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1.
Pigeon “milk” (PM) collected from the crop of 1- to 5-day-old squabs was analyzed to examine whether there were changes in
lipid composition during the first week of secretion. The high PM fat content (9–11%) remained fairly constant in the first
5 days of secretion. The mean percentage of neutral lipids, glycolipids and phospholipids was 80, 12 and 8%, respectively.
Unlike the content of neutral lipids, glycolipid and phospholipid levels increased significantly between day 1 and day 5 of
secretion. Triglycerides, the major neutral lipids, decreased by 24% between day 1 and day 5, while free sterols, monoglycerides
and hydrocarbons increased by 8%, 11% and 2.5%, respectively, during the same period; diglycerides and sterol esters, however,
remained unchanged. The ratio of saturated to unsaturated fatty acids was 0.27 and it remained unchanged. Medium-chain (C10, C12 and C14) and oddchain (C15 and C17) fatty acid contents were low. Fatty acids longer than C20 were absent. Palmitic acid, the major saturated fatty acid, increased by 42% from day 1 to day 5, whereas stearic acid decreased
by 48% during the same period. Oleic acid, the predominant unsaturated fatty acid, also decreased from 51 to 45% between the
first and fifth day of PM secretion. Polyunsaturated acids (18∶2, 18∶3 and 20∶4) accounted for 26% and 30% of the total fatty
acids on day 1 and day 5, respectively. Although lipid changes in the crop of squabs prior to collection of samples cannot
totally be ruled out, the nature of lipid changes is likely to reflect cellular breakdown that precedes PM secretion by parent
pigeons. 相似文献
2.
J. D. Weete M. Sancholle K. A. Patterson K. S. Miller M. Q. Huang F. Campbell M. Van den Reek 《Lipids》1991,26(8):669-674
Changes in the unsaturated fatty acid content of the fungusTaphrina deformans as a function of growth, temperature, and sterol content were investigated. It was found that the highest growth rate was
accompanied by a relatively high degree of fatty acid unsaturation (18∶1<18∶2+18∶3) and low sterol (brassicasterol) content.
Also, a substantial shift in the degree of unsaturation from mainly 18∶2+18∶3 to 18∶1 occurred in the later stages (mid-linear)
of culture development. Cells readily adapted from 18°C to 13°C, and exhibited a higher growth rate at the lower temperature
after a period of acclimation. Growth was readily inhibited by the sterol biosynthesis inhibitors propiconazole and naftifine,
which blocked brassicasterol biosynthesis at C-14 demethylation and squalene epoxidation, respectively. Growth was also inhibited
by tunicamycin which did so without affecting sterol content. The shift in degree of fatty acid unsaturation did not occur
in cells from cultures at reduced temperature or treated with any of the inhibitors. Since tunicamycin did not affect the
sterol content, delay in the shift in the degree of fatty acid unsaturation was attributed to factors other than a reduction
in sterol content.
Based on a paper presented at the Symposium on Plant and Fungal Sterols: Biosynthesis, Metabolism and Function, held at the
AOCS Annual Meeting, Baltimore, MD, April 1990. 相似文献
3.
Characterization of polar and nonpolar seed lipid classes from highly saturated fatty acid sunflower mutants 总被引:4,自引:0,他引:4
Rosario Álvarez-Ortega Sara Cantisán Enrique Martínez-Force Rafael Garcés 《Lipids》1997,32(8):833-837
The seed lipids from five sunflower mutants, two with high palmitic acid contents, one of them in high oleic background, and
three with high stearic acid contents, have been characterized. All lipid classes of these mutant seeds have increased saturated
fatty acid content although triacylglycerols had the highest levels. The increase in saturated fatty acids was mainly at the
expense of oleic acid while linoleic acid levels remained unchanged. No difference between mutants and standard sunflower
lines used as controls was found in minor fatty acids: linolenic, arachidic, and behenic. In the high-palmitic mutants palmitoleic
acid (16∶1n−7) and some palmitolinoleic acid (16∶2n−7, 16∶2n−4) also appeared. Phosphatidylinositol, the lipid with the highest
palmitic acid content in controls, also had the highest content of palmitic or stearic acids, depending on the mutant type,
suggesting that saturated fatty acids are needed for its physiological function. Positional analysis showed that mutant oils
have very low content of saturated fatty acids in the sn-2 position of triacylglycerols, between the content of olive oil and cocoa butter. 相似文献
4.
