bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for acyl transfer reactions between neutral glycerolipids in dogfish (Squalus acanthias) serum
Authors: Malins Donald C. , Robisch Paul A. 
Published: November 2006

AbstractRadioactively labeled triacylglycerols, 1,3‐dioleoyl‐2‐[1‐14C]‐palmitoylglycerol and 1,3‐[9,10‐3H]‐dioleoyl‐2‐palmitoylglycerol, were incubated with dogfish (Squalus acanthias) serum for periods of up to 10.0 hr. Changes in the positional distributions of carbon‐14 and tritium within the triacylglycerols in 5.0 hr and 10.0 hr indicate that intermolecular and intramolecular shifts occur among the fatty acids. In addition, a maximum of 8.3% of the carbon‐14 and 5.9% of the tritium was incorporated into 1‐alkyl‐2,3‐diacylglycerols; essentially all of this incorporated radioactivity was associated with the acyl chains in the 1.5 and 5.0 hr incubations. In the 10.0 hr incubations, however, 25% of the tritium incorporated into the 1‐alkyl‐2,3‐diacylglycerols was associated with the 0‐alkyl chains. Radioactivity was not incorporated significantly into free fatty acids in the 1.5 and 5.0 hr incubations. These results indicate that acyl transfer reactions take place among molecular species of triacylglycerols, as well as between triacylglycerols and 1‐alkyl‐2,3‐diacylglycerols. In the latter case, the conversions appear to be operative in the virtual absence of net biosynthesis.
On extraction of acyl and alkyl dihydroxyacetone phosphate from incubation mixtures
Authors: Hajra Amiya K. 
Published: November 2006

AbstractChloroform‐methanol mixture was shown to extract acyl and alkyl dihydroxyacetone phosphate from enzyme incubation mixtures. However, when the lipid extract was washed with water to remove nonlipid materials, 70–80% of acyl and alkyl dihydroxyacetone phosphate were lost in the aqueous phase. It was shown that, keeping the pH low (<2.5) during the partition of lipids by the Bligh and Dyer method, most (>95%) of the acyl and alkyl dihydroxyacetone phosphate were recovered in the chloroform‐rich phase. n‐Butanol was shown to extract 80–90% of these lipids from incubation mixtures at neutral pH.
Effects of chronic ethanol ingestion upon acyl‐CoA: Carnitine acyltransferase in liver and heart
Authors: Parker Sharon L. , Thompson John A. , Reitz Ronald C. 
Published: November 2006

AbstractChronic alcohol ingestion has been shown to cause a profound decrease in the activity of acyl‐coenzymeA:carnitine acyltransferase in the liver. Twelve diferent acyl‐coenzymes were used as substrates, and the decrease in acyltranser rates ranged from 22–60% of the control. This enzyme was not affected as drastically in the heart. Of 11 acyl‐coenzymes tested, only two resulted in significantly lower rates of acyltransfer, even though the rates were decreased with all substrates tested. The specificities of this enzyme showed that increasing the chain length of the acyl group resulted in a decreased acyltransfer when the acyl groups were either saturated, monoenoic, dienoic, or trienoic. Also, increasing the number of ethylenic bonds present in the acyl group of fatty acyl‐coenzymes of the same chain length resulted in increased rates of acyltransfer. One exception to this ethylenic bond effect was noted in the heart. Linolenate resulted in an acyl‐transfer rate lower than linoleate. Ethanol had little or no effect upon these specificities.
Effects of age, sex, and diet upon carcass and liver fatty acid composition of pitman‐moore miniature pigs
Authors: Filer L. J. , Fomon Samuel J. , Anderson Thomas A. , Nixt Thomas L. , Andersen Dean W. 
Published: November 2006

AbstractFatty acid composition of carcass and liver and proximate analysis of liver were studied in 14–28 day old Pitman‐Moore miniature pigs, 26 sow‐reared and 30 fed a semisynthetic diet in which the fat was lard. With increasing age, fat of carcass, but not of liver, became significantly more unsaturated. The percentage of palmitic acid (16∶0) and total saturated fatty acids was significantly greater and the percentage of linoleic acid (18∶2) and total unsaturated fatty acids significantly less in carcasses of male than of female pigs. No sex‐related differences in proximate or fatty acid composition of the liver were noted. Carcasses of sow‐reared pigs contained significantly greater percentages of myristic (14∶0), palmitoleic (16∶1), and linoleic acids and significantly lesser percentages of stearic (18∶0) and oleic (18∶1) acids than did those of pigs fed the semisynthetic diet. Diet‐related differences in fatty acid composition of liver closely paralleled those of carcass, although liver contained markedly greater percentages of stearic and arachidonic (20∶4) acids and lesser percentages of palmitoleic and oleic acids than did carcass. Diet‐related differences in fatty acid composition of carcass and liver are discussed in relation to the fatty acid composition of dietary fat (sow milk and lard).
Isovaleric acid as a precursor of odd numbered iso fatty acids in Tetrahymena
Authors: Conner Robert L. , Koo Kim‐Eng , Landrey J. R. 
Published: November 2006

