Showing papers in "Lipids in 1969"

Species variations in phospholipid class distribution of organs: I. Kidney, liver and spleen

Abstract: Improved procedures for preparation of lipid extracts and determination of phospholipids by phosphorus analysis of spots separated by thin layer chromatography (TLC) were employed to determine the phospholipid class distributions of vertebrate (human, bovine, rat, mouse, frog) kidney, liver and spleen. The absence of significant changes arising from postmortem enzymatic degradation was demonstrated by analysis of lipids of organs after standing for different times postmortem. Intraspecies variability was evaluated by separate analysis of several rat organs. Accuracy of analytical results was insured by demonstrating the absence of spot overlap by two-dimensional TLC and low values for standard deviations. The values for kidney and liver demonstrate little or no species variability, whereas values for spleen indicate two groups which differ in cellular composition. The findings for kidney and liver are in keeping with data obtained from heart, skeletal muscle, lung and highly purified subcellular particulates which indicate that, among vertebrates, there is little or no species variability of phospholipid class distribution of organs and most subcellular particulates.

Species variations in phospholipid class distribution of organs. II. Heart and skeletal muscle.

Abstract: Total lipid, lipid phosphorus and phospholipid class distribution were determined for heart and skeletal muscles from five vertebrates (human, bovine, rat, mouse and frog) and skeletal muscles from four invertebrates (lobster, abalone, scallop and sea urchin). The precision of the analytical method [separation by two-dimensional thin layer chromatography (TLC) and phosphorus analysis of spots] was demonstrated by small values for standard deviations. Accuracy of spot identification and analytical values was insured by comparison with results obtained by TLC of triethylaminoethyl cellulose column chromatographic fractions. Values for total lipid, total phospholipid and phospholipid class distribution of heart and skeletal muscles from the five vertebrate species showed essentially the same variability observed for the same organ from different animals of one species (rat). The data indicate that, among vertebrates there is little or no variability for phospholipid class distribution in muscle membranes in agreement with data for other organs and subcellular particulates presented in other reports. Invertebrate skeletal muscles were found to differ qualitatively and/or quantitatively from those of vertebrates. In one species (sea urchin), ceramide phosphorylethanolamine was the only sphingolipid, sphingomyelin characteristic of vertebrates being absent. In two species (abalone and scallop) ceramide aminoethylphosphonate was present and sphingomyelin was absent. In one (lobster), sphingomyelin was the only sphingolipid. Quantitatively, higher levels of sphingolipid and phosphatidyl serine and lower levels of phosphatidyl inositol were found in invertebrate skeletal muscle. The significance of the data is discussed in relation to subcellular particulate lipid class composition.

Flotation rates, molecular weights and hydrated densities of the low-density lipoproteins.

Abstract: A method involving three computer programs is described for characterizing the major component of the Sf 0–12 low-density lipoprotein class by its Sf rate, hydrated density and molecular weight. All necessary information is obtained from a standard low and high-density lipoprotein ultracentrifugal analysis. Moving-boundary flotation rates are measured in 1.061 g/ml sodium chloride and 1.200 g/ml sodium bromide solutions and are corrected to flotation at zero concentration. Hydrated densities are calculated from η Fo versus ρ plots and minimum hydrated molecular weights calculated using Stokes' frictional factor, assuming spherical molecules. Preliminary application of this procedure indicates higher Sfo rates, higher molecular weights, and lower hydrated densities in females than in males. Molecular weights and standard deviations of the principal Sf 0–12 component for non-fasting normal adult females and males were 2.36±0.16 and 2.12±0.20 millions, respectively.

Comparison of lipoprotein analysis by agarose gel and paper electrophoresis with analytical ultracentrifugation

Abstract: A comparison has been made of human serum lipoprotein analysis by agarose gel and paper electrophoresis with a standard method of analytical ultracentrifugation. Samples were obtained from 28 patients with various disorders of lipoprotein metabolism. Correspondence was shown between the following electrophoretic and ultracentrifugal fractions: β and Sf 0–20; pre-β and Sf 20–400; α1 and total HDL. The deviations observed with the electrophoretic methods, though sizable, were smaller than the usual clinically significant abnormalities. Semiquantitative application is there fore justified. Agarose gel electrophoresis is slightly more difficult than paper electrophoresis, but gives improved resolution of pre-β- and β-lipoproteins and better densitometric scans. Evidence was also presented that the agarose method, when used in conjuction which ultracentrifugation, may be a valuable research technique for the study of lipoprotein properties.

