Utilization of endogenous lipid by the isolated perfused rat heart

1. The lipids of the rat heart have been studied with regard to amount, classes present and fatty acid composition of free fatty acids, triglycerides and phospholipids. Myocardial lipid contained 300μmoles of total fatty acid/g. dry wt. of which only 2–4μmoles were free; the remainder was esterified, chiefly as phospholipid. Neutral esters, of which triglyceride was the principal form, made up 15% of the total fatty acids. 2. When normal hearts were perfused with a nutrient-free medium until exhaustion, the triglyceride concentration declined from 43 to 13μmoles/g. dry wt. The content of phospholipids, partial glycerides and cholesteryl esters did not change. When the lipids of the rat heart were labelled with [1-¹⁴C]palmitate before perfusion with non-nutrient medium, radioactivity disappeared from the triglyceride, diglyceride and free fatty acid fractions, but not from the phospholipid or other ester classes. 3. These experiments support the view that only a small fraction of the total cardiac lipid, principally triglycerides and to a smaller extent diglycerides, is available as a source of fuel in the absence of exogenous substrate.     

A comparison of triglycerides from aphids and their cornicle secretions

Direct mass spectrometry of extracts showed that body triglycerides from 30 species of aphids contained the same fatty acid radicals, C₆ (hexanoyl), C_6:2 (sorboyl), C₁₄ (myristoyl), and C₁₆ (palmitoyl) as did the cornicle secretions, but in many species the proportions of hexanoyl and/or palmitoyl triglycerides were greater in the body. When cornicle secretions were collected progressively so as to draw increasingly upon body fat reserves, their composition changed gradually towards that of the body extracts.All summer forms of Myzus persicae had similar body triglycerides, even when selected for resistance to organophosphorus insecticides, or bred for 3 months on an artificial diet. The composition of body triglycerides was also independent of colour in two aphid species in which pink and green forms were compared.Body extracts contain enough triglycerides for their composition to be determined in single aphids and the use of body extracts allows examination of aphids lacking cornicles and of specimens that do not give cornicle secretion because of low body turgor. Although, as in the case of cornicle secretions, the triglyceride composition of body extracts was not well correlated with taxonomic position, body extracts provide a second chemical characteristic that can be used to define a particular species.     

Lipid composition of the fat body and haemolymph and its relation to lipid release in Oncopeltus fasciatus

Lipid composition of the fat body and haemolymph of male milkweed bug, Oncopeltus fasciatus, was determined. Triglycerides were the predominant lipids of the fat body while diglycerides accounted for the major lipid in the haemolymph. Sterols, sterol esters, and non-esterified fatty acids were present in both fat body and haemolymph besides triglycerides and diglycerides. Only traces of monoglycerides were detected.Gas chromatographic analysis of the fatty acids revealed a difference in the fatty acid composition between fat body and haemolymph glycerides and sterol esters. Oleate and linoleate were the predominant unsaturated fatty acids in both fat body and haemolymph lipids and in the milkweed seeds as well.When fat body was labelled in vivo and in vitro with ¹⁴C-palmitate, the fatty acid was incorporated largely into the triglycerides. When the prelabelled fat body was incubated with a medium containing haemolymph the fat body released lipids mainly as diglycerides. Some radioactivity was observed in the triglycerides and non-esterified fatty acids also.Electrophoretic analysis of the incubation medium containing the haemolymph revealed that the released lipids were bound to three haemolymph lipoprotein bands. Lipid mobilization, release, and transport in Oncopeltus are discussed in relation to studies on other insects.     

The Neutral Lipids of Paramecium tetraurelia: Changes with Culture Age and the Detection of Steryl Esters in Ciliary Membranes1

Neutral lipids, particularly triglycerides, accounted for the major decrease in the total lipid content in Paramecium cells that occurs with culture age. Sterols, triglycerides, and steryl esters were the major classes of neutral lipids in cells and isolated cilia. Free as well as high concentrations of esterified sterols were detected in purified ciliary membrane preparations. Stigmasterol and 7-dehydrostigmasterol were the major components of both free and esterified sterols of cells and cilia; however, when cholesterol was present in the growth medium, it was desaturated to 7-dehydrocholesterol and incorporated into cellular and ciliary lipids. Free fatty acids from cells and triglycerides from cells and cilia were low in polyunsaturated fatty acids and reflected the composition of fatty acids in the culture medium. An exception was the reduced concentration of stearate in triglycerides from whole cells. Greater than 50% of triglyceride fatty acids from cilia were saturated. The fatty acid compositions of cellular triglycerides and ciliary steryl esters did not change with culture age, but those of cellular steryl esters and ciliary triglycerides did change. In comparison with phospholipids, these neutral lipid fatty acid compositional changes were smaller. The sensitivity of these stigmasterol-containing cells to polyene antibiotics indicated that they were killed by nystatin > filipin > amphotericin B. The unexpected finding of high concentrations of steryl esters in ciliary membrane preparations is discussed.     

