Effect of fatty acid supplementation on the lipid composition of Mycobacterium smegmatis ATCC 607, grown at 27° and 37°C

Mycobacterium smegmatis ATCC 607 was grown at 27 and 37°C, with and without exogenous unsaturated fatty acids, viz. elaidic, oleic and palmitoleic acids, added to the growth medium. The total lipid content of M. smegmatis ATCC 607 was lower at 27°C, and with added oleic acid, when compared with the controls, but higher in presence of palmitoleic acid. At 37°C no significant differences were noted in the total lipid content. In general, the total lipid content was lower with all of the fatty acid supplementations at both 27 and 37°C. The phosphatidylethanolamine content was slightly higher at 27°C in the presence of elaidic or palmitoleic acid, but was markedly lower with oleic acid supplementation at 37°C. The cardiolipin content was lower in the presence of any of the fatty acids at 27°C, and higher in the medium supplemented with elaidic or oleic acid at 37°C. The unsaturated to saturated fatty acids ratio was higher with palmitoleic acid supplementation at 27°C, but remained unchanged in cells grown at 37°C. The modifications in mycobacterial lipids are a reflection of the organism's ability to adapt to changing growth conditions.     

Effect of salinity on the formation of avermectins, odor compounds and fatty acids byStreptomyces avermitilis

Streptomyces avermitilis was cultivated at different concentrations (0–12%) of NaCl in the medium and the content of fatty acids, production of odorous compounds and avermectins were measured. With increasing medium salinity the content of monoenoic fatty acids, particularly palmitoleic acid, increased while the quantity of branched fatty acids dropped. The production of avermectin was constant up to 0.5% of the salt in the medium and then it strongly decreased, reaching zero at 2.5% salt. The biosynthesis of oxolones and geosmin differed: the content of oxolones increased with growing salinity whereas the production of geosmin dropped.     

Effect of salinity on the lipid and fatty acid composition of the halophyteNavicula sp.: potential in mariculture

Navicula sp. (cf.N. tenelloides) was isolated from a salt marsh in Kuwait. The alga grew best with 0.5M NaCl, but abundant growth still occurred up to 2.5M NaCl. The total lipid content and the carotene to chlorophyll ratio of the cells increased with increasing salinity of the medium from 0.5 to 1.7M NaCl, but declined with 2.5M NaCl. Irrespective of the medium salinity, the major lipid class was that of triacylglycerols. The predominant fatty acids in the total lipids of cells grown at different NaCl concentrations were palmitic (16:0) and palmitoleic (16:1) acids; eicosapentaenoic acid (20:5) made up 8–9% of the total fatty acids. The fatty acid composition of the individual lipid classes of cells grown at different salinities is described. The highest concentration of 20:5 occurred in monogalactosyldiacylglycerols and digalactosyldiacylglycerols. In view of the rather small size of this diatom, its halotolerance and its fair content of 20:5, it is suggested as a potential food source for the mariculture industry.     

Effect of salinity of medium on cellular fatty acid composition of marine algaPorphyridium cruentum (Rhodophyceae)

Porphyridium cruentum Näg. (clone 161) was found to grow best in medium containing between 0.45 M and 0.8 M NaCl. From studies done on growing cultures, the palmitic acid content of the cells decreased with increasing NaCl concentration of the medium. Conversely, when the culture was transferred from a 0.8 M NaCl medium to 0.2 M NaCl, the amount of palmitic acid in thePorphyridium cells increased with time of incubation and it contributed up to 64.5% of the total fatty acid content. There appears to be a negative correlation between the cellular content of palmitic acid and the growth lag. The oleic acid content varied only marginally with increasing NaCl concentration. The poly-unsaturated acid content (linolenic and arachidonic acids) decreased initially and then increased with NaCl concentration up to and beyond ca. 0.8 M NaCl respectively. At 1.5 M NaCl, the poly-unsaturated fatty acids amounted to 78.2% of the total fatty acids in the cell. For stationary phaseP. cruentum cultures, a similar relationship existed between fatty acids and NaCl concentration. However, palmitic acid was accumulated up to three-fold more when compared to the exponential culture grown in low salinity. In addition stearic acid was also found in significant quantities.     

