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1.
Liver mitochondrial and microsomal phosphatidyl cholines differing in the degree of unsaturation of their fatty acids have
been separated into four fractions by silver ion silica gel TLC. The levels of the four phosphatidyl choline fractions were
determined for male and female rats and mice, fetal and young rabbits, and female hamsters and guinea pigs. The sum of phosphatidyl
choline fractions 1, 2, and 3 of mitochondria and microsomes was greater in the female rat than in the male rat with the difference
being a reflection of a higher level of fraction 3 which contains arachidonic acid. The female rat has greater concentration
of phosphatidyl choline fractions 1 and 3 of mitochondria. Similar results were seen in mouse liver microsomes but not in
mitochondria. The levels of the individual four fractions varied from species to species. No change occurred in the levels
of the phosphatidyl choline fractions of fetal (−9 and −3 days) rabbits, but an increase was seen in the level of fraction
4 between day 3 and day 35 in both the mitochondria and microsomal fractions of liver. The concentration of mitochondrial
and microsomal protein, total phospholipid and total lecithin phosphorus were determined in rat, mouse, hamster and guinea
pig. The total phospholipid phosphorus/protein (μg/mg) of microsomes was greater in all species than that observed in mitochondria.
Liver microsomes contain 45–50% of total phospholipid phosphorus as lecithin whereas mitochondria contains 32–37%. The fatty
acid patterns of mitochondria and microsomal phosphatidyl cholines were determined and the ratio of palmitate to stearate
was greater than two for mice and hamsters and approximately 0.5 for rat and guinea pigs. 相似文献
2.
Phosphatidyl choline is a major lung surfactant. Insufficient development of the surfactant in neonates is often associated
with the Respiratory Distress Syndrome. The concentration and fatty acid composition of phosphatidyl choline have not been
studied in the subcellular organelles of the developing lung. This study has investigated the development of the concentration
and fatty acid composition of phosphatidyl choline in subcellular fractions of 28-day and 30-day fetal and maternal New Zealand
rabbit lungs. The concentration of total phospholipids in lamellar bodies increased four to five fold from 28-day fetus to
30-day fetus which, in turn, was similar to the maternal level. Total phospholipid content increased only about 50% in mitochondria
and microsomes. The percentage of phosphatidyl choline among total phospholipids in lamellar bodies increased successively
from 60% at 28 days gestation to 84% at 30 days gestation and leveled at 84% in maternal lamellar bodies. Microsomal PC increased
steadily from 52% in the 28-day fetus to 65% in the adult. Analysis of the fatty acid composition of phosphatidyl choline
in lamellar bodies confirmed 16∶0 as the major fatty acid, and its content remained constant from 28 days gestation to adult.
In contrast, the content of 16∶0 of the microsomal phosphatidyl choline decreased with increasing gestation. Changes of several
unsaturated fatty acid components were observed in both lamellar bodies and microsomes in the developing lungs. Maturational
development of phosphatidyl choline is reflected in an increase in the concentration of this surfactant, particularly in lamellar
bodies, and possibly in remodeling of fatty acid composition in both lamellar bodies and microsomes. 相似文献
3.