AbstractTris isovalerate‐supplementedTetrahymena pyriformis W showed no qualitative change in fatty acid composition; however, an increase in polar lipids that contain odd numbered iso acids (C13, C15, C17, C19) occurred. This change was accompanied by a decrease in the proportional amount of even numbered normal acids (C14, C16, C18). The neutral and polar lipids from cells incubated with [1‐14C] isovaleric acid were found to contain radioactivity. The methyl esters of the saturated fatty acids obtained from the polar lipids by alkaline methanolysis were separated by reversed phase chromatography, the identities confirmed by gas chromatography‐mass spectrometry, and the specific activities determined. Iso acids were found to be the most heavily labeled materials. In addition to ceramide, two sphingolipid components were detected. One yielded saturated fatty acids after acidic methanolysis, while the other contained >93% α‐hydroxy fatty acids. Radioactivity was noted in the long chain base fraction derived from the sphingolipids. Progressive growth inhibition occurred as the isovalerate concentration was increased in the culture medium; however, the ciliates were morphologically indistinguishable from unsupplemented cells.
Effects of triparanol and AY‐9944 upon sterol biosynthesis inChlorella
Authors: Patterson G. W. , Doyle P. J. , Dickson L. G. , Chan J. T. 
Published: November 2006

AbstractThe growth rates of three species ofChlorella were inhibited by triparanol and AY‐9944.Chlorella emersonii was noticeably more resistant to both inhibitors than the other species. A large number of sterols were isolated and identified in inhibited cultures. Ca. 18 of these were identified from nature for the first time. Triparanol resulted in inhibition of the removal of the 14α methyl group. It also inhibited the second alkylation of the side chain and, in one species, strongly inhibited the Δ8 → Δ7 isomerase reaction. InC. ellipsoidea, triparanol also inhibited Δ14‐reductase and Δ7‐reductase. The introduction of the Δ22 double bond was inhibited by both drugs. The effect of AY‐9944 was similar to that of triparanol inC. emersonii, but it was an extremely effective Δ14‐reductase inhibitor inC. ellipsoidea. These various types of inhibition of sterol synthesis indicate a lack of specificity of both drugs inChlorella and suggest that primitive plants such as these may be valuable as test organisms in an evaluation of the activity of potential inhibitors of sterol biosynthesis.
Distribution of sterols in the fungi I. Fungal spores
Authors: Weete John D. , Laseter John L. 
Published: November 2006

AbstractThe freely extractable sterols of spores ofLinderina pennispora, Spicaria elegans, Penicillium claviforme, Aspergillus niger, Ustilago nuda, U. maydis, Puccinia graminis, andP. striiformis were examined using mass spectrometric techniques. Each species contained at least 3–5 detectable sterol components in the 4‐desmethyl sterol fraction, and, when present, ergosterol was generally the most abundant sterol produced by an individual species. Smaller relative concentrations of fungisterol (ergost‐Δ7‐enol) di‐ and tetraunsaturated C28 sterols also were found. In some species, fungisterol was the most abundant sterol. In uredospores of rust fungi, stigmast‐Δ7‐enol (C29) was predominant and was accompanied by lower relative concentrations of a diunsaturated C29 sterol and fungisterol. Cholesterol was found only in the teliospores of the corn smut fungus (U. maydis). Application of glass capillary columns to the separation of yeast sterols by gas liquid chromatography is illustrated.
Phytosterol side chain biosynthesis
Authors: Goad L. J. , Lenton J. R. , Knapp F. F. , Goodwin T. W. 
Published: November 2006

AbstractThe typical plant sterols contain a substituent at C‐24 of the side chain. This can be a methylene, ethylidene, methyl, or ethyl group; with the last three groups, all possible isomers have been reported in nature. The C‐24 alkyl groups are derived by a transmethylation reaction from methionine. The details of several distinct alkylation mechanisms, which are now recognized in a range of lower and higher plants, have been reviewed. The operation of these different routes may have some phylogenetic significance.
Role of sterols in membranes
Authors: Nes Williams R. 
Published: November 2006

