Lipid Composition of the Arthrospores, Yeastlike Cells, and Mycelium of the Fungus Mucor hiemalis

The fungus Mucor hiemalisF-1156, which is believed to be monomorphic, was found to be able to grow dimorphically in a liquid medium that is free of chemical agents influencing morphogenesis. The growing mycelium produced arthrospores in large amounts. The lipids of the mycelium, yeastlike budding cells, and arthrospores differed in the contents of saturated and unsaturated fatty acids and in the proportion of polar and neutral lipids. The arthrospores contained more monoenoic fatty acids in the total lipids, more triacylglycerides and sterol esters in the neutral lipids, and more phosphatidylcholine and phosphatidylethanolamine in the polar lipids than the yeastlike cells. These differences in the lipid composition of different types of fungal cells should be taken into account in the studies of the lipogenesis of M. hiemalis.     

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%.     

Changes in the lipid composition of Mucor hiemalis sporangiospores related to the age of the spore-forming culture

Analysis of sporangiospore lipids of the fungus Mucor hiemalis F-1156 showed that alterations occur in the content of fatty acids and individual classes of lipids during long-term cultivation (for about 20 days). The changes in the lipid composition related to the age of the spore-forming mycelium suggest an important role of sporangiospore lipids in spore germination and in further development of the spherical cells formed in this processes. The M. hiemalis F-1156 sporangiospores with a lipid pool exhausted during long-term cultivation can give rise to both mycelial and yeastlike growth.     

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%.     

Metabolic characteristics and lipid composition of yeastlike cells and mycelium of Mucor circinelloides var. lusitanicus INMI grown at a high glucose content in the medium

It is shown that the fungus Mucor circinelloides var. lusitanicus INMI grown under aerobic conditions in a medium with a high glucose concentration (20%) is capable of both yeastlike and mycelial growth. In the mycelium, the activity of NAD-dependent isocitrate dehydrogenase was more than twice as high as in yeastlike cells, whereas the isocitrate lyase activity was lower. A number of significant differences were found in the lipid composition of the cells of two different morphological variants. Yeastlike cells contained more polar lipids and free fatty acids and less principal reserve lipids (triacylglycerides) than mycelial cells; the content of gamma-linolenic acid and the degree of lipid unsaturation were significantly lower in these cells than in the mycelium. In yeastlike cells, glycolipids composed the bulk of polar lipids; the proportion of phospholipids (primarily phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and cardiolipin) was lower. The relationship between cellular metabolism and the lipid composition of fungal cells of different morphotypes grown at high concentrations of glucose, one of the main inducers of dimorphic growth, is discussed.     

Metabolic characteristics and lipid composition of yeastlike cells and mycelium of <Emphasis Type="Italic">Mucor circinelloides</Emphasis> var. <Emphasis Type="Italic">lusitanicus</Emphasis> INMI grown at a high glucose content in the medium

It is shown that the fungus Mucor circinelloides var. lusitanicus INMI grown under aerobic conditions in a medium with a high glucose concentration (20%) is capable of both yeastlike and mycelial growth. In the mycelium, the activity of NAD-dependent isocitrate dehydrogenase was more than twice as high as in yeastlike cells, whereas the isocitrate lyase activity was lower. A number of significant differences were found in the lipid composition of the cells of two different morphological variants. Yeastlike cells contained more polar lipids and free fatty acids and less principal reserve lipids (triacylglycerides) than mycelial cells; the content of γ-linolenic acid and the degree of lipid unsaturation were significantly lower in these cells than in the mycelium. In yeastlike cells, glycolipids composed the bulk of polar lipids; the proportion of phospholipids (primarily phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and cardiolipin) was lower. The relationship between cellular metabolism and the lipid composition of fungal cells of different morphotypes grown at high concentrations of glucose, one of the main inducers of dimorphic growth, is discussed.     

