Altered cholesterol ester proportions in embryonic tissues of dystrophic chicken

The concentrations of cholesterol esters in tissues of dystrophic chicken embryos are altered from normal. These changes are accompanied by significant changes in the proportions of the esterified fatty acids (the fatty acid profile). In serum and pectoral muscles there is a shift to a higher proportion of unsaturated fatty acids (in particular 18:1). Thigh muscle esters are little changed and in liver and brain the proportion of unsaturated fatty acids decreases.     

Role of the season and of the nutritonnal state on the distribution of tissular fatty acids in the hibernating dormouse (Eliomys quercinus L.)]

Seasonal changes were observed in fatty acid composition of plasma, liver and cardiac muscle. During hibernation unsaturated fatty acids levels increase in plasma cholesterol esters (CE), glycerides (GL) and phospholipids. After spring arousal, the oleic acid content decreases in total fatty acids of liver and cardiac muscle. In summer fasting induces lipid changes similar to that occuring in natural hibernation. Desaturation observed in winter can be explained by the accumulation of unsaturated GL and CE in the tissues.     

Phospholipids and their fatty acids in mitochondria, synaptosomes and myelin from the liver and brain of trout and rat: a new view on the role of fatty acids in membranes

The content of different phospholipids (PL) and their fatty acid (FA) composition in subcellular fractions from the liver and brain of rat (Rattus rattus) and trout (Salmo irideus) were estimated. It was shown that despite higher content of unsaturated fatty acids in myelin compared to synaptosomes, the unsaturation index of the latter is equal or higher than that of myelin. The total content of PL polyunsaturated fatty acids (PUFA) was shown to be higher in membrane structures with more active ion transport (mitochondria). This feature seemed to be characteristic of membranes from both representatives of homoiotherms and poikilotherms studied. A possible role for PUFA information within the lipid monolayer of areas with different capacity to accept electrons and transport them along a sort of intermolecular 'tunnel' is discussed. The double bonds of PUFA in this area seem to be able to produce bonds similar to conjugated bonds.     

Seasonal variations of lipid fatty acids of boreal freshwater fish species

1. The fatty acid levels of muscle and liver lipids of perch, vendace and rainbow trout (Salmo gairdneri) cultivated in the same area (for comparison) were monitored. 2. The total lipid content in the muscle of perch (Perca fluviatilis) and vendace (Coregonus albula) was less than 50% of that in rainbow trout and a seasonal variation was clear only in vendace. 3. The relative amounts of polyunsaturated fatty acids as well as omega-3 acids were higher in vendace and perch than in cultivated rainbow trouts. Arachidonic acid content was much higher in vendace and perch than in rainbow trout. The content of monoenes was considerably higher in rainbow trout than in free freshwater fish. 4. The seasonal variations in the degree of unsaturation were small in fish muscle. 5. In the muscle of rainbow trout the relative amount of polyunsaturated fatty acids diminished with the increase of total lipids.     

The fatty acids of trichinellae]

The composition of fatty acids of lipids in the muscles of rats and larvae of Trichinella spiralis and T. nativa developing in them were studied. Both species are characterized by practically the same composition of fatty acids, only in the frost-resistant species T. nativa there was a sufficient amount (up to 3.5%) of docosapenta- and docosahexaenic acids (22:5 and 22:6). The comparison of the content of individual fatty acids in larvae and in muscles of the host by means of statistical correlation analysis suggests that larvae obtain a considerable portion of palmitic acid from the host and transform in into necessary long-chain saturated and unsaturated fatty acids by means of elongating and desaturating enzymes. Changes in the contents of fatty acids in larvae extracted from dead rats, which during some days were undergone freezing at negative temperatures (-8-10 degrees), are the same in quality for both species. These changes can be explained if we assume that the activity of elongases and desaturases of Trichinella decreases with cooling to a greater extent than the supply of palmitic acid from the host's tissues. A higher frost-resistance of T. nativa may be associated as with a greater protection of enzymes in the membranes by long-chain polyene acyls so with a higher thermal stability of proteins themselves.     

