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The lipid composition of Mycoplasma laidlawii strain B.

1. Total lipid was extracted from Mycoplasma laidlawii strain B with chloroform-methanol mixtures and fractionated into neutral lipid, glycolipid and phospholipid components by chromatography on silicic acid. 2. Saponification of the glycolipid fraction, which represented nearly half of the total lipid, yielded two glycosides for which the structures O-alpha-d-glucopyranosyl-(1-->1)-d-glycerol and O-alpha-d-glucopyranosyl-(1-->2)-O-alpha-d-glucopyranosyl-(1-->1)-d-glycerol were established. 3. The ratio of monoglucosyl diglyceride to diglucosyl diglyceride increased with the age of the culture, though the total glycolipid concentration remained virtually constant. The glycolipid concentration was unaffected by the addition of cholesterol to the culture medium. 4. The phospholipid fraction consisted of two components, phosphatidylglucose and phosphatidylglycerol. Organisms harvested at acidic pH also contained O-amino acyl esters of phosphatidylglycerol. No lipids containing inositol could be detected.

Cholesterol↗

Glycerol kinase activities in muscles from vertebrates and invertebrates.

1. Glycerol kinase (EC 2.7.1.30) activity was measured in crude extracts of skeletal muscles by a radiochemical method. The properties of the enzyme from a number of different muscles are very similar to those of the enzyme from rat liver. Glycerol kinase from locust flight muscle was inhibited competitively by l-3-glycerophosphate with a K(i) of 4.0x10(-4)m. 2. The activity of glycerol kinase was measured in a variety of muscles from vertebrates and invertebrates in an attempt to explain the large variation in the activity of this enzyme in different muscles. 3. In vertebrates glycerol kinase activities were generally higher in red muscle than in white muscle; the highest activities (approx. 0.2mumole/min./g. fresh wt.) were found in the red breast muscle of some birds (e.g. pigeon, duck, blue tit) whereas the activities in the white breast muscle of the pheasant and domestic fowl were very low (approx. 0.02mumole/min./g.). 4. On the basis of glycerol kinase activities, muscles from insects can be classified into three groups: muscles that have a low enzyme activity, i.e. <0.3mumole/min./g. (leg muscles of all insects studied and the flight muscles of cockroaches and the tsetse fly); muscles that have an intermediate enzyme activity, i.e. 0.3-1.5mumoles/min./g. (e.g. locusts, cockchafers, moths, water-bugs); and muscles that have a high enzyme activity, i.e. >1.5mumoles/min./g. (e.g. bees, wasps, some blowflies). 5. The function of glycerol kinase in vertebrate and insect muscles that possess a low or intermediate activity is considered to be the removal of glycerol that is produced from lipolysis of triglyceride or diglyceride by the muscle. Therefore in these muscles the activity of glycerol kinase is related to the metabolism of fat, which is used to support sustained muscular activity. A possible regulatory role of glycerol kinase in the initiation of triglyceride or diglyceride lipolysis is discussed. 6. The function of glycerol kinase in the insect muscles that possess a high activity of the enzyme is considered to be related to the high rates of glycolysis that these muscles can perform. The oxidation of extramitochondrial NADH, and therefore the maintenance of glycolysis, is dependent on the functioning of the glycerophosphate cycle; if at any stage of flight (e.g. at the start) the rate of mitochondrial oxidation of l-3-glycerophosphate was less than the activity of the extramitochondrial glycerophosphate dehydrogenase, this compound would accumulate, inhibit the latter enzyme and inhibit glycolysis. It is suggested that such excessive accumulation of l-3-glycerophosphate is prevented by hydrolysis of this compound to glycerol; the latter would have to be removed from the muscle when the accumulation of l-3-glycerophosphate had stopped, and this would explain the presence of glycerol kinase in these muscles and its inhibition by l-3-glycerophosphate.

Adenine Nucleotides↗

Turnover of the glycerolipids of pumpkin leaves. The importence of phosphatidylcholine.

