TOTAL LIPID PRODUCTION OF THE GREEN ALGA NANNOCHLOROPSIS SP. QII UNDER DIFFERENT NITROGEN REGIMES1

The green alga Nannochloropsis sp. QII was cultivated in media with sufficient and growth-limiting levels of nitrogen (nitrate). Nitrogen deficiency promoted lipid synthesis yielding cells with lipids comprising 55% of the biomass. The major lipids were triacylglycerols (79%), polar lipids (9%) and hydrocarbons (2.5%). The polar lipids consisted of a broad range of phospholipids, glycolipids and sulfolipids. Other lipids identified were pigments, free fatty acids, saponifiable and unsaponifiable sterol derivatives, various glycerides, a family of alkyl-1, 4-dioxane derivatives and a series of alkyl- and hydroxyalkyl-dimethyl-acetals. Experiments in which ¹⁴CO₂ was provided at different times in the growth cycle demonstrated that enhanced lipid biosynthesis at low nitrogen levels resulted principally from de novo CO₂ fixation.     

Seasonal variability of lipids and fatty acids in the tree-growing lichen Xanthoria parientina L.

The composition of lipids, PLs and FAs in the treegrowing lichenXanthoria parientina, collected during the period from Marchto May, was studied. The major polar lipids found, includingphospholipids, were DGTS, PC, PE, and PG. Polar and PL contentswere also identified, and certain trends in the changing proportionsof PC (increasing from 17.8 to 50.1%) and DGTS (decreasing from27.1 to 12.6%) were determined. The fatty acid composition wasexamined using capillary GC-MS in the neutral, glyco- and PLfractions. Hydroxy acids were detected only in the glycolipidfraction; their seasonal dynamics were also studied. The seasonalchanges occurring in lipid composition due to the temperaturefactor were identified. It was found that X. parientina hada characteristic temperature-based lipid pattern, increasingin its neutral lipid content from 40.6% in March to 52.7% inMay but decreasing in glycolipid from 39.0% in March to 27.0%in May. Key words: Xanthoria, lipids, DGTS, fatty acids, lichen     

Fatty‐Acid Profile of Total and Polar Lipids in Cultured Rainbow Trout (Oncorhynchus mykiss) Raised in Freshwater and Seawater (Croatia) Determined by Transmethylation Method

Fatty acids from total lipids and polar lipids in cultured rainbow trout (Oncorhynchus mykiss) raised in seawater (SW) and freshwater (FW) were identified and quantified from the muscle samples in January, April, and July. The highest total lipid and polar lipid amounts were found in April. July contents of total lipids were low, but percent of the polyunsaturated fatty acids (PUFAs) was high in SW and FW environment (particularly n‐3 PUFAs). Variety of 17 fatty acids was identified by GC‐FID after transmethylation. The predominant fatty acids in rainbow trout from SW and FW were: docosahexaenoic acid among n‐3 PUFAs, palmitic acid among saturated fatty acids (SFAs), and oleic acid among monounsaturated fatty acids (MUFAs). Appreciably higher n‐3/n‐6 ratio was found in total lipids in April (6.40, FW fish) and in polar lipids in July (18.76; SW fish). High n‐3/n‐6 ratio in total lipids and polar lipids of rainbow trout from SW and FW, besides beneficial n‐3/n‐6 ratio in the commercial fish food, could be characteristic for the local environmental conditions (Croatia).     