Sterols of the fungus Mucor hiemalis sporangiospores

We earlier reported that the viability and lipid composition of Mucor hiemalis F-1156 sporangiospores, as well as their capacity to develop yeast-like cells, depend on the age of the spore-forming culture [1]. With the increase in the time of the culture growth, sporangiospores exhibit a decrease in the levels of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, cardiolipin, and reserve lipids, as well as in the degree of fatty acid unsaturation, whereas the level of glycolipids increases. However, sterol composition was not been studied. Sterols are involved in morphogenetic processes [2, 3], and therefore we suggested that sporangiospores from senescent cultures, which, upon germination, develop mycelium and yeast-like cells, may exhibit a distinctive sterol pattern, along with the changed composition of fatty acids and polar and neutral lipids.     

Changes in the Lipid Composition of Mucor hiemalis Sporangiospores Related to the Age of the Spore-Forming Culture

Analysis of sporangiospore lipids of the fungus Mucor hiemalis F-1156 showed that alterations occur in the content of fatty acids and individual classes of lipids during long-term cultivation (for about 20 days). The changes in the lipid composition related to the age of the spore-forming mycelium suggest an important role of sporangiospore lipids in spore germination and in further development of the spherical cells formed in this processes. The M. hiemalis F-1156 sporangiospores with a lipid pool exhausted during long-term cultivation can give rise to both mycelial and yeastlike growth.     

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     

Lipids of Pinus halepensis pollen

The total lipids of Pinus halepensis pollen were separated into individual classes of neutral and polar lipids and the components of each class were identified and determined quantitatively. Free fatty acids, waxes and triacylglycerols were found as the main constituents of neutral lipids and phosphatidylcholine and phosphatidylethanolamine of polar lipids. Glycerylether derivatives were detected in neutral and polar lipid fractions. Free and esterified volatile fatty acids were also found in pollen and its neutral lipid fraction.     

Membrane Lipids of Mycoplasma hominis

Essentially all of the lipids of Mycoplasma hominis (200 mug/mg of cell protein) were found to be located in the cell membrane. Over one-half were neutral lipids incorporated from the growth medium and consisting of 43% free cholesterol, 19% esterified cholesterol, 23% triglycerides, 10% free fatty acids, and small amounts of di- and monoglycerides. The polar lipids accounting for about 40% of the total were synthesized by the organisms. Phosphatidylglycerol was the predominant lipid of this fraction. The minor components, tentatively identified as lysophosphatidylglycerol and phosphatidic acid, seem to represent breakdown products of phosphatidylglycerol. No glycolipids were detected. Being unable to synthesize long-chain fatty acids, M. hominis utilized the fatty acids of the growth medium for polar lipid synthesis, preferentially the saturated ones, so that the polar lipids had highly saturated hydrocarbon chains. It is proposed that the large take up of unsaturated neutral lipids and cholesterol from the medium offsets the marked condensing effect of the saturated polar lipids, although electron paramagnetic resonance spectrometry of spin-labeled fatty acids incorporated into the M. hominis membrane indicated that the lipid region is still more rigid than that of the Acholeplasma laidlawii membrane.     

Lipid composition of the mycelium of the fungus Mucor hiemalis cultivated with trehalose, triacylglycerols, and itraconazole

We investigated the growth and cell lipid composition of the fungus Mucor hiemalis VKMF-1431 cultivated under aerobic conditions in the presence of the morphogenetic agents itraconazole, exogenous triacylglycerols, and trehalose. The sporangiospores of a 6-day culture were used as inocula. Under these conditions, the fungus produced mycelium; nevertheless, solitary yeastlike cells also developed on the glucose-containing medium and in the presence of itraconazole and sterilized triacylglycerols (sTAGs). No yeastlike growth occurred in the system with trehalose and with unsterilized (native) TAGs (nTAGs). With trehalose and nTAGs in the cultivation medium, the ratio between PEA and PC, the two main types of membrane lipids, was low. This testified to a relatively high PC percentage and, accordingly, a stable structure and a highly functional state of the membranes. Moreover, if the development of the fungus occurred exclusively as mycelium formation, the level of polyunsaturated fatty acids (??-linolenic and arachidonic acid) increased in the presence of trehalose and that of linoleic acid increased in the presence of nTAGs. These results may suggest that unsaturated fatty acids and membrane lipids are related to the cell wall formation and the implementation of morphogenetic programs in mucorous fungi.     