To see how the metabolism of specific phosphatidyl choline fractions might be affected when only a limited source of methyl groups was available, rats were fed for 7 days a low methionine, cholinedeficient diet or one supplemented with either choline or methionine. Prior to killing, they were injected with14C-methyl methionine and liver and plasma phosphatidyl choline isolated and separated by argentation chromatography into 3 major unsaturated fractions. Fatty acid composition and radioactivity of the fractions were determined. Deficient rats had reduced total liver phosphatidyl choline when compared with the supplemented groups, but the proportions of 20∶4 and 22∶6 fatty acids in the total phosphatidyl choline were unchanged. Plasma phosphatidyl choline also was reduced sharply by the deficiency, as was its proportion of 20∶4 fatty acid. Specific activities of the liver 22∶6, 20∶4, and 18∶2 phosphatidyl choline fractions showed that deficient rats had less radioactivity in their 20∶4 and 18∶2 phosphatidyl choline than did the supplemented animals. Plasma phosphatidyl choline fractions presented a similar pattern. Feeding methionine or choline nearly doubled radioactive methyl group incorporation into the 20∶4 phosphatidyl choline fraction of liver and plasma, while incorporation into the 22∶6 phosphatidyl choline was reduced or unchanged. The results suggested that, in the rat, limited availability of methyl groups altered the metabolism of liver and plasma phosphatidyl choline fractions. Methionine, as a source of labile methyl groups, appears necessary for the normal synthesis of certain unsaturated phosphatidyl choline fractions (particularly 20∶4 phosphatidyl choline). Transmethylation of phosphatidyl ethanolamine molecular species to the corresponding phosphatidyl choline species may be an important reaction in normal lipid metabolism and transport. Relative affinities for incorporation of the labeled methyl groups into the phosphatidyl choline fractions of either deficient or supplemented rats were: 22∶6>20∶4>18∶2. 相似文献
4.
Total lipids from whole pig adrenal glands as well as from their mitochondria, microsomes, liposomes, and cell sap were extracted and fractionated first into neutral lipids and phospholipids. The highest percentage of neutral lipids was found in the cell sap, and the lowest in the microsomal fraction. Neutral lipids were subfractionated into cholesteryl esters, free cholesterol, triglycerides, and free fatty acids. Cholesteryl esters were distributed throughout the liposomes. Free fatty acids represented a substantial part of cell sap lipids, but were present also in the mitochondria, microsomes, and liposomes. Fatty acids of all fractions were analyzed by gas liquid chromatography. Free fatty acids and cholesteryl ester fatty acids from all cellular fractions were similar in composition and were characterized by considerable quantities of linoleic and arachidonic acid. Triglycerides were characterized by an increased percentage of palmitic and a low content of arachidonic acid. Phosphatidyl choline, phosphatidyl ethanolamine, diphosphatidyl glycerol, and sphingomyelin plus phosphatidyl inositol were isolated from the lipids by preparative thin layer chromatography, and their fatty acids analyzed by gas liquid chromatography. Phosphatidyl choline and phosphatidyl ethanolamine from mitochondria, microsomes, and cell sap were very similar in respect of their fatty acid composition. Sphingomyelin plus phosphatidyl inositol was characterized by a high content of C22:2omega6. Diphosphatidyl glycerol was present in mitochondria and in the cell sap. 相似文献
5.
The influence of different fat diets on liver phospholipid, cholesterol and dolichol was studied. Rats were separated into
four groups and fed standard laboratory chow (control), a diet containing linolenic acid, a coconut oil diet, or a corn oil-containing
diet. After five weeks, microsomes and mitochondrial/lysosomal fractions were prepared from the liver, and lipid compositions
were analyzed. No changes in phospholipid content were observed. In control animals, the fatty acid compositions of phosphatidylcholine
and phosphatidylethanolamine in the two subfractions were similar. However, these two phospholipids showed different fatty
acid patterns, which were altered independently upon dietary treatment. The dietary treatments resulted, in most cases, in
decreased cholesterol and dolichol contents and, especially in microsomes, in a decreased level of esterification of both
lipids. The fatty acid compositions of cholesteryl esters in the two subfractions showed significant differences and cholesterol
was esterified to a large extent with linolenic acid when this fatty acid was supplied in the diet. The same dietary treatment
exerted different effects on the cholesterol localized in the two different intracellular compartments. This difference was
most pronounced in rats fed the corn oil-containing diet; microsomal cholesteryl esters exhibited increased saturation, whereas
cholesteryl esters in the mitochondrial/lysosomal fraction displayed decreased saturation. Dolichyl esters in the two cellular
compartments had different fatty acyl compositions, with a considerably higher degree of saturation in microsomes. The various
diets influenced the nature of the fatty acid moieties present in the isolated fractions and the effects on the two subfractions
were opposite. The diet containing linolenic acid decreased the degree of saturation in microsomal dolichyl esters and increased
the degree of saturation in the mitochondrial/lysosomal fraction. The results demonstrate that the fatty acid compositions
of both dolichyl and cholesteryl esters display organelle specificity. Both the content of these lipids and their fatty acid
compositions are greatly influenced by dietary conditions, and the esterification processes at different cellular locations
exhibit independent regulation, regardless of the fatty acid content of the diet. 相似文献
6.