Lipids of marine cold-water fishes

The study deals with the lipid and fatty acid compositions of the muscles, gills and liver of marine fishes inhabiting cold waters (0.5–6°C) and caught in Peter the Great Bay (3 species) and Vostok Bay (2 species), as well as with the fatty acid compositions of the main phospholipids in the muscle tissues of fish from Olyutorskii Bay (4 species). The average content of phosphatidylcholine was about 60% in muscles and in the liver and 53.8% of the sum of all phospholipids in gills. The phosphatidylethanolamine content was on the average 24.3, 25.1 and 22.3% in muscles, liver and gills, respectively. Increased contents of phosphatidylserine and sphingomyeline were recorded in the gills. The mean (S.D.) molar ratios of cholesterol/phospholipids were 0.20, 0.32, and 0.58 in the muscles, liver, and gills, respectively. It was established that phosphatidylcholine has a higher content of saturated fatty acids, whereas phosphatidylethanolamine was richer in monoenic acids and docosahexaenoic acid (DHA). It was noted that the level of polyenic fatty acids was increasing and the level of monoenic and saturated acids was decreasing in the series from gills-liver-muscles. The species with a more active mode of life were distinguished by an increased content of docosahexaenoic acid.     

Fatty acid composition and energy state of liver mitochondria after the administration of antioxidants of the ionol group to albino rats

Injections of albino rats with antioxidants of the ionol group cause cyclic changes in the energy state of liver mitochondria which are correlated with changes in the fatty acid composition of mitochondrial membranes. The increase in the degree of coupling between oxidation and phosphorylation coincides in time with the increment in the content of saturated fatty acids and a decrease in the unsaturated fatty acid content in the total fraction of mitochondrial membrane lipids. Conversely, the activation of the external pathway of NADH oxidation and a decrease of the respiratory control are correlated with the diminution of the saturated fatty acid content and an increased percentage of unsaturated fatty acids. These changes are especially well pronounced in the case of fatty acids carrying 18 carbon atoms.     

Incorporation of 1-14C-acetate into fatty acids and sterols by isolated hepatocytes of thermally acclimated rainbow trout (Salmo gairdneri)

Summary Rates of 1-¹⁴C-acetate incorporation into specific fatty acids and sterol fractions were determined at assay temperatures of 5°C and 20°C in hepatocytes isolated from warm (20°C)- and cold (5°C)- acclimated rainbow trout (Salmo gairdneri). Rates of sterol lipogenesis were 2.5- to 3-fold higher in hepatocytes from cold-acclimated trout. Rates of acetate oxidation and of total fatty acid lipogenesis did not differ significantly between acclimation groups. Fatty acid compositions did not change significantly during the experiment (9–12 h), but hepatocytes from cold-acclimated trout possessed significantly higher levels of polyunsaturates and unsaturates of the linolenic acid (n-3) family, and significantly lower levels of monounsaturates than did hepatocytes from warm-acclimated animals. Hepatocytes from cold-acclimated trout channeled a larger percentage of their total acetate incorporation into unsaturated fatty acids at 5°C than at 20°C due primarily to increased recovery of acetate in polyunsaturates and monoenes at 5°C. In contrast, hepatocytes from warm-acclimated trout channeled a slightly smaller percentage of their total acetate incorporation into unsaturates at 5°C than at 20°C. Hepatocytes from warm-acclimated trout incorporated significantly more 1-¹⁴C-acetate into the unsaturated fatty acid fraction (due primarily to incorporation into the diene fraction and less importantly all other classes of unsaturates) and significantly less into the saturated fatty acid fraction than hepatocytes from cold-acclimated trout when assayed at 20°C; similar but less dramatic differences were observed at 5°C. Consequently, unsaturated/saturated ratios for acetate incorporation ranked: warm-acclimated at 20°Cwarm-acclimated at 5°Ccold-acclimated at 5°C>cold-acclimated at 20°C. These results suggest that regulation of the relative rates of unsaturated and saturated fatty acid synthesis is involved in lipid restructuringduring adaptation from one temperature regime to another, but that other mechanisms must be invoked to explain the maintenance of observed steady state differences between the fatty acid compositions of warm- and cold-acclimated trout.This work was supported by grant PCM-76-04313-AO1 from the National Science Foundation     

Studies to determine the role rates of chain elongation and desaturation play in regulating the unsaturated fatty acid composition of rat liver lipids.