AbstractSterols, or in rare cases structurally similar molecules, are biosynthesized or at least required by all eucaryotic organisms, as well as by many procaryotic ones, regardless of their status as plants, animals, or protista. This information, together with quantitative, structural, metabolic, and other data is reviewed. It is interpreted to mean that the primary role sterols play in nature is a nonmetabolic one as architectural components of membranes and that this role can be played, but less well, by other molecules which approximate the steroidal structure. The biosynthetic process should, therefore, and actually does not appear to be correlatable with this role, which, in turn, is correlatable with phylogenesis. The Δ24‐reduction‐alkylation bifurcation, for instance appears to be interrelated profoundly with the evolutionary differentiation of the animal from the plant kingdom.
Function of steryl esters in plants: A hypothesis that liquid crystalline properties of some steryl esters may be significant in plant sterol metabolism
Authors: Atallah A. M. , Nicholas H. J. 
Published: November 2006

AbstractThe synthesis of a wide variety of desmethyl, 4α‐ and 4,4‐dimethyl steryl esters, whose physical properties have been described elsewhere, has indicated that side chain structure and the position of a double bond in the nucleus are critical in determining whether or not a steryl ester can form a mesophase (liquid crystalline state). Since the capability of mesophase formation seems rather specifically distributed in the biosynthetic steps leading to the formation of animal, plant, and fungal sterols, the hypothesis is presented that such mesophase formation, or lack of it, may control the biosynthetic sequence by virtue of the viscosity changes associated with the formation of liquid crystals. Mesophase formation of thermotropic liquid crystals is influenced by a number of physical factors, including heat, electrical current, pressure, and impurities, e.g. solvents. Some preliminary experiments with incubation of cell‐free extracts ofPhaseolus vulgaris are reported, with heat as the physical parameter studied, following the addition of cholesteryl‐1,2‐3H, sitosteryl‐22,23‐3H(N) palmitates, and the respective free compounds to the cell‐free extracts. Although some possible influence of heat during the incubation of the compounds upon their distribution in subcellular fractions was indicated, no consistent pattern was found. However, some observations on the capability of the subcellular organelles to hydrolyze the added esters and esterify the free compounds are presented. The data suggest that hydrolysis of steryl esters and their synthesis by plant cell‐free extracts are both of more than coincidental occurrence.
Improved synthesis of 7‐dehydrositosterol
Authors: Kircher Henry W. 
Published: November 2006

AbstractSitosteryl acetate was brominated in petroleum ether by the gradual addition of N‐bromosuccinimide to a refluxing, illuminated solution and dehydrobrominated by the dropwise addition of the bromo derivative to a refluxing solution of collidine in mesitylene to give a 38% yield of 7‐dehydrositosteryl acetate.
Location of double bonds in long chain esters by methoxymercuration‐demercuration followed by mass spectroscopy
Authors: Minnikin D. E. , Abley P. , McQuillin F. J. , Kusamran K. , Maskens K. , Polgar N. 
Published: November 2006

AbstractMethyl esters of simple mono‐, di‐, and triunsaturated long chain fatty acids quantitatively react with mercuric acetate in methanol to produce methoxyacetoxymercuri derivatives. Demercuration of these derivatives with sodium borohydride yields methoxylated fatty acid esters, readily isolable by thin layer chromatography. Mass spectra of the methoxylated esters are characterized by intense peaks due to cleavage adjacent to methoxy‐functions which allow the position of the original double bond in the chain to be ascertained. The methoxylated derivatives are conveniently analyzed by gas liquid chrovmatography and also by combined gas chromatographymass spectrometry. In comparison with other methods for double bond location, the procedure described in simple, reliable, and rapid.
Characteristics of the lipase from the mold,Geotrichum candidum: A review
Authors: Jensen Robert G. 
Published: November 2006

AbstractThe moldGeotrichum candidum produces an extracellular lipase, readily concentrated by removal of the culture medium in which the microorganism is grown. The lipase is characterized by a unique, but not absolute, specificity for fatty acids containingcis‐9 orcis,cis‐9, 12 unsaturation, hydrolyzing both regardless of position within the triglyceride molecule. The enzyme also hydrolyzescis‐9‐16∶1,cis,trans‐9,12‐18∶2,trans,cis‐9,12‐18∶2, palmitoyl oleate and cholesteryl oleate. Digested at comparatively slow rates are:trans,trans‐9,12‐18∶2, double bond positional isomers of 18∶1 (other thancis‐9), stearolic acid, oleoylpalmitate, dilinoleoyl phosphatidyl choline, and saturated acids. The enzyme has an optimum pH of 8.2, and the lyophilized powder is extremely stable, retaining activity for at least eight years when stored at‐20 C. A purification of 81‐fold has been achieved.
Sterols, methylsterols, and triterpene alcohols in threeTheaceae and some other vegetable oils
Authors: Itoh Toshihiro , Tamura Toshitake , Matsumoto Taro 
Published: November 2006

