Control of the potassium ion-stimulated adenosine triphosphatase of pig gastric microsomes: effects of lipid environment and the endogenous activator

The K⁺-stimulated ATPase activity associated with the purified gastric microsomes from the pig gastric mucosa can be completely inactivated by treatment with 15% ethanol for 60 s at 37 °C but not at 25 °C. Sequential exposure of the microsomes to 15% ethanol at 25 and 37 °C caused the release of 2.9 and 4.3% of the total membrane phospholipids, respectively, consisting entirely of phosphatidyl choline and phosphatidyl ethanolamine. The ethanol-treated (37 °C) membrane had high basal (with Mg²⁺ as the only cation in the assay mixture) activity, which was further enhanced during reconstitution with phosphatidyl choline or phosphatidyl ethanolamine. The high basal activities could be reduced to the normal control level by assaying the enzyme in presence of the “activator protein,” partially purified from the soluble supernatant of the pig gastric cells. Phosphatidyl choline was somewhat more effective than phosphatidyl ethanolamine in the restoration of the activity of the ethanol-treated enzyme while phosphatidyl serine, phosphatidyl inositol, and sphingomyelin were without any effect. Synthetic phosphatidyl choline with various fatty acid substitutions were tested for their effectiveness in the restoration of the ethanol-inactivated enzyme. The distearoyl (18:0), dioleoyl (18:1), and dilinoleoyl (18:2) derivatives of phosphatidyl choline were almost equally effective while dipalmitoyl (16:0) phosphatidyl choline was somewhat less effective in the reconstitution process. Cholesterol appeared to interfere with phosphatidyl choline in the restoration of the activity of ethanol-treated enzyme. The fatty acid composition of phosphatidyl choline and phosphatidyl ethanolamine extracted by 15% ethanol at 37 °C was clearly different than those of the total microsome. Our data suggest that the phospholipids extracted by 15% ethanol at 37 °C are derived primarily from the immediate lipid environment of the enzyme and ATP together with Mg²⁺ and K⁺ help the partially delipidated enzyme to retain the appropriate conformation for the subsequent reconstitution. Furthermore, ethanol appears to either release or inactivate the membrane-associated activator protein, demonstrated to be essential for the K⁺-stimulated activity of the pig gastric ATPase.     

Effect of feeding water washed neem (Azadirachta indica) seed kernel cake on the quality,lipid profile and fatty acid composition of goat meat

Three groups of five indigenous male goats 5–6 months of age, were offered control concentrate mixture (Group I) and those of Groups II and III were fed experimental concentrates containing 15 and 25% of water washed neem (Azadirachta indica) seed kernel cake (NKC). After 180 days of feeding the goats were slaughtered. Longissimus dorsi (LD) muscle from lumbar region was analysed for certain physico-chemical characteristics, organoleptic quality, detailed lipid profile and fatty acid composition; phosopholipids were fractionated into phosphatidyl inositide (PI), phosphatidyl serine (PS), lysophosphatidyl choline (LPC), lysophosphatidyl ethanolamine (LPE), sphingomyelin (SPH), phosphatidyl choline (PC) phosphatidyl ethanolamine (PE) and phosphatidic acid (PA). Fatty acids; capric, lauric, myristic, myristoleic, palmitic, palmitoleic, heptadecanoic, stearic, oleic, linoleic acid were also identified. Feeding of NKC did not affect slaughter weight and dressing out yield. The dressing percentage ranged between 42.2 and 43.8%. The pH, colour, moisture, total crude protein, different protein fractions; water extractable, salt extractable and content of NPN did not differ among the groups. There was a significant decrease in the total lipid content of LD of experimental groups. PC and PE were the major fractions accounting for 60% of total phospholipids. There was a significant increase in PC and LPC fractions while LPE+SPH, PE and PA fractions decreased in goats fed NKC. A significant increase was noticed in unsaturated fatty acid content and decrease in total saturates. It is concluded that NKC feeding has the ability of reducing lipid content and increasing the unsaturated fatty acids, which are considered to be beneficial in reducing the cholesterol level. It may be used beneficially as an alternative for costly conventional oil cakes for economic lean chevon production without affecting the quality of goat meat.     