Between 1 and 5% of the (14)C recovered from pumpkin leaves within 15-60min after pulse-labelling with (14)CO(2) was in the lipids. The specific radioactivity of the phospholipids was higher than that of the glycolipids. Phosphatidylcholine had five times the specific radioactivity of monogalactosyl diglyceride, and the specific radioactivity of neither galactolipid changed significantly between 1 and 48h after labelling. It therefore seemed unlikely that the galactose moieties of the galactolipids were involved in the transport of assimilated compounds across the chloroplast membrane. Within 60min of the application of [1-(14)C]acetate to the surfaces of mature, intact pumpkin leaves 70% of the recovered (14)C was in the lipid fraction. Of the separated glycerolipids, phosphatidylcholine had by far the highest specific radioactivity at the shorter time-intervals, and the glycolipids again had the lowest specific radioactivities. Phosphatidylcholine was the only lipid to show a significant turnover of radiocarbon as judged by the decrease in specific radioactivity with time. From a comparison of the changes with time of the labelling of fatty acid fractions from phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and monogalactosyl diglyceride, it is suggested that the primary site of linolenic acid biosynthesis in leaf cells is within the phosphatidylcholine molecule.

Carbon Isotopes↗

The enzymic deacylation of phospholipids and galactolipids in plants. Purification and properties of a lipolytic acyl-hydrolase from potato tubers.

An enzyme preparation that catalyses the deacylation of mono- and di-acyl phospholipids, galactosyl diglycerides, mono- and di-glycerides has been partially purified from potato tubers. The preparation also hydrolyses methyl and p-nitrophenyl esters and acts preferentially on esters of long-chain fatty acids. Triglycerides, wax esters and sterol esters are not hydrolysed. The same enzyme preparation catalyses acyl transfer reactions in the presence of alcohols and also catalyses the synthesis of wax esters from long-chain alcohols and free fatty acids. Gel filtration, DEAE-cellulose chromatography and free-flow electrophoresis failed to achieve any separation of the acyl-hydrolase activities towards different classes of acyl lipids (phosphatidylcholine, monogalactosyl diglyceride, mono-olein, methyl palmitate and p-nitrophenyl palmitate) or any separation of these activities from a major protein component. For each class of lipid the acyl-hydrolase activity was subject to substrate inhibition, was inhibited by relatively high concentrations of di-isopropyl phosphorofluoridate and the pH responses were changed by Triton X-100. The hydrolysis of phosphatidylcholine was stimulated 30-40-fold by Triton X-100. The specific activities of the potato enzyme with galactolipids were at least 70 times higher than those reported for a homogeneous galactolipase enzyme purified from runner bean leaves. The possibility that a single lipolytic acyl-hydrolase enzyme is responsible for the deacylation of several classes of acyl lipid is discussed.

Carbon Isotopes↗

Further studies on the lipids of corynebacteria. The mannolipids of Corynebacterium aquaticum.

1. The major free lipids of Corynebacterium aquaticum were characterized as dimannosyl diglyceride, monomannophosphoinositide and phosphatidylethanolamine. Bisphosphatidylglycerol and phosphatidylglycerol were also tentatively identified. 2. We regard this as the only well-documented case of an organism containing monomannophosphoinositide to the exclusion of dimannophosphoinositides and the higher homologues. 3. The co-existence of the two mannolipids in one organism is a distinctive feature. So also is the presence of phosphatidylethanolamine in a corynebacterium. 4. The monomannophosphoinositide apparently does not utilize phosphatidylinositol as a precursor, unlike the monomannophosphoinositide of Propionibacterium shermanii. CDP-diglyceride may be necessary for its synthesis.

Carbon Isotopes↗

Metabolism of fatty acids by bovine spermatozoa.

The incorporation of (14)C-labelled myristic, palmitic, stearic, oleic and linoleic acids in vitro into the lipids of bovine spermatozoa was measured at intervals from 2min to 2h. All acids were rapidly incorporated into diglycerides, myristic acid being metabolized to the greatest extent. Whereas the low incorporation of acids into total phospholipids reflected the relative stability of the major phospholipid fractions in sperm, the minor phospholipids, particularly phosphatidylinositol, showed comparatively high metabolic activity. Although, in general, saturated acids were incorporated more actively than unsaturated substrates, stearic acid was poorly incorporated into all lipids except phosphatidylinositol. In regard to fatty acid composition of sperm lipids it was notable that diglycerides contained myristic acid as the major component, and this acid was also a prominent moiety of phosphatidylinositol. Docosahexaenoic acid was the principal fatty acid of the major phospholipid classes. These findings have been discussed in relation to the role of lipids in the metabolism of spermatozoa.

Animals↗

The lipid-teichoic acid complex in the cytoplasmic membrane of Streptococcus faecalis N.C.I.B. 8191.