Lipid composition of the entomopathogenic fungus Nomuraea rileyi

The total lipid content, neutral and polar lipid composition, and fatty acid profiles were determined for the different developmental stages of the entomopathogenic fungus, Nomuraea rileyi. In general, the lipid composition of N. rileyi was found to be very similar to that of other Fungi Imperfecti. Triacylglycerides and sterols were the major neutral lipids and phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were the major polar lipids. Phosphatidylcholine, resolved in conidial and mycelial samples, was not detected in hyphal body samples. The major fatty acids were palmitic, oleic, and linoleic. Stearic acid was detected as a minor component of hyphal body samples. During conidiogenesis the overall lipid composition was altered in (1) a reduction in total lipid content, (2) an increase in the polar/neutral lipid ratio, and (3) an increase in the degree of fatty acid unsaturation.     

Triglyceride metabolism in germinating Andropogon gayanus seeds

Seed triglycerides of Andropogon gayanus contained 17 fatty acid moieties, principally palmitic, oleic and linoleic acids. These were distributed in an essentially random manner amongst the triglycerides to form the following main types: POL, PLL, OOL, LLO and LLL. Triglycerides decreased during both light and dark germination but there was no evidence for selective hydrolysis. Free fatty acids appear to be derived from triglyceride hydrolysis but the free and triglyceride fatty acid composition differed. Less palmitic, oleic and linoleic acids and more stearic, linolenic and C₂₀-acids were found in the free state than combined in the triglycerides. Free fatty acids did not accumulate during germination.     

Carbohydrate and fatty acid titres during flight of the migrant noctuid moth,Anticarsia gemmatalis Hübner

Haemolymph concentrations of total carbohydrate and fatty acids were determined in velvetbean caterpillar (Anticarsia gemmatalis Hübner, Lepidoptera: Noctuidae) adult females throughout a 4-hr period of tethered flight. Total carbohydrate concentration decreased from approx. 30 to 10 μg/μl during the first 45 min of flight. Total fatty acid concentration increased from approx. 20 to 40 μg/μl during the first 60 min of flight and then declined to and stabilized at preflight levels. The decrease in wet weight (from approx. 97 to 80 mg/moth) during flight was probably due to defecation since no change in dry weight or haemolymph volume occurred. After 4 hr of flight, no apparent change in whole body lipid content (approx. 12 mg/moth) was observed but the much smaller carbohydrate content was reduced approx. 80% (from approx. 0.6 to 0.1 mg/moth). Approximately equal amounts (approx. 360–550 μg) of carbohydrate and lipid were removed from the haemolymph during 4 hr of flight. Changes in the haemolymph concentrations of palmitic, oleic and linoleic acids correspond to the changes in total fatty acid concentration of the haemolymph, indicating that these are the major components of the lipid mobilized and utilized during flight of A. gemmatalis.     

Influence of growth medium on surface and wall lipid of fungal spores

Conidiospores of Alternaria tenuis, Botrytis fabae, Neurospora crassa and sporangiospores of Rhizopus stolonifer from cultures on various media were shown by microelectrophoresis to have lipid on their surface. Analyses of lipid fractions obtained by sequential solvent extraction demonstrated that surface lipid forms a small but discrete layer different in composition from that within the wall. Free fatty acids, alkanes, triglycerides and other acyl lipids were identified by GC-MS. Phospholipids and sterols were absent. The qualitative and quantitative composition of both the surface and wall lipid fractions was dependent upon the growth medium used.     