Lipid and Fatty-acid Composition of Diatoms

The lipids and fatty acids of two freshwater diatoms Nitzschiapalea Kutz, Navicula muralis Lewin, and one marine species,Navicula incerta Grun. have been studied. The major lipid components in all species were triglycerides,monogalactosyl, digalactosyl and sulphoquinovosyl diglycerides,phosphatidyl glycerol, phosphatidyl choline (lecithin), andphosphatidyl ethanolamine; while palmitoleic, palmitic, eicosapentaenoicand eicosate-traenoic acids were the major fatty acid constituents.The two galactolipids, monogalactosyl and digalactosyl diglyceridescontained large amounts of C₁₆ and C₂₀ polyunsaturated fattyacids. Lipids of diatoms, whether grown in the light or in the dark,were the same apart from quantitative differences. More storagelipids such as triglycerides were synthesized in the light thanin the dark.     

Lipid and sterol composition of the pollen of the west african oilpalm, Elaeis guineensis

The lipid classes, fatty acid methyl esters and the sterols of oilpalm pollen were analysed. The neutral lipid fraction consisted of triglycerides, esterified and free sterols and trace amounts of hydrocarbons. Monogalactosyl and digalactosyl diglycerides, phosphatidyl choline, phosphatidyl inositol and phosphatidyl ethanolamine represented the polar lipids. The major fatty acids were linoleic, palmitic and linolenic acids together with small to trace amounts of oleic, stearic, arachidic, myristic, lauric, palmitoleic and margaric acids. Unsaturated fatty acids predominated over saturated ones in the ratio of 3:2. The 4-desmethyl sterols were the major phytosterols in the free form but they constituted a lower proportion of the sterols in the esterified state. 28-Isofucosterol was isolated and characterized as the principal sterol.     

Phosphatidyl inositol-specific phospholipase C from Clostridium novyi type A

From the culture broth of Clostridium novyi type A, phosphatidyl inositol-specific phospholipase C was separated from the major part of phospholipase C (γ-toxin) which hydrolyzes phosphatidyl choline, phosphatidyl ethanolamine, and sphingomyelin. Sodium deoxycholate stimulated the activity of phosphatidyl inositol phospholipase C. The concentration of sodium deoxycholate for maximal stimulation was 0.2% with 2 mm phosphatidyl inositol. Divalent cations (Mg²⁺, Ca²⁺, and Zn²⁺) were rather inhibitory above 10^?3m. Phosphatidyl inositol phospholipase C was not inhibited by EDTA or o-phenanthroline. When phosphatidyl inositol phospholipase C was incubated with rat liver slices, not only alkaline phosphatase but also 5′-nucleotidase was liberated into the soluble fraction.     

Lipid composition of thermophilic moulds Acremonium alabamensis and Thermomucor indicae-seudaticae

The total lipid content of Acremonium alabamensis and Thermomucor indicae-seudaticae ranged 2.6–7.3 and 8.5–13.0% of dry mycelium, respectively during development. Neutral lipid fraction increased during growth while polar and phospholipids declined. Both moulds contained palmitic, oleic, linoleic and palmitoleic acids as major fatty acid components in lipids. Degree of unsaturation of lipids of A. alabamensis was greater than that of T. indicae-seudaticae. Neutral lipids were more unsaturated than the polar lipids. The ratio of unsaturation index of polar lipids to neutral lipids was either one or less than one. The principal phospholipids of these moulds were phosphatidyl choline, phosphatidyl ethanolamine and phosphatidic acid. However, phosphatidic acid was not found in very high amounts as observed in Humicola grisea var. thermoidea.     

