Polyunsaturated fatty acids and neutral lipids in developing larvae of the oyster,Crassostrea virginica

The fatty acid composition of oyster larvae at various stages, as well as of the algal diet, were determined by gas liquid chromatography (GC). Saturated fatty acids are the major fatty acid components in all larval stages and account for 34–62%, 30–35% and 35–81% of the neutral, polar and total lipids of algal-fed larvae respectively. Weight percentage of saturated fatty acid in “starved” larvae was consistently higher (63–81%) during the whole period. The total polyunsaturated fatty acids were higher in the polar lipids than in the neutral lipids. The concentration of the ω3 fatty acids also was comparatively higher in the polar lipids than in the neutral lipids. In the total and neutral lipid fractions, the weight percentage of polyunsaturated and ω3 fatty acids was higher in the eyed than in the pre-eyed (pediveliger) larvae. Eicosapentaenoic acid (20∶5ω3) and 22∶6ω3 were not detected in lipids of “starved” and young larvae. There was an accumulation of 20∶5ω3, 22∶6ω3, and total ω3 fatty acids in the older larvae. Lipid classes were separated by thin layer chromatography (TLC). There was no qualitative change in lipid composition during larval development, but a marked increased of triacylglycerol in larvae up to the stage of maturation in algae-fed larvae. Contribution number 1195 of the Virginia Institute of Marine Science, Gloucester Point, VA 23062     

Occurrence and chemical structure of nonmethylene-interrupted dienoic fatty acids in american oysterCrassostrea virginica

The American oyster,Crassostrea virginica, was found to contain structurally homologous nonmethylene-interrupted dienoic (NMID) fatty acids. The major C₂₀ and C₂₂ nonmethylene-interrupted dienoic fatty acid isomers were shown to occur as two pairs of homologues 5,13–20∶2 with 7,15–22∶2 and 5,11–20∶2 with 7,13–22∶2. A combination of analytical procedures was required for conclusive structure determination.     

Reevaluation of the neutral lipids ofTilletia controversa andTilletia tritici

Differential scanning calorimetry of whole teliospores and lipid extracts ofTilletia controversa Kühn andT. tritica Tul. indicated that the lipid composition of teliospores was different than earlier reported. An exothermic peak at −40 to −45°C and an endotherm at −25 to −15°C indicated that the majority of lipids were triacylglycerols (TAG). Hot isopropanol was used to inactivate lipases during lipid extraction. Thin-layer chromatographic analysis of extracted lipids showed that free fatty acids (FFA) were not present in great quantities unless water was present during lipid extraction. As measured by gas chromatography. FFA accounted for 1–5% of the lipid content in teliospores ofTilletia spp. The TAG content of teliospores was 60–80% of total lipids.     

Study of the neutral lipids of sunflower meal and isolates

Two types of sunflower protein isolates have been obtained from prepress and solvent extracted sunflower meal. The first was obtained by precipitation (at the isoelectric point) of the alkaline extract of the meal, and washing the curd with water. In the second, the alkaline extraction was carried out in the presence of sodium sulfite, and the curd was washed with water, ethanol and acetone. Both isolates were air-dried and then dried under vacuum at 50 C. From the total lipids, obtained with 86% ethanol, the neutral lipids were separated using a column of Florisil. The lipids studied were those of the two isolates mentioned above as well as those of the original meal. The following types of compounds were separated, identified and quantified: hydrocarbons, waxes, methyl esters, triglycerides, free fatty acids, diglycerides, free sterols, and hydroxy fatty acids.     

The metabolism of neutral lipids in the spur dogfish,Squalus acanthias

Cell free studies have shown that liver and intestine are the major sites of synthesis of triacyl glycerols inSqualus acanthias. The liver and to a lesser extent the intestine and stomach are major sites of wax ester synthesis. Muscle does not synthesize either triacyl glycerols or wax esters significantly. In vivo studies have shown that intravenously injected (³H) fatty alcohol is massively oxidized to (³H) fatty acid, the bulk of which appears in muscle. Liver appears to export both free fatty acids and triacyl glycerols to serum and thence to muscle. Free fatty acids, triacyl glycerols, wax esters and cholesteryl esters are all turned over within 48 hr inSqualus serum. The turnover of triacyl glycerols greatly exceeds the turnover of alkyl diacyl glycerols.     