Composition of plasma fatty acids and non-cholesterol sterols in anorexia nervosa

Anorexia nervosa is a model of simple starvation accompanied by secondary hyperlipoproteinemia. The pattern of plasma fatty acids influences the levels of plasma lipids and lipoproteins. The concentration of plasma lathosterol is a surrogate marker of cholesterol synthesis de novo, concentrations of campesterol and beta-sitosterol reflect resorption of exogenous cholesterol. The aim of the study was to evaluate fatty acids in plasma lipid classes and their relationship to plasma lipids, lipoproteins, cholesterol precursors and plant sterols. We examined 16 women with anorexia nervosa and 25 healthy ones. Patients with anorexia nervosa revealed increased concentrations of total cholesterol, triglycerides, HDL-cholesterol, campesterol and beta-sitosterol. Moreover, a decreased content of n-6 polyunsaturated fatty acids was found in all lipid classes. These changes were compensated by an increased content of monounsaturated fatty acids in cholesteryl esters, saturated fatty acids in triglycerides and both monounsaturated and saturated fatty acids in phosphatidylcholine. The most consistent finding in the fatty acid pattern concerned a decreased content of linoleic acid and a raised content of palmitoleic acid in all lipid classes. The changes of plasma lipids and lipoproteins in anorexia nervosa are the result of complex mechanisms including decreased catabolism of triglyceride-rich lipoproteins, normal rate of cholesterol synthesis and increased resorption of exogenous cholesterol.     

Release of free fatty acids from Ehrlich ascites tumor cells

Ehrlich ascites tumor cells release free fatty acids (FFA) during in vitro incubation in media that contain albumin. The released FFA are derived by lipolysis from endogenous lipid esters. Addition of glucose to the incubation medium greatly decreases the quantity of fatty acid released by the cells. Cyanide, which inhibits endogenous lipid oxidation but not lipolysis, increases the quantity of fatty acid released to media containing albumin and causes free fatty acid to accumulate in the cells in the absence of exogenous albumin. The release of fatty acid, either preformed or derived by lipolysis during prolonged incubations, occurs under conditions of net fatty acid uptake from the incubation medium. Net release of fatty acid from the cell occurs only when fatty acid-extracted albumin is present in the extracellular medium; extrapolation of the data suggests that net release will not occur under physiological conditions. It is postulated that free fatty acid uptake and release are independent processes, the direction of net fatty acid movement being determined by the relationship between cellular free fatty acid concentration (regulating efflux) and the molar ratio of free fatty acid to albumin in the extracellular medium (regulating uptake).     

Ethanol-induced changes in profile of fatty acids in isolated rat hepatocytes and the influence of magnesium ions

The influence of magnesium and ethanol on the fatty acid content in isolated rat hepatocytes was examined in this study. The isolated liver cells were obtained according to the Selgen method and then subjected to ethanol alone or both ethanol and magnesium activity. MgCl2 was used in two concentrations: 2 and 4 mM. The profile of fatty acids in the hepatocytes was evaluated after 5 hours of incubation. Our results revealed that magnesium ions presented together with ethanol in hepatocyte medium changed the hepatocyte fatty acid profile. The total amounts depended on the concentration of magnesium ions.     