The carbon and energy source for aerobically grown cultures ofCandida guilliermondii profoundly influenced the neutral lipid content and the fatty acid composition of the individual lipid components. Methanol
(0.80%, w/v) grown cells cultivated at 30 C in presence of 0.025% ammonium sulfate contained 12% total lipids, 67% of which
was neutral lipids. Glucose (0.74%, w/v) or ethanol (0.53%, w/v) grown cells contained 21–22% total lipids, 80% of which was
neutral lipids, under the same conditions. Methanol-grown cells contained a decreased 18∶1 acid (52–54% of total fatty acids)
and an increased 18∶2 acid (23–25%), as compared with glucose- or ethanol-grown cells which contained 57–66% 18∶1 acid and
8–14% 18∶2 acid, in both neutral and polar lipid fractions. The relationship between methanol metabolism and desaturation
of fatty acid in yeast was discussed. 相似文献
5.
Nikolaus Weber Klaus Vosmann Kurt Aitzetmüller Christin Filipponi Horst Taraschewski 《Lipids》1994,29(6):421-427
The sterol composition of free sterol and steryl ester fractions of the fish parasiteParatenuisentis ambiguus was determined. In addition, the fatty acid composition of various neutral lipid classes, i.e., wax esters, steryl esters,
triacylglycerols and free fatty acids, as well as the composition of the 1-O-alkyl moieties of total ether glycerolipids of the parasite, were investigated. The results of these studies were compared
with those obtained on the intestinal tract tissue of its host, the eel (Anguilla anguilla). Cholesterol is the major sterol in bothP. ambiguus andA. anguilla. However, the sterols ofP. ambiguus contain high proportions (>20%) of other sterols, such as campesterol and various dehydrosterols. [e.g., 7-dehydrocholesterol
and cholesta-5,22(E)-dienol]. The presence of these minor sterols agrees with the known biotransformations of exogenous sterols in various helminths.
Considerable differences are found in the fatty acid composition of neutral lipid fractions, as well as the total lipid extract
from the endoparasite as compared to the host tissue. In particular, eicosapentaenoic acid (20∶5n−3), other polyunsaturated
fatty acids, such as 20∶4n−6, 22∶5n−3 and 22∶6n−3, as well as long-chain saturated fatty acids, such as 20∶0, are generally
enriched in the neutral lipid fractions of the parasite as compared to those of infected eel intestine. The analysis of ether
glycerolipids revealed that 1-O-hexadecyl (16∶0) and 1-O-hexadecenyl (16∶1) moieties were present in similar proportions in the ether lipids of bothP. ambiguus and eel intestine, whereas 1-O-octadecyl (18∶0) moieties are more prominent in the parasite and 1-O-octadecenyl (18∶1) moieties in the eel. The results of these studies show thatP. ambiguus has specific mechanisms for the regulation of the sterol and fatty acid composition of its neutral lipids.
Dedicated to Professor Helmut K. Mangold on the occasion of his 70th birthday. 相似文献
6.