Rat liver microsomes were used to measure the rates of chain elongation and desaturation of acids in the linoleate, oleate and palmitoleate biosynthetic pathways. These studies were designed to determine whether there is a relationship between rates of conversion and the types of unsaturated fatty acids found in rat liver lipids. In some cases rates of conversion correlate well with the types of unsaturated fatty acid found inrat liver lipids. In other cases, rates of conversion must be correlated with other controls such as competitive interactions, retroconversion, and specificities for incorporating given acids into lipids in order to explain the unsaturated fatty acid composition of rat liver lipids. The roles and interrelationships of these various metabolic processes are discussed relative to the control of polyunsaturated fatty acid biosynthesis.     

Effects of saturated and unsaturated fats given with and without dietary cholesterol on hepatic cholesterol synthesis and hepatic lipid metabolism

Hepatic cholesterol synthesis was studied in rats after consuming diets of varying neutral lipid and cholesterol content. Cholesterol synthesis was evaluated by measuring 3-hydroxy-3-methylglutaryl-CoA reductase and by determining the rate of 3H-labeled sterol production from [3H]mevalonate. Results were correlated with sterol balance data and hepatic lipid content. Hepatic cholesterol synthesis was relatively great when cholesterol was excluded from the diet. The source of neutral dietary lipids, saturated vs. unsaturated, produced no change in hepatic sterol synthesis. Values for fecal sterol outputs and hepatic cholesterol levels were also similar in rats consuming either saturated or unsaturated fats. When 1% cholesterol was added to the diet, hepatic cholesterol synthesis was suppressed but the degree of suppression was greater in rats consuming unsaturated vs. saturated fats. This was associated with greater accumulation of cholesterol in livers from rats consuming unsaturates and a reduction in fecal neutral sterol output in this group as opposed to results from rats on saturated fats. Cholesterol consumption also altered the fatty acid composition of hepatic phospholipids producing decreases in the percentages of essential polyunsaturated fatty acids. It is concluded that dietary cholesterol alters cholesterol and fatty acid metabolism in the liver and that this effect is enhanced by dietary unsaturated fats.     

Comparative study of the lipid composition of rabbit and lobster sarcoplasmic reticulum.

Sarcoplasmic reticulum (SR) membranes isolated from rabbit and lobster muscles have similar phospholipid classes, but they differ in plasmalogen content. The plasmalogenic species are mostly distributed among phosphatidylethanolamines (PE's) and make up about 62% of the total in rabbit SR and about 46% in lobster membranes. Lobster SR phospholipids contain large amounts of polyunsaturated fatty acids which are present in low amounts in rabbit membranes. The total unsaturated fatty acids of phosphatidylcholines (PC's) represent about 53% and 73% of the total fatty chains for rabbit and lobster SR, respectively. The values found for PE's were about 56% and 64%, respectively. Furthermore, lobster membranes contain significant amounts of PC and PE molecular species with unsaturated fatty acids in positions 1 and 2, whereas rabbit SR contain low amounts.     

Change of the content of lipids and their fatty acid composition in egg yolks and liver of breeding hens and embryos depending on the level of carotenoids in their diet

The paper presents the results of studies on the content of total lipids, phospholipids and total lipids' fatty acid composition of Shaver-579 breeding hens' liver, egg yolk and 19 days embryo's liver. The reverse dependence is established between the content of unsaturated fatty acids in lipids of egg yolk and intensity index of lipid metabolism in the liver of 19 days embryo.     

Species differences in membrane susceptibility to lipid peroxidation

The susceptibility of liver microsomes to lipid peroxidation was evaluated in seven species: rat, rabbit, trout, mouse, pig, cow, and horse. Lipid peroxidation was measured as thiobarbituric acid reactive substances formed in the presence of either FeCl₃-ADP/ascorbate or FeCl₂/H₂O₂ initiating systems. For rat, rabbit, and trout microsomes, the order of susceptibility to peroxidation was rat > rabbit >> trout. The lack of peroxidation in trout microsomes could be explained by high microsomal vitamin E levels. Membrane fatty acid levels differed between species. Docosahexaenoic acid predominated in the trout, arachidonic acid in the rat, and linoleic acid in the rabbit. The contribution of individual fatty acids to lipid peroxidation reflected the degree of unsaturation with docosahexaenoic > arachidonic >>> linoleic. For all species except trout, the predicted susceptibility to peroxidation, based on the response of individual fatty acids, agreed well with directly measured microsomal peroxidation. With the exception of the trout, vitamin E content ranged from 0.083–0.311 nmol/mg microsomal protein between species, and low levels did not influence susceptibility to peroxidation. Trout microsomes peroxidized only after vitamin E depletion by prolonged incubation. The data indicate that below a vitamin E threshold, species differences in membrane susceptibility to peroxidation can be reasonably predicted based only on content of individual peroxidizable fatty acids.     