1. A lipid-teichoic acid complex was isolated from Streptococcus faecalis N.C.I.B. 8191. The covalent nature of the linkage between teichoic acid and lipid was established. 2. The complex exhibits macromolecular properties in solution, and ultracentrifugation studies show that these are due to micelle formation. 3. From chemical studies it is concluded that the teichoic acid is a poly(glycerol phosphate) in which some of the glycerol hydroxyl groups possess kojibiosyl [2-O-alpha-d-glucopyranosyl-(1-->2)-alpha-d- glucopyranosyl] substituents, together with d-alanine ester residues. 4. The lipid is 1-kojibiosyl diglyceride, already known as a membrane component of this organism, with probably a phosphatidyl substituent. The phosphatidyl kojibiosyl diglyceride is attached to the teichoic acid through a phosphodiester linkage, and the chain of the teichoic acid contains 28-35 units. 5. Although the complex represents the whole of the membrane teichoic acid in this organism, only about 12% of the membrane glycolipid is associated with teichoic acid. 6. Two phosphatidyl glycolipids, closely resembling that bearing the teichoic acid, were isolated from the lipids of the organism and were partly characterized.

Chromatography, Gas↗

Hormone-sensitive lipase in differentiated 3T3-L1 cells and its activation by cyclic AMP-dependent protein kinase.

Differentiation of 3T3-L1 fibroblasts to adipocyte-like cells was accompanied by a 19-fold increase in neutral triglyceride lipase activity, a 12-fold increase in diglyceride lipase activity, a 10-fold increase in monoglyceride lipase activity, and a 280-fold increase in cholesterol esterase activity. In contrast, acid acylhydrolase activities did not increase during differentiation. The rate of glycerol release from unstimulated intact cells increased by more than 1 order of magnitude upon differentiation. Isoproterenol (1 microM) and 1-methyl-3-isobutylxanthine (0.1 mM) further stimulated this rate of glycerol release 3-fold. The neutral triglyceride lipase activity in cell-free preparations of differentiated cells was activated 105% by cyclic AMP-dependent protein kinase. Neutral cholesterol esterase, diglyceride lipase, and monoglyceride lipase were also activated (117%, 10%, and 37+, respectively) by cyclic AMP-dependent protein kinase. In contrast, protein kinase had no effect on any of the four lysosomal acid acylhydrolase activities. Thus, hormone-sensitive lipase, the most characteristic and functionally important enzyme of adipose tissue, has been characterized in differentiated 3T3-L1 cells. The 3T3-L1 cell should be a valuable model system in which to study regulation of hormone-sensitive lipase, particularly its long-term regulation.

Adipose Tissue↗

Induction of apoptotic DNA damage and cell death by activation of the sphingomyelin pathway.

The potential involvement of ceramide-related signaling processes in the induction of apoptosis by tumor necrosis factor alpha was assessed by multiple biochemical strategies in the human leukemic cell lines HL-60 and U937 and the murine fibrosarcoma cell lines L929/LM and WEHI 164/13. Exposure of these cells to tumor necrosis factor alpha resulted in internucleosomal cleavage of genomic DNA, yielding laddered patterns of oligonucleosomal fragments characteristic of apoptosis when resolved by agarose gel electrophoresis; similar responses were observed after exposure to exogenous sphingomyelinase or synthetic ceramides. Quantitative spectrofluorophotometry demonstrated that these treatments promoted time- and concentration-dependent degradation of DNA, resulting in the formation of and eventual release of small DNA fragments (< or = 3.0 kb). Corresponding damage to bulk DNA was demonstrated by enhanced-fluorescence alkaline unwinding analysis. DNA fragmentation was not induced by phospholipase C or synthetic diglyceride; in fact, the effects of sphingomyelinase and ceramide were substantially reduced by coexposure to these agents, suggesting opposing roles for diglyceride- and ceramide-mediated signals in the regulation of apoptosis. Phospholipase A2 and arachidonic acid failed to promote DNA fragmentation, as did phospholipase D. Characterization of DNA strand breaks by alkaline and neutral elution analyses confirmed that ceramide action was restricted to breakage of mature, double-stranded DNA but not of nascent DNA. The induction of DNA damage was associated with appearance of apoptotic morphology and decreased clonogenicity. These results demonstrate that the ceramide-dependent signaling system selectively induces apoptosis and raise the possibility that ceramide-activated enzymes represent important components in a signaling cascade involved in the regulation of programmed cell death.

