Effect of sub-inhibitory concentration of chlorhexidine on lipid and sterol composition of shape Candida albicans

The effect of a sub-inhibitory concentration of chlorhexidine on lipid and sterol composition of Candida albicans was investigated. The total lipid content of this yeast grown in the presence of chlorhexidine was reduced whilst the total sterol content was increased compared with control-grown cells. Lipids and sterol analyses of this yeast grown in the presence and absence of chlorhexidine are presented. Chlorhexidine-grown yeast had a higher level of phosphatidylethanolamine, phosphatidylcholine and monogalactosyldiacylglycerol. Lower proportions of phosphatidylinositol plus phosphatidylserine, phosphatidic acid and cardiolipin were found in C. albicans grown in the presence of the drug when compared with control-grown yeast. The major fatty acids in control-grown cells were C16 and C18. Drug grown-cells had higher proportions of palmitic acid (16 : 0) and stearic acid (18 : 0), but lower proportions of palmitoleic acid (16 : 1) and oleic acid (18 : 1). Chlorhexidine also decreased the unsaturated-to-saturated fatty acid ratio, while the C16/C18 ratios increased compared to control-grown cells. Differences in the fatty acid composition of major phospholipids and neutral lipids between drug and control-grown yeast were also detected. Sterol analysis of control-grown cells showed that the major sterol present was ergosterol (55.4% wt). A significant increase in ergosterol and obtusifoliol was observed in chlorhexidine-treated cells and a significant decrease in squalene and lanosterol. Our results suggested that chlorhexidine affected the lipid and sterol composition of C. albicans. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dimorphism-associated variations in the lipid composition of Candida albicans

Yeast and mycelial forms of Candida albicans ATCC 10231, growing together in 12 h and in 96 h cultures, were separated and their lipids were extracted and characterized. The total lipid content of the yeast forms was always lower than that of the mycelial forms. In 12 h cultures the lipids from the two morphological forms consisted mainly of polar compounds, viz, phospholipids and glycolipids. In 96 h cultures both the yeast and mycelial forms accumulated substantial amounts of apolar compounds, mainly steryl esters and triacylglycerols. The mycelial forms were more active than the yeast forms in this respect. Major differences in the lipid composition between the two morphological forms involved the contents of sterols and complex lipids that contain sterols. As a rule, the yeast lipids contained much larger proportions of free sterols than the mycelial lipids. However, the mycelial lipids contained several times more sterols than the yeast forms but bound as steryl glycosides, esterified steryl glycosides and steryl esters. Steryl glycosides and esterified steryl glycosides occurred in yeast lipids only in traces, if at all. The major steryl glycoside in the mycelial forms was unequivocally identified as cholesteryl mannoside. At both phases of growth the apolar and polar lipid fractions from the mycelial forms contained higher levels of polyunsaturated fatty acids (18:2 and 18:3) but lower levels of oleic acid (18:1) than the corresponding fractions from the yeast forms. The lipid content and composition of 12 h and 96 h yeast and mycelial forms of C. albicans KCCC 14172, a clinical isolate, were almost identical with those of C. albicans ATCC 10231.     

Evidence for a Composite State of an F′his,gnd Element and a Cryptic Plasmid in a Derivative of Salmonella typhimurium LT2

The zoospores of Blastocladiella emersonii, when derived from cultures grown on solid media, contain about 11% total lipid. This lipid was separated chromatographically on silicic acid into neutral lipid (46.6%), glycolipid (15.8%), and phospholipid (37.6%). Each class was fractionated further on columns of silicic acid, Florisil, or diethylaminoethyl-cellulose, and monitored by thin-layer chromatography. Triglycerides were the major neutral lipids, mono- and diglycosyldiglycerides were the major glycolipids, and phosphatidylcholine and phosphatidylethanolamine were the major phospholipids. Other neutral lipids and phospholipids detected were: hydrocarbons, free fatty acids, free sterols, sterol esters, diglycerides, monoglycerides, lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidic acid, phosphatidylserine, and phosphatidylinositol. Palmitic, palmitoleic, stearic, oleic, gamma-linolenic, and arachidonic acids were the most frequently occurring fatty acids. When B. emersonii was grown in (14)C-labeled liquid media, lipid again accounted for 11% of both mature plants and zoospores released from them. The composition of the lipid extracted from such plants and spores was also the same; however, it differed markedly from that of the lipid in spores harvested from solid media, consisting of 28.3% neutral lipid, 12.0% glycolipid, and 59.7% phospholipid. The major lipids were again triglycerides for neutral lipids, mono- and diglycosyldiglycerides for glycolipids, and phosphatidyl choline and phosphatidylethanolamine for phospholipids.     