Lipid storage and changes during flight by triatomine bugs (Rhodnius prolixus and Triatoma infestans)

Exceptionally large amounts of lipid are stored in flight muscles of Rhodnius prolixus and Triatoma infestans (197 and 90 μmoles glyceride glycerol per g fresh weight respectively). The bulk of this lipid is in the form of triacylglycerol.A significant decrease in the muscle lipid occurs during the first hour of flight. Over the same period there is an increase in haemolymph lipid (particularly of diacylglycerol) which is taken to indicate the use of lipid from the fat body. The carbohydrate content of muscle and haemolymph is low, so it is likely that the supply of energy for flight is provided almost exclusively by the oxidation of fat. Oleate and palmitate are the major fatty acid components of lipid from both Triatoma and Rhodnius and are probably also the major fatty acids used for oxidation.Maturation of flight ability is temporally associated with the development of flight muscle size and increase in glyceride content.     

Effect of essential fatty acid deficiency on the lipid composition of the Yoshida ascites hepatoma (AH 130) and of the liver and blood plasma from host and normal rats.

In order to study the response of a poorly differentiated tumor to nutritional manipulation, the Yoshida ascites hepatoma (AH 130) was grown in rats fed an essential fatty acid (EFA)-deficient diet and in rats fed a control diet. Hepatomas, livers, and blood plasma from host rats and normal rats were studied as to the effects of EFA deficiency on the lipid composition. Normal rats fed an EFA-deficient diet showed an increased concentration of triglycerides and cholesteryl esters in the liver and a reduced level of total phospholipids in plasma. Host rats fed the EFA-deficient diet showed a lower concentration of triglycerides in the liver when compared with the host rats fed a control diet. In addition, EFA-deficient host rats had reduced levels of plasma free fatty acids and triglycerides. These latter were markedly high in host rats under normal dietetic conditions. As compared to the livers of either host rats or normal rats fed the control diet, the Yoshida hepatoma cells had a lower content of total phospholipids and free fatty acids as well as a higher level of free cholesterol; they also showed a typical fatty acid pattern in their phospholipids. The main characteristics of this pattern were a high content of oleic and palmitoleic acids and a low level of C20 and C22 polyunsaturated fatty acids. Exposure of Yoshida hepatoma cells to an EFA-deficient environment resulted in a decrease in the concentration of total phospholipids and free fatty acids and in changes in the fatty acid composition similar to those observed in the livers of normal and host rats. These changes suggest that, under the experimental conditions used, the Yoshida hepatoma cells are responsive to EFA deficiency.     

Haemolymph lipids and fat body lipases of the southern armyworm moth

The haemolymph lipid of the southern armyworm moth, Prodenia eridania, is chiefly diglyceride with smaller amounts of triglyceride, monoglyceride, and free fatty acid also present. The stored lipid of moth fat body is almost all triglyceride. Although flight muscle contains a very active monoglyceride lipase, its ability to hydrolyse tri- and diglycerides is very low. The fat body contains enzymes able to hydrolyse tri-, di-, and monoglycerides. These data do not support the suggestion that fat body triglyceride is converted to diglyceride, which is carried in the haemolymph to the flight muscle and then hydrolysed to free fatty acid for oxidation during flight; rather, they indicate that triglyceride can be completely hydrolysed in the fat body, and the resulting free fatty acid is carried to the flight muscle to provide energy for flight.     

Light,temperature and nitrogen starvation effects on the total lipid and fatty acid content and composition ofSpirulina platensis UTEX 1928

The total lipid and fatty acid content ofSpirulina platensis UTEX 1928 was 7.2 and 2.2% respectively of cellular dry weight under controlled conditions supporting high growth rates. With increases in irradiance from 170 to 870 μmol photon m^?2 s^?1, growth rate increased, total lipid decreased, and fatty acid composition was unaffected. At 1411 μmol photon m^?2 s^?1, total lipid increased slightly and percent composition of the fatty acid gamma linolenic acid increased. Growth and total lipid content ofS. platensis were affected by changes in growth temperature from 25 to 38 °C. With increased growth rate, total lipid content increased. This suggests that the storage of carbon increases at temperatures supporting high growth rates. The degree of saturation increased with temperature. Although the percent composition of gamma linolenic acid was higher at lower growth temperature, production was still primarily a function of growth rate. The effect of temperature on fatty acid content and degree of saturation was of secondary importance. Nitrogen starvation increased total lipid content but decreased fatty acid content as a percentage of dry weight; composition of the fatty acids was unaffected. N-starvation appeared to suspend synthesis of long chain fatty acids inS. platensis, suggesting that some other compound stores fixed carbon when nitrogen is limiting. It was concluded that fatty acid production inS. platensis is maximized by optimizing culture conditions for growth.     