The effects on [14C] sterol synthesis and excretion by exposure of L-929 cells to several phosphatidylcholines (PC) has been examined. No significant
effects were noted on either parameter during a 6-hr period if exposure of cells to the phospholipid preceded the addition
of [1-14C] acetate by just 30 min. However, if cultures were grown in media containing delipidized serum and 2×10−5 M PC through 2 or more subculturings prior to adding [1-14C] acetate, the amount of [14C] sterol increased in both cells and medium by 70–200% when saturated or monounsaturated PC were used. Dilinoleylphosphatidylcholine
(18∶2 PC) at the same concentration did not stimulate synthesis or excretion of newly synthesized sterol. Total cellular sterol
was determined by gas chromatography, and was only marginally affected by long-term exposure to dipalmitylphosphatidylcholine
(16∶0 PC), whereas the total sterol of the medium increased by 4-fold over a 19-hr period. Cultures which had been exposed
to 16∶0 PC through 3 subculturings continued to display enhanced de novo sterol synthesis, but not excretion, for up to 5
hr after replacement with fresh medium lacking 16∶0 PC. The disparity in response to 2×10−5 M levels of 16∶0 PC and 18∶2 PC may relate to differences in metabolism of cellular fatty acids, whereas relatively small
changes in the cellular fatty acid composition were noted with 16∶0 PC-treated cells. The results indicate that extracellular
PC can promote sterol synthesis and excretion by L-929 cells, and that the magnitude of this response is influenced by the
time of exposure to the phospholipid and by its fatty acid composition. 相似文献
7.
Robert S. Burkhalter Carol A. Smith David C. White Ronald Fayer Andrew B. White 《Lipids》1998,33(8):829-833
Heating or freezing leads to loss in infectivity of oocysts of Cryptosporidium parvum toward neonatal BALB/c mice and is reflected in the profile of the polar lipid fatty acids. Upon loss of infectivity, the
ratio of polar lipid to neutral lipid fatty acid decreased and the relative proportions of 18∶1n-9 also decreased; proportions
of 18∶2n-6 and 20∶5n-6 increased, whereas the proportions of 16∶0 remained constant with freezing. During these investigations,
a novel fatty acid, 10-OH 18∶0, was discovered in the glycolipid fraction. The identification of a fatty acid unique to species
of Cryptosporidium was thought to provide a specific biomarker for this organism. Cryptosporidium also demonstrated fluctuations in absolute quantities of 10-OH 18∶0 with events that lead to loss of infectivity. This led
to the presumed correlation of this biomarker with infectious Cryptosporidium. The 10-OH 18∶0 was putatively localized at the sn-2 position of phosphatidylethanolamine. High-performance liquid chromatography/electrospray ionization mass spectrometry
revealed that the 10-OH 18∶0 existed principally in the free fatty acid form. Herein, we establish that the free fatty acid
10-OH 18∶0 was, in actuality, an artifact of the procedures for sample preparation. 相似文献
8.
The total lipids and fatty acid composition ofEntomophthora coronata were determined. The fungus was grown on a chemically defined medium and a chemically nondefined medium (Sabouraud dextrose
yeast extract) for a period of 26 days. The organism contained from 16.2% to 44.6% total lipids depending upon the days of
growth. The major fatty acids were 12∶0 (5.5–9.0%), 13∶0 (1.2–8.2%), 14∶0 (33.5–43.5%), 16∶0 (9.7–13.9%), 18∶19 (20.4–22.4%), and 18∶29,12 (3.5–10.5%). Lesser amounts of 15∶0, 16∶1, 16∶2, 17∶0, 18∶0, two other 18∶2 (both having conjugated double bonds), 18∶36,9,12, another 18∶3 (conjugated double bonds), 20∶38,11,14, 20∶45,8,11,14, another 20∶4 (conjugated double bonds), and 24∶1 acids were found. Trace amounts of 20∶0, 20∶1, 20∶2, 22∶0 and 24∶0 were
also present. The relative percentage of most of the fatty acids did not vary appreciably with growth. However, 18∶29,12 and 20∶45,8,11,14 increased with age of the chemically defined culture. Peak E (18∶2, conjugated double bonds) increased and 13∶0 and 18∶36,9,12 decreased with age of the chemically nondefined culture. The fatty acids were predominately saturated (56.9–69.1%) and contained
a high percentage of shorter chain fatty acids (C 12 to C 15). The fatty acids of the chemically defined culture were more
unsaturated than the Sabouraud culture and the unsaturation increased with age of the culture. 相似文献
9.