Seasonal Changes of Fatty Acid Compositions in Overwintering Larvae of Rice Stem Borer,Chilo suppressalis (Lepidoptera: Pyralidae)

Cold acclimation and overwintering state can affect fatty acid compositions of insects. To determine compositional change of fatty acids during nondiapause and diapause stages, an experiment was conducted to investigate fatty acid constituents from whole body of C. suppressalis larvae. Five most abundant fatty acids were found to be palmitoleic (35–58%), palmitic (18–44%), oleic (14–23%), stearic (0.5–2.5%) and linoleic acid (0.4–2%). However, linolenic, erucic, lauric and myristic acid were found at lower level. Saturated fatty acids significantly decreased and conversely unsaturated fatty acids increased from August (pre-diapause) to October (initiation of diapause). The increase in seasonal cold hardiness during cold acclimation, exposed at −15°C for 24 h, was related to degree of fatty acid unsaturation. The elevation of palmitoleic acid content at low temperature resulted in an increase in the overall degree of unsaturation in the whole body. These results indicated the importance of unsaturated fatty acids composition to prepare larvae entering diapause phase.     

Aldosterone alters the phospholipid composition of rat colonocytes

Previous studies have shown that aldosterone treatment of amphibian epithelial cells results not only in stimulation of Na(+) absorption but also in changes in phospholipid composition which are necessary for the mineralocorticoid action of aldosterone. The present study was designed to investigate the effect of aldosterone on phospholipids of mammalian epithelia. Phospholipid and fatty acid composition was examined in colonic epithelium (mineralocorticoid target tissue) and thymus (non-mineralocorticoid but glucocorticoid target tissue) of rats which had received aldosterone or vehicle by a miniosmotic pump for 7 days. Aldosterone increased the mass of colonic phospholipids relative to cellular proteins with concomitant changes in the percentage distribution of fatty acids, whereas the relative distribution of membrane phospholipds was not changed. Phosphatidylcholine increased the content of polyunsaturated and decreased that of monounsaturated fatty acids, which predominantly reflected the accretion of arachidonic and a decrease in oleic and palmitoleic acids. Within the phosphatidylethanolamine subclass, pretreatment of rats with aldosterone decreased the content of monounsaturated fatty acids (predominantly oleic and palmitoleic acid) and of n-3 fatty acids, and increased the content of saturated fatty acids (palmitic acid). The saturated-to-nonsaturated fatty acid ratio also significantly increased after aldosterone treatment. No changes in thymic phospholipids were seen. The results are consistent with the contention that aldosterone specifically modulates phospholipid concentration and metabolism in mineralocorticoid target tissue. The changes in phospholipid content and its fatty acid composition during the fully developed effect of aldosterone may reflect a physiologically important phenomenon with long-term consequences for membrane structure and function.     

Mechanism of free fatty acid re-esterification in human adipocytes in vitro

Within adipose tissue, free fatty acids liberated by lipolysis may be re-esterified into newly synthesized triacylglycerol. We hypothesized that re-esterification may occur via an extracellular route, such that free fatty acids arising from lipolysis must leave the adipocyte and be taken up again before they can be re-esterified. We simultaneously measured rates of lipolysis, acylglycerol synthesis, and free fatty acid re-esterification in human adipose tissue and isolated adipocytes in vitro, utilizing a dual-isotopic technique. We manipulated incubations to increase mixing of released free fatty acids with the incubation medium. Such manipulations should decrease the probability that released free fatty acids would be taken up and re-esterified. We found that re-esterification was decreased in isolated adipocytes compared to fragments of tissue, in shaken compared to unshaken incubations, and in low adipocyte concentrations compared to high adipocyte concentrations. Rates of acylglycerol synthesis and lipolysis were unaltered by these manipulations, indicating that changes in free fatty acid re-esterification are not secondary to effects on these processes. The results are consistent with an extracellular route for free fatty acid re-esterification. Such a mechanism suggests that adipose tissue blood flow may play an important role in the regulation of free fatty acid release from adipose tissue.     