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.     

Impact of morphogenetic effectors on the growth pattern and the lipid composition of the mycelium and the yeastlike cells of the fungus Mucor hiemalis

We investigated the growth and the cell lipid composition of the mycelium and of the yeast-like form of Mucor hiemalis VKMF-1431 obtained under aerobic conditions by treatment with the morphogenetic agents itraconazole, exogenous triacylglycerols (TAGs), and trehalose. The sporangiospores of a 20-day culture were inoculated on the medium with glucose. Under these conditions, the fungus produced both mycelium and yeast-like cells. It was established that, upon the germination of old (20-day) sporangiospores, the fungus predominantly used the mycelium development strategy in the presence of trehalose and TAGs. It was characterized by a low ratio between the two bulk membrane lipids (PEA/PC) and increased levels of PC and polyunsaturated fatty acids (FA). Compared to the mycelium, the yeast cell morphotype obtained on the medium with glucose was distinguished by an elevated PEA/PC ratio, lowered TAG, free sterol (FS) and esterified sterol (ES) levels, a decreased ES/FS ratio that correlated with the reserve sterol pool size, and a lowered content of unsaturated fatty acids (the linoleic and the ??-linolenic acid). These peculiarities of the lipid composition of yeastlike cells correlated with the intensity of yeastlike growth. Light and electron microscopy revealed differences between the above cell morphotypes. With itraconazole, yeast-like cells were characterized by the destruction of the endoplasmic reticulum membranes and formation of a large number of vacuoles. The suggestion was confirmed that the state/age of inoculum sporangiospores exerts an influence on the capacity for dimorphism in mucorous fungi such as M. hiemalis. The data obtained testify to an involvement of lipids in the process of adaptation to environmental factors and to their regulatory role in morphogenetic processes associated with the formation of alternative morphotypes of the mucorous fungus.     

Physiological studies on Phymatotrichum omnivorum VI. Lipid composition of mycelium and sclerotia

The lipid composition of the mycelium and sclerotia ofPhymatotrichum omnivorum was compared. The lipids of the mycelium contained 47.9 % polar lipids as compared to 21.4 % in the sclerotia. Sterols represented 10 % of the lipids in sclerotia as contrasted to 3.6 % of the mycelium. More monoglycerides (17.5 %) were detected in the sclerotia as compared to the mycelium (1.6 %). Fatty acid analysis indicated that linoleic acid was the predominant fatty acid in the total fatty acids fraction in both the mycelium and the sclerotia. Palmitic acid was the major free fatty acid in the mycelium, whereas myristic acid was the predominant free fatty acid in the sclerotia. In the fatty acids of the diglycerides of sclerotia, palmitic acid represented 71 % of that fraction, as compared to 6.6 % of the fatty acids of the diglycerides in the mycelium. The major fatty acid in the diglycerides of the mycelium was oleic acid.     

Lipids of Rhizopus arrhizus Fischer

The lipids of Rhizopus arrhizus Fischer mycelia and sporangiospores were extracted, isolated, and separated by thin-layer, liquid, and gas chromatography. Structural confirmations of the compounds were made by a gas chromatographmass spectrometer combination. The n-heptane fraction contained squalene (1%) as a major hydrocarbon constituent. Other major lipid classes detected were free fatty acids, naturally occurring methyl esters of fatty acids, triglycerides, sterols, and polar lipids. The polar lipids (44.4%) were found in the highest concentrations, and the triglycerides (22.1%), sterols (16.7%), and free fatty acids (11.7%) were present in lesser concentrations. This is the first report of naturally occuring methyl esters of long-chain fatty acids being present in fungal mycelium. There appears to be a preference for incorporation of unsaturated acids into the complex lipids, with the exception of the triglycerides. The major saturated fatty acids in the mycelium were palmitic (C(16)) and arachidic (C(20)), whereas the major unsaturated acids were oleic (C(18:1)) and linoleic (C(18:2)), respectively.     