The fatty acid composition of individual phospholipids in subcellular fractions of sheep platelets and the asymmetrical distribution
of phosphatidylethanolamine (PE) fatty acyl chains across the plasma membrane were examined. The main fatty acids of total
lipid extracts were oleic (18∶1; 32–41%), linoleic (18∶2, 10–17%), stearic (18∶0; 13–15%), palmitic (16∶0; 11–15%) and arachidonic
(20∶4; 8–12%) acids, with a saturated/unsaturated ratio of about 0.4. Each phospholipid class had a distinct fatty acid pattern.
Sphingomyelin (SM) showed the highest degree of saturation (50%), with large proportions of behenic (22∶0), 18∶0 and 16∶0
acids. The main fatty acid in PE, phosphatidylserine (PS) and phosphatidylcholine (PC) was 18∶1n−9. Our findings suggest that
fatty acids are asymmetrically distributed between thecholineversus the non-choline phospholipids, and also between plasma membranes and intracellular membranes. The transbilayer distribution
of PE fatty acids in plasma membranes from non-stimulated sheep platelets was investigated using trinitrobenzenesulfonic acid
(TNBS). A significant degree of asymmetry was found, which is a new observation in a non-polar cell. The PE molecules from
the inner monolayer contained higher amounts of 18∶2 and significantly less 18∶1 and 20∶5 than those found in the outer monolayer,
although no major differences were detected in the transbilayer distribution of total unsaturatedversus saturated PE acyl chains. 相似文献
10.
Neurospora crassa incorporated exogenous deuterated palmitate (16∶0) and 14C-labeled oleate (18∶1Δ9) into cell lipids. Of the exogenous 18∶1Δ9 incorporated, 59% was desaturated to 18∶2Δ9,12 and 18∶3Δ9,12,15. Of the exogenous 16∶0 incorporated, 20% was elongated to 18∶0, while 37% was elongated and desaturated into 18∶1Δ9, 18∶2Δ9,12, and 18∶3Δ9,12,15. The mass of unsaturated fatty acids in phospholipid and triacylglycerol is 12 times greater than the mass of 18∶0. Deuterium
label incorporation in unsaturated fatty acids is only twofold greater than in 18∶0, indicating a sixfold preferential use
of 16∶0 for saturated fatty acid synthesis. These results indicate that the release of 16∶0 from fatty acid synthase is a
key control point that influences fatty acid composition in Neurospora. 相似文献
11.
Uptake and metabolism of saturated (16∶0, 18∶0) and unsaturated [18∶1(n−9), 18∶2(n−6), 18∶3(n−3)] fatty acids by cultured
epimastigotes ofTrypanosoma cruzi were studied. Between 17.5 and 33.5% of the total radioactivity of [1-14C]labeled fatty acids initially added to the culture medium was incorporated into the lipids ofT. cruzi and mostly choline and ethanolamine phospholipids. As demonstrated by argentation thin layer chromatography, gas liquid chromatography
and ozonolysis of the fatty acids synthesized, exogenous palmitic acid was elongated to stearic acid, and the latter was desaturated
to oleic acid and 18∶2 fatty acid. The 18∶2 fatty acid was tentatively identified as linoleic acid with the first bond in
the Δ9 position and the second bond toward the terminal methyl end. Exogenous stearic acid was also desaturated to oleic and
18∶2 fatty acid, while oleic acid was only converted into 18∶2. All of the saturated and unsaturated fatty acids investigated
were also converted to a small extent (2–4%) into polyunsaturated fatty acids. No radioactive aldehyde methyl ester fragments
of less than nine carbon atoms were detected after ozonolysis of any of the fatty acids studied. These results demonstrate
the existence of Δ9 and either Δ12 or Δ15 desaturases, or both, inT. cruzi and suggest that Δ6 desaturase or other desaturases of the animal type are likely absent in cultured forms of this organism. 相似文献
12.