AbstractThe unsaponifiables from threeTheaceae (Camellia japonica L.,Camellia Sasanqua Thunb., andThea sinensis L.) oils and alfalfa, garden balsam, and spinach seed oils and shea fat were separated into four fractions: sterols, 4‐methylsterols, triterpene alcohols, and less polar compounds by thin layer chromatography. While the sterol fraction was the major one for the unsaponifiables from alfalfa and spinach seed oils, the triterpene alcohol fraction was predominant for the unsaponifiables from all other oils. The sterol, 4‐methylsterol, and triterpene alcohol fractions were analyzed by gas chromatography. All the sterol fractions were alike in their compositions, consisting exclusively of Δ7‐sterols, such as α‐spinasterol and Δ7‐stigmastenol as predominant components together with Δ7‐avenasterol and 24‐methylcholest‐7‐enol. Obtusifoliol, gramisterol (occasionally accompanied with cycloeucalenol), and citrostadienol, together with several other unidentified components, were found in the 4‐methylsterol fractions from all of the oils except shea fat. The 4‐methylsterol fraction from shea fat showed a characteristic composition containing a large proportion of unidentified components which had relative retention time greater than that of citrostadienol, while no citrostadienol was detected. β‐Amyrin, lupeol, and butyospermol were major components of the triterpene alcohol fractions from most of the oils, but the fraction from spinach seed oil contained cycloartenol and 24‐methylene‐cycloartanol as predominant components. There is a close similarity in the compositions of unsaponifiables (sterols, 4‐methylsterols, and triterpene alcohols) of the threeTheaceae oils. Two sterols, α‐spinasterol and Δ7‐stigmastenol, and five triterpene alcohols were isolated from tea seed oil. Moreover, five unidentified components beside parkeol, butyrospermol, α‐amyrin, and lupeol were isolated from the triterpene alcohol fraction of shea fat.
Modification of in vitro rat adrenal corticosteroidogenesis by dietary fat
Authors: Egwim Peter O. , Kummerow F. A. 
Published: November 2006

AbstractThree groups of male weanling Holtzman rats were maintained, ad libitum, for 4 and 8 weeks on 1 of 3 diets: Purina Chow, hydrogenated soybean fat, and milk fat diets. The fats were added at the level of 36% total calories in the case of the hydrogenated soybean and milk fat diets. Adrenal homogenates prepared from tissues of each group of animals at the end of the dietary periods were used to measure the relative abilities to synthesize corticosteroids from endogenous substrates. Endogenous free cholesterol levels were found adequate to sustain the level of corticosteroids obtained. No concomitant cholesteryl ester hydrolysis was observed under the experimental conditions used. The adrenal synthetic ability for the three dietary groups was in the order milk fat > Purina Chow > hydrogenated milk fat. This order appeared not to be a reflection of the essential fatty acid status of the animals in the three dietary groups. The possible basis for this trend, and the implications of the findings for carbohydrate, protein, and lipid metabolism in the animal are indicated.
Lipid products formed during desaturation of [1‐14C] stearyl CoA by hen liver microsomes
Authors: Holloway Caroline T. , Holloway P. W. 
Published: November 2006

AbstractA number of lipid products are formed during the desaturation of stearyl CoA by hen liver microsomes. This article presents an analysis of the products formed when [1‐14C] stearyl CoA is incubated with hen liver microsomes for various time periods. [1‐14C] Oleyl CoA was the first radioactive unsaturated product formed. Synthesis of phospholipids containing [1‐14C] oleic acid occurs only after the desaturase activity has begun to decline. The specific radioactivity of [1‐14C] oleyl CoA was similar to the specific radioactivity of [1‐14C] stearyl CoA at all time periods tested. The specific radioactivities of [1‐14C] oleic acid and phospholipids containing [1‐14C] oleic acid were much lower than that of the [1‐14C] stearyl CoA.
On the levels of alkyl and alk‐1‐enyl glycerolipids in normal and neoplastic tissues: A method of quantification
Authors: Su Kwei Lee , Schmid Harald H. O. 
Published: November 2006