Four normal and two individuals with Type IIa hyperlipoproteinemia were placed on the National Heart and Lung Institute Type IIa diet (low cholesterol, smaller than 300 mg/day, high polyunsaturated, low saturated fat diet) for 1 week and on a normal diet the following week. Plasma samples were obtained and the triacylglycerols, phospholipids, and cholesterol contents of plasma and of very low density lipoproteins, low density lipoproteins, and high density lipoproteins determined. Triacyglycerol fatty acid composition was determined and stereospecific analyses of triacglycerols and phosphatidyl cholines performed. Structural determinations were limited to one normal and one Type IIa individual. In normal and Type IIa individuals, chylomicrons contained twice the amount of 18:0 as did the very low density lipoproteins, low density lipoproteins, or high density lipoproteins. The structure of the triacyglycerols from the very low density lipoproteins and low density lipoproteins was asymmetric with at least 50M% 16:0 in the sn-1 position and mostly 18:1 in positions sn-2 and 3. There was a marked difference in the distribution of 18:2 in low density lipoproteins of the normal and Type IIa individuals. The control contained equal amounts of 18:2 in the sn-1 and sn-3 positions, whereas IIa low density lipoprotein was asymmetric with 26% of the 18:2 in position sn-1 and 3% in the sn-3 position. Very low density lipoprotein was asymmetric with regard to 18:2 in control and IIa samples with an average of 5% of the 18:2 in position sn-1 and 40% in position sn-3. The phosphatidyl cholines contained predominantly 16:0 and 18:0 in position sn-1, whereas the acids in position sn-2 were unsaturated with very little difference between lipoprotein classes. Neither the short dietary periods nor source of plasma affected the structure of the phosphatidyl cholines. 相似文献
7.
Chemical composition of subcellular components of HeLa, KB, human heart and liver tissue-culture cell lines have been studied.
The concentration of RNA, protein and phospholipid (μg/μg of DNA) of total subcellular particles was similar for all four
cell lines studied. The greatest RNA concentration and lowest protein concentration is found in the microsomes as compared
to the other subcellular fractions of HeLa and KB cells.
The lipid P/Protein N ratio of mitochondria was greater than the other subcellular fractions from tissue-culture cell lines
studied. Phosphatidyl choline and phosphatidyl ethanolamine are the major phospholipids with the former more predominant in
all of the subcellular fractions of tissue-culture cells studied. Phosphatidyl inositol, phosphatidyl serine, sphingomyelin
and polyglycerol phosphatide were shown to be present. Phosphatidyl choline composition (per cent of total lipid-P) is greatest
in the microsomes when compared with the other subcellular fractions obtained from all of the cell lines studied except the
nuclear fraction of human liver cells. Correspondingly, the mitochondrial fraction for all of the tissue culture cell lines
contains the greatest composition of phosphatidyl ethanolamine except for the human liver and heart cells. The mitochondrial
fraction contains the lowest amount of phosphatidyl inositol. Polyglycerol phosphatide is mainly present in the mitochondrial
fraction of the tissue-culture cells.
Part of a thesis submitted to the Graduate School of the University of North Dakota in partial fulfillment for the degree
of Doctor of Philosophy. 相似文献
8.
Bile phosphatidyl choline from sheep, in contrast to that from nonruminants, contains low levels of the normal range of polyunsaturated fatty acids. A comparison has been made of the composition of bile phosphatidyl cholines from sheep receiving either a control diet, a control diet supplemented with unprotected maize oil, or a control diet supplemented with soybean oil or tallow that had been protected against hydrolysis and hydrogenation of the rumen. The composition of bile phosphatidyl choline from sheep receiving protected soybean oil supplement was virtually indistinguishable from that from nonruminants. 相似文献
9.