Isolation of highly purified human and bovine brain endothelial cells and nuclei and their phospholipid composition.

Abstract: sphingomyelin (as percentage of the lipid phosphorus) --. 38.44 (log age in years)-15.20. Similar plots for the other major phospholipid classes also gave straight lines but with opposite slopes. Equations for the other phospholipids were: per cent phosphatidyl choline = 54.9117.88 (log age in years); per cent phosphatidyl ethanolamine = 38.73-15.71 (log age in years); per cent phosphatidyl serine -19.31-8.262 (log age in years); and per cent phosphatidyl inositol = 8.315-3.804 (log age in years).

Microbial hydration ofCis‐9‐alkenoic acids

Abstract: The activity of acis-9-fatty acid hydratase produced by aPseudomonas sp (NRRL B-3266) isolated from soil was compared with that of another isolate previously reported (NRRL B-2994) The presence of appropriate fatty acids for at least 4 hr during aerobic growth in yeast extract medium increased subsequent enzyme activity Such cells anaerobically hydrated severalcis-9-alkenoic acids to 10-hydroxy fatty acids and aerobically formed 10-keto acids, which were partially degraded to shorter chain keto acids Melting point, gas chromatography, infrared, mass spectrometry and optical rotatory dispersion data are given Six fatty acids havingcis-9-unsaturation produced hydrated products, but several enoic acids havingtrans-9-unsaturation or double bonds in other than the 9 position were inactive as substrates The (−)-10-hydroxypalmitic acid produced from palmitoleic acid is considered to have the D configuration Yields of 71% crude crystalline product from 15 g of oleic acid and 53% from 11 g of palmitoleic acid were obtained in 5-liter anaerobic fermentations with NRRL B-3266 Methyl esters, triolein and oleyl alcohol were not hydrated

Acceleration and inhibition of lipid oxidation by heme compounds.

Abstract: The acceleration and inhibition of unsaturated fatty acid oxidation by heme compounds was followed in model systems with an oxygen analyzer. The linoleate to heme molar ratios for maximum catalysis were 100 for hemin and catalase, 250 for metmyoglobin, 400 for cytochrome c and 500 for methemoglobin. With heme concentrations of 2 to 4 times the optimum catalytic amount, no oxidation occurred. Rapid heme destruction was observed with catalyzing ratios of lipid to heme, but with inhibitory ratios a stable red compound formed, believed to be a lipid hydroperoxide derivative of the heme. The ratios of lipid to metmyoglobin for maximum acceleration varied with the pH. Linolenate was much less sensitive to heme catalysis than linoleate. Colorless products of heme degradation had a marked antioxidant effect. A possible mechanism for the antioxidant effect of hemes is advanced, based on the formation of stable heme peroxide complexes or stable heme radicals, or both, during the early stages of oxidation. Prooxidant activity is believed to occur only when the peroxide to heme ratio is so high that the oxidation of the hemes goes beyond the initial stages.

Variations among vertebrates of lung phospholipid class composition

Abstract: Species va r i a t ions in m e m b r a n e lipid class c o m p o s i t i o n can be s tudied by analys is o f h ighly purif ied subce l lu l a r pa r t i cu la tes and m o r e rap id ly by analys is o f w h o l e o rgans . Th i s r epo r t p r e sen t s ana lyses o f lipid c lasses in h u m a n , bovine , rat , m o u s e , and f rog lungs . T h e close s imi lar i ty o f the va lues ob t a ined s h o w s that , a m o n g ver tebra tes , t he re is little species var iat ion o f lung p h o s p h o l i p i d compos i t i on . Rep re sen t a t i ve s a m p l e s o f w h o l e h u m a n and bovine lung w e r e ob t a i ned f r o m h o m o g e n a t e s . Severa l lungs f r o m smal l an ima l s were poo led and ext rac ted . Lipids were ex t r ac t ed wi th c h l o r o f o r m m e t h a n o l (2:1 and 1:2 v / v ) (1 ) and nonl ip id c o n t a m i n a n t s r e m o v e d by Sephadex c o l u m n c h r o m a t o g r a p h y ( 1 , 2 ) . P h o s p h o lipids were d e t e r m i n e d in S e p h a d e x f r ac t ion I by p h o s p h o r u s analys is o f spo ts a f te r s epa ra t i on b y t w o d i m e n s i o n a l thin layer c h r o m a t o g r a p h y ( 3 ) . Tab l e 1 s h o w s only smal l va r i a t ions in c o m p o s i t i o n w h e n lung lipids of several indiv idua l ra ts were analyzed. Likewise, var ia t ion in lipid c o m p o s i t i o n fo r the species e x a m i n e d was also small . O n l y three va lues ( p h o s p h a t i d y l e t h a n o l a m i n e in h u m a n lung; p h o s p h a t i d y l cho l ine and s p h i n g o m y e l i n in bov ine l ung ) were dis t inct ly ou ts ide the r ange obse rved for diff e r e n t s a m p l e s o f r a t lung. Even these relat ively