AbstractA method is described for the quantification of the constituentO‐alkyl andO‐alk‐1‐enyl glycerols of neutral lipids or phospholipids. The method involves chemical degradation, the preparation of derivatives, and quantification by gas chromatography using internal standards. Alk‐1‐enyl moieties are converted to alkyl substituted dioxanes in the presence of 1,1‐dimethoxyheptadecane as standard; alkyl glycerols are analyzed as isopropylidene derivatives using 1‐O‐heptadecyl glycerol as internal standard. The method is applied to the quantification of alkyl and alk‐1‐enyl glycerols derived from total lipids of rat heart, liver, testes, and brain and of various transplantable tumors, i.e. amelanotic melanoma, melanoma B16, sarcoma T241, and Novikoff hepatoma. The levels of alkyl glycerols range from 0.11–1.07% total lipids and those of alk‐1‐enyl glycerols from 0.49–5.03%. The data are compared to those obtained by other methods.
Slow exchange of erythrocyte and plasma phospholipids
Authors: Calvert G. D. , Scott P. J. 
Published: November 2006

Abstract32P‐Orthophosphate was injected intravenously into a pig, and the specific activities of serum phospholipids and phosphatidylcholine, serum and urine inorganic phosphorus, and erythrocyte phospholipids were followed for the next eight days. The specific activities of serum phospholipids, phosphatidylcholine, and inorganic phosphorus declined monoexponentially and were not significantly different from each other after the first day. These data imply that there are no large poorly labeled pools of inorganic phosphorus or phospholipids supplying serum phospholipid. Phospholipid metabolism is sufficiently rapid to obscure any immediate precursor product relationship. The specific activity of erthrocyte phospholipid rose slowly to a maximum on ca. the fourth day. The data were consistent with a precursor product relationship between serum phospholipids and part of the erythrocyte phospholipids.
Ethanolamine kinase activity and compositions of diacylglycerols, phosphatidylcholines and phosphatidylethanolamines in livers of choline‐deficient rats
Authors: Tinoco J. , Endemann G. , Medwadowski B. , Miljanich P. , Williams M. A. 
Published: November 2006

AbstractThese experiments were performed to find the reasons for the increased concentrations of docosahexaenoyl phosphatidylethanolamines (PE) in livers of choline‐deficient rats. We measured the activity of ethanolamine kinase, which catalyzes the first step in PE formation. We also measured the compositions of PE and phosphatidylcholines (PC) and concentrations and fatty acid compositions of diacylglycerols (DG), which are precursors of PE. Young male rats were fed for one week a low‐methionine, choline‐deficient diet, or the same diet supplemented with choline. Ethanolamine kinase activity was measured in liver cytosol (100,000 g supernatant). Fatty acids were measured in total liver diacylglycerols and in microsomal PE and PC. Ethanolamine kinase activities were equal in choline‐deficient and choline‐supplemented rats. Concentrations of DG were elevated 6‐fold by choline deficiency. The percentage of docosahexaenoic acid (22∶6n−3) in microsomal PE was nearly doubled by choline deficiency. Although the increased concentrations of PE in choline‐deficient livers cannot be attributed to increased activity of ethanolamine kinase, the rate of PE formation probably was increased by increases in concentrations of its precursors, including DG. The disproportionate increase in 22∶6n−3 PE probably was caused by a selective formation of PE from DG that contain 22∶6n−3.
The lipid composition of erythrocytes in european cattle and buffalo steers
Authors: O'Kelly J. C. , Mills S. C. 
Published: November 2006

AbstractThis study compared the lipid composition of the red blood cells of European cattle and of buffalo steers at the same level of feed intake in a thermoneutral evironment. The mean volumes of the erythrocytes and their lipid content were greater in buffalo than those in cattle. However, the amounts of phospholipid and cholesterol in cells of equal volume were higher in buffalo than in cattle. In contrast, the phospholipid level at a given cholesterol level was higher in cattle than in buffalo. The distribution of the different molecular species of phospholipids in the red cells of the two breeds were similar, but there were significant distinctions in their fatty acid patterns, notably in the levels of 24∶0 and 24∶1 in the sphingomyelin fractions. The proportion of total monounsaturated acids in the erythrocytes were similar from both breeds. However, there was a higher percentage of polyunsaturated fatty acids with a corresponding lower content of total saturated fatty acids in the red cells from buffalo than in those from cattle. The breed differences in erythrocyte lipid composition are discussed in relation to breed differences in red cell characters and could lead to a better understanding of the mechanisms of environmental adaptation.