Study of neutral lipids ofLupinus mutabilis meal and isolates

Two types of protein isolates have been obtained from defattedLupinus mutabilis meal. The isolates, MA and MB, were obtained by alkaline extraction with 0.2% NaOH and 0.25% sodium bisulfite, respectively, followed by precipitation at the isoelectric point (pH 4.8). Total associated lipids were extracted with 86% ethanol. Neutral lipids were separated in a Florisil column. The lipids in the isolates were similar to those found in the original meal. The following types of compounds were separated, identified, and quantitated: hydrocarbons, waxes, methyl esters, triacylglycerols, free fatty acids, diacylglycerols, and free sterols.     

Lipids ofCrassostrea virginica. I. Preliminary investigations of aldehyde and phosphorous containing lipids in oyster tissue

Oyster tissue contained 2.4% lipid, 0.14 μmole aldehyde per milligram lipid and at least 10 μg phosphorous per milligram lipid. The neutral lipid represented 58%, the glycolipid 6%, and the polar lipid 36% of the total lipid recovered after silicic acid column chromatography. Aldehydes were found in all fractions, but the presence of plasmalogen was verified in only the neutral and polar lipid fractions. At least 68% of the plasmalogen in oyster lipid was found in the polar lipid fraction. At least 13% of the phosphorous in oyster lipids was present as phosphonolipid. The distribution of phosphate and phosphonate lipids was: diacyl phospholipid 38.1%, plasmalogen phospholipid 21.8%, sphingophosphonolipid 13.5%, glyceryl ether phospholipid 8.3%, sphingophospholipid 6.9%, plasmalogen phosphonolipid 6.4%, diacyl phosphonolipid 2.6%, and glyceryl ether phosphonolipid 2.4%. When the per cent of phosphorous as phosphonolipid within the plasmalogen and glyceryl ether classes was calculated, similar values were obtained. These results support the hypothesis that there is a product precursor relationship between these two classes of lipids. Some of the data taken from a thesis to be submitted to the Graduate School, University of Maryland, by Leslye Johnson in partial fulfillment of the requirements for the M.S. degree in biochemistry.     

Total,polar and neutral lipids ofRhizopus arrhizus fischer

The changes in total lipid content, neutral and polar lipids, total fatty acids, and free fatty acids were investigated over a 4 day period in the zygomycete,Rhizopus arrhizus Fischer. The highest concentration of lipids occurred at the 72 hr period. The degree of unsaturation in the total fatty acid fraction increased during the growth period, whereas the degree of unsaturation decreased in the free fatty acid fraction during the same time period. The ratios of neutral to polar lipids over the 4 day period were: 0.75, 0.22, 1.94 and 0.94. The major components of polar lipids were phosphatidyl ethanolamine, lecithin, lysolecithin, and fatty acids. The fatty acids in the mono- and diglycerides were predominately saturated (67–96%). The fatty acids in the triglycerides shifted from a predominately unaturated (69%, 24 hr) to a more saturated pattern (62%, 96 hr).     

Distribution of hydrocarbons in bovine tissues

Liver, heart, kidneys, muscle and adipose (perirenal and subcutaneous) tissues were collected from six animals for analysis of their hydrocarbon composition. Qualitative and quantitative determinations were carried out by gas chromatography and combined gas chromatography-mass spectrometry. Although differing in the proportions, a homologous series of n-alkanes ranging from n-C₁₂ to n-C₃₁ was found in all the samples examined. The isoprenoid hydrocarbons phytane and phytene (phyt-1-ene and phyt-2-ene) were also identified.     

Canavalia ensiformis neutral lipids,a rich source of lupeol

The composition of the neutral lipids ofCanavalia ensiformis, which represent 2.21% of whole seeds, has been investigated. The fatty acid composition is characterized by the presence of palmitic (15%), oleic (54%), linoleic (7%) and linolenic (8%) acids. The unsaponifiable matter (7.9% of the neutral lipids), was examined for sterol, 4α-methylsterol and triterpene alcohols. The occurrence of lupeol in high amount in the last fraction (96%) constitutes an interesting source for this compound.     