Apoptosis↗

Microsomal triglyceride transfer protein. Specificity of lipid binding and transport.

Microsomal triglyceride transfer protein (MTP) is a lipid transfer protein that is required for the assembly and secretion of very low density lipoproteins by the liver and chylomicrons by the intestine. To further elucidate the nature of the lipid molecule binding and transport site on MTP, we have studied the relative rates at which MTP transports different lipid species. Assay conditions were chosen in which there were minimal changes in the physical properties of the substrate membranes so that transfer rates would reflect MTP-lipid interactions at a membrane surface. Lipid transport rates decreased in order of triglyceride > cholesteryl ester > diglyceride > cholesterol > phosphatidylcholine. Changes in the hydrophobic nature of a lipid molecule by the addition of a fatty acid, modulated the ability of MTP to transport it. Addition of one acyl chain from diglyceride to triglyceride, lysophosphatidylcholine to phosphatidylcholine, or cholesterol to cholesteryl ester increased the rate of MTP-mediated transport 10-fold. In contrast, the lipid transport rate was insensitive to the changes in the structure or charge of the polar head group on phospholipid substrates. Zwitterionic, net negative, or net positive charged phospholipid molecules were all transported at a comparable rate. The ability of MTP to transport lipids is strongly correlated to the binding of these lipids to MTP. Thus, MTP has a specific preference for binding and transporting nonpolar lipid compared with phospholipids, and within a class of lipid molecules, a decrease in polarity increases its tendency to be transported.

Animals↗

Nuclear translocation of RhoA mediates the mitogen-induced activation of phospholipase D involved in nuclear envelope signal transduction.

In this paper we demonstrate for the first time a mitogen-induced activation of a nuclear acting phosphatidylcholine-phospholipase D (PLD) which is mediated, at least in part, by the translocation of RhoA to the nucleus. Addition of alpha-thrombin to quiescent IIC9 cells results in an increase in PLD activity in IIC9 nuclei. This is indicated by an increase in the alpha-thrombin-induced production of nuclear phosphatidylethanol in quiescent cells incubated in the presence of ethanol as well as an increase in PLD activity in isolated nuclei. Consistent with our previous report (Wright, T. M., Willenberger, S., and Raben, D. M. (1992) Biochem. J. 285, 395-400), the presence of ethanol decreases the alpha-thrombin-induced production of phosphatidic acid without affecting the induced increase in nuclear diglyceride, indicating that the increase in nuclear PLD activity is responsible for the effect on phosphatidic acid, but not that on diglyceride. Our data further demonstrate that RhoA mediates the activation of nuclear PLD. RhoA translocates to the nucleus in response to alpha-thrombin. Additionally, PLD activity in nuclei isolated from alpha-thrombin-treated cells is reduced in a concentration-dependent fashion by incubation with RhoGDI and restored by the addition of prenylated RhoA in the presence of guanosine 5'-3-O-(thio)triphosphate. Western blot analysis indicates that this RhoGDI treatment results in the extraction of RhoA from the nuclear envelope. These data support a role for a RhoA-mediated activation of PLD in our recently described hypothesis, which proposes that a signal transduction cascade exists in the nuclear envelope and represents a novel signal transduction cascade that we have termed NEST (nuclear envelope signal transduction).

Animals↗

The formation of ceramide-1-phosphate during neutrophil phagocytosis and its role in liposome fusion.

Ceramide, a product of agonist-stimulated sphingomyelinase activation, is known to be generated during the phagocytosis of antibody-coated erythrocytes by polymorphonuclear leukocytes. Agonist-stimulated formation of ceramide-1-phosphate is now shown to occur in 32PO4-labeled neutrophils. Ceramide-1-phosphate is formed by a calcium-dependent ceramide kinase, found predominately in the neutrophil plasma membrane. The neutrophil kinase is specific for ceramide because, in contrast to the bacterial diglyceride kinase, ceramide is not phosphorylated under conditions specific for diglyceride phosphorylation. Conversely, 1,2-diacylglycerol does not serve as substrate for the neutrophil ceramide kinase. Ceramide kinase activation occurs in a time-dependent fashion, reaching peak activity 10 min after formyl peptide stimulation and challenge with antibody-coated erythrocytes. The lipid kinase activity is optimal at pH 6.8. Because the formation of the phagolysosome is a critical event in phagocytosis, the effect of ceramide-1-phosphate in promoting the fusion of liposomes was determined. Both the addition of increasing concentrations of sphingomyelinase D and ceramide-1-phosphate promoted liposomal fusion. In summary, ceramide-1-phosphate is formed during phagocytosis through activation of ceramide kinase. Ceramide-1-phosphate may promote phagolysosome formation.