Phospholipid Composition and Metabolism of Micrococcus denitrificans

The phospholipid composition of Micrococcus denitrificans was unusual in that phosphatidyl choline (PC) was a major phospholipid (30.9%). Other phospholipids were phosphatidyl glycerol (PG, 52.4%), phosphatidyl ethanolamine (PE, 5.8%), an unknown phospholipid (5.3%), cardiolipin (CL, 3.2%), phosphatidyl dimethylethanolamine (PDME, 0.9%), phosphatidyl monomethylethanolamine (PMME, 0.6%), phosphatidyl serine (PS, 0.5%), and phosphatidic acid (0.4%). Kinetics of ³²P incorporation suggested that PC was formed by the successive methylations of PE. Pulse-chase experiments with pulses of ³²P or acetate-1-¹⁴C to exponentially growing cells showed loss of isotopes from PMME, PDME, PS, and CL with biphasic kinetics suggesting the same type of multiple pools of these lipids as proposed in other bacteria. The major phospholipids, PC, PG, and PE, were metabolically stable under these conditions. The fatty acids isolated from the complex lipids were also unusual in being a simple mixture of seven fatty acids with oleic acid representing 86% of the total. Few free fatty acids and no non-extractable fatty acids associated with the cell wall or membrane were found.     

Lipids of ocular tissues: VII. Positional distribution of the fatty acids in the phospholipids of bovine retina rod outer segments

The positional distribution of the fatty acids in the major phospholipids of bovine retina rod outer segments was determined. Phosphatidyl ethanolamine and phosphatidyl serine have mostly saturated acids in the 1-position and docosahexaenoic acid in position 2. These phospholipids contain 94 and 79%, respectively, of polyun-saturated acids in the 2-position. Phosphatidyl choline contains mostly saturated acids in the 1-position, but has significant quantities of palmitic in the 2-position along with docosahexaenoic acid. The levels of docosahexaenoic acid in rod outer segment phospholipids are among the highest yet reported for membrane phospholipids, amounting to 23% in phosphatidyl choline, 39% in phosphatidyl ethanolamine, and 45% in phosphatidyl serine.     

Turnover of Phospholipids in Normal and Phosphorus-deficient Spirodela

When ³²P₁ was supplied as a 15-minute pulse to normal Spirodela oligorrhiza plants, the first phospholipid to become fully labeled was phosphatidic acid. Phosphatidyl glycerol reached maximum labeling before the other major phospholipids. In phosphorus-deficient plants, however, phosphatidyl glycerol became labeled much more slowly than either phosphatidyl choline or phosphatidyl ethanolamine, and also the proportion of phosphatidyl glycerol present was smaller. Thus, phosphatidyl glycerol synthesis is sensitive to phosphorus deficiency. Since most of the phosphatidyl glycerol present in Spirodela was localized in the chloroplast, this effect appeared to be specifically one on chloroplast composition. The phosphorus-deficient chloroplast had a 60% lower phospholipid content and a normal phospholipid pattern, but the phospholipid which was present was apparently cycling much less rapidly. Zeatin, which ameliorates the visual symptoms of phosphorus deficiency, also reduces the effect of phosphorus deficiency on phospholipid synthesis.     

Activation of phosphorylating vesicles by net transfer of phosphatidyl choline by phospholipid transfer protein

Vesicles formed with phosphatidyl ethanolamine, phosphatidyl choline, cardiolipin, coupling factors and hydrophobic proteins from bovine heart mitochondria catalyzed a rapid³²P_i-ATP exchange. When phosphatidyl choline was deleted during the assembly of the vesicles, little³²P_i-ATP exchange was observed. Exchange activity was induced by incubating such deficient vesicles with phosphatidyl choline liposomes in the presence of a phosphatidyl choline transfer protein isolated from bovine heart. Transfer of [³²P] phosphatidyl choline was demonstrated by isolation of the activated vesicles by sucrose density centrifugation.     