Boron trifluoride as catalyst to prepare methyl esters from oils containing unusual acyl groups

Abstract: The procedure of Metcalfe et al. (3) for the preparation of fatty acid methyl esters, using boron trifluoride as catalyst, is shown to be suitable for use with oils containing fatty acids of unusual structures, such as conjugated unsaturation, hydroxyl or epoxy groups, and cyclopropenes in addition to oils with only the common acids. In some cases, boron trifluoride was less destructive to unusual groups than conventional mineral acid catalysts; in others, derivatives were formed that were suitable for quantitation in subsequent gas chromatographic analysis.

Fatty acid desaturase systems of hen liver and their inhibition by cyclopropene fatty acids

Abstract: Hen liver preparations which desaturate stearic acid at the 9,10 position to form oleic acid have been found to desaturate other saturated fatty acids of carbon chain length from 12 to 20 and 22. The 9,10-monoenoic fatty acid of the same chain length as the substrate fatty acid is the major product formed. Minor amounts of the 10,11- and 11, 12-monoenoic acids are also formed. Maximum desaturation occurred with the C14 fatty acid substrate and with the fatty acids C17 and C18, suggesting the presence of at least two desaturating systems. The cyclopropene fatty acids, sterculic and malvalic acids, inhibited the desaturation of all thefatty acids at the 9,10 position but desaturation at the 10,11 and 11, 12 positions was affected only slightly. The effect is not due to inhibition of the primary activating enzyme, the long chain acyl CoA synthetase. Sterculic acid is a more effective inhibitor than either malvalic acid or sterculyl alcohol, probably because these cyclopropene compounds do not block the desaturating site of the enzyme as completely as sterculic acid.

Physical studies of lipid-lipid and lipid-protein interactions.

Abstract: This is a review of studies of lipid-lipid and lipid-protein interactions conducted in the author's laboratory. Studies of the thermotropic mesomorphism of phospholipids and effects due to the presence of water are described. The relevance of these thermal transitions to monolayer, bilayer and membrane systems is discussed. Studies on the interactions of phospholipids and cholesterol are reviewed. Finally, lipid-protein interactions under various conditions are discussed with special attention being given to serum lipoproteins and natural membranes.

Melting points of synthetic wax esters.

Abstract: Saturated, monoenoic and dienoic wax esters, C26−C40, have been synthesized from even-numbered fatty alcohols and acids. In homologous series of saturated esters, the increments of melting points follow a regular trend except for those esters which have an acid moiety two carbon atoms shorter than the alcohol moiety. These wax esters have melting points higher than interpolation would predict. Monoenoic wax esters with the double bond in the alcohol chain have melting points about 10 C higher than their isomers with the double bond in the acid chain.

Specific distribution of fatty acids in the milk fat triglycerides of goat and sheep

Abstract: The triglycerides of the fat globules of sheep and goat milk were isolated and separated into short and long chain lengths by silicic acid column chromatography. The short chain lengths comprised major triglycerides with 34–44 acyl carbon atoms and accounted for nearly 50% of the total milk fat. The long chain lengths contained major triglycerides with 40–54 acyl carbons. Stereospecific analyses of the short chain triglyceride fraction showed that of the 20–23 moles per cent of C4−C8 fatty acids present, at least 95% were specifically attached to the glycerol molecule in the position corresponding to carbon 3 ofsn-glycerol. The distribution of the other fatty acids (C10 or greater) did not show such marked specificity for either the 1 or the 2 position. Although individual triglycerides were not identified, the specific placement of the fatty acids could best the accounted for by assuming a common pool of long chain 1,2-diglycerides which served as precursors of the bulk of both short and long chain triglycerides during milk fat synthesis.