Calcium↗

Defective uptake and utilization of long chain fatty acids in muscle and adipose tissues of CD36 knockout mice.

The transmembrane protein CD36 has been identified in isolated cell studies as a putative transporter of long chain fatty acids. In humans, an association between CD36 deficiency and defective myocardial uptake of the fatty acid analog 15-(p-iodophenyl)-3-(R, S)-methyl pentadecanoic acid (BMIPP) has been reported. To determine whether this association represents a causal link and to assess the physiological role of CD36, we compared tissue uptake and metabolism of two iodinated fatty acid analogs BMIPP and 15-(p-iodophenyl) pentadecanoic acid (IPPA) in CD36 null and wild type mice. We also investigated the uptake and lipid incorporation of palmitate by adipocytes isolated from both groups. Compared with wild type, uptake of BMIPP and IPPA was reduced in heart (50-80%), skeletal muscle (40-75%), and adipose tissues (60-70%) of null mice. The reduction was associated with a 50-68% decrease in label incorporation into triglycerides and in 2-3-fold accumulation of label in diglycerides. Identical results were obtained from studies of [(3)H]palmitate uptake in isolated adipocytes. The block in diglyceride to triglyceride conversion could not be explained by changes in specific activities of the key enzymes long chain acyl-CoA synthetase and diacylglycerol acyltransferase, which were similar in tissues from wild type and null mice. It is concluded that CD36 facilitates a large fraction of fatty acid uptake by heart, skeletal muscle, and adipose tissues and that CD36 deficiency in humans is the cause of the reported defect in myocardial BMIPP uptake. In CD36-expressing tissues, uptake regulates fatty acid esterification at the level of diacylglycerol acyltransferase by determining fatty acyl-CoA supply. The membrane transport step may represent an important control site for fatty acid metabolism in vivo.

Adipose Tissue↗

Source and function of keto elaidic acids from lungs of cotton workers.

A series of cytotoxic oxygenated derivatives of oleic acid, 8-oxo-9, 9-oxo-10, 10-oxo-8-, and 11-oxo-9 trans octadecenoic acid, uniquely found at post-mortem in airway cells of cotton workers, were synthesized and shown to be cytotoxic, i.e., inhibitory of growth for several cell lines, including HL-60 and U-937 promyelocytes and Eagle's KB carcinoma cells. At microM concentrations, the 8- and 11- keto acids: are chemokinetic for human neutrophils; activate production of O2-. and H2O2; stimulate promyelocytes in culture to differentiate into neutrophils; and increase diglyceride metabolism in inflammatory cells. These results indicate that these four monooxygenated fatty acids, which are found in airways of cotton workers and initiate both inflammation and differentiation in vitro, may be etiologic in the abnormal differentiation and inflammation seen in small airways of cotton workers. This abnormal differentiation in bronchi may result from altered diglyceride metabolism with resultant activation of phosphoprotein kinase C initiated by the keto fatty acids.

Cells, Cultured↗

Studies on the carrier function of phosphatidic acid in sodium transport. I. The turnover of phosphatidic acid and phosphoinositide in the avian salt gland on stimulation of secretion.

Incubation of slices of the salt gland of the albatross with acetylcholine, which is the physiological secretogogue for this tissue, led to a 13-fold increase in the rate of incorporation of P(32) into phosphatidic acid and a 3-fold increase in the incorporation of P(32) and inositol-2-H(3) into phosphoinositide. The incorporation of P(32) into phosphatidyl choline and phosphatidyl ethanolamine was increased relatively slightly or not at all. Respiration was doubled. The "phospholipid effect" occurred in the microsome fraction, which is known to contain fragments of the endoplasmic reticulum. The enzymes, diglyceride kinase and phosphatidic acid phosphatase, which catalyze the stimulated turnover of phosphatidic acid in brain cortex, were also found in highest concentration in the microsome fraction. The phosphatides which respond to acetylcholine are bound to protein in the membrane. On the basis of these findings it appears that phosphatidic acid and possibly phosphoinositide participate in sodium transport. A scheme, termed the phosphatidic acid cycle, is presented as a working hypothesis, in which the turnover of phosphatidic acid in the membrane, catalyzed by diglyceride kinase and phosphatidic acid phosphatase, functions as a sodium pump.