Fatty Acid Composition of Hydrocarbon-Assimilating Yeast

As a part of extensive program on microbial utilization of hydrocarbons, lipid components of Candida petrophillum SD-14 grown on n-alkanes and glucose as carbon sources were studied. In any carbon source, cellular fatty acids of the yeast contained palmitic, palmitoleic, stearic, oleic and linoleic acids as major components.

When n-tridecane was fed to the yeast, fatty acids with odd- and even-number of carbon atoms were produced in almost identical quantity. Another yeast, Torulopsis petrophillum SD-77, also gave a very similar fatty acid pattern by n-tridecane substrate. These phenomena indicate the existence of C₂ addition and β-oxidation of the fatty acid formed in the yeasts.

In the cases of n-tridecane, n-hexadecane and glucose as substrate, about a half of SD-14’s lipid was phospholipid, which consisted of phosphatidyl ethanolamine and phosphatidyl choline principally. Free alcohol and wax were not detected in any case.     

The influence of ionic detergents on the phospholipid fatty acid compositions of Porphyridium purpureum

The phospholipid fatty acid composition of Porphyridium purpureum on a solid medium was studied in the presence of sodium dodecyl sulphate (SDS) and cetyl trimethylammonium bromide (CTAB). The most common fatty acids in phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) were palmitic (16:0), stearic (18: 0), linoleic (18:2ω 6), arachidonic (20:4ω 6) and eicosapentaenoic (20:5ω 3) acids, 20:4ω 6 being very abundant. In phosphatidyl glycerol (PG) the most common acids were 16:0, trans-hexadecenoic acid (tr 16:1ω 13), oleic acid (18:1) and 20:4ω 6. Both detergents increased the saturation grade of PC and PE by decreasing the relative amount of the polyunsaturated acids, especially 20:4ω 6. A corresponding increase in the amounts of saturated acids was observed in PC and PE. The changes in PG fatty acid composition were not very significant: a slight increase was observed in the amounts of 16:0 and tr 16:1ω 13 , with a corresponding decrease in the amounts of 20:4ω 6 and 20:5ω 3. Both detergents decreased the PC/PE and the (PC + PE)/PG ratios very markedly, most probably as a result of increases in the amounts of PE and PG. In the presence of CTAB the cells seemed to contain much more phospholipids than in the presence of SDS, perhaps as a result of the mucilage-precipitating effect of CTAB. The significance of the findings is discussed.     

Incorporation of [1-14C]Palmitic Acid into Neutral Lipids and Phospholipids of Rat Cerebral Cortex In Vitro

Abstract: Incorporation of [1-¹⁴C]palmitic acid into neutral lipids and phospholipids of rat cerebral cortex was examined in vitro in normal Krebs-Ringer bicarbonate buffer containing 3% (wthol) albumin and 0.75 mM palmitic acid. Under standard assay conditions, radioactivity in the triacylglycerol fraction increased rapidly during the first 30 min, and then decreased after 60 min, with corresponding increase in radioactivity in phosphatidyl choline, phosphatidyl ethanolamine, and a fraction of phosphatidyl inositol plus phosphatidyl serine. Diacylglycerol was shown to be an intermediate metabolite. Radioactivity increased in triacylglycerol, and decreased in phosphatidyl choline and phosphatidyl ethanolamine throughout incubation under NZ gas. In the fraction of phosphatidyl inositol plus phosphatidyl serine, radioactivity decreased after 30 min during incubation under N, gas. A possible acylation-deacylation cycle, in which triacylglycerol could be a source of free fatty acids for phospholipids, is discussed.     