The quantitative production of aldehydes from O-alk-1-enyl glycerols

Abstract: The quantitative recovery and structural alterations of aldehydes liberated from O-alk-1-enyl glycerols on thin layer chromatographic layers have been evaluated by using14C-labeled fatty aldehydes and chromatography. The results led to the development of a quantitative procedure for isolating the aldehydes produced from O-alk-1-enyl glycerols by shaking an ethereal solution of the ether-linked lipids with concentrated hydrochloric acid. The procedure is rapid and silicic acid does not interfere.

A rapid microozonolysis-GLC procedure for locating unsaturation in olefinic acids, including trienes and tetraenes

Abstract: Increased versatility has been achieved in the identification of unknown olefinic fatty acids by ozonolysis. The method has been applied to purified methyl esters containing up to four double bonds. Aldehydic fragments, obtained from esters by the Stein-Nicolaides procedure (2), were determined by GLC on two columns of different polarity. Equivalent chain lengths of each fragment on the two columns provide identification. For monoenoic esters the location of the double bond is clearly indicated by the aldehyde and aldehyde-ester fragments. Dienes are identified by the aldehyde and aldehyde-ester fragments when the original chain length of the ester is known; the dialdehyde fragment provides confirmatory evidence. Trienes and tetraenes are analyzed by interrupting the ozonolysis at various times, thereby producing unsaturated, as well as saturated, aldehydes and aldehyde-esters. Unsaturated fragments locate the central or interior double bonds.

Essential fatty acid-deficient rats: I. Growth and testes development

Abstract: Partially hydrogenated oils as the sole dietary fat enhances the development of essential fatty acid (EFA) deficiency in young rats. Partially hydrogenated herring oil (HHO) caused total impairment of the spermatogenic tissue after five weeks of experiment, while partially hydrogenated arachis oil (HAO) caused severe degeneration of this tissue in 15 weeks. A fat-free diet caused degeneration in 26 weeks. In the dietary fats, the total content oftrans acids, calculated as elaidic acid, was 47% and 23% in HAO and HHO, respectively. Further, varying amounts of different positional isomeric fatty acids were also present in the partially hydrogenated oils. Besides the specific tissue changes, poor growth, poor feed efficiency and skin signs characteristic of EFA deficiency were noticed. On the other hand, partially hydrogenated soybean oil (HSO) as the sole dietary fat kept the animals normal in all respects. this oil still contained 32% linoleic acid; the total content oftrans acids amounted to 11%, calculated as elaidic acid.

Lipids of retina: I. Analysis of gangliosides in beef retina by thin layer chromatography

Abstract: Lipids were extracted from beef retina by chloroform-methanol (2∶1); the gangliosides were removed from the total lipid extract by partitioning into water and chromatographing on thin layer plates coated with silica gel The analytical methods are described for estimating ganglioside components, ie, N-acetyl neuraminic acid, hexoses, hexosamine, sphingosine and fatty acids, in the presence of silica gel Major gangliosides present in beef retina have been tentatively identified as follows: a ganglioside containing two N-acetyl neuraminyl groups but no hexosamine; two gangliosides containing two N-acetyl neuraminyl groups and one hexosamine; and a ganglioside with three N-acetyl neuraminyl moieties and one hexosamine

Cis-Trans isomerization of unsaturated fatty acid methyl esters without double bond migration

Abstract: Trans isomerization of monoenoic and dienoic fatty acid methyl esters has been carried out with thiols and diphenylphosphine in the presence of azobisisobutylnitrile. The equilibrium mixture contained 75–80%trans double bonds and there was no migration of the double bonds.

Peroxidation of microsomal membrane protein—Lipid complexes

Abstract: Nonenzymatic lipid peroxidation was studied using the TBA test on rat liver microsomal fractions, lipid micelles and structural protein-lipid micelle complexes. The kinetics, response to divalent cations, and iron-ascorbate catalysis were alike in the microsomal fraction and in the complex, but different in lipid micelles. The structural protein represented 41% of the total membrane protein, had a S20,obs of 3.5 and was hydrophobic. The binding of lipid micelles by structural protein proceeded in two steps, with an initial fast rate followed by a slower rate. The binding appeared to involve a hyrophobic association between lipid and protein as evidenced by insensitivity to pH, ionic strength and lack of preference for the individual classes of phospholipid micelles. Deoxycholate caused an increase in the initial peroxidation rate in microsomal fractions. Iron and ascorbate catalyzed lipid peroxidation in both the microsomal fraction and in the complex. Iron catalyzed lipid peroxidation but calcium, cobalt and copper inhibited the reaction in the SP-lipid micelle complex. Lipid peroxidation in microsomal suspensions, therefore, appears to be determined, in part, by the hydrophobic nature of the protein-lipid association found in membranes.