Effect of crowding, food deprivation, and diet on flight initiation and lipid reserves of the lesser grain borer, Rhyzopertha dominica

Effects of crowding, food deprivation, and type of cereal diet upon flight initiation, development, body weight, lipid content, and fatty acid composition of the lesser grain borer, Rhyzopertha dominica (F.), were studied in two field strains and one laboratory strain. Beetles of all strains reared under crowded conditions had significantly higher flight initiation than beetles reared on isolated kernels (uncrowded). Regardless of degree of crowding, flight initiation increased with the period of food deprivation up to a maximum at 24 h, after which flight initiation declined. Body weight and lipid content decreased as the food deprivation period increased, whereas fatty acid composition was not significantly affected by food deprivation. Beetles from a field strain collected in 1995 had higher flight initiation and increased lipid content compared with beetles from the laboratory strain. However, beetles from the laboratory strain were larger, developed faster, and were more fecund than beetles from this field strain. The cereal diet on which beetles were reared also had a significant effect on flight initiation, lipid content, and fatty acid composition. Beetles reared on whole rice and wheat produced adults with higher flight initiation, higher lipid content, and higher oleic acid concentration than beetles reared on whole corn and sorghum.     

Effects of two different medium-chain triglycerides (tri C8:O and tri C12:O) on liver lipids in the growing rat.

Results presented in this study emphasize the long-term effects of dietary fatty acid chain length on some biochemical parameters of the liver in the growing rat. High levels of medium-chain fatty acids feeding (C8:O and C12:O) from 40 to 340 g of body weight induced liver growth and lipid contents intermediary between values recorded with a lipid-free diet and with a diet containing long-chain fatty acids. No steatosis was recorded but neutral lipid contents appeared to be correlated with the dietary fatty acid chain length while phospholipid contents remained much more stable. In the four tested nutritional conditions, only dodecano?c or lauric acid (C12:O) feeding induced important alterations in the fatty acid pattern of liver neutral lipids. Medium-chain fatty acids, and even lauric acid which was intensely esterified in adipose tissue triglycerides, did not appreciably modify the fatty acid composition of liver phospholipids and were not esterified in it.     

Comparison of muscle lipid composition between marine and landlocked forms of sockeye salmon (Oncorhynchus nerka)

• 1.1. Total lipid content, and lipid class and fatty acid compositions in the muscle were analyzed for marine and landlocked forms of sockeye salmon.
• 2.2. Little difference was found for the total lipid content in the muscle between both forms.
• 3.3. Triglycerides were higher in the marine form than those in the landlocked one, but phospholipids showed an opposite tendency.
• 4.4. In the fatty acid composition of total lipid, percentages of 20:1 and 22: 6n-3 were higher in the marine form, while 18:2, 18:3n-3, 18:4n-3 and 20:4n-3 were more abundant in the landlocked one. Fairly high levels of 22:1 were present only in the marine form.

     

Lipid and protein composition and thermotropic lipid phase transitions in fatty acid-homogeneous membranes of Acholeplasma laidlawii B

The membrane composition and lipid physical properties have been systematically investigated as a function of fatty acid composition for a series of Acholeplasma laidlawii B membrane preparations made homogeneous in various fatty acids by growing cells on single fatty acids and avidin, a potent fatty acid synthetic inhibitor. The membrane protein molecular weight distribution is essentially constant as a function of fatty acid composition, but the lipid/protein ratio varies over a 2-fold range when different fatty acid growth supplements are used. The membrane lipid head-group composition varies somewhat under these conditions, particularly in the ratio of the two major neutral glycolipids. Differential thermal analytical investigations of the thermotropic phase transitions of various combinations of membrane components suggest that these compositional changes are unlikely to result in qualitative changes in the nature of lipid-protein or lipid-lipid interactions, although lesser changes of a quantitative nature probably do occur. The total lipids of membranes made homogeneous in their lipid fatty acyl chain composition exhibit sharper than normal gel-to-liquid-crystalline phase transitions of which midpoint temperatures correlate very well with the phase transition temperatures of synthetic hydrated phosphatidylcholines with like acyl chains. Our results indicate that using avidin and suitable fatty acids to grow A. laidlawii B, it is possible to manipulate the position and the sharpness of the membrane lipid phase transition widely and independently without causing major modifications in other aspects of the membrane composition. This fact makes the fatty acid-homogeneous A. laidlawii B membrane a very useful biological membrane preparation in which to study lipid physical properties and their functional consequences.     