Relationship between embryonic and tumor lipids: I. Changes in the neutral lipids of the developing chick brain,heart and liver

Organ dry weight, per cent total lipid, per cent neutral lipid, per cent phospholipid, and neutral lipid class composition of embryonic and mature brain, heart and liver were determined at 10, 13, 16, 19, 22, 27 and 53 days after incubation was initiated. All three tissues showed an increase in total lipids from the 10th day to hatching (21st day). The 10th day brain showed relatively high levels of sterol esters which decreased with increased development while free sterol levels increased. Heart free sterol and sterol ester percentages decreased with increassed time, while triglyceride levels increased dramatically after the 16th day. Liver showed a massive accumulation of neutral lipid after the 17th day. The neutral lipid was not triglyceride, as might have been expected, but sterol ester. Liver sterol, sterol ester and triglyceride levels were approximately equal at the 10th and 13th days, after which time sterol ester rose rapidly to more than 90% of the total neutral lipids by the 19th day. The neutral lipid class distributions were characteristically different for each tissue throughout embryonic development. The relative high sterol ester levels in each of the tissues early in development suggests that the high level of sterol esters in neoplastic tissue may be related to the growth process of increasing cell numbers. On the other hand, the absence or the presence of only trace amounts of glyceryl ether diesters in any of the embryonic tissues suggests that the elevated levels of this lipid class in most tumors may be related to the neoplastic process or to conditions resulting from neoplasia.     

Rapid separation of neutral lipids,free fatty acids and polar lipids using prepacked silica sep-Pak columns

A method is described for the separation of neutral lipid, free fatty acid and polar lipid classes using small (600 mg), prepacked silica Sep-Pak columns. Combinations of hexane and methyltertiarybutylether were used to progressively elute cholesteryl ester first then triglyceride from the column. After column acidification, fatty acids were eluted followed by cholesterol. Recoveries of these lipids were 96% or greater. Polar lipids were eluted from the column using combinations of methyltertiarybutylether, methanol and ammonium acetate. Phospholipid classes could not be separated completely from each other. Phosphatidylethanolamine and phosphatidylinositol eluted together, whereas the more polar phosphatidylcholine, sphingomyelin and lysophosphatidylcholine were eluted as a second fraction. Recoveries of each phospholipid was greater than 98%.     

Thin layer chromatographic procedure for class separation of plant neutral lipids

A thin layer chromatographic method has been developed for the class separation of plant neutral lipids. Utilizing a two-step development in one dimension, lipid mixtures are separated into hydrocarbon waxes, steryl esters, methyl esters, triglycerides, fatty acids, diglycerides, sterols, and monoglycerides. The method may be employed for either qualitative or preparative purposes.     

Distribution of methylene and nonmethylene-interrupted dienoic fatty acids in polar lipids and triacylglycerols of selected tissues of the hardshell clam (Mercenaria mercenaria)

Fatty acid profiles of polar lipids and triacylglycerols were determined for 6 tissues of the hardshell clam (Mercenaria mercenaria), namely, mantle, gill, mouth, foot, digestive tract/gonadal tissue and adductor muscle. The largest concentrations of nonmethylene-interrupted dienoic (NMID) fatty acids were found in the gill, mantle, and foot. Structural analyses were undertaken to determine the double bond configurations of the various NMID isomers. The major 22C NMID species were Δ7,13- and Δ7,15-docosadienoic acid. The major 20C NMID species were Δ7,11- and Δ7,13-eicosadienoic acid and Δ5,11-eicosadienoic acid.     