The lipid content, distribution and fatty acid composition of highly purified bovine liver nuclear membranes was determined
and compared to those of microsomes prepared in parallel. Contrasted with microsomes, nuclear membranes while containing nearly
the same levels of lipid had more cholesterol and total neutral lipid and less phospholipid. Phospholipid and neutral lipid
patterns generally were similar for the two types of membranes. The same fatty acids, in similar proportions, were observed
in respective total lipid, total polar lipid, phosphatidyl choline and phosphatidyl ethanolamine fractions of the two membrane
types. The microsomal lipid fractions contained slightly greater percentages of unsaturated fatty acids. With respect to previous
results from preparations contaminated with nonmenbranous nuclear material, purified fractions contained more total lipid
on a protein basis and more total unsaturated fatty acids. Only minor differences in levels and distribution of phospholipids
and neutral lipids were observed between the crude and highly purified fractions.
Purdue University AES Journal Paper No. 4482. 相似文献
10.
The effect of ethanol ingestion on choline phosphotransferase and phosphatidyl ethanolamine methyltransferase activities,
the two enzymes involved in phosphatidyl choline biosynthesis in liver microsomes, has been investigated. Female rats were
fed a 5% ethanol-liquid diet containing amino acids, minerals, vitamins, with and without choline, for 2, 6, and 10 weeks.
Control animals were pair-fed the same isocaloric diet with 5% sucrose with and without choline. Ethanol administration with
or without dietary choline stimulated significantly (P<0.001) the specific activities of phosphatidyl ethanolamine methyltransferase
in liver microsomes in the animals fed 5% ethanol for 2, 6, and 10 weeks, when compared to those control animals pairfed the
isocaloric diet with or without choline. Ethanol administration with or without dietary choline for 2 weeks stimulated significantly
(P<0.02) the specific activities of choline phosphotransferase. The specific activities of phosphatidyl ethanolamine methyltransferase
continued to increase in the liver microsomes from the animals in which dietary choline was omitted for 2, 6, and 10 weeks
in the sucrose controls and alcohol-fed animals. Ethanol administration stimulates significantly (P<0.001) the phosphatidyl
ethanolamine methyltransferase specific activities in liver microsomes of animals fed the liquid diet with dietary omission
of choline and methionine for 2 weeks. 相似文献
11.
Rats of weaning age were fed for a period of 1,3 or 6 weeks either a control diet (laboratory stock diet) or a semisynthetic
diet containing 20% by weight of either mustard seed oil (1/3 of the total fatty acids were comprised of erucic acid) or corn
oil (2/3 of the total fatty acids consisted of linoleic acid). Mitochondrial and microsomal fractions were isolated from the
hearts and livers of these rats, and the rate of acylation ofsn-[U-14C] glycerol 3-phosphate (P) was examined using palmitoyl-CoA or erucoyl-CoA as the acyl donor. In addition, activities of
phosphatidate phosphatase of the mitochondrial, microsomal and soluble fractions were assayed. Studies on the acylation of
glycerol 3-P with palmitoyl-CoA demonstrated that feeding of the high fat/high erucic acid diet for 1,3 or 6 weeks significantly
increased the rate of formation of monoacylglycerol 3-P by the cardiac subcellular fractions as compared to the control. The
rate of formation of diacylglycerol 3-P also increased but to a lesser degree. Feeding the high fat/high linoleic acid diet
tended to increase acylation of glycerol 3-P by cardiac subcellular fractions. However, neither high fat diet influenced acyltransferase
activities of the hepatic subcellular fractions or phosphatase activities of the cardiac and hepatic fractions. Studies on
the acylation of glycerol 3-P with erucoyl-CoA demonstrated that the rate of acylation was ca. 1/10 that measured using palmitoyl-CoA
in all experiments; in particular, the formation of diacylglycerol 3-P was extremely slow, suggesting that erucoyl-CoA is
an unsuitable substrate for the position-2 of the monoacylglycerol 3-P. The rate of acylation by the cardiac and hepatic subcellular
fractions was not influenced by the feeding of the high-fat diets. The rate of glycerol 3-P acylation by both cardiac and
hepatic mitochondrial fraction was ca. 2/3 of the rate of acylation by the respective microsomal fraction. In addition, the
ratio of monoacyl-to diacylglycerol 3-P synthesized by the mitochondrial fraction was smaller than that by the microsomal
fraction. These results suggest that acylation of glycerol 3-P by the mitochondrial cannot be attributed to the action of
the contaminating microsomal enzymes. 相似文献
12.