Hepatic Subcellular Fractions Lipids in Rats Fed Millet (Sorghum vulgarie) at Different Protein Levels

Effect of feeding defatted millet (Sorghum vulgarie) flour at 5, 10 and 14.5% protein levels respectively for six weeks has been studied on rat liver mitochondrial, microsomal and supernatant fractions total lipids, cholesterol, triglycerides, total phospholipids, phosphatidyl choline and phosphatidyl ethanolamine. The results have been compared with rats fed casein at 10% level for the same period. The metabolism of liver subcellular fractions lipids of millet diet and casein diet fed rats has been studied by the incorporation of acetate-1-¹⁴C and . A significant increase in mitochondrial triglycerides of rats fed millet diet at 5 and 10% protein level, in microsomes of rats fed millet diet at 5, 10 and 15% protein levels and in supernatant fractions of rats fed millet diet at 5 and 15% protein levels was observed. A significant increase in total cholesterol in mitochondria and microsomes and a significant decrease in supernatant fraction of rats fed millet diet at 10% protein level was observed. A significant increase in mitochondrial total phospholipids, phosphatidyl choline and phosphatidyl ethanolamine in rats fed millet diet at 10% protein level and a decrease in these in rats fed millet diet at 5 per cent protein level was observed. In microsomes total phospholipids were increased in rats millet diet at 10% protein level and phosphatidyl choline was increased in rats fed millet diet at 15% protein level. Total phospholipids, phosphatidyl choline and phosphatidyl ethanolamine were significantly reduced in the supernatant fraction of rats fed millet at 10% protein level.

Incorporation of acetate-1-¹⁴C into nonsaponifiable fraction of mitochondria, microsomes and supernatant fractions of rats fed millet diet at 5 and 15 % protein levels was significantly greater, and in saponifiable fractions of the above subcellular fractions was greater in rats fed millet diet at 5 per cent protein level. The specific activity (counts/min/mg) of free cholesterol in mitochondria, microsomes and supernatant fractions of millet diet fed rats was significantly greater, whereas the specific activity of triglycerides was not significantly different from the controls. The acetate-1-¹⁴C specific activity of phosphatidyl choline and phosphatidyl ethanolamine was significantly greater in all the above subcellular fractions of millet diet fed rats (except of phosphatidyl choline in rats fed millet diet at 5 % protein level). The specific activities of phosphatidyl choline were significantly greater in mitochondria of rats fed millet diet at 5 % protein level and of phosphatidyl choline and phosphatidyl ethanolamine in microsomes and supernatant fractions of rats fed millet diet at 5 and 15% protein levels. The specific activities of phosphatidyl choline were significantly decreased in mitochondria and microsomes of rats fed millet diet at 10% protein level. The total acetate-1-¹⁴C activities (counts/min/g equivalent wet liver) of free and esterified cholesterol triglycerides, phosphatidyl choline and phosphatidyl ethanolamine showed that their synthesis from acetate-1-¹⁴C was either enhanced in millet diet fed rats or was comparable to the controls. The total activity of (counts/min/g equivalent wet liver) into phosphatidyl choline and phosphatidyl ethanolamine showed that their synthesis was decreased in microsomes of rats fed millet diet at 10% protein level, increased in rats fed millet diet at 5 and 15% protein levels.     

Total polar lipid biosynthesis during growth of Crotalaria juncea pollen tubes

[1-¹⁴C]-Acetate incorporation into total and polar lipids was studied in the growing pollen tubes of Crotalaria juncea. Ungerminated pollen had phosphatidyl inositol, phosphatidyl serine, phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl glycerol, monogalactosyl diglyceride, digalactosyl diglyceride, sulpholipid and steryl glycosides. In the growing pollen tubes considerable [1-¹⁴C]-acetate incorporation was observed into the individual polar lipids. The exogenous carbon source significantly influenced lipid biosynthesis. Boric acid (20mg/l.) promoted both pollen tube growth and acetate incorporation into phospholipids. In comparison to 5′-adenosine monophosphate, cyclic-3′,5′-adenosine monophosphate (cAMP) promoted tube growth and also enhanced phospho-and glycolipid biosynthesis. The regulation of membrane component biosynthesis by cAMP is suggested.     

