Different mechanisms of the biochemical adaptation of mycelial fungi to temperature stress: Changes in the lipid composition

A comparative study was conducted concerning the effect of temperature stress on the lipid composition of representatives of the subkingdomsEomycota andNeomycota. Changes in the composition of lipid acyl chains (such as saturation and desaturation, isomerization, and changes in the length of fatty acid carbon chains), in the phospholipid composition, and in the contents of sterols and other neutral lipids were revealed. Hyperthermia resulted in (i) an increase in the phosphatidylcholine level, (ii) a decrease in the phosphatidylethanolamine level, (iii) a rise in the content of reserve lipids (triacylglycerols), and (iv) a decline in the free fatty acid level in the neutral lipids. An inverse pattern occurred under hypothermic conditions. The peculiarities in the patterns of the temperature adaptation-related changes in the lipid bilayer composition are considered in terms of the systematic position of the fungi.     

Importance of lipidic acyl chains in the process of biochemical thermal adaptation of <Emphasis Type="Italic">Cunninghamella japonica</Emphasis> mucoraceous fungus

The temperature of C. japonica cultivation influences the lipid content and composition of acyl chains, especially the content of such polyunsaturated acids as linoleic and linolenic. Thermal adaptation is accompanied by the modulation of fatty acid isomeric composition and acyl chain length and, at low temperatures, promotes the appearance of fatty acids uncommon to the fungus, in particular, arachidonic acid. The changes occur on a background of significant alterations in the fungus metabolism (in glucose uptake, ATP content, economic coefficient value, etc.). In experiments on the inhibition of translation with cycloheximide, abrupt temperature change (supraoptimal to cold) did not lead to desaturase de novo synthesis, but rather stimulated the activity of the named enzymes, except for palmitoleoyl-CoA desaturase. In the process of temperature adaptation, polar lipid microviscosity modulating compounds influenced fatty acid acyl chain composition. Microviscosity differences between polar and neutral lipids and correlation to the degree of fatty acid unsaturation during temperature fluctuation were established.     

The effect of variations in growth temperature, fatty acid composition and cholesterol content on the lipid polar head-group composition of Acholeplasma laidlawii B membranes

We have systematically investigated the effect of variations in growth temperature, fatty acid composition and cholesterol content on the membrane lipid polar headgroup composition of Acholeplasma laidlawii B. Two important lipid compositional parameters have been determined from such an analysis. The first parameter studied was the ratio of the two major neutral glycolipids of this organism, monoglucosyldiacylglycerol (MGDG) and diglucosyldiacylglycerol (DGDG). As the former lipid prefers to exist in a reversed hexagonal phase at higher temperatures, with unsaturated fatty acyl chains or in the presence of cholesterol, the ratio of these two lipids reflects the phase state preference of the total A. laidlawii membrane lipids. Although we find that the MGDG/DGDG ratio is reduced in response to an increase in fatty acid unsaturation, increases in growth temperature or cholesterol content reduce this ratio only in cells enriched in a saturated but not an unsaturated fatty acid. The second parameter studied was the ratio of these neutral glycolipids to the only phosphatide in the A. laidlawii membrane, phosphatidylglycerol (PG); this parameter reflects the relative balance of uncharged and charged lipids in the membrane of this organism. We find that the MGDG + DGDG/PG ratio is lowest in cells enriched in the saturated fatty acid even though these cells already have the highest lipid bilayer surface charge density. Moreover, this ratio is not consistently related to growth temperature or changes in cholesterol levels, as expected. We therefore conclude that A. laidlawii strain B, apparently unlike strain A, does not possess coherent regulatory mechanisms for maintaining either the phase preference or the surface charge density of its membrane lipid constant in response to variations in growth temperature, fatty acid composition or cholesterol content.     

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.     