Metabolism of endogenous sterol ester by the superovulated rat ovary in vitro

Sterol, glyceride and phospholipid were found to account for more than 90% (w/w) of the lipid extracted from whole superovulated rat ovaries. These lipids, together with non-esterified fatty acids, were assayed in slices of the tissue after incubation for various times. Whereas the concentrations of triglyceride, diglyceride and phospholipid did not change significantly during incubation, that of sterol ester markedly decreased and those of free sterol, monoglyceride and non-esterified fatty acid increased. Evidence is presented that in this tissue (in contrast with other mammalian tissues) the main endogenous substrate for respiration is fatty acid derived from sterol ester.     

Plasma and muscle phospholipids are involved in the metabolic response to long-distance migration in a shorebird

We studied: (1) concentrations and fatty acid compositions of plasma non-esterified fatty acids, neutral lipids, and phospholipids, and (2) fatty acid composition of flight muscle phospholipids in wintering, premigratory, and spring and fall migrating western sandpipers ( Calidris mauri). Plasma neutral lipid and phospholipid levels were elevated in migrants, reflecting high rates of fat deposition. An important role of phospholipids in fattening is suggested by the fact that the amount of fatty acids in plasma phospholipids was similar to, or in spring as much as twice, that of neutral lipids. Changes in the ratio of plasma neutral lipids to phospholipids may indicate seasonal changes in triacylglycerol stores of invertebrate prey. Monounsaturation and total unsaturation of plasma neutral lipids and phospholipids increased during migration. Muscle phospholipids were more monounsaturated in spring and fall, but total unsaturation was reduced in fall. Arachidonic acid [20:4(n-6)] was especially abundant in muscle phospholipids in winter (29%) and declined during migration (19-22%), contributing to a decline in the ratio of n-6 to n-3 fatty acids. The abundance of plasma phospholipids and variability of neutral lipid to phospholipid ratio indicates that measurement of plasma phospholipids will improve methods for assessment of fattening rates of birds. The functional significance of changes in muscle phospholipids is unclear, but may relate to depletion of essential n-6 fatty acids during exercise.     

Lipid synthesis during reinitiation of growth from stationary phase cultures of Candida albicans

Lipid synthesis has been studied in the dimorphic fungus Candida albicans. ¹⁴C-acetate incorporation into lipid material was used to measure new lipid synthesis in two cultures in which either yeast or mycelial growth was initiated from stationary phase yeast cells. When resuspended in fresh medium at 37 °C, cells resume growth and change morphology while at 30 °C cells resume budding growth. When resuspended at the appropriate temperature, both yeast and germ tube cultures immediately incorporated ¹⁴C-acetate into lipid material. The labeled lipid was more or less evenly divided between neutral and phospholipid. Phosphatidyl choline was the major phospholipid fraction and along with phosphatidyl ethanolamine accounted for 60–65 % of the total phospholipid. Lipid synthesis during growth initiation of either morphology showed a similar pattern, with no significant differences observed in neutral or phospholipid or phospholipid components between yeast and mycelial forms.     

Effect of Milk Components on IgA Production in Peyer’s Patch Cell Cultures from Mouse

The lipid composition of some commercial bakers’ yeasts having different freeze-sensitivity in frozen dough was investigated to clarify the correlation between their lipid composition and freeze-tolerance. The total lipid content including neutral lipid, free fatty acid, sterol, and phospholipid ranged between 23.0 to 32.2 mg/100 mg protein of the yeasts tested. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were the main phospholipids found in all yeast strains, but no distinct difference in these components between freeze-tolerant and freeze-sensitive strains was observed. Palmitoleic (C16:l), oleic (C18:l), palmitic (16:0), and stearic (CI8:0) acids were the major fatty acids present in total lipid and phospholipid, and unsaturation indices of fatty acid in these lipid components were almost equal by the strains. The molar ratios of sterol to phospholipid of freeze-sensitive strains were higher than those of freeze-tolerant strains. The difference in the sterol-pho-spholipid ratio that influences the fluidity of plasma membranes in yeast cells was supposed to reflect the difference in freeze-sensitivity of bakers’ yeast.     

