for by a reduction in the content of each phospholipid fraction with the exception of cardiolipin. The specific activity of each phospholipid fraction, was elevated in this group. It is concluded that insulin is involved in the regulation of the nuclear phospholipid content.     

Changes in Phospholipid Composition of a Winter Wheat Cultivar during Germination at 2 C and 24 C

Evaluation of various solvent systems for lipid extraction of wheat Triticum aestivum L. cv. Rideau seeds showed that boiling 2-propanol followed by the Bligh-Dyer procedure was the most efficient method, with respect to lipid yield and ability to inactivate lipolytic enzymes. Ten phospholipids were identified in dry seeds; the major components being phosphatidylcholine, lysophosphatidylcholine, N-acyl lysophosphatidyl-ethanolamine, N-acylphosphatidylethanolamine, and phosphatidylethanolamine. After growth for 1 week (2 C) or 31 hours (24 C), the proportions of phosphatidylethanolamine + lysophosphatidic acid and phosphatidic acid increased, lysophosphatidylcholine decreased, and the remaining phospholipids showed little change. At 5 weeks (2 C) or 72 hours (24 C), the seedlings showed 5-fold increases in the proportion of phosphatidic acid largely at the expense of phosphatidylcholine, small decreases in N-acyl lysophosphatidylethanolamine and N-acylphosphatidylethanolamine, and significant increases in lysophosphatidylcholine. The changes in phosphatidic acid and phosphatidylcholine are interpreted as being partially due to increasing phospholipase D activity during germination. In general, the phospholipid composition was similar in morphologically equivalent seedlings grown at 2 C or 24 C. The increased membrane content in seedlings grown at 2 C does not reflect any preferential synthesis of individual phospholipids.     

Activation of D-beta-hydroxybutyrate apodehydrogenase using molecular species of mixed fatty acyl phospholipids

D-beta-Hydroxybutyrate apodehydrogenase is a lipid-requiring enzyme with a specific requirement of lecithin for enzymatic function. The purified enzyme which is devoid of lipid can be reactivated with lecithin or mixtures of natural phospholipid-containing lecithin. However, it is mitochondrial phospholipid which activates the enzyme optimally and with kinetic parameters similar to that of the native membrane-bound enzyme. Mitochondrial phospholipid consists of three classes of phospholipid (lecithin:phosphatidylethanolamine:diphosphatidylglycerol in a ratio of approximately 2:2:1 by phosphorus); each class consists of a multiplicity of different molecular species due to diversity in the fatty acyl substituents. In this study, we have synthesized defined molecular species of mixed fatty acyl phospholipids to evaluate whether multiplicity of phospholipid molecular species are essential for optimal reactivation. We find that: 1) ternary mixtures of single molecular species of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylpropan-1,3-diol in the liquid crystalline state mimic the optimal reactivation of the enzyme obtained with mitochondrial phospholipids; 2) although some negatively charged phospholipid appears necessary for optimizing the efficiency of activation, diphosphatidylglycerol can be replaced by phosphatidylpropan-1,3-diol, another negatively charged phospholipid; and 3) biphasic Arrhenius plots can be correlated with the liquid crystalline and gel states of the phospholipid.     

Modulation by phospholipids of the activity of monoamine oxidase purified from pig liver

Monoamine oxidase was purified from pig liver mitochondria to homogeneity. The enzyme sample contained a large amount of phospholipids. Depletion of lipids from the enzyme sample resulted in a decrease in its activity, while activity was restored by the binding of the lipid-depleted enzyme to phosphatidylcholine, phosphatidylethanolamine, or mitochondrial lipids. Upon binding the lipid-depleted enzyme to the mixture of phosphatidylcholine and phosphatidylethanolamine (molar ratio, 1 : 1), the enzymatic activity toward serotonin was elevated over that of the purified enzyme, but not toward benzylamine, suggesting a change in substrate specificity. Upon lipid depletion, inhibition by deprenyl became weaker, while that by clorgyline became stronger. This alteration was reversed by the binding to lipids. By the binding of the lipid-depleted enzyme to some lipids such as the mixture of phosphatidylcholine and phosphatidylethanolamine (molar ratio, 1 : 1), inhibition by clorgyline became even weaker than for the original enzyme sample.     