The desaturation of14C-1-linoleic acid to γ-linolenic acid and their incorporation into the microsomal lipids of rats fed on a balanced diet and
a protein diet were measured in vitro. It was shown that a protein diet does not change significantly the distribution of
the radioactivity among the different lipidic fractions compared to the animals fed on a balanced diet. However the microsomal
desaturation of linoleic acid to γ-linolenic acid increased in the rats maintained on a protein diet. Besides, the amount
and composition of the free fatty acids present in the microsomes of the animals fed on both diets were similar enough to
discard the hypothesis that they may modify the desaturation of linoleic acid produced by the diet. The enzymic activity of
the linoleyl desaturase of liver microsomes of animals fed on a protein diet, measured in substrate saturating conditions,
is greater than in animals with balanced diet. Consequently the results support the hypothesis that a protein diet increases
specifically the desaturating activity of the microsomes. 相似文献
13.
We have studied the effect of streptozotocin (SZ)-induced diabetes on fatty acyltransferase and phospholipase enzyme activities
involved in the synthesis and degradation of rat liver phosphoglycerides. Neither mitochondrial nor microsomal acyl-CoA: glycerol
3-phosphate acyltransferase (GPAT) activity was altered, although insulin treatment stimulated mitochondrial GPAT activity.
However, microsomal acyl-CoA: 1-acylglycerol 3-phosphate acyltransferase (1-acyl-GPAT) activity increased (24–33 per cent,
p<0.01) in the diabetic animals using 3 different acyl-CoA donors: palmitoyl-CoA, oleoyl-CoA and linoleoyl-CoA. SZ-induced
diabetes also increased acyl-CoA:1-acylglycerol 3-phosphorylcholine acyltransferase (GPCAT) activity (38–45 per cent, p<0.01)
with 3 different acyl-CoA donors: oleoyl-CoA, linoleoyl-CoA and arachidonoyl-CoA. 1-acyl-GPAT and GPCAT activity returned
to normal with insulin treatment. In contrast to the increased activity of the microsomal fatty acyltransferases 1-acyl-GPAT
and GPCAT, SZ-induced diabetes decreased mitochondrial phospholipase A2 activity and lysophospholipase activity (49–70 per cent, p<0.01). Insulin treatment of the diabetic rats corrected the decreased
lysophospholipase and stimulated phospholipase A2 activity 35 per cent higher than controls. Since microsomal 1-acyl-GPAT and GPCAT are known to have higher activity toward
unsaturated fatty acyl-CoA donors, the increased GPCAT activity coupled with the decreased lysophospholipase activity and
the increased 1-acyl-GPAT activity in diabetes would tend to increase the formation of newly synthesized phospholipids containing
unsaturated fatty acids. This mechanism plus the decreased fatty acid desaturase (4) may be the factors which alter the fatty
acid composition of phosphoglycerides in diabetic rat liver microsomes. 相似文献
14.
Methods for isolation and characterization of subcellular particles as well as procedures for analysis of lipid class composition
are discussed. The literature on distribution of lipids in subcellular particles is then reviewed. Pertinent new data from
our laboratories are presented as well. The isolated particles are related to the organelles to which they correspond in the
cell and are discussed with regard to heterogeneity and morphological integrity. Confusion can arise with regard to subcellular
particles unless it is appreciated that: 1) preparation of particles of high purity generally requires more than the classical
differential centrifugation scheme (both differential and gradient centrifugation may be required); 2) it is hazardous to
apply exactly the same procedure for all tissues; 3) all subcellular fractions must be thoroughly characterized.