Composition of lipids from yeast-like and mycelial cells of the fungus Mucor hiemalis, grown in the presence of 4-chloroaniline

The fungus Mucor hiemalis, which is commonly thought to be monomorphic, produced two types of cells, yeastlike and mycelial, during growth in a medium containing 4-chloroaniline. Among the polar lipids of yeastlike cells, diphosphatidylglycerol was dominant, while phosphatidylcholine and phosphatidylethanolamine were present in minor amounts. Conversely, mycelial cells mainly contained phosphatidylcholine and phosphatidylethanolamine, whereas the content of diphosphatidylglycerol was low. The neutral lipids of yeastlike cells were dominated by diacylglycerides, sterols, and fatty acids. The content of triacylglycerides and sterol esters was low. Yeastlike cells contained higher amounts of saturated fatty acids and lower amounts of unsaturated fatty acids than the mycelium. The content of stearic acid in the fatty acids of the mycelium grown in the presence of 4-chloroaniline was as high as 25.3-29.9%.     

Phospholipid furan fatty acids and ubiquinone-8: lipid biomarkers that may protect dehalococcoides strains from free radicals

Dehalococcoides species have a highly restricted lifestyle and are only known to derive energy from reductive dehalogenation reactions. The lipid fraction of two Dehalococcoides isolates, strains BAV1 and FL2, and a tetrachloroethene-to-ethene-dechlorinating Dehalococcoides-containing consortium were analyzed for neutral lipids and phospholipid fatty acids. Unusual phospholipid modifications, including the replacement of unsaturated fatty acids with furan fatty acids, were detected in both Dehalococcoides isolates and the mixed culture. The following three furan fatty acids are reported as present in bacterial phospholipids for the first time: 9-(5-pentyl-2-furyl)-nonanoate (Fu18:2omega6), 9-(5-butyl-2-furyl)-nonanoate (Fu17:2omega5), and 8-(5-pentyl-2-furyl)-octanoate (Fu17:2omega6). The neutral lipids of the Dehalococcoides cultures contained unusually large amounts of benzoquinones (i.e., ubiquinones [UQ]), which is unusual for anaerobes. In particular, the UQ-8 content of Dehalococcoides was 5- to 20-fold greater than that generated in aerobically grown Escherichia coli cultures relative to the phospholipid fatty acid content. Naphthoquinone isoprenologues (MK), which are often found in anaerobically grown bacteria and archaea, were also detected. Dehalococcoides shows a difference in isoprenologue pattern between UQ-8 and MK-5 that is atypical of other bacteria capable of producing both quinone types. The difference in UQ-8 and MK-5 isoprenologue patterns strongly suggests a special function for UQ in Dehalococcoides, and Dehalococcoides may utilize structural modifications in its lipid armamentarium to protect against free radicals that are generated in the process of reductive dechlorination.     

Use of an unsaturated fatty acid auxotroph of Saccharomyces cerevisiae to modify the lipid composition and function of mitochondrial membranes

KD115 (ol1), an unsaturated fatty acid auxotroph of S. cerevisiae, was grown in a semi-synthetic medium supplemented with 3.3 x 10(-4) M palmitoleic (cis 16:1) or palmitelaidic (trans 16:1) acids. The parent strain S288C was studied as a control. The lipid composition (fatty acids, neutral lipids, and phospholipids), respiratory activity (O2 consumption), and ultrastructure were compared in mutant yeast grown with each unsaturated fatty acid supplement. The fatty acid supplement represented 70-80% of the yeast fatty acids. Yeast grown in trans 16:1 contained more squalene, a higher ratio of phosphatidylethanolamine (PE) to phosphatidylcholine (PC), and had 10-20% of the respiratory activity compared to the same yeast grown in cis 16:1. The mitochondrial morphology of yeast in each growth supplement was notably different. The use of mixtures of cis and trans 16:1 in different proportions revealed that the PE/PC ratio, the squalene content, the respiratory defect, and the mitochondrial morphology were all similarly dependent on the fraction of trans 16:1 in the mixtures. As little as 10-20% of cis 16:1 in the mixture was sufficient to abrogate the physiological effects of trans 16:1 on each of the parameters noted above. The combined effects of high content of trans unsaturated fatty acid and the altered phospholipid composition seem to account for the decrease in lipid fluidity, the defective structure and function of the mitochondrial membrane.     