The phospholipid headgroup specificity of an atp-dependent calcium pump

We have replaced the lipid associated with a purified calcium transport protein with a series of defined synthetic dioleoyl phospholipids in order to determine the effect of phospholipid headgroup structure on the ATPase activity of the protein. At 37°C the zwitterionic phospholipids (dioleoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine) support the highest activity, while a phospholipid with two negative charges (dioleoyl phosphatidic acid) supports an activity which is at least twenty times lower. Dioleoyl phospholipids with a single net negative charge support at intermediate ATPase activity which is not affected by the precise chemical structure of the phospholipid headgroup. The protocol used to determine the phospholipid headgroup specificity of calcium transport protein is novel because it establishes the composition of the lipid in contact with the protein without the need to isolate defined lipid-protein complexes. This allows the lipid specificity to be determined using only very small quantities of test lipids.We also determined the ability of the same phospholipids to support calcium accumulation in reconstituted membranes. Two requirements had to be met. The phospholipid had to support the ATPase activity of the pump protein and it had to form sealed vesicles as determined by electron microscopy. Since a number of phospholipids met those requirements it is clear that in vitro the lipid specificity of the calcium-accumulating system is rather broad.     

Effects of insulin and protein synthesis inhibitors on phospholipid metabolism, diacylglycerol levels, and pyruvate dehydrogenase activity in BC3H-1 cultured myocytes

BC3H-1 myocytes were cultured with 32PO4 for 3 days to label phospholipids to constant specific activity. Subsequent treatment with physiological concentrations of insulin provoked 40-70% increases in 32PO4 levels (reflecting increases in mass) in phosphatidic acid, phosphatidylinositol, and polyphosphoinositides, and, lesser, 20-25% increases in phosphatidylserine and the combined chromatographic area containing phosphatidylethanolamine plus phosphatidylcholine plus phosphatidylcholine. Insulin-induced increases in phospholipids were significant within 5 min and near-maximal at 15-30 min. Comparable rapid insulin-induced increases in [3H]phosphatidylinositol were observed in myocytes prelabeled with [3H]inositol. These insulin effects (as per prolonged pulse-chase experiments) were due to increase phospholipid synthesis rather than decreased phospholipid degradation. Cycloheximide (and puromycin) pretreatment prevented insulin-induced increases in phospholipids and rapidly reversed ongoing insulin effects on phospholipids and pyruvate dehydrogenase activity. Insulin also rapidly increased diacylglycerol levels. These findings suggest that: (a) insulin provokes rapid increases in de novo synthesis of phosphatidic acid and its derivatives, e.g. phosphoinositides and diacylglycerol; (b) protein synthesis inhibitors diminish phospholipid levels in insulin-treated (but not control) tissues by increasing phospholipid degradation (?phospholipase(s) activation); and (c) changes in phospholipids and diacylglycerol may be important for changes in pyruvate dehydrogenase and other enzymatic activities during treatment with insulin and/or protein synthesis inhibitors.     

The effect of corticotropin on phospholipid metabolism in isolated adrenocortical cells.

Trypsin-dispersed cat adrenocortical cells were incubated at 37 degrees C in modified Eagle's medium containing [14C]arachidonic acid of sodium [14C]-acetate and then in non-radioactive medium. Radioactive incorporation was obtained in all phospholipids, with the greatest amount of radioactivity in phosphatidylcholine, followed by phosphatidylethanolamine, phosphatidyl-serine, and phosphatidylinositol. Concentrations of individual phospholipids generally paralleled the relative amounts of corresponding radiolabeled phospholipids, although the percentage of phosphatidylinositol was considerably lower than its radioactive counterpart, resulting in a high specific activity of this particular phospholipid. Although a potently steroidogenic concentration of corticotropin failed to enhance release of label from any particular phospholipid, analysis of specific activity showed that corticotropin stimulation was accompanied by an increased turnover of phosphatidylinositol and phosphatidic acid. These studies demonstrate that isolated cortical cells have the capacity to synthesize phospholipids from radioactive precursors. The finding that the acute effects of corticotropin are associated with changes in specific phospholipids, including phosphatidylinositol and phosphatidic acid, conforms to the general pattern observed in other secretory systems.     