Earthworms (Lumbricus terrestris) were extracted with chloroform-methanol (2∶1) and examined primarily for neutral lipids and fatty acids. TLC showed spots
for sterols, hydrocarbons, free fatty acids, phospholipids and pigments but none for glycerides (tri-, di- or mono). Saponification
of the crude lipid extract yielded 32% fatty acids, 25% unsaponifiables and 43% unidentified. The lipid contained 3% hydrocarbon
and 16% sterols. GLC of the hydrocarbons showed at least 13 components. GLC of the sterol fraction showed peaks corresponding
to cholesterol (the major component), γ-sitosterol, β-sitosterol, stigmasterol, campesterol, and ergosterol. GLC showed that
at least 38 fatty acids were present, with 18∶1, 18∶2, 18∶0, 20∶1 and 17∶0 predominanting.
Abstracted in part from the Ph.D. dissertation of J. Cerbulis, Rutgers, The State University, 1966. 相似文献
13.
The lipid classes, fatty acids of total and individual lipids and sterols of Antarctic krill (Euphausia superba Dana) from two areas of the Antarctic Ocean were analyzed by thin layer chromatography (TLC), gas liquid chromatography (GLC)
and gas liquid chromatography/mass spectrometry (GLC/MS). Basic differences in the lipid composition of krill from the Scotia
Sea (caught in Dec. 1977) and krill from the Gerlache Strait (caught in Mar. 1981) were not observed. The main lipid classes
found were: phosphatidylcholine (PC) (33–36%), phosphatidylethanolamine (PE) (5–6%), triacylglycerol (TG) (33–40%), free fatty
acids (FFA) (8–16%) and sterols (1.4–1.7%). Wax esters and sterol esters were present only in traces. More than 50 fatty acids
could be identified using GLC/MS, the major ones being 14∶0, 16∶0, 16∶1(n−7), 18∶1(n−9), 18∶1(n−7), 20∶5(n−3) and 22∶6(n−3).
Phytanic acid was found in a concentration of 3% of total fatty acids. Short, medium-chain and hydroxy fatty acids (C≤10)
were not detectable. The sterol fraction consisted of cholesterol, desmosterol and 22-dehydrocholesterol. 相似文献
14.
AVibrio species of bacterium known to contain the polyunsaturated fatty acid 20∶5n−3 was grown in both freshwater and seawater media
at 5 and 20°C and examined for adaptive changes in lipid composition. Phosphatidylethanolamine (PE) and phosphatidylglycerol
(PG), together with a smaller proportion of nonesterified fatty acids (NEFA), comprised almost all the lipid under all growth
conditions examined. Temperature had a more pronounced effect than the salinity of the medium on lipid composition. The proportion
of PE in total lipid was always higher at 5 than at 20°C. Conversely, the proportion of NEFA was lower at 5 than 20°C whereas
that of PG was not altered. The levels of saturated fatty acids in total lipid, PE and PG were all decreased by growth at
5°C. No differences were observed with respect to growth temperature in the levels ofcis 16∶1n−7, the principal monoenoic fatty acid in both PE and PG.Trans 16∶1n−7 was found to comprise 12.8–15.2% of fatty acids in PE and PG of bacteria grown at 5°C but only 4.4–8.5% of phospholipid
fatty acids in bacteria cultured at 20°C. Regardless of medium composition, a reduction in growth temperature from 20 to 5°C
also caused the proportions of 20∶5n−3 to increase from around 0.8 to 4.4% in PE and from around 4 to 20% in PG. The simultaneous
occurrence oftrans 16∶1n−7 and 20∶5n−3 is unique to thisVibrio species of bacterium. The increased proportions of both these fatty acids with decreasing temperature suggest that they have
a role in retailoring biomembrane phospholipids during temperature acclimation of the bacterium. 相似文献
15.