Effect of benomyl on the growth and lipid composition ofTrichoderma koningii

The effect of the fungicide benomyl on growth and lipid composition ofTrichoderma koningii was investigated. The fungal growth was strongly inhibited in the presence of 1 and 2 mg/L benomyl while lower concentrations (0.1 and 0.5 mg/L) increased the fungal biomass through the stimulation of mycelial branching. The total lipid and the total neutral lipid were decreased, while the total phospholipid was enhanced in benomyl-treated mycelia. Important quantitative changes were detected in the proportions of fatty acids, neutral lipid fractions (decrease of free sterols, diacylglycerols and free fatty acids and increase of triacylglycerols and sterol esters) and phospholipid constiuents (decrease of phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine and increase of phosphatidylglycerol and phosphatidylinositol). The unsaturation index of the identified fatty acids was increased with increasing benomyl concentration.     

Effects of in vitro treatment with ozone on the physical and chemical properties of membranes

Treatment of microsomal membranes from cotyledons of Phaseolus vulgaris with ozone raises the liquid-crystalline to gel lipid phase transition temperature and results in the formation of distinct domains of gel phase lipid in the membranes. Liposomes prepared from the total lipid extracts of ozone-treated membranes undergo phase separations just a few degrees below the transition temperature for intact membranes, indicating that the formation of gel phase lipids is largely attributable to ozone-induced alterations in the membrane lipids. Levels of unsaturated fatty acids as well as the sterol to phospholipid ratio are markedly reduced in the ozone-treated membranes, and the neutral lipid fraction from treated membranes shows, an increased propensity to induce the formation of gel phase phospholipid when incorporated into liposomes of egg phosphatidylcholine. Since gel phase phospholipid also forms in naturally senescing plant membranes and appears to be attributable to changes in the neutral lipid fraction, the effects of natural senescence and ozone on membranes have been compared.     

Lipid Composition of the Yeastlike and Mycelial Mucor hiemalis Cells Grown in the Presence of 4-Chloroaniline

The fungus Mucor hiemalis F-1156, which is commonly thought to be monomorphic, produced two types of cells, yeastlike and mycelial, during growth in a medium containing 4-chloroaniline. Among the polar lipids of yeastlike cells, diphosphatidylglycerol was dominant, while phosphatidylcholine and phosphatidylethanolamine were present in minor amounts. Conversely, mycelial cells mainly contained phosphatidylcholine and phosphatidylethanolamine, whereas the content of diphosphatidylglycerol was low. The neutral lipids of yeastlike cells were dominated by diacylglycerides, sterols, and fatty acids. The content of triacylglycerides and sterol esters was low. Yeastlike cells contained higher amounts of saturated fatty acids and lower amounts of unsaturated fatty acids than the mycelium. The content of stearic acid in the fatty acids of the mycelium grown in the presence of 4-chloroaniline was as high as 25.3–29.9%.     

Lipid composition of a freeze-tolerant yeast,Torulaspora delbureckii,and its freeze-sensitive mutant

We analyzed the lipid compositions of a freeze-tolerant strain of yeast Torulaspora delbrueckii D2-4 and its freeze-sensitive mutant 60B3 to clarify the relationship between the lipid composition and freeze tolerance of yeast. The total lipid content of D2-4 was similar to that of 60B3, whereas the content of phospholipids and neutral lipids was different from those of 60B3. The molar ratio of sterol to phospholipid in D2-4 was 60% of that in 60B3. The analysis of lipid components indicated that D2-4 contained larger amounts of phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol, but smaller amounts of triglyceride as compared to 60B3. These results suggest that the plasma membrane of freeze-tolerant strain D2-4 may have a higher fluidity than that of freeze-sensitive strain 60B3.     