Comparison of the effect of individual saturated and unsaturated fatty acids on cell growth and death induction in the human pancreatic beta-cell line NES2Y

We tested the effects of various types of fatty acids, differing in the degree of saturation and in the cis/trans configuration of the double bond, on the growth and viability of NES2Y cells (a human pancreatic beta-cell line). We found that during a 48-hour incubation period, saturated fatty acids, i.e. palmitic and stearic acids, at a physiologically relevant concentration of 1 mM and higher concentrations induced death of the beta-cells while their counterpart unsaturated fatty acids, i.e. palmitoleic and oleic acids, did not induce cell death at concentrations up to 3 mM. We also found that unsaturated elaidic acid with a trans double bond exerted significant inhibition of growth of the beta-cells at a concentration approximately ten times lower, i.e. 0.1 mM vs. 1 mM, than counterpart oleic acid with a cis double bond. This is the first direct evidence that a trans unsaturated fatty acid is significantly more effective in inhibiting beta-cell growth than a counterpart cis unsaturated fatty acid. Furthermore, we newly demonstrated that beta-cell death induced by saturated fatty acids is related to significant increase of caspase-2 activity (2 to 5-fold increase) but not to caspase-3 activation. The growth-inhibiting effect of saturated fatty acids at concentrations lower than death-inducing concentrations correlates with certain increase of caspase-2 activity.     

Influence of ethanol on the lipid content and fatty acid composition ofSaccharomyces cerevisiœ

The content of total lipid as well as of ergosterol, squalene, and major fatty acids were compared in the cells of a distillery strain ofSaccharomyces cerevisiœ incubated for 3, 48 and 120 h in the presence of 5, 10 and 15% ethanol. Ethanol induced lipid accumulation with preferential ergosterol biosynthesis. The relative contents of palmitic and stearic acid decreased whereas the amount of palmitoleic and oleic acid increased. The total content of all fatty acids rose as a consequence of the ethanol treatment.     

Growth temperature affects accumulation of exogenous fatty acids and fatty acid composition in <Emphasis Type="Italic">Schizosaccharomyces pombe</Emphasis>

The incorporation of exogenously supplied fatty acids, palmitic acid, palmitoleic acid, oleic acid and linoleic acid, was examined in the yeast Schizosaccharomyces pombe at two growth temperatures, 20 °C and 30 °C. Fatty acids supplied to S. pombe in the growth medium were found to be preferentially incorporated into the cells, becoming a dominant species. The relative increase in exogenous fatty acids in cells came at the expense of endogenous oleic acid as a proportion of total fatty acids. Lowering the temperature at which the yeast were grown resulted in decreased levels of incorporation of the fatty acids palmitic acid, palmitoleic acid and linoleic acid compared to cells supplemented at 30 °C. In addition, the relative amount of the endogenously produced unsaturated fatty acid oleic acid, while greatly reduced compared to unsupplemented cells, was increased in cells supplemented with fatty acids at 20 °C compared to supplemented cells at 30 °C. The differential production of oleic acid in S. pombe cells indicates that regulation of unsaturated fatty acid levels, possibly by control of the stearoyl-CoA desaturase, is an important control point in membrane composition in response to temperature and diet in this species.     

Effect of lysophospholipids, arachidonic acid and other fatty acids on regulation of Ca2+ transport in permeabilized pancreatic islets.

The immediate reaction products of PLA2-mediated hydrolysis of phospholipids were tested for their ability to induce Ca2+ mobilization from internal stores in permeabilized ob/ob mouse pancreatic islets. Lysophospholipids and unsaturated fatty acids increased the free Ca2+ concentration in the incubation medium of permeabilized ob/ob mouse pancreatic islets. The potency of the lysophospholipids decreased in the following order: lysophosphatidylcholine = lysophosphatidylglycerol much greater than lysophosphatidylinositol greater than lysophosphatidylserine much greater than lysophosphatidylethanolamine. Arachidonic acid and palmitoleic acid had a potency comparable to lysophosphatidylinositol, while palmitic acid was ineffective. The Ca(2+)-mobilizing effect of inositol-1,4,5-trisphosphate (IP3) in permeabilized islet cells was additive to the lysophospholipid effect, indicating different sites of action. Both Ca(2+)-mobilizing effects were counteracted by the polyamine spermine, while the presence of Mg2+ shifted the Ca2+ concentrations to higher levels. Since not only an activation of a phospholipase C but also an activation of a phospholipase A2 with subsequent generation of lysophospholipids and free fatty acids is reported to occur in glucose-induced insulin secretion, the interaction of the phospholipase C reaction product IP3 with a lysophospholipid or an unsaturated fatty acid may affect the extent and duration of the rise in the free cytoplasmic Ca2+ concentration responsible for initiation of insulin secretion.     