Acyl coenzyme A: Phospholipid acyltransferases in porcine platelets discriminate between ω-3 and ω-6 unsaturated fatty acids

The properties of porcine platelet acyltransferases which catalyze the incorporation of unsaturated fatty acids into the 2 positions of phospholipids were compared with those of porcine liver microsomes and rat liver microsomes. There were significant differences in the relative rates of incorporation of acyl groups into phospholipids as catalyzed by the membranes from different species and organs. The 1-acylglycerophosphate acyltransferase system showed relatively broad specificity for saturated and unsaturated fatty acids, with 14- to 20-carbon chains, while unsaturated acyl-CoAs with 18- and 20-carbon chains were generally good substrates in the acylations of 1-acylglycerophosphocholine and 1-acylglycerophosphoinositol. ω-3 and ω-6 unsaturated fatty acids were recognized differently by different acyltransferase systems in platelets. When activities for combinations of ω-3 and ω-6 unsaturated acyl-CoAs with the same number of carbons and with similar number of double bonds were compared, ω-6 fatty acids were relatively more preferred substrates than ω-3 fatty acids for the 1-acylglycerophosphoinositol acyltransferase system as compared with 1-acylglycerophosphocholine acyltransferase system.     

Different role of saturated and unsaturated fatty acids in beta-cell apoptosis

It is believed that free fatty acids contribute to the pathogenesis of type 2 diabetes in humans. We have recently shown that lipoapoptosis of human beta-cells is specifically induced by saturated fatty acids while unsaturated had no effect. In the present study we tested the effect of co-incubation of different saturated and unsaturated free fatty acids on lipoapoptosis in beta-cells. RIN1046-38 cells and isolated human beta-cells were incubated with combinations of saturated fatty acids (palmitate, stearate) and mono- or polyunsaturated fatty acids (palmitoleate, oleate, and linoleate). Cells were incubated for 24-72 h with 1mM fatty acids. All unsaturated fatty acids tested completely prevented palmitate- or stearate-induced apoptosis of rat and human beta-cells as assessed by flow cytometric cell cycle analysis and TUNEL assay. This might suggest that apoptosis in vivo is predominantly determined by the content of unsaturated fatty acids in a mixed fatty acid pool.     

Fatty acyl CoA synthetase from Antarctic notothenioid fishes may influence substrate specificity of fat oxidation

Antarctic notothenioid fishes possess large lipid stores that are important fuels for aerobic metabolism. Oxidative muscle tissues of these animals oxidize long-chain mono-unsaturated fatty acids more readily than saturated fatty acids. The mechanistic basis(es) for the substrate specificity of their fatty acid-oxidizing pathway is unknown. We examined the substrate specificity of fatty acyl coenzyme A synthetase (FACS) to determine whether the enzyme contributes to targeting unsaturated fatty acids for preferential transport into mitochondria as fuels for beta-oxidation. Maximal activities of FACS were measured in isolated mitochondria from Notothenia coriiceps and Chaenocephalus aceratus oxidative skeletal muscles in the presence of fatty acids differing in chain lengths and degrees of unsaturation. With the exception of C(22:6), maximal activities were greater with unsaturated substrates than with C(16:0), a saturated fatty acid. Monoenoic fatty acids did not produce the highest activities. Predicted amino acid sequences of FACS from Antarctic C. aceratus, Gobionotothen gibberifrons, and N. coriiceps and sub-Antarctic Notothenia angustata and Eleginops maclovinus were determined to identify amino acid candidates that may be important for determining the substrate specificity of FACS. Substitutions cysteine548 and polar threonine552 within the putative fatty acid binding pocket may contribute to preference for unsaturated fatty acyl substrates compared to saturated fatty acids.     

Effects of phospholipase A2 and albumin on the calcium-dependent ATPase and the lipid composition of sarcoplasmic membranes.