Enrichment of phospholipids from neutral lipids in peanut oil by high-performance liquid chromatography

Phospholipids from crude peanut oil were enriched on a 2-cm silica column and subsequently separated from neutral lipids within the chromatographic system without prior concentration. Hexane effectively removed the bulk neutral lipids, leaving the adsorbed phospholipids on the silica precolumn. Individual phospholipids were separated from the remaining neutral lipids and from each other by using two mixed solvents and a gradient program. This method separates the phospholipids in approximately 27 min after the desired enrichment level has been reached. The research reported in this paper was a cooperative effort by the Agricultural Research Service of the United States Department of Agriculture and the North Carolina Agricultural Research Service, Raleigh, NC 27695-7625.     

The phytanic acid content of the lipids of bovine tissues and milk

In three steers which were given grass silage for six months, the content of phytanic acid (i.e. 3,7,11,15-tetramethylhexadecanoic acid) in plasma lipid increased to about 8% of the total fatty acids, whereas after this time the proportion in the total fatty acids of liver and heart lipids was about 1%, and only 0.1% in those of kidney lipids; the acid was present in trace amounts in adipose-tissue triglycerides and was apparently absent from brain lipids. In eight lactating cows which were given grass silage for about 3 months, the content of phytanic acid in the total long chain fatty acids of milk and of plasma was 0.7% and 13%, respectively. In the plasma lipids of both steers and lactating cows, phytanic acid constituted a substantial proportion of the total fatty acids of the triglycerides and phospholipids; the acid was present in lowest proportion in the cholesteryl esters.     

Comparative evaluation of solvent extraction methods for the determination of neutral and polar lipids in beef

Samples of lean (< 5% fat), medium (13–15%) and high-fat (> 20%) ground beef were extracted for total lipid by 4 methods of wet extraction employing chloroform/methanol (CM), n-hexane/iso-propanol (HIP) and ethyl alcohol/ethyl ether (AE), and by 3 methods of soxhlet extraction of freeze-dried material by petroleum ether (PE) or eithyl ether (EE), CM and methylene chloride/ methanol (MM). The purified lipid was fractionated into neutral and polar lipid fractions by silicic acid chromatography and the frac-tions were analyzed for fatty acid distribution by gas liquid chroma-tography (GLC). The soxhlet procedure employing either PE or EE extracted less than 75% of total lipid, 89% of triglycérides and 15% of polar lipids from lean beef as compared to other methods, and as the fat content increased from 3 to 20%, extracted amounts of polar lipid which increased to 40% of that extracted by other methods. The fatty acid distribution of the fractionated triglycerides and polar lipids was generally within experimental error for each frac-tion, irrespective of the method of extraction. The percentages of 16:0 and 18:1 were significantly less in polar lipids than in trigly-cerides. In addition to significantly higher percentage of 18:2, the polar lipids contained up to 20% of long-chain fatty acids not detected in triglycerides. The soxhlet procedures with CM or MM were as effective as wet extraction procedures in extracting neutral and polar lipids. Presented at the 73rd AOCS annual meeting, Toronto, 1982. Contribution No. 512, Food Research Institute, Agriculture Canada.     

Characterization of castor bean neutral lipids by mass spectrometry/mass spectrometry

A method has been developed for the characterization of intact neutral lipids isolated from castor bean (Ricinus communis L.) by mass spectrometry/mass spectrometry (MS/MS). The molecular weights of the trimethylsilyl (TMS) derivatives of the neutral lipids are determined by using both electron impact and chemical ionization (ammonia). Collision-induced dissociation daughter spectra of the (M-CH₃)⁺ ions yield fragment ions that allow easy determination of the acyloxy groups present. The chainlength and degree of unsaturation for each acyloxy group are indicated by R in the ion represented by the general formula (RCO + 74)⁺. Other ions of diagnostic value include (M-RCOO)⁺, (M-RCOOH)⁺, [(M-CH₃-RCOOH]⁺ and [(M-RCOOH)-16]⁺. The presence of a TMS group in any of these fragments results in the formation of ions representing the loss of OTMSH. Prior to MS/MS analysis, partial fractionation by high-performance liquid chromatography (according to degree of unsaturation in the neutral lipids) is useful because daughter spectra are generated free of any isotopic contamination, and minor components are concentrated in single fractions, which aids their characterization. By using this method, 11 neutral lipids were characterized in castor bean.