Changes in the amount of fatty acids produced by Melosira dastei culture on synthetic medium

Some of fatty acids contents of the marine Diatom, Melosira dastei, were characterized. The major constituents of them are palmitic, palmitoleic and eicosapentaenoic acids. Linolenic acid type appeared to be a minor constituent. When that Diatom is cultured on an artificial medium, it might be considered as a potential source of valuable eicosapentaenoic acid. Even when the cells concentration is low, in batch cultures, eicosapentaenoic acid constitutes up to 5% of the dry weight and reaches about 20% of the triglycerids content. This level might be improved.     

Palmitic acid uptake by the rat soleus muscle in vitro.

Abstract: The rate of fatty acid uptake, oxidation, and deposition in skeletal muscles in relation to total and unbound to albumin fatty acids concentration in the medium were investigated in the incubated rat soleus muscle. An immunohistochemical technique was applied to demonstrate whether the albumin-bound fatty acid complex from the medium penetrates well within all areas of the muscle strips. It was found that the percentage of incorporation of palmitic acid into intramuscular lipids was fairly constant, independently of the fatty acid concentration in the medium, and amounted to 63-72% for triacylglycerols, 7-12% for diacylglycerols-monoacylglycerols, and 19-26% for phospholipids. Both palmitic acid incorporation into the muscle triacylglycerol stores and its oxidation to CO2 closely correlated with an increase in both total and unbound to albumin fatty acid concentrations in the incubation medium. Under conditions of increased total but constant unbound to albumin palmitic acid concentrations, the incorporation of palmitic acid into triacylglycerols and its oxidation to CO2 were also increased, but to a lower extent. This supports the hypothesis that the cellular fatty acid metabolism depends not only on the availability of fatty acids unbound to albumin, but also on the availability of fatty acids complexed to albumin.     

囊状黄丝藻在不同初始氮浓度条件下特殊的油脂积累规律

对不同初始氮浓度条件下囊状黄丝藻(Tribonema utriculosum SAG22.94)的生长状况、油脂含量和脂肪酸组成与含量进行研究。结果显示,囊状黄丝藻在氮浓度为3.0 mmol/L时,获得生物质浓度最高,为6.39 g/L;氮浓度为18.0 mmol/L时获得总脂和总脂肪酸含量最高,分别为细胞干重的44.62%和42.21%;上述3个指标单位体积的产率均在氮浓度3.0 mmol/L时达到最高值,分别为0.538、0.209和0.206 g·L~(-1)·d~(-1)。在4种初始氮浓度条件下,囊状黄丝藻油脂和脂肪酸含量可随着氮浓度增加而增加。脂肪酸含量分析结果显示,该藻的主要脂肪酸为豆蔻酸(C14∶0)、棕榈酸(C16∶0)、棕榈油酸(C16∶1ω7)、花生四烯酸(C20∶4ω6)和二十碳五烯酸(C20∶5ω3,EPA)。其中棕榈油酸含量最高,占总脂肪酸含量的36.53%~50.08%。研究结果表明囊状黄丝藻在不同初始氮浓度条件下具有特殊的油脂积累规律,是一株具有重要应用价值的产油丝状微藻。     