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     

Effect of growth temperature on lipid composition of Streptococcus faecium

The effect of growth temperature on the lipid and fatty acid composition of Streptococcus faecium has been studied. No differences in the qualitative composition of S. faecium lipids were observed. In all isolated fractions (neutral lipids, glycolipids, and phospholipids plus other polar lipids), the major fatty acids were palmitic (C-16:0), palmitoleic (C-16:1), octadecenoic (C-18:1), and cyclopropane (C-19:0). Changes in the fatty acid composition of the different fractions were observed which depended on growth temperature; the most significant one was the decrease of octadecenoic acid and the increase of palmitic acid in glycolipids and polar lipids as the temperature increased. The level of cyclopropane C-19:0 was approximately eightfold lower at 8 degrees C than at the other temperatures tested (20, 30, and 45 degrees C).     

Modification of the fatty acid composition of individual phospholipids and neutral lipids after infection of the simian erythrocyte by Plasmodium knowlesi

Using capillary gas-liquid chromatography, we have analyzed the alteration in the total fatty acid, phospholipid and neutral lipid compositions of the monkey erythrocyte, after infection by the malarial parasite Plasmodium knowlesi. Data based on fatty acid quantitation show that the phospholipid composition is altered, with particularly large increases in phosphatidylcholine (PC) and phosphatidylethanolamine (PE), the most abundant phospholipids in normal and P. knowlesi-schizont-infected cells. Unesterified fatty acids were found to be less abundant in infected cells. The total fatty acid content of the cell is increased 6-fold during infection, and total fatty acid composition is also changed: the infected cells are richer in palmitate (+23%), oleate (+29%) and linoleate (+89%), but contained less stearate (-27%) and arachidonate (-40%). The determination of the fatty acid composition of individual phospholipids, neutral lipids and unesterified fatty acids showed that choline-containing phospholipids (PC and sphingomyelin) were not as altered in their fatty acid pattern as anionic phospholipids (PE, phosphatidylserine (PS) and phosphatidylinositol (PI) and lysophosphatidylcholine (lysoPC). Specific alterations in the fatty acid compositions of individual phospholipids were detected, whereas the rise in linoleic acid was the only change during infection that was recovered in each phospholipid (except PC), neutral lipid and unesterified fatty acids. The fatty acid composition of the neutral lipids and unesterified fatty acids was particularly modified: the only rise in arachidonic acid level was observed in these lipid classes after infection. The total plasmalogen level of the erythrocyte is decreased in infected cells (-60%), but their level is increased in PI.     

Change in chemical composition of membrane of Bacillus caldotenax after shifting the growth temperature

Membranes from Bacillus caldotenax contain neutral lipids and phospholipids such as phosphatidylethanolamine, phosphatidyl glycerol and cardiolipin. Each of the lipids has almost the same fatty acid composition. When the growth temperature decreases, not only the fatty acid composition but also the lipid composition changes such that the membrane fluidity increases, and the composition of membrane-bound proteins also changes. On shifting the growth temperature from 65° to 45°C, the bacterium grows immediately with a doubling time at 45°C, but the compositions of proteins and lipids in membranes gradually change and reach the compositions typical of cells growing at 45°C one doubling time after the temperature shift, respectively. It is concluded that the change in chemical composition of membrane of the bacterium on the temperature shift from 65° to 45°C is not prerequisite for growth at 45°C.     

Effect of cobalt ions on lipid and sterol metabolism in the marine invertebrates Mytilus galloprovincialis and Actinia equina

The lipid and sterol fractions of the mussel Mytilus galloprovincialis and the anemone Actinia equina were analyzed before and after incubation with cobalt ions. There were significant changes in the lipid and sterol composition, strongly depending on the cobalt ions concentrations. The changes in the lipid composition of both invertebrates were different for neutral lipids and phospholipids. These changes concern the length of the fatty acid chains as well as their unsaturation. The cobalt ions inhibited the oxidation of sterols and their alkylation at C-24. Because of these results we can assume that some of the changes caused by cobalt ions might possess adaptive value.     