Acetylcholine↗

Effect of unsaturated fatty acids and Ca2+ on phosphatidylinositol synthesis and breakdown.

CDP-diglyceride : inositol transferase was inhibited by unsaturated fatty acids. The inhibitory activity decreased in the following order: arachidonic acid greater than linolenic acid greater than linoleic acid greater than oleic acid greater than or equal to palmitoleic acid. Saturated fatty acids such as myristic acid, palmitic acid, and stearic acid had no effect. Calcium ion also inhibited the activity of CDP-diglyceride : inositol transferase. In rat hepatocytes, arachidonic acid inhibited 32P incorporation into phosphatidylinositol and phosphatidic acid without any significant effect on 32P incorporation into phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine. Ca2+ ionophore A23187 also inhibited 32P incorporation into phosphatidylinositol. However, 32P incorporation into phosphatidic acid was stimulated with Ca2+ ionophore A23187. Phosphatidylinositol-specific phospholipase C was activated by unsaturated fatty acids. Polyunsaturated fatty acids such as arachidonic acid and linolenic acid had a stronger effect than di- and monounsaturated fatty acids. Saturated fatty acids had no effect on the phospholipase C activity. The phospholipase C required Ca2+ for activity. Arachidonic acid and Ca2+ had synergistic effects. These results suggest the reciprocal regulation of phosphatidylinositol synthesis and breakdown by unsaturated fatty acids and Ca2+.

Animals↗

Turn-over of phospholipids in Selenomonas ruminantium.

The particulate enzyme prepared from Selenomonas ruminantium subsp. lactilytica catalyzed the formation of phosphatidylserine (PS) from CDP-diglyceride and serine, and phosphatidylethanolamine (PE) from PS. This indicates that PS and PE in this organism are synthesized through a similar pathway to that in Escherichia coli. In turn-over experiments with [32P]orthophosphate and [14C]caproate, a rapid turn-over of PE was observed, while ethanolamine plasmalogen was relatively stable. The decrease of 14C-radioactivity in PE side-chains was accompanied by an increase of 14C-radioactivity in side-chains of ethanolamine plasmalogen. In pulse label-chase experiments with [32P]orthophosphate, significant amounts of 32P-radioactivities were incorporated into plasmalogens at the beginning of the chase and a precursor product relationship was observed between serine plasmalogen and ethanolamine plasmalogen. On the contrary, in pulse-label-chase experiments using [14C]caproate and [3H]glycerol, no significant radioactivity was incorporated into plasmalogens at the beginning of the chase and radioactivities in plasmalogens slowly increased during the chase. These results indicate that 1-O-alk-1'-enyl-2-acyl-glycerol moieties of plasmalogens are derived from a large precursor pool, but the phosphorous moiety is not. This concept was supported by the fact that synthesis of plasmalogens occurred in the absence of fatty acid synthesis. We wish to propose the possibility that 1-O-alk-1'-enyl-2-acyl-glycerol moieties of plasmalogens are derived from the diglyceride moieties of diacyl phospholipids.

CDPdiacylglycerol-Serine O-Phosphatidyltransferase↗

Effect of lipids on chloride and sodium transport in bean and cotton plants.

This paper describes experiments on Cl transport into the roots, stem and leaves of bean plants, the roots of which have been exposed to lipids in the root solution. Monoand digalactose diglyceride strongly increased Cl transport into all plant parts, probably by transport of the glycolipids further into the plant. Phosphatidyl choline increased Cl absorption by the roots, but transport into the stem and leaves was not affected. This phospholipid was only absorbed by the root tissue. (32)P-glycerophosphoryl choline added to the root solution was readily transported and esterified as phospholipid in all plant parts. This chemical did increase Cl uptake by the roots but Cl accumulation in the leaves was reduced by as much as 40%. Phosphatidyl glycerol, phosphatidyl inositol, and sulfolipid increased Cl transport into roots, stem, and leaves, and a high mobility of (32)P-phosphatidyl glycerol was demonstrated. Generally no significant effect of the above lipids on Na transport in beans and cotton was noted except that monogalactose diglyceride did increase Na transport in cotton.

Journal Article↗