The seeds of the winged bean,Psophocarpus tetragonolobus L. were found to be rich in oil. The oil was examined for its iodine value, saponification value and fatty acid composition
by gas liquid chromatography. The value (area percent) for fatty acids as methyl esters were: 14∶0 (0.2%); 16∶0 (9.1%); 16∶1
(0.4%); 18∶0 (5.4%); 18∶1 (41.0%); 18∶2 (29.5%); 18∶3 (1.9%); 20∶0 (2.0%); 20∶1 and 18∶4 together (2.2%); 22∶0 (7.3%) and
24∶0 (1.0%). The iodine value (Wij solution) was 91. The oil contains an appreciable amount of unsaturated fatty acids, especially
linoleic 18∶2 (29.5%). The predominant saturated fatty acid is palmitic 16∶0 (9.1%). 相似文献
16.
The lipid class compositions of adult Pacific oysters [Crassostrea gigas (Thunberg)] were examined using latroscan thin-layer chromatography/flame-ionization detection (TLC/FID), and fatty acid
compositions determined by capillary gas chromatography and gas chromatography/mass spectrometry (GC/MS). The fatty acid methyl
esters were separated using argentation TLC and also analyzed as their 4,4-dimethyloxazoline derivatives using GC/MS. Major
esterified fatty acids inC. gigas were 16∶0, 20∶5n−3, and 22∶6n−3. C20 and C22 nonmethylene interrupted (NMI) fatty acids comprised 4.5 to 5.9% of the total fatty acids. The NMI trienoic fatty acid 22∶3(7,13,16) was also identified. Very little difference was found in the proportions of the various lipid classes, fatty acids or sterols
between samples of adult oysters of two different sizes. However, significant differences in some of the lipid components
were evident according to the method of sample preparation used prior to lipid extraction with solvents. Lyophilization (freeze
drying) of samples led to a significant reduction in the amounts of triacylglycerols (TG) extracted by solvents in two separate
experiments (7.0 and 52.5% extracted). Extracts from lyophilized samples had less 16∶0, C18 unsaturated fatty acids, and 24-ethylcholest-5-en-3β-ol, while C20 and C22 unsaturated fatty acids comprised a higher proportion of the total fatty acids. There was no significant change in the amounts
of polar lipids, total sterols, free fatty acids or hydrocarbons observed in extracts from lyophilized samples relative to
extracts from nonlyophilized samples. Addition of water to the freezedried samples prior to lipid extraction greatly improved
lipid yields and resulted in most of the TG being extracted. 相似文献
17.
James B. Saddler Robert R. Lowry Hugo M. Krueger Ian J. Tinsley 《Journal of the American Oil Chemists' Society》1966,43(5):321-324
To study the fatty acids of the coho salmon, entire fish were homogenized and the total lipids extracted with methanol-chloroform.
The fish ranged in size from 75 to 85 mm total length and contained from 2.1%–6.9% lipid in the tissues. Methyl esters of
the fatty acids were produced with anhydrous methanol and HCl. Qualitative identification of the fatty acid methyl esters
was accomplished by gas-liquid chromatography.
Thin layer silver nitrate-silicic acid plates were used to separate the component methyl esters according to the number of
double bonds. Location of the ethylenic groups of the unsaturated fatty acid methyl esters was established by reductive ozonolysis
and identification of the aldehydes and aldehyde-esters produced. The number of carbons in the unsaturated fatty acid methyl
esters was determined by hydrogenation of each of the fractions.
Fatty acids found in the highest concentrations were: 16∶0, 16∶1, 18∶0, 18∶1, 18∶4, and 22∶6. Fatty acids 16∶0, 18∶1, 18∶2,
20∶5, and 22∶6, differed markedly from concentrations found in tubificid worms, the exclusive diet of the fish during the
experiment.