Quantitative Studies of Total Lipids of Pathogenic Fungi

Ten species of dermatophytes and four of the systemic fungi were assayed for total lipids, acetone-soluble fraction, and phospholipid content in different types of cultures. The yeast phase of each of the systemic fungi grown on solid medium exhibited a higher total lipid content than did the mycelial growth in liquid medium, either shake or still. Shake cultures, in all the fungi tested, produced the least lipids. The yeasts were consistently higher also in the acetone-soluble fraction. Histoplasma duboisii in the yeast phase and Microsporum gypseum produced the greatest amount of phospholipid, and Blastomyces dermatitidis in the yeast phase and M. canis produced the largest acetone-soluble fraction among the systemic fungi and dermatophytes, respectively.     

The lipid composition of flight muscle mitochondria isolated from the blowfly, Phormia regina.

The role of lipids in membrane structure and function was studied by measuring the major lipid classes in mitochondria isolated from flight muscle of the blowfly, Phormia regina. Approximately 98% of the total lipid is phospholipid. Neutral lipid constitutes the remaining 2% of the total. Phosphatidylethanolamine accounts for 55–60% of the phospholipid. A molecular ratio of 4:1:1 is found for phosphatidylethanolamine, phosphatidylcholine, and cardiolipin (diphosphatidylglycerol). The neutral lipids include cholesterol, about 20%, and quinone, 40–45% of the total. The free fatty acid content of the neutral lipid fraction is variable, apparently being generated by endogenous phospholipase activity. The fatty acids of the neutral and phospholipid classes are predominantly 14–18 carbon acids; long-chain fatty acids of 20 and 22 carbons are essentially absent. The neutral lipid fraction contains 43% saturated and 51% monoenoic fatty acids. More than 65% of the phospholipid fatty acids are unsaturated. The principal fatty acids are palmitic, palmitoleic, oleic, linoleic, and linolenic. No trace of α- or β-tocopherol is detected. As vitamin E is considered an important naturally occuring antioxidant that prevents lipid peroxidation, the apparent absence of α- and β-tocopherol in these mitochondria coupled with intense oxidative activity of the mitochondria leads to the suggestion that blowfly flight muscle mitochondria may be particularly susceptible to peroxidative damage.     

Effects of in utero and in vitro incubation on the lipid-bound fatty acids and sterols of porcine spermatozoa

Sperm-rich semen and washed porcine spermatozoa were incubated for up to 2 hr either in utero in the presence of oviduct fluid or in vitro at 37°C. Sperm lipids were extracted and separated into phospholid and neutral lipid fractions. Eleven phospholipid and five neutral lipid fatty acids were identified and quantified using GC and GC-MS. The percentage of 22:5n6, the major phospholipid fatty acid, decreased slightly but significantly during 1.5 hr of in utero incubation (41.2–38.0%), but after 2.0 hr of in utero incubation no significant difference was observed (40.0%). None of the phospholipid fatty acids changed in concentration during in vitro incubation. The mole ratio of phospholipid to phospholipid fatty acid (1.00:1.27) did not change during incubation. The levels of neutral lipid-bound 14:0 decreased (43.5% to 31.8%) and that of 18:0 increased (11.1% to 18.2%) during in utero incubation. Similar but less pronounced changes were observed during in vitro incubation. (43.5% to 36.0%; and 11.1% to 15.8%, respectively). Two major sterols, cholestrol (73%) and desmosterol (27%) were identified by gas chromatography–mass spectrometry. The mole ratio of phospholipid to sterol (2.47:1:00) did not change during incubation.     

Structure and lipid distribution of polyenoic very-long-chain fatty acids in the brain of peroxisome-deficient patients (Zellweger syndrome).