Acetyl phosphatidylethanolamine in the reconstitution of ion pumps.

Acetyl phosphatidylethanolamine was compared with phosphatidylethanolamine in the reconstitution of several biological membrane activities with the following results. 1. The proton pump reconstituted with the purple membrane of Halobacterium halobium and acetyl phosphatidylethanolamine was quite active. However, some differences in the kinetic properties, particularly in the decay rate, were noted between vesicles reconsituted with phosphatidylethanolamine and acetyl phosphatidylethanolamine. 2. Acetyl phosphatidylethanolamine could not replace phosphatidylethanolamine in the reconstitution of a Ca-2 plus pump with ATPase isolated from sacoplasmic reticulum. However, inclusion of suitable amounts of stearylamine or oleylamine during reconstitution yielded acetyl phosphatidylethanolamine vesicles with Ca-2 plus translocation activity comparable to that of phosphatidylethanolamine vesicles. 3. A mixture of acetyl phosphatidylethanolamine and stearylamine or oleylamine substituted for phosphatidylethanolamine in the reconstitution of mitochondrial hydrophobic proteins to form vesicles that catalyze 32-Pi-ATP exchange. Since phosphatidylcholine is also required in this system, these findings point to two functions of phosphatidylethanolamine, one related to the specific properties of its amino group, the other to a structural role of its small polar head group. A hydrophobic alkylamine can fullfill the first function, acetyl phosphatidylethanolamine the second. 4. The importance of the charge was also observed in experiments with the reconstituted rutamycin-sensitive ATPase of mitochondria. After depletion of phospholipids from the hydrophobic proteins, ATPase activity and rutamycin sensitivity were restored only if a phospholipid as well as the appropriate charge were present.     

Liver cell plasma membrane lipids and the origin of biliary phospholipid.

The liver cell plasma membranes of fed male Wistar rats were separated into a fraction rich in bile canaliculi and the remainder of the plasma membrane. Electron-microscopically, the bile canalicular fraction consisted almost exclusively of intact bile canaliculi with thier contiguous membranes. The remaining plasma membrane fraction consisted primarily of vesicles and sheets of membranes essentially free from the bile canaliculi. The bile canalicular membrane fraction contained relatively more total lipid, cholesterol, and phospholipid, and relatively less protein. Although the phospholipid composition of the two fractions was the same, the specific activity of the bile canalicular membrane phosholipids, up to 12 h following in vivo administration of [2-3H]glycerol, was always significantly greater than that of the remaining plasma membranes, and showed a biphasic response not found in the latter. The specific activity of the phosphatidylcholine, phosphatidylethanolamine and lysophosphatidylcholine of the bile canalicular membranes rose to a peak within 40 min after administration of the label, fell sharply and then rose to a second peak after 120 min. The specific activity of the sphingomyelin and phosphatidylserine plus phosphatidylinositol of the bile canalicular membranes and of all the phospholipids of the remaining plasma membranes diphasic pattern but increased steadily to reach a maximum at 120 min. The specific activity of biliary phosphatidylcholine followed a pattern identical to that of the phosphatidylcholine, phosphatidylethanolamine and lysophosphatidylcholine of the bile canalicular membrane fraction. These results show that the average rate of turnover of phospholipid in the bile canalicular membranes is considerably greater than that in the remaining plasma membrane and other cell membrane fractions; they indicate that the phospholipid of the bile canalicular membranes exists in two or more pools, turning over a different rates; and they support the concept that biliary phospholipid is derived from the bile canalicular membrane. The results also suggest that bile canalicular phospholipid may be derived from two different sources, in contrast to the remainong plasma membrane.     