Acid lipase of the castor bean

Abstract: The acid lipase of the castor bean is present in the dormant seed. It is extracted from the fat pad obtained by centrifuging a macerate of the seed in pH 7.0 buffer containing cysteine and ethylene diaminetetraacetic acid. The pH optimum of the enzyme is 4.2; it is rather heat-stable, and is inhibited by mercurials and sulfhydryl reagents. Maximum hydrolysis of saturated triglycerides occurs with fatty acids of chain length C4 to C8; unsaturated C18 triglycerides are hydrolyzed at a slightly lower rate.

Phospholipid composition of human, bovine and frog myelin isolated on a large scale from brain and spinal cord.

Abstract: by the previous investigators. These contaminants are suggested by the higher sphingomyelin values (high in myelin and endothelial cells), lower values for phosphatidyl choline, and the presence of diphosphatidyl glycerol (from mitochondria) which was not detected in extracts of most of our bovine brain nuclear preparations. The present lipid values for endothelial cells and glomeruli appear to be the first reported. The availability of a rapid procedure (2-3 hr) for isolation of highly purified endothelial cells provides a novel approach to the study of cerebral metabolism and allows direct study of the composition and permeability of these cells and factors influencing their metabolic activity. A. N. SIAKOTOS Department of Pathology Indiana University Medical Center Indianapolis, Indiana 46207 GEORGE ROUSER Section of Lipid Research Division of Neurosciences City of Hope Medical Center Duarte, California 91010 SIDNEY FLEISCHER Department of Molecular Biology Vanderbilt University Nashville, Tennessee 37203

Differences between the metabolism of linoleic and palmitic acid: utilization for cholesterol synthesis and oxidation to respiratory CO2.

Abstract: Measurements were made of the incorporation of intragastrically administered 1-C14-labeled linoleic and palmitic acid carbon into the total body cholesterol of the intact rat and of the rat's ability to oxidize these two labeled acids to respiratory CO2. As compared with palmitic acid, the intact rat and isolated rat tissues exhibit a greater ability to metabolize linoleic acid. This is evidenced by a greater utilization of linoleic acid carbon for synthesis of total body cholesterol and also by a preference for the oxidation of linoleic acid. The greater incorporation of linoleic acid carbon into cholesterol appears to reflect the preferential oxidation of linoleic acid by the liver, a main site of fatty acid oxidation and cholesterol biosynthesis. This preference of the rat to utilize linoleic acid carbon for the synthesis of cholesterol may help to explain the well documented observation that the plasma cholesterol of the rat increases as the linoleic acid content of the diet increases.

The separation, structure and metabolism of monogalactosyl diglyceride species inChlorella vulgaris

Abstract: The monogalactosyl diglyceride fraction from heterotrophically cultured cells ofChlorella vulgaris has been fractionated into species of different fatty acid composition by argentation thin layer chromatography of the unmodified glycolipid. Five major subfractions were isolated, corresponding to groups of molecular species containing 1, 2, 3, 4 and 5 double bonds per molecule, respectively. Incubation ofChlorella vulgaris with 2-14C-sodium acetate, followed by radiochemical analysis of the fatty acids of the individual monogalactosyl diglyceride species, demonstrated that at any time the specific activity of a single fatty acid can vary considerably among the various species in which it occurs. These results are consistent with previously reported evidence that significant changes in the fatty acid composition of the monogalactosyl diglyceride fraction ofChlorella vulgaris occur following its de novo synthesis.