Pannonibacter indica sp. nov., a highly arsenate-tolerant bacterium isolated from a hot spring in India

A novel aerobic bacterium, strain HT23^T, able to grow on 500 mM sodium arsenate was isolated from a hot-spring sediment sample collected from Athamallik, Orissa, India. Cells of this isolate were Gram negative. Heterotrophic growth was observed at pH 6.0–11.0 and 20–45 °C. Optimum growth was observed at 37 °C and pH 7.0–10.0. The major polar lipids are diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl choline and phosphatidyl monomethyl ethanolamine. The major isoprenoid quinone was Q-10. 16S rRNA gene sequence analysis indicated that the bacterium clustered with the genus Pannonibacter and showed 98.9 % similarity with Pannonibacter phragmitetus C6-19^T (DSM 14782^T) and 98 % with the P. phragmitetus group B and P. phragmitetus group E strains. Levels of DNA–DNA relatedness between the strain HT23^T and P. phragmitetus C6-19^T (DSM 14782^T) and other strains of P. phragmitetus group B and group E strains were below 55 %. On the basis of phenotypic and chemotaxonomic characteristics, 16S rRNA gene sequence analysis and DNA–DNA hybridization data, strain HT23^T is considered to represent a novel species of the genus Pannonibacter, for which the name Pannonibacter indica sp. nov. is proposed. The type strain is HT23^T (=JCM 16851^T = DSM 23407^T = LMG 25769^T).     

Die Lipide von Endomycopsis vernalis bei verschiedener Stickstoff-Ernährung

1. Endomycopsis vernalis was cultivated on media with different N supply: series A 1%, series B 0,125% asparagine. Sonified cells were extracted and yielded 14.3% (A) and 65.3 (B) total lipids/non lipid dry matter respectively.
2. Neutral and complex lipids were separated by rubber membrane dialysis. There is no difference in the percentage of complex lipids of both series. The increase of lipids in cells grown on low N level is due to a higher content of neutral lipids.
3. Components of the neutral lipids, analysed by DC, were diglycerides, triglycerides, free and esterified ergosterol. Their percentage is influenced by the nutritional conditions. There is a significant increase of triglycerides and of sterol esters in the high lipid cells of series B.
4. Methyl esters of component fatty acids of glycerides and sterol esters were analyzed by GLC. Saturated acids C₁₄, C₁₅, C₁₆, C₁₇, C₁₈, monoenic acids C₁₆ and C₁₈, linoleic and linolenic acids were found to be present. Major acids were in all cases 18:1 (17–57%), 18:2 (18–50%) and 16:0 (10–18%). Linolenic acid is higher in di-and triglycerides of low lipid cells of series A than in high lipid cells of series B. Both qualitative and quantitative differences of fatty acids were found in sterol esters of series A and B respectively.
5. The major components of complex lipids, identified by DC and isolated by CC, in both series, were phosphatidyl choline (A:36.5, B:41.0%) and phosphatidyl ethanolamine (A:24.9, B:20.5%) in addition to small amounts of lysophosphatidyl choline, lysophosphatidyl ethanolamine, phosphatidyl serine, monophosphoinositide, diphosphatidyl glycerol and, possibly cerebroside like substances.
6. Methyl esters of the fatty acids of phosphatidyl choline and ethanolamine from both series were determined by GLC. In all samples 16:0, 18:0, 18:1, 18:2 and 18:3 acids were present besides of traces of 16:1 and 17:0. In contrast to neutral lipids the major acid of phospholipids is linoleic (53–58%), followed by oleic (8–24%) and linolenic acid (1–18%). The percentages of palmitic (4–8%) and stearic acids (tr.-1%) are small. Low lipid cells of series A differ from high lipid cells of series B by an increase of linolenic, and a decrease of linoleic acids, both in phosphatidyl choline and phosphatidyl ethanolamine.

     

Galactolipids and phospholipids of orange peel and juice chromoplasts

Chromoplasts from yellow orange (Citrus sinensis) fruit peel contain monogalactosyl diglycerides (MGDG), digalactosyl diglycerides (DGDG) and phosphatidyl glycerol (PG) in amounts similar to those found in chloroplasts from green fruit peel. Juice chromoplasts contain relatively little MGDG and no DGDG with high levels of phosphatidyl choline and phosphatidyl ethanolamine but no PG.     