1. The calcium-dependent ATPase activity of phospholipase-A2-digested sarcoplasmic vesicles decreases concomitantly with the contents of residual lysophospholipids and fatty acids when increasing albumin concentrations are applied. 2. Delipidated albumin preferentially removes unsaturated fatty acids and lysophosphatidylcholine. A complete removal of the phospholipids by albumin does not occur. 3. The membrane-bound lysophospholipids were analysed with respect to type of phospholipid, plasmalogen content and fatty acid chains by means of thin-layer chromatography and gas chromatography. 4. While the fatty acid composition of the lysophospholipids is independent of the degree of delipidation, the composition of the residual free fatty acids is found to change with the albumin concentration. 5. Reactivation of the Ca2+-ATPase by oleate leads to reasonable activities at room temperature as long as a minimum of about 30 lysophospholipid molec-les per ATPase is left. The course of the residual Ca2+-ATPase activity with the degree of delipidation is related to the presence of unsaturated fatty acids. 6. No specific role of either sphingomyelin or the plasmalogens has been found.     

Seasonal dynamics of fatty acid composition in female northern pike (Esox lucius L.)

Seasonal changes in the fatty acid composition of neutral and polar lipids were measured in the ovary, liver, white muscle, and adipopancreatic tissue of northern pike. The role of environmental and physiological factors underlying these changes was evaluated. From late summer (August–September) to winter (January–March), the weight percentage of n-3 polyunsaturated fatty acids (especially 22:6n3) declined significantly in the neutral lipids of all somatic tissues examined. However, large quantities of n-3 polyunsaturated fatty acids accumulated in the recrude cing ovaries during fall and the weight percentage of n-3 polyunsaturated fatty acids in ovary polar lipids also increased significantly. Additionally, the n-3 polyunsaturated fatty acid content of somatic polar lipids increased significantly during fall due to increases in the total polar lipid content of the somatic tissues. This suggests that during fall n-3 polyunsaturated fatty acid are diverted away from somatic neutral lipids and thereby conserved for use in ovary construction and for incorporation into tissue polar lipids. The percentage of n-3 polyunsaturated fatty acid in ovary neutral lipids also declined during fall and early winter, perhaps as an adaptation to conserve these fatty acids for storage in oocyte polar lipids and later incorporation into cellular membranes of the developing embryo. Reductions in the n-3 polyunsaturated fatty acids content of somatic and ovarian neutral lipids during fall were compensated for specifically by increases in the percentage of monounsaturated fatty acids rather than saturated fatty acids. This suggests that the ratio of saturated to unsaturated fatty acids in pike neutral lipid, is regulated physiologically, and hence may influence the physiological functioning of these lipids. During fall and early winter the percentage of saturated fatty acids declined significantly in the polar lipids of all tissues examined. This change was consistent with the known effects of cold acclimation on the fatty acid composition of cellular membranes. As the ovaries were recrudescing from September to January, liver polar lipids exhibited significant decreases in the percentage of total polyunsaturated fatty acids and n-3 polyunsaturated fatty acids and increases in monounsaturated fatty acids, and acquired a fatty acid composition very similar to that of ovary polar lipids. Therefore, seasonal changes in the percentage of polyunsaturated and monounsaturated fatty acids in liver polar lipids probably reflect the liver's role in vitellogenesis rather than the effects of temperature on membrane fatty acid composition. At all times of year, the fatty acid compositions of white muscle and adipopancreatic tissue neutral lipids were very similar, which may indicate a close metabolic relationship between these lipid compartments.Abbreviations AP adipopancreatic - BHT butylated hydroxytoluene - CI confidence interval - EFA essential fatty acids - MUFA monounsaturated fatty acids - NL neutral lipids - PL polar lipids - PUFA polyunsaturated fatty acids - SFA saturated fatty acids     

Comparison of Different Methods for Preparation of Human Milk Casein

Changes of the estradiol and lipid concentrations in hen serum, and those in the fatty acids of hen and cockerel livers were studied during the maturing period. The concentrations of estradiol and lipid in serum reached a maximum level a few days before the onset of laying, and then fell. A marked increase in oleate, and decreases in stearate and arachidonate were observed in both the liver and serum lipids of the hen when reaching laying. The fatty acid compositions of the serum and liver of the hen at 145 and 167 days of age were close to those of yolk lipid. In the cockerel, high contents of stearate and arachidonate and a low content of oleate were observed, and the fatty acid composition did not change appreciably with age. On estrogenization of the male chick, the fatty acid cmposition of the liver lipid was similar to that of the laying hen liver. The ratio of the unsaturated fatty acid/saturated fatty acid in the liver of hen increased when reaching laying, the value at 167 days old being close to that of yolk lipid. This ratio in the liver lipid of cockerel did not change significantly throughout the experimental period.