The more recently devised DEAE cellulose column and thin-layer chromatographic procedures for analysis of lipid class composition
are more reliable than the older hydrolytic or silicie acid column or paper chromatographic techniques.
The chief lipid components of mitochondria from all organs and species are lecithin, phosphatidyl ethanolamine, and cardiolipin
(diphosphatidyl glycerol). Despite the fact that reports in the literature are in agreement that phosphatidyl inositol is
a major component of mitochondria, it is concluded on the basis of new data obtained from highly purified mitochondria and
improved analytical methods that phosphatidyl inositol is not a major component of mitochondria. The presence of a relatively
large amount of phosphatidyl inositol in mitochondrial preparations is probably related in part to contamination with other
particles. Some analytical procedures are demonstrated to give erroneous values for this lipid class. It is also concluded
that phosphatidyl serine, phosphatidic acid, sphingomyelin, cerebrosides, and lysophosphatides, reported to occur in mitochondria,
are not characteristic mitochondrial components and furthermore that the large amount of uncharacterized mitochondrial phospholipid
reported is actually an analytical artifact. Microsomes appear to be similar to mitochondria except that cardiolipin is either
low in or absent from microsomes. Available data indicate nuclei to be rather similar to mitochondria and microsomes, at least
in some organs.
Studies of the fatty acids of subcellular particles indicate that different particles from one organ have very similar fatty
acid compositions. It is clear that there are marked variations in fatty acid composition of particles from different organs
and from different species. Differences in dietary fat may be associated with marked changes in fatty acid composition, although
brain mitochondrial lipids are largely unchanged. Each lipid class from mitochondria of most organs appears to have a fairly
characteristic fatty acid composition. Cardiolipin from some organs contains primarily linoleic acid, phosphatidyl ethanolamine
contains large amounts of linoleic and higher polyunsaturates, and lecithin is similar to phosphatidyl ethanolamine except
that it does not contain as much arachidonic acid and/or other highly unsaturated fatty acids. New data, the first to be reported,
are presented for heart mitochondrial cardiolipin, phosphatidyl ethanolamine, and lecithin.
It is concluded that there are two basically different types of membranous structures. Myelin is the chief representative
of the metabolically stable type of membrane structure while mitochondria represent the more labile type. The two types of
membranes have very different in vivo properties and very different lipid compositions. Myelin is characterized by a high
content of cholesterol and sphingolipids with more long chain saturated or monoenoic fatty acids while mitochondria are characterized
by a low cholesterol content, little or no sphingolipid, and highly unsaturated fatty acids. It is clear that formulations
of the myelin type membrane structure such as that of Vandenheuvel cannot apply to mitochondria. It is postulated that membrane
structures intermediate between the extremes represented by myelin and mitochondria exist. 相似文献
15.
The proportions of the different lecithin fractions have been determined in HeLa and KB tissue culture cells and Ehrlich Ascites
tumor. 82.8% of the total phosphatidyl choline phosphorus is found in fraction 3 of HeLa cells. The major phosphatidyl cholines
found in KB cells and Ehrlich Ascites tumor are in fractions 3 and 4 and representing 66.6% and 88.7% of the total phosphatidyl
choline P, respectively. The incorporation of 1,2-14C-choline and 1,2-14C-ethanolamine into the various phosphatidyl choline fractions has been assayed to determine their biosynthesis in Ehrlich
Ascites tumor. The incorporation of 1,2-14C-choline into fractions 3 and 4 is 100 times the 1,2-14C-ethanolamine. This evidence indicates that the methylation pathway of phosphatidyl choline synthesis is very low in HeLa,
KB and Ehrlich Ascites cells.