Technical Paper No. 2059, Oregon Agricultural Experiment Station
Work supported in part by research Grant No. EF105, U.S.P.H.S. 相似文献
18.
The fatty acid composition of diacyl phosphatidylcholine and phosphatidylethanolamine from the brain of rats 3, 6, 9, 12,
15, 18, and 21 days old were determined. In phosphatidylcholine, the relative amounts of stearic and oleic acid increased
from 25% to 33% while the relative amounts of myristic, palmitic, and palmitoleic decreased from 65% to 50% during this time
period. The same pattern was seen in phosphatidylethanolamine with stearic and oleic increasing from 38% to 49% and the shorter
chain acids decreasing from 17% to 13%. The polyunsaturated fatty content of phosphatidylcholine was approximately 10% and
increased slightly during the first 3 weeks, while the polyunsaturated content of phosphatidylethanolamine decreased from
44% to 37%. The molecular species composition of phosphatidylcholine and phosphatidylethanolamine was determined in brains
of rats 3, 6, and 9 days old. The relative amounts of the molecular species remained nearly constant during this time period
with phosphatidylcholine containing 35% saturated, 40% monoenoic, 6% dienoic, 11% tetraenoic, 2% pentaenoic, and 5% hexaenoic.
Phosphatidylethanolamine contained 1% saturated, 8% monoenoic, 3% dienoic, 40% tetraenoic, 9% pentaenoic, and 37% hexaenoic
species. Analysis of the fatty acid composition of the molecular species reveals that in phosphatidylcholine the polyunsaturated
fatty acids 20∶4 and 22∶6 are predominately paired with 16∶0, while in the phosphatidylethanolamine these two unsaturated
fatty acids are paired with 18∶0. Furthermore, dipalmitoyl phosphatidylcholine accounts for approximately 25% of the total
molecular species of that lipid. 相似文献
19.
We have studied the effect of various diets on the phospholipid fatty acid composition andin vitro Δ5 desaturase activity of hepatic microsomes derived either from the normal or streptozotocin-induced diabetic rat. The diets
studied were the standard rat chow diet and a basal fat-free diet supplemented either with 20 percent saturated fat, 20 percent
unsaturated fat, or 20 percent menhaden oil. Phospholipid fatty acid composition analysis revealed that the normal rat fed
the saturated fat or menhaden oil diet had significantly decreased arachidonate levels, consistent with decreased Δ5 desaturase
activities and decreased 18∶2n−6 intake. On the contrary, the unsaturated fat diet decreased dihomo-γ-linolenate and increased
arachidonate levels, without increased Δ5 desaturase activity. Streptozotocininduced diabetes resulted in decreased arachidonate
and Δ5 desaturase activity. The unsaturated fat diet fed to the diabetic rat also failed to correct this decreased Δ5 desaturase
activity. The unsaturated fatty acids in this diet also displaced a substantial amount of n−3 fatty acids in both normal and
diabetic microsomes, due to the competition between these two fatty acid families for incorporation into the membrane phospholipids.
Conversely, the menhaden oil diet fed to the normal and diabetic rats displaced n−6 fatty acids, reduced Δ5 desaturase activity,
and enhanced 22∶6n−3 incorporation into diabetic microsomes. 相似文献
20.
Milk triglycerides from the platypus were subjected to fatty acid and stereospecific analysis to determine the positional
distribution of fatty acids in the triglycerides. Of the major fatty acids, 12∶0 was preferentially esterified at thesn-3 position, 14∶0 and 16∶0 were selectively associated with thesn-2 position, and 18∶0 was located predominantly at thesn-1 position. The unsaturated fatty acids, 14∶1, 16∶1, 18∶1, 18∶2 and 18∶3, were preferentially esterified at thesn-3 position. The fatty acid distribution pattern of the platypus, a monotreme, is similar to that of marsupials and eutherians
but is in contrast to the only other extant monotreme, the echidna. 相似文献