Lipids and fatty acid composition of developing winged bean seeds

The moisture, lipids and fatty acid composition of developing winged bean (Psophocarpus tetragonolobus) seeds were studied. The moisture content decreased steadily as the seeds matured. The lipid content increased gradually and reached a maximum ca 6 weeks after flowering (WAF). In the early stage (2 WAF) of the developing seeds there were more polar lipids (glycolipids and phospholipids) than neutral lipids but, as the seeds developed, neutral lipids gradually accumulated while the polar lipids decreased until 6 WAF. Thereafter, both the neutral lipid and polar lipid levels remained little changed. The amounts of palmitic and stearic acids decreased, but the level of behenic acid increased as the seeds matured. On the other hand, the oleic acid content increased while that of linolenic acid decreased rapidly as the seeds matured. The concentration of linoleic acid, however, fluctuated during the development of the seeds.     

Fluid phase lipid areas and bilayer thicknesses of commonly used phosphatidylcholines as a function of temperature

The structural parameters of fluid phase bilayers composed of phosphatidylcholines with fully saturated, mixed, and branched fatty acid chains, at several temperatures, have been determined by simultaneously analyzing small-angle neutron and X-ray scattering data. Bilayer parameters, such as area per lipid and overall bilayer thickness have been obtained in conjunction with intrabilayer structural parameters (e.g. hydrocarbon region thickness). The results have allowed us to assess the effect of temperature and hydrocarbon chain composition on bilayer structure. For example, we found that for all lipids there is, not surprisingly, an increase in fatty acid chain trans-gauche isomerization with increasing temperature. Moreover, this increase in trans-gauche isomerization scales with fatty acid chain length in mixed chain lipids. However, in the case of lipids with saturated fatty acid chains, trans-gauche isomerization is increasingly tempered by attractive chain-chain van der Waals interactions with increasing chain length. Finally, our results confirm a strong dependence of lipid chain dynamics as a function of double bond position along fatty acid chains.     

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.     

Altered lipid composition of adipose tissue in human muscular dystrophy

Lipids of subcutaneous adipose tissue from normal and dystrophic human samples were investigated with particular reference to the fatty acid composition of neutral lipids and phospholipids. The free fatty acid pattern did not show much change. Triglyceride, which together with cholesterol composed most of the neutral lipid fraction, showed significant changes in fatty acid composition by gas-liquid chromatography (GLC). There was a decrease in the total phospholipids. Analysis of the levels of individual phospholipids, however, showed an increase in sphingomyelin and ethanolamine phosphoglyceride contents. Fatty acid composition of the different phospholipid classes analyzed by GLC showed significant changes.     

The effect of temperature on hairy root cultures of Catharanthus roseus: Growth,indole alkaloid accumulation and membrane lipid composition

Cultivation of Catharanthus roseus hairy root cultures at different temperatures was found to have an effect on growth rate and indole alkaloid content as well as lipid composition. When lowering the temperature, the roots responded by increasing the degree of unsaturation of cellular lipids, which was mainly due to an increased proportion of linolenic acid in the main lipid classes. The modifications in lipid composition were obviously necessary for the roots to retain the proper cell membrane fluidity at each temperature. Despite of changes in membrane lipids, no effect on the distribution of indole alkaloids between the roots and the medium could be detected. Instead, the level of alkaloid accumulation showed a clear increase with lowering temperature.Abbreviations PC phosphatidylcholine - PE phosphatidylethanolamine - PI phosphatidylinositol - PS phosphatidylserine - PG phosphatidylglycerol - CL cardiolipin - DGD digalactosyldiglyceride - MGD monogalactosyldiglyceride - NL neutral lipids - DU degree of fatty acid unsaturation     

Changes in the Amount of Complex Lipids in the Seeds and in the Pericarp during the Development of Ivy Fruit (Hedera helix)