One of 13 papers presented at the symposium “Lipid Metabolism in Cells in Culture,” AOCS Meeting, Houston, May 1971.
Part of a thesis submitted to the Graduate School of the University of North Dakota in partial fulfillment of the Degree of
Master of Science. 相似文献
16.
Triiodothyronine-induced alteration of the lipid pattern in rat-liver mitochondria and microsomes has been investigated. In
mitochondria, a 25% total cholesterol decrease and a 14% phospholipid increase have been detected. In these hyperthyroid rat
liver organelles, a strong decrease in the total cholesterol/phospholipid molar ratio occurs. On the contrary, in microsomes
from the same animals, a decrease of about 23% has been measured for both total cholesterol and phospholipids; hence, in this
fraction, the total cholesterol/phospholipid molar ratio is unaffected by hyperthyroidism. The liver mitochondrial phospholipid
composition, unlike the microsomal composition, is altered significantly in hyperthyroid rats; a 7.4% phosphatidylcholine
decrease is accompanied by a similar additive percentage increase of both phosphatidylethanolamine and cardiolipin. In regard
to total phospholipid fatty acid composition in liver microsomes from hyperthyroid rats, no variation has been observed compared
with the control rats, whereas in mitochondria from the same animals, a meaningful linoleic acid decrease with a similar arachidonic
acid increase has been found. In addition to fatty acid alteration, the separated mitochondrial phospholipid classes also
exhibit some increase in stearic acid. Among phospholipids, cardiolipin changes the most of the esterified fatty acids in
hyperthyroid rat liver. In this compound, a strong increase in the percentage of both palmitic and stearic acid and a 32.4%
decrease of linoleic acid have been found. 相似文献
17.
The fatty acid composition of the major liver microsomal phospholipids has been studied during pre- and postnatal development
of the rabbit. The fatty acid composition of the total lipids, phosphatidyl choline, and phosphatidyl ethanolamine from animals
−6, −3, 0, +3, +6, +9, +16, and +112 days of age was determined. Fatty acid composition is similar in phosphatidyl choline
and phosphatidyl ethanolamine for oleic acid at +3, +6, +9, and +16 day old animals; palmitoleic acid at +9 day old animals
and linoleic acid at −6, −3, and 0 day old animals.
Palmitoleic acid demonstrated a uniform decrease during early development in the total lipids and in both phosphatidyl choline
and phosphatidyl ethanolamine; however, in the 112 day animal, the amount was just slightly lower than that observed for the
earliest prenatal animal studied. Oleic acid decreased considerably during early postnatal development in the total lipids,
phosphatidyl choline and phosphatidyl ethanolamine, but an increase in the 112 day animal was observed. Linoleic acid fluctuated
considerably throughout postnatal development in the total lipids as well as in the two major phosphatides.
Lecithin biosynthesis has been studied by two pathways during development of rabbit liver from −6 days to +110 days. The two
pathways of lecithin biosynthesis were evaluated by assaying the activities of the liver enzymes choline phosphotransferase
and phosphatidylmethyltransferase at different time intervals during development. The greater enzymatic activity was observed
in the cholinephosphotransferase during development. 相似文献
18.
The fatty acid patterns of rat liver mitochondrial and microsomal phospholipids were analyzed from term fetuses, 1 and 4 days
old, and adult rats. The main fatty acids of phosphatidylethanolamine and-choline were stearic and palmitic acids, although
the patterns differed slightly. The fatty acid composition of corresponding phospholipids in mitochondria and microsomes was
similar. The fatty acid pattern of cardiolipin was dominated by linoleic acid. The most consistent feature of the developmental
changes in the fatty acid patterns of all phospholipids studied was a decrease in the relative amount of monounsaturated fatty
acids. The percentages of saturated fatty acids in phosphatidyl-ethanolamine and-choline increased during neonatal development.
It is suggested that the high levels of fetal monounsaturated fatty acids were due to low availability of polyunsaturated
fatty acids. 相似文献
19.