Preferential incorporation of eicosanoid precursor fatty acids into human umbilical vein endothelial cell phospholipids

We have examined the preferential incorporation of specific fatty acids into phospholipid classes of cultured human umbilical vein endothelial cells. Pulse-labeling of human umbilical vein endothelial cell phospholipids with radiolabeled fatty acids and inhibition of radiolabeled fatty acid incorporation by competition with excess, unlabeled fatty acids in pair-wise combinations revealed two distinct classes of esterification systems into human umbilical vein endothelial cell phospholipids. The eicosanoid precursor fatty acids, including arachidonate, 8,11,14-eicosatrienoate (ETA) and 5,8,11,14,17-eicosapentaenoate (EPA), exhibited high affinity incorporation into total phospholipids, whereas other fatty acids, including docosahexaenoate and monohydroxy eicosatetraenoates, showed low affinity incorporation. The relative degree of incorporation of eicosanoid precursor fatty acids into phospholipid classes was phosphatidylcholine (PC) greater than phosphatidylethanolamine (PE) greater than phosphatidylinositol (PI) greater than phosphatidylserine (PS). The specific activity of [14C]arachidonic acid-labeled PI was two times higher than that of any other radiolabeled phospholipids. When competitive incorporation of eicosanoid precursor fatty acids into phospholipid classes was studied, they were found to be acylated into different phospholipid classes at different rates. Although eicosanoid precursor fatty acids were not preferentially incorporated into PC, arachidonic acid was preferentially incorporated into the other phospholipids and exhibited particular selectivity in comparison with the other eicosanoid precursor fatty acids for incorporation into PI. These results demonstrate that human umbilical vein endothelial cells possess selective incorporation mechanisms for specific fatty acids into various phospholipids via the deacylation-reacylation pathway.     

Phospholipid composition and phospholipid asymmetry of ram spermatozoa plasma membranes

The phospholipid composition of ram spermatozoa plasma membranes has been investigated. An exclusively high participation of the choline- and ethanolamine-plasmalogens in the phosphatidylcholine and phosphatidylethanolamine fractions has been established. Phosphatidylcholine of ram spermatozoa plasma membranes contains a great amount of polyunsaturated fatty acids. The phospholipid distribution in spermatozoa plasma membrane was investigated. It was established that the choline containing phospholipids are situated mainly in the outer membrane lipid monolayer, whereas diphosphatidylglycerol and phosphatidylserine are localized predominantly in the inner monolayer. The rest of the phospholipids are evenly distributed among the two monolayers. Ram spermal plasma membranes exhibit high phospholipase A2 activity.     

Lipids of Leishmania promastigotes.

A chromatographic analysis of lipids of cultured promastigotes of Leishmania donovani, L. braziliensis, L. mexicana, L. tropica, L. enriettii, L. hertigi, L. adleri, and L. tarentolae showed that total lipids were 2--15% of dry wt, and neutral and polar lipids were 14--55% and 45--86% of total lipids. Major lipid classes were as follows: sterol ester, triacylglycerol, sterol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylcholine. Predominant fatty acids were 18:2 (n - 6) greater than 18:3 (n - 3) greater than 18:1 (n - 9) greater than 18:0 greater than 22:6 (n - 3) greater than 22:5 (n - 6) greater than 16:0 greater than 14:0 greater than 18:4 (n - 3) greater than 20:3 (n - 3). Some remarkable distributions of fatty acids among the phospholipid fractions were observed, as follows: diphosphatidylglycerol 18--33% 22:6 (n - 3); phosphatidylinositol 31--68% 18:1 (n - 9); phosphatidylcholine 13--41% 18:3 (n - 3). Alk-l-enyldiacyl glycerols, and alk-l-enylacyl and alkylacyl forms of phosphatidylethanolamine and of phosphatidylinositol were found, and their glyceryl ethers and fatty adehydes analyzed. Notable in the phosphatidylethanolamine of some leishmanias was a cyclopropane fatty acid (4--11%), identified as cis-9,10-methylene octadecanoic acid by chromatographic, and by mass and proton resonance spectrometric analyses. The comparative biochemistry of the cyclopropane fatty acid, characteristic of many prokaryotes, and of alpha-linolenic acid, characteristic of photosynthetic plants, are commented upon.