The polyenoic fatty acids with carbon chain lengths from 26 to 38 (very-long-chain fatty acids, VLCFA) previously detected in abnormal amounts in Zellweger syndrome brain have been shown to be n-6 derivatives and therefore probably derived by chain elongation of shorter-chain n-6 fatty acids such as linoleic acid and arachidonic acid. Polyenoic VLCFA are also present in Zellweger syndrome liver, but this tissue differs significantly from brain in that the saturated and mono-unsaturated derivatives are the major VLCFA. Zellweger syndrome brain polyenoic VLCFA are present in the neutral lipids predominantly in cholesterol esters, with smaller amounts in the non-esterified fatty acid and triacylglycerol fractions. These fatty acids are barely detectable in any of the major phospholipids, but are present in significant amounts in an unidentified minor phospholipid. The polyenoic VLCFA composition of this lipid differs markedly from that observed for all other lipids, as it contains high proportions of pentaenoic and hexaenoic fatty acids with 34, 36 and 38 carbon atoms. A polar lipid with the chromatographic properties in normal brain contains similar fatty acids. It is postulated that the polyenoic VLCFA may play an important role in normal brain and accumulate in Zellweger syndrome brain because of a deficiency in the peroxisomal beta-oxidation pathway, although a possible peroxisomal role in the control of carbon-chain elongation cannot be discounted.     

Temperature-induced modifications of glycosphingolipids in plasma membranes of Neurospora crassa

Plasma membranes isolated from a cell-wall-less mutant of Neurospora crassa grown at 37 and 15 degrees C display large differences in lipid compositions. A free sterol-to-phospholipid ratio of 0.8 was found in 37 degrees C membranes, while 15 degrees C plasma membranes exhibited a ratio of nearly 2.0. Membranes formed under both growth conditions were found to contain glycosphingolipids. Cultures grown at the low temperature, however, were found to contain 6-fold higher levels of glycosphingolipids and a corresponding 2-fold reduction of phospholipid levels. The high glycosphingolipid content at 15 degrees C compensates for the reduced levels of phospholipids in such a way that sterol/polar lipid ratios are almost the same in plasma membranes under the two growth conditions. Temperature-dependent changes in plasma-membrane phospholipid and glycosphingolipid species were also observed. Phosphatidylethanolamine levels were sharply reduced at 15 degrees C, in addition to a moderate increase in levels of unsaturated phospholipid fatty acids. Glycosphingolipids contained high levels of long-chain hydroxy fatty acids, which constituted 75% of the total fraction at 37 degrees C, but only 50% at 15 degrees C. Compositional changes were also observed in the long-chain base component of glycosphingolipids with respect to growth temperature. Fluorescence polarization studies indicate that the observed lipid modifications in 15 degrees C plasma membranes act to modulate bulk fluidity of the plasma-membrane lipids with respect to growth temperature. These studies suggest that coordinate modulation of glycosphingolipid, phospholipid and sterol content may be involved in regulation of plasma-membrane fluid properties during temperature acclimation.     

Phosphorus Effects on the Mycelium and Storage Structures of an Arbuscular Mycorrhizal Fungus as Studied in the Soil and Roots by Analysis of Fatty Acid Signatures

The distribution of an arbuscular mycorrhizal (AM) fungus between soil and roots, and between mycelial and storage structures, was studied by use of the fatty acid signature 16:1(omega)5. Increasing the soil phosphorus level resulted in a decrease in the level of the fatty acid 16:1(omega)5 in the soil and roots. A similar decrease was detected by microscopic measurements of root colonization and of the length of AM fungal hyphae in the soil. The fatty acid 16:1(omega)5 was estimated from two types of lipids, phospholipids and neutral lipids, which mainly represent membrane lipids and storage lipids, respectively. The numbers of spores of the AM fungus formed in the soil correlated most closely with neutral lipid fatty acid 16:1(omega)5, whereas the hyphal length in the soil correlated most closely with phospholipid fatty acid 16:1(omega)5. The fungal neutral lipid/phospholipid ratio in the extraradical mycelium was positively correlated with the level of root infection and thus decreased with increasing applications of P. The neutral lipid/phospholipid ratio indicated that at high P levels, less carbon was allocated to storage structures. At all levels of P applied, the major part of the AM fungus was found to be present outside the roots, as estimated from phospholipid fatty acid 16:1(omega)5. The ratio of extraradical biomass/intraradical biomass was not affected by the application of P, except for a decrease at the highest level of P applied.