Alteration of lipid constituents of cellular membranes has been proposed as a possible mechanism for cancer promotion by fumonisin
B1 (FB1). To further investigate this hypothesis a dietary dosage which initiates and promotes liver cancer (250 mg FB1/kg) was fed to male Fischer rats for 21 days and the lipid composition of plasma, microsomal, mitochondrial and nuclear subcellular
fractions determined. The effect of FB1 on the cholesterol, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), as well as sphingomyelin (SM) and the phospholipids-associated
fatty acid (FA) profiles, were unique for each subcellular membrane fraction. PE was significantly increased in the microsomal,
mitochondrial and plasma membrane fractions, whereas cholesterol was increased in both the microsomal and nuclear fraction.
In addition SM was decreased and increased in the mitochondrial and nuclear fractions, respectively. The decreased PC/PE and
polyunsaturated/saturated (P/S) FA ratio in the different membrane fractions suggest a more rigid membrane structure. The
decreased levels in polyunsaturated fatty acids in PC together with a pronounced increase in C18:1ω9 and C18:2ω6 were indicative
of an impaired delta-6 desaturase. The increased ω6/ω3 ratio and decreased C20:4ω6 PC/PE ratio due to an increase in C20:4ω6
in PE relatively to PC in the different subcellular fractions suggests a shift towards prostanoid synthesis of the E2 series.
Changes in the PE and C20:4ω6 parameters in the plasma membrane could alter key growth regulatory and/or other cell receptors
in lipid rafts known to be altered by FB1. An interactive role between C20:4ω6 and ceramide in the mitochondria, is suggested to regulate the balance between proliferation
and apoptosis in altered initiated hepatocytes resulting in their selective outgrowth during cancer promotion effected by
FB1. 相似文献
20.
The aim of the present study was to investigate the hepatic regulation and β-oxidation of long-chain fatty acids in peroxisomes
and mitochondria, after 3-thia- tetradecylthioacetic acid (C14-S-acetic acid) treatment. When palmitoyl-CoA and palmitoyl-l-carnitine were used as substrates, hepatic formation of acid-soluble products was significantly increased in C14-S-acetic acid treated rats. Administration of C14-S-acetic acid resulted in increased enzyme activity and mRNA levels of hepatic mitochondrial carnitine palmitoyltransferase
(CPT)-II. CPT-II activity correlated with both palmitoyl-CoA and palmitoyl-l-carnitine oxidation in rats treated with different chain-length 3-thia fatty acids. CPT-I activity and mRNA levels were,
however, marginally affected. The hepatic CPT-II activity was mainly localized in the mitochondrial fraction, whereas the
CPT-I activity was enriched in the mitochondrial, peroxisomal, and microsomal fractions. In C14-S-acetic acid-treated rats, the specific activity of peroxisomal and microsomal CPT-I increased, whereas the mitochondrial
activity tended to decrease. C14-S-Acetyl-CoA inhibited CPT-I activity in vitro. The sensitivity of CPT-I to malonyl-CoA was unchanged, and the hepatic malonyl-CoA concentration increased after C14-S-acetic acid treatment. The mRNA levels of acetyl-CoA carboxylase increased. In hepatocytes cultured from palmitic acid-
and C14-S-acetic acid-treated rats, the CPT-I inhibitor etomoxir inhibited the formation of acid-soluble products 91 and 21%, respectively.
In contrast to 3-thia fatty acid treatment, eicosapentaenoic acid treatment and starvation increased the mitochondrial CPT-I
activity and reduced its malonyl-CoA sensitivity. Palmitoyl-l-carnitine oxidation and CPT-II activity were, however, unchanged after either EPA treatment or starvation. The results from
this study open the possibility that the rate control of mitochondrial β-oxidation under mitochondrion and peroxisome proliferation
is distributed between an enzyme or enzymes of the pathway beyond the CPT-I site after 3-thia fatty acid treatment. It is
suggested that fatty acids are partly oxidized in the peroxisomes before entering the mitochondria as acylcarnitines for further
oxidation. 相似文献