By a combination of thin-layer chromatography and gas liquid chromatography, a complete study of the development of the different lipid classes and of their fatty acids, during the development of the fruit of Hedera helix L., the English Ivy, has been achieved. In any part of the fruit observed, at any particular stage, the phospholipids and the neutral lipids are the most abundant lipid classes. They accumulate during the entire process of maturation, whereas significant changes occur in their relative proportions, phospholipids being largely dominant until fruit blackening. The accumulation of fatty acids during maturation is characterized by large amounts of C_18:1 in the neutral lipids, especially in the seed, where petroselinic acid (C_18:1Δ⁶) reaches 86% of the total fatty acids. To a smaller extent, the phospholipids also accumulate and thus have the character of reserve molecules. However, their composition remains more stable, which relates them to the “structural lipids” such as galactolipids that maintain their characteristic fatty acid composition, despite the radical changes occurring in the fatty acid metabolism during fruit ripening.     

A moderate change in temperature induces changes in fatty acid composition of storage and membrane lipids in a soil arthropod

A moderate change in ambient temperature can lead to vital physiological and biochemical adjustments in ectotherms, one of which is a change in fatty acid composition. When temperature decreases, the composition of membrane lipids (phospholipid fatty acids) is expected to become more unsaturated to be able to maintain homeoviscosity. Although different in function, storage lipids (triacylglycerol fatty acids) are expected to respond to temperature changes in a similar way. Age-specific differences, however, could influence this temperature response between different life stages. Here, we investigate if fatty acid composition of membrane and storage lipids responds similarly to temperature changes for two different life stages of Orchesella cincta. Juveniles and adults were cold acclimated (15 °C → 5 °C) for 28 days and then re-acclimated (5 °C → 15 °C) for another 28 days. We found adult membranes had a more unsaturated fatty acid composition than juveniles. Membrane lipids became more unsaturated during cold acclimation, and a reversed response occurred during warm acclimation. Membrane lipids, however, showed no warm acclimation, possibly due to the moderate temperature change. The ability to adjust storage lipid composition to moderate changes in ambient temperature may be an underestimated fitness component of temperature adaptation because fluidity of storage lipids permits accessibility of enzymes to energy reserves.     

The effect of fluoride on the growth and fatty acid composition of Sphagnum fimbriatum at two temperatures

The fatly acid composition of different lipid fractions (neutral, glyco- and phospholipids) was studied in Sphagnum fimbriatum Wils, gametophytes grown in aseptic cultures at two temperatures (15°C and 25°C). The effect of a growth-retarding concentration (0.1 mM) of KF was also investigated. Fifteen-day treatment with KF affected the fatty acid composition more strongly at the higher than at the lower temperature. The proportion of palmitic acid (16:0) increased but the proportion of linoleic (18:2) decreased in all the lipid fractions, and that of linolenic (18:3) acid decreased in the fractions containing glyco- and neutral lipids. This indicates that the fluoride ions inhibit lengthening of the fatty acid chain. Compared with gametophytes grown at 25°C, material cultivated at 15°C had a much higher proportion of a highly unsaturated fatty acid, linolenic acid (18:3), in all the lipid fractions, but a lower proportion of oleic acid (18:1) in the neutral and phospholipids, and a lower proportion of linoleic (18:2) acid in all three fractions.     

Analysis of Lipids of Citrullus lanatus (cv. Sugar baby) During Seed Germination and Seedling Growth

Changes in the dry weight (dry wt.), total and neutral lipids,and fatty acid composition were determined in the cotyledonsand axis of Citrullus lanatus cv. Sugar baby seedlings duringtheir first 12 d growth in the dark, at 25 ? 1 ?C. The major stored reserves were mobilized between days 3 and8. The lipid concentration after day 4 decreased rapidly inthe cotyledons. On the first day the lipid concentration inthe axis was higher than in the cotyledons but decreased rapidlyand from day 5 up to the end of the experiments it remainedat very low values. In the cotyledons, the change in the fattyacid composition was relatively small compared to the significantchange observed in the axis. The neutral lipids of the cotyledonsdecreased sharply between days 2 and 6 while their fatty acidcomposition suffered no significant change. The axis, comparedto the cotyledons, contained a small but concentrated amountof neutral lipids, which decreased up to day 6. Thereafter,an increase was observed. The fatty acid composition of theaxis neutral lipids changed significantly, linoleic and oleicacid decreased while palmitic and linolenic acid increased. Key words: Citrullus lanatus, seed germination, seedling growth, lipids, fatty acids     