高、低氮浓度对2株真眼点藻的生长和油脂积累的影响

【目的】研究氮浓度对真眼点藻纲(Eustigmatophyceae)的2株高产油微藻大真眼点藻(Eustigmatos magnus,EM)和波氏真眼点藻(Eustigmatos polyphem,EP)的细胞形态、生长、总脂含量、脂质组成和脂肪酸组成与含量的时序变化规律。【方法】利用高氮(18.0 mmol/L NO3?-N)和低氮(3.6 mmol/L NO3?-N)浓度培养微藻。【结果】形态观察结果表明,大真眼点藻(E. magnus)和波氏真眼点藻(E. polyphem)营养细胞具有1个周生的裂叶状叶绿体,细胞质中有液泡,内含能够振动的颗粒物,以及一个较为明显的红色色素体;生殖方式通过形成2个D形或4个四角形的似亲孢子;随着培养周期的延伸和营养盐的消耗,细胞中油体逐步形成,其数量不断增加,体积不断增大。实验结果表明,初始氮浓度对2种微藻的总脂积累及生长均有显著影响(P<0.05),低氮浓度下2种微藻的生物质浓度分别为9.0 g/L和8.5 g/L,均低于高氮浓度下的生物质浓度。而低氮浓度下2种微藻的总脂、中性脂和总脂肪酸的含量以及总脂、中性脂与总脂肪酸的单位体积产率均明显高于高氮浓度组,其最高值分别为：59.10%、51.90%、46.95%和0.28、0.24、0.22 g/(L·d) (EM);64.20%、56.80%、50.01%和0.32、0.28、0.25 g/(L·d) (EP)。脂肪酸分析结果表明,两种微藻的脂肪酸主要成分均为棕榈酸(C16:0)、棕榈油酸(C16:1)、油酸(C18:1)和二十碳五烯酸(C20:5,EPA),四者的总含量(占总脂肪酸)分别达到85.83%和85.48%,其中棕榈油酸的含量最高。【结论】低氮浓度胁迫有利于大真眼点藻和波氏真眼点藻细胞内油脂的积累,两种微藻均为适合于生产生物柴油的油脂生产藻株。     

Effects of prolonged incubation and cell concentration on lipogenesis from glucose in isolated human omental fat cells

The behavior of human omental fat cells in vitro has been examined in order to define conditions under which glucose is converted to glyceride-glycerol and glyceride fatty acids. Synthesis of glyceride fatty acids from glucose reached maximal rates only after several hours of incubation in Krebs-Henseleit bicarbonate buffer, with or without added bovine albumin. Conversion of glucose to glyceride fatty acids was readily demonstrable with concentrated cell suspensions and was stimulated 3- to 8-fold by insulin. With dilute cell suspensions, little fatty acid was synthesized even after prolonged incubation in the presence of insulin. Conversion of glucose to glyceride-glycerol was linear during 6-hr incubations in buffer and unaffected by the concentration of the cell suspension. In the presence of bovine albumin, glyceride-glycerol synthesis was readily demonstrable at all cell concentrations used, although synthesis was faster in dilute suspensions. Thus, different incubation conditions produce widely divergent patterns of glucose metabolism in human omental fat cells.     

Alteration of the fatty acid composition of Escherichia coli by growth in the presence of normal alcohols.

The addition of normal alcohols in the series n-butanol to n-octanol to cultures of Escherichia coli ML308 grown on defined or lipid-free medium (at 17, 27, and 37 degrees C) caused an alteration in the fatty acid composition of this organism: the ratio of saturated to unsaturated fatty acids increased. Changes in the relative quantities of individual fatty acid species elicited by increasing concentrations of these alcohols were as follows: (i) myristic acid remained constant: (ii) palmitic acid increased; and (iii) the combined amount of palmitoleic plus cis-methylene hexadecanoic acids changed in a way which was reflected inversely by changes in the amount of cis-vaccenic acid. Comparable changes were not observed when cells were grown in the presence of n-nonanol and n-decanol in the concentration range tested. The changes observed upon addition of normal alcohols (n-butanol to n-octanol) paralleled, in part, the alterations in fatty acid composition observed when growth temperature was increased.