Lipid composition of thermophilic moulds Acremonium alabamensis and Thermomucor indicae-seudaticae

The total lipid content of Acremonium alabamensis and Thermomucor indicae-seudaticae ranged 2.6–7.3 and 8.5–13.0% of dry mycelium, respectively during development. Neutral lipid fraction increased during growth while polar and phospholipids declined. Both moulds contained palmitic, oleic, linoleic and palmitoleic acids as major fatty acid components in lipids. Degree of unsaturation of lipids of A. alabamensis was greater than that of T. indicae-seudaticae. Neutral lipids were more unsaturated than the polar lipids. The ratio of unsaturation index of polar lipids to neutral lipids was either one or less than one. The principal phospholipids of these moulds were phosphatidyl choline, phosphatidyl ethanolamine and phosphatidic acid. However, phosphatidic acid was not found in very high amounts as observed in Humicola grisea var. thermoidea.     

Composition of sterols from arthrospores and mycelia of the fungus Mucor hiemalis

Sterol composition of the arthrospores and mycelium of the fungus Mucor hiemalis 1156 was studied by the method of chromatography-mass spectrometry. Along with ergosterol, the major sterol of the culture studied, ten minor sterol were identified, which were either precursors or products of ergosterol degradation. The content of individual sterols differed substantially in arthrospores and mycelium, which represent different stages of ontogenetic development of the fungus. In arthrospores, the content of ergosterol was lower than in mycelium (55.9 and 78%, respectively). Among the precursors of ergosterol, methylated sterols predominated in arthrospores (24.1% versus 11.6% in mycelium). Eburicol and 4,4-dimethylfecosterol were the major methylated sterols of arthrospores (10.6 and 8.1%, respectively). In addition, two uncommon and extremely rare sterols, 1-dihydro-dehydroneoergosterol and dehydroneoergosterol, were identified (for the first time in M. hiemalis). These substances, containing a complex system of conjugated double bonds in their A and B rings, are the products of ergosterol degradation. The data on sterol composition are discussed in terms of their morphogenetic implication.     

Fungal lipid accumulation and development of mycelial structures by two arbuscular mycorrhizal fungi

We monitored the development of intraradical and extraradical mycelia of the arbuscular mycorrhizal (AM) fungi Scutellospora calospora and Glomus intraradices when colonizing Plantago lanceolata. The occurrence of arbuscules (branched hyphal structures) and vesicles (lipid storage organs) was compared with the amounts of signature fatty acids. The fatty acid 16:1omega5 was used as a signature for both AM fungal phospholipids (membrane constituents) and neutral lipids (energy storage) in roots (intraradical mycelium) and in soil (extraradical mycelium). The formation of arbuscules and the accumulation of AM fungal phospholipids in intraradical mycelium followed each other closely in both fungal species. In contrast, the neutral lipids of G. intraradices increased continuously in the intraradical mycelium, while vesicle occurrence decreased after initial rapid root colonization by the fungus. S. calospora does not form vesicles and accumulated more neutral lipids in extraradical than in intraradical mycelium, while the opposite pattern was found for G. intraradices. G. intraradices allocated more of its lipids to storage than did S. calospora. Thus, within a species, the fatty acid 16:1omega5 is a good indicator for AM fungal development. The phospholipid fatty acid 16:1omega5 is especially suitable for indicating the frequency of arbuscules in the symbiosis. We propose that the ratio of neutral lipids to phospholipids is more important than is the presence of vesicles in determining the storage status of AM fungi.