Biosynthesis of glycolipids: Incorporation of N‐acetyl galactosamine by a rat brain particulate preparation

Abstract: A mixture of UDP-(N-acetyl)glucosamine-114C and UDP-(N-acetyl)galactosamine-114C (7∶3) served as a substrate to demonstrate in young rat brain tissue the presence of enzymes which catalyzes the reactions: UDP-glcNAc⇌UDP-galNAc (EC513) and UDP-galNAc+ gal-glc-cer→ galNAc-gal-glc-cer+UDP The glycolipid acceptor specificity was examined and preliminary kinetic data were obtained for the UDP-(N-acetyl)galactosamine: gal-glc-ceramide N-acetyl galactosamine transferase The products of the reaction were identified The relationship of this reaction to ganglioside biosynthesis is discussed

Structure of bovine milk fat triglycerides. II. Long chain lengths

Abstract: The long chain triglycerides of bovine milk fat were isolated by thin layer chromatography, and their chemical structure determined by combined thin layer and gas liquid chromatography, and a stereospecific analysis of a molecular distillate of butteroil of comparable composition. The milk fat fraction (39% of total) contained C8–C20 fatty acids which were distributed among the glycerides of 40–56 acyl carbon atoms in a manner not unlike that found for the same acids in the short chain triglycerides. Although individual triglycerides were not identified, the specific distribution of the fatty acids could best be accounted for by assuming a common pool of long chain 1,2-diglyceride precursors from which the bulk of both short and long chain triglycerides are synthesized by a stereospecific introduction of C4–C18 fatty acids in position 3 of sn-glycerol. This hypothesis is compatible with the results of stereospecific analyses of the short and long chain fractions and of the total butteroil. It is supported by the nonrandom distributions demonstrated for the molecular weights of the milk fat triglycerides of different degrees of saturation.

The enzymic synthesis of ganglioside: I. Brain uridine diphopphate D-galactose: N-acetyl-galactosaminyl-galactosyl-glucosyl-ceramide galactosyl transferase

Abstract: An enzyme which catalyzes the transfer of galactose from UDP-galactose to galNAc-gal-glc-ceramide is described. The enzyme is found mainly in the nervous tissue of tadpole (Taylor and Kollros stage 17), adult frog, adult and 8 day old rat. The enzymic activity is localized in the 11,500 xg, 20,000 xg and 100,000 xg particles. The UDP-galactose: galNAc-gal-glc-ceramide from the particles by treatment with sodium desoxylcholate and Triton X-100. The pH optimum for the solubilized enyme is between 6.8 and 7.0 in cacodylate buffer, and the Km is 4.25 ×10−5 M. The enzymic reaction is proportional to time for 4 hr and to the amount of protein added. The product of the transferase reaction, using galNAc-gal-glc-ceramide. A pathway for the biosynthesis of brain gangliosides requiring UDP-galactose: galNAc-gal-glc-ceramide galactosyl transferase is proposed.

Molecular species of phosphatidyl ethanolamine from egg yolk.

Abstract: Phosphatidyl ethanolamine was isolated from total egg yolk lipids by preparative thin layer chromatography (TLC). The purified phosphatide contained 3% of the alkoxy derivative. It was degraded to diglycerides in the presence of purified sphingomyelin by phospholipase C fromClostridium welchii. The diglycerides were acetylated and resolved on the basis of unsaturation by argentation TLC. The fatty acid composition of the original phosphatidyl ethanolamine and the derived acetates was determined by gas chromatography, as was the molecular weight distribution of the diglyceride acetates. The placement of the fatty acids in the parent phosphatide was deduced by hydrolysis with phospholipase A fromCrotalus atrox, and in the acetates with pancreatic lipase. Some 33 major species of phosphatidyl ethanolamine were identified and compared to those for egg yolk lecithins.

Cis‐11‐hexadecenoic acid fromcytophaga hutchinsonii lipids

Abstract: The principal fatty acid (90+%) of the monoene fraction ofCytophaga hutchinsonii has been identified ascis-11-hexadecenoic acid. This fatty acid, which constitutes 29% of the total lipid fatty acids, is located principally in the phosphatidyl ethanolamine fraction.

Mass spectrometry of long-chain aliphatic aldehydes, dimethyl acetals and alk-1-enyl ethers.

Abstract: Mass spectra of long-chain saturated and unsaturated aliphatic aldehydes, dimethyl acetals and alk-1-enyl methyl ethers are reported and discussed. Using deuterium labeled aldehydes, knowledge about the mass spectral fragmentation is obtained. The m/e M-44 ion is formed by a rearrangement different from the mechanism postulated previously for short-chain aldehydes. A series of hydrocarbon fragments with even mass numbers of 68+14n (n=0,1,2...) appear in the spectra of all three series of compounds.