Effect of dietary sunflower oil and coconut oil on adipose tissue gene expression, fatty acid composition and serum lipid profile of grower pigs

The present study was conducted to assess whether the partial replacement of feed energy by vegetable oils containing high medium-chain saturated fatty acids (MCFA) and n-6 polyunsaturated fatty acids (PUFA) would modify lipogenic gene expression and other parameter of fat metabolism in pigs. Eighteen pigs (17-19 kg body weight) received one of three experimental diets for 60 days (six animals per group): (i) Control diet; (ii) a diet with sunflower oil (SO) or (iii) a diet with coconut oil (CO). In diets SO and CO, 10% of the feed energy was replaced by the respective oils. The experimental treatment did not influence the performance of the pigs. In blood serum, an increased content of total cholesterol was observed for SO and CO fed animals, whereas no significant changes for total triglycerides and different lipoprotein fractions were detected. The fatty acid composition of adipose tissue was significantly modified, with an increased content of MCFA and n-6 PUFA in CO and SO fed pigs, respectively. The gene expression for fatty acid synthase was decreased for SO and CO fed pigs; for stearoyl CoA desaturase and sterol regulatory element binding protein, a depression was observed in SO but not in CO fed pigs. The results of present study suggest that the type of dietary fat can modulate the adipose tissue gene expression and fatty acid composition differentially, with minimal effect on serum lipid profile.     

Lipoidal Components of Bacterial Lipopolysaccharides: Nature and Distribution of Fatty Acids in Aerobacter aerogenes

The fatty acid distribution of Aerobacter aerogenes was studied by comparing the fatty acid composition of the lipoidal component of the endotoxin (lipid A) with the fatty acids of the readily extractable native lipids and total cellular fatty acids. The results for total cellular fatty acids and readily extractable native lipids were generally similar, but both quantitative and qualitative differences exist. In addition, profound differences between these two fractions and lipid A were observed. These differences included fewer fatty acids and lower concentrations of unsaturated and cyclopropane fatty acids in the lipid A. Hydroxy fatty acids persisted in the lipid A. The significance of these differences with respect to mammalian toxicity of endotoxins is discussed.     

Changes in the biochemical composition of Balanus balanoides (L.) under experimental conditions: The effect of a starch diet

A comparison has been made of the changes in biochemical composition of experimental and natural populations of Balanus balanoides (L.). The ‘bodies’ and the ovary were separately analysed. The lipid components have been investigated in some detail; lipid classes were separated and the component fatty acids of the major components (triglycerides + diglycerides and phospholipids) determined.Animals fed on brine shrimp increased in weight more than the natural population, that of the starved animals was less, and that of animals fed on starch only, even less. The starch-fed animals continued to produce faecal pellets and it is suggested that the greater energy expenditure in feeding (cirral) activity with little gain of useful metabolic substrate was responsible for this decrease in body weight. These differences extend to the component lipid classes. Even so, these starch-fed animals produced ovarian tissue as, indeed, did starved animals, presumably by transfer of body material; the low level or absence of nutrients did not interfere with the hormonal stimulation of reproduction.     

Effects of temperature and nutritional changes on the fatty acids of agmenellum quadruplicatum.

The fatty acid composition of the blue-green bacterium Agmenellum quadruplicatum was examined under a wide variety of growth conditions. The fatty acid composition was found to undergo significant changes with variations in temperature, media composition, and growth phase (log versus stationary). With increasing growth temperature (20 to 43 C) log-phase cells exhibited an increase in saturated fatty acids (38.4% at 20 C to 63.6% at 43 C). Striking changes were seen with some of the individual fatty acids such as 18.3, which made up 16.0% of the total fatty acid at 20 C but was not neasurable at 43 C. Fatty acid 12:0 was not measurable at 20 C but made up 16.3% of the total fatty acids at 43 C. Cell lipids were separated into neutral lipid, glycolipid, and very polar liquid fractions. The neutral lipid fraction was composed almost entirely of 12 carbon fatty acids (12:0, 12:1). Glycolipid and very polar lipids were more similar in their fatty acid composition when compared to the total cellular fatty acids, although they did lack 12 carbon fatty acids. The total of 12 carbon fatty acids in the cell can be used as an indicator of the amount of neutral lipid present.