Lipids in Cruciferae IX. The Effect of Growth Temperature and Stage of Development on the Fatty Acid Composition of Leaves, Siliques and Seeds of "Zero-erucic-acid" Breeding Lines of Brassica napus

Two breeding lines of “zero-erucic-acid” rapeseed (Brassica napus) were grown in climate chambers at a constant night temperature (12°C) and constant photoperiod (16 hours) but with different day temperatures (15, 20 and 25°C). Samples of leaves, siliques and immature seeds were analysed for total fatty acid pattern. The content of different acyl lipids and the fatty acid pattern of these lipids were also determined in some of the samples by use of preparative TLC followed by GLC of the fatty acids. The mature seeds produced by ten plants of each selection in each climate were analysed separately for total fatty acid composition. Mono- and digalactosyl diglycerides (MGDG, DGDG) were the predominant acyl lipids in leaves and siliques. In developing seeds they also were more abundant than the phospholipids, but in this case the neutral lipids, mainly triacylglycerols, contained about 95% of the total fatty acids. Large variations were found in the fatty acid composition of monogalactosyl diglyceride and digalactosyl diglyceride, isolated from leaves, siliques and immature seeds. The palmitic acid content of leaf MGDG was about 15 %, atypically high for MGDG from photosynthetic tissue. The linolenic acid content of the MGDG was about 45 %, 30 % and 10 % in the leaf, silique and seed tissues respectively. A hexadecatrienoic acid (16: 3) was found almost exclusively in the MGDG samples of leaves, siliques and immature seeds (about 25 %, 10 % and 3 % 16:3 respectively). The lipids of siliques — mainly photosynthetising tissue — were different from those of leaves and had especially high contents of stearic acid (6–12 % in the different lipids). For all lipid classes studied, leaves grown at the lowest day temperature had a slightly lower oleic and higher linolenic acid content than those grown at the highest temperature. On the other hand, increasing the day temperature caused a decreased level of oleic, an increased level of linoleic and an essentially unchanged level of linolenic acids in the mature seeds from both selections.     

Dietary fats,selected body temperature and tissue fatty acid composition of agamid lizards (Amphibolurus nuchalis)

The composition of tissue and membrane fatty acids in ectothermic vertebrates is influenced by both temperature acclimation and diets. If such change in body lipid composition and thermal physiology were linked, a diet-induced change in body lipid composition should result in a change in thermal physiology. We therefore investigated whether the selected body temperature of the agamid lizardAmphibolurus nuchalis (body mass 20 g) is influenced by the lipid composition of dietary fatty acids and whether diet-induced changes in thermal physiology are correlated with changes in body lipid composition. The selected body temperature in two groups of lizards was indistinguishable before dietary treatments. The selected body temperature in lizards after 3 weeks on a diet rich in saturated fatty acids rose by 2.1 °C (photophase) and 3.3 °C (scotophase), whereas the body temperature of lizards on a diet rich in unsaturated fatty acids fell by 1.5 °C (photophase) and 2.0 °C (scotophase). Significant diet-induced differences were observed in the fatty acid composition of depot fat, liver and muscle. These observations suggest that dietary lipids may influence selection of body temperature in ectotherms via alterations of body lipid composition.Abbreviations bm body mass - FA fatty acid(s) - MUFA monounsaturated fatty acids - PUFA polyunsaturated fatty acids - SFA saturated fatty acids - T _a air temperature - T _b body temperature - UFA unsaturated fatty acids