Glycinebetaine biosynthesis and its control in detached secondary leaves of spinach

In secondary leaves from spinach plants pretreated in vermiculite for 24 h with 300 mM NaCl, glycinebetaine accumulated at a rate of circa 0.16 mol 100 g^-1 Chl d^-1 (2 mol g^-1 FW d^-1), about three times the rate of control plants. The soluble carbohydrate and free amino acid contents did not increase significantly following salinisation until after 4 d when the relative growth rate also decreased. Leaf proline levels remained very low throughout the experimental period. K⁺ on a tissue water basis remained constant at 200 mM while Cl^- and Na⁺ levels increased linearly to reach 175 and 100 mM respectively after 5 d of saline treatment. The osmotic pressure of leaf tissue also increased from 300 to 500 mosmol kg^-1. These experimental conditions were considered suitable to study glycinebetaine biosynthesis and its induction by salinity in the absence of marked growth inhibition or metabolic disturbance. Radioactive labelled [¹⁴C]serine, ethanolamine and choline (all 1 mol, 13.3 MBq in 10 l) were fed to detached secondary leaves via the petiole 24 h after the exposure of plants to salt. The rate of isotope incorporation into water soluble products, lipids and residue was measured over a further 24 h. The major metabolic fate of exogenous [¹⁴C]choline and [¹⁴C]ethanolamine was incorporation into glycinebetaine while less ¹⁴C-label was found in phosphatidyl choline and phosphatidyl ethanolamine. Incorporation rates were identical in control and salinised leaves and were adequate to account for observed values of glycinebetaine accumulation previously reported in spinach. In contrast the labelling of glycinebetaine from [¹⁴C]serine was twice as great in salinated plants as in the controls. These results, together with short term labelling experiment with [¹⁴C]ethanolamine using leaf slices, were consistent with the formation of glycinebetaine via serine, ethanolamine and its methylated derivatives to choline with some control being exerted at the serine level. However a flux through the phosphorylated intermediates is not excluded.From a consideration of these results and the published data on barley subjected to water stress (Hanson and Scott, 1980 Plant Physiol. 66, 342–348) there appear to be significant differences in the biosynthetic pathways in spinach and barley.Abbreviations BHT butylated hydroxytoluerte (2,6-di-tert-butyl-4-methylphenol) - C₁ one-carbon fragment - 1,2DG diglyceride moiety - DW day weight - MCW methanol-chloroform-water (12:5:1, by vol.) - PA phosphatidic acid - PC phosphatidyl choline - PMME phosphatidyl monomethylethanolamine - PDME phosphatidyl dimethylethanolamine - PE phosphatidyl ethanolamine - PPO 2,5-diphenyloxazole - POPOP 1,4-bis(5-phenyloxazoyl) benzene     

Synthesis and release of lipophorin in larvae of the southwestern corn borer,Diatraea grandiosella: An in vitro study

The source of the lipophorin present in the larval haemolymph of the southwestern corn borer, Diatraea grandiosella, was examined in vitro. Although lipophorin was shown to be one of several proteins released from cultured fat body and midgut, only fat body was shown to synthesize lipophorin. Fat body, incubated in a medium containing [³H]leucine, was shown to release radiolabelled lipophorin using immunoprecipitation. Similar studies using midguts incubated in a medium containing [³H]leucine did not reveal any synthesis of lipophorin. Lipophorin was isolated by density-gradient ultracentrifugation from media in which the fat bodies of about 600 diapausing larvae had been incubated for 4 hr. The isolated lipophorin had a peak density of 1.11 g/ml, and contained various lipids including diacylglycerol, triacylglycerol, sterol, hydrocarbon, free fatty acid, phosphatidyl choline, phosphatidyl ethanolamine and sphingomyelin.