Effect of weak constant magnetic field on the composition and content of lipids in radish seedlings at various temperatures

We studied the effects of weak permanent homogenous hirizontal magnetic field (PMF) (400 A/m) on the composition and content of lipids and composition of their fatty acids (FAs) in radish (Raphanus sativus L. var. radicula D.C., cv. Rosovo-krashyi s belym konchikom) seedlings at temperatures of 20 and 10°C. We compared lipid composition and content in seedlings at the phase of developed cotyledons (20°C, 5-day-old, and 10°C, 8-day-old seedlings) under low light and in darkness with the lipid composition and content in dry seeds. The seedlings grown in geomagnetic field (GMF) served as a control. In dry seeds, about 99% of total lipids comprised neutral lipids (NL) and only 1% were polar lipids (PL). Triacylglycerols predominated among NL comprising 93% of total seed lipids. During seed germination, NLs were consumed and PL were produced: the amount of glycolipids increased in control by 3.5–5 times and the amount of phospholipis, by 1.5–2 times.In the light at 20°C, PMF suppressed the formation of PL (by 18%), whereas in darkness, it stimulated it approximately by 80% as compared with control. In the light at 10°C, PMF slightly stimulated PL formation; in darkness, it did not almost affect their synthesis. In all treatments, PMF increased the ratio of phospholipids to sterols by 30–100%. Among FA, PMF exerted the strongest effect on the content of erucic acid: it increased in the light and in darkness at 20°C approximately by 25% and decreased at 10°C in the light by 13%. PMF behaved as a correction factor affecting lipid metabolism on the background of light and temperature action.     

The bioenergetic fuel for non-feeding larval development in an endemic palaemonid shrimp from the Iberian Peninsula,Palaemonetes zariquieyi

Palaemonetes zariquieyi, an endemic palaemonid species of shrimp that lives in freshwater and brackish coastal habitats in eastern Spain, shows an abbreviated, non-feeding larval development comprising only three zoeal stages. To identify the endogenous bioenergetic fuel that allows for food-independent development from hatching to metamorphosis, larvae were reared under controlled laboratory conditions, and ontogenetic changes in dry weight (W), elemental (CHN), and lipid composition (total lipids, principal lipid classes, and fatty acids [FA]) were quantified at the onset of each zoeal stage and in the first juvenile. Values of W, C, and H per larva and per mass unit of W decreased throughout the time of larval development, while the N content showed only a weak decline (suggesting strong lipid but only little protein degradation). Correspondingly, directly measured values of total lipids (both in μg/larva and in % of W) decreased gradually, with neutral lipids (NL) consistently remaining the predominant and most strongly used fraction; sterol esters and waxes were not detected. In contrast to the NL, the fraction of polar lipids (PL) per larva remained stable and, as a consequence, tended to increase as a percentage of total lipids. Likewise, other important lipid fractions such as free FA and cholesterol remained stable throughout the time of larval development. Among the FA, palmitic (16:0), oleic (18:1n–9), linoleic (18:2n–6), and eicosapentaenoic (20:5n–3) acid were predominant, showing a significant decrease during larval development; stearic (18:0), vaccenic (18:1n–7), and arachidonic acid (20:4n–6) were found only in small amounts. Our results indicate that the lecithotrophic development of P. zariquieyi is primarily fuelled by the utilization of lipids (especially triacylglycerides and other NL), which is reflected by a decreasing carbon content. Proteins and PL, by contrast, are preserved as structurally indispensable components (nerve and muscle tissues, cell membranes). The abbreviated and non-feeding mode of larval development of P. zariquieyi may have an adaptive value in land-locked freshwater habitats, where planktonic food limitation is likely to occur. The patterns of reserve utilization are similar to those previously observed in other palaemonid shrimps and various other groups of decapod crustaceans with lecithotrophic larvae. This suggests a multiple convergent evolution of bioenergetic traits allowing for reproduction in food-limited aquatic environments.     

Cell Structure of Yeasts Grown Anaerobically in Aspergillus orpzae-Proteolipid-supplemented Media

Effects of Aspergillus oryzae-proteolipid (PL) on the formation of high concentrations of alcohol, more than 20% as in sake brewing, have been studied. Electron microscopy revealed that there were no vacuoles but many lipid deposits in cytoplasm of the alcoholtolerant cells of Saccharomyces sake Kyokai No. 7, which were obtained by the anaerobic culture supplemented with PL. Sphaeroplasts from the alcohol-tolerant cells were stable in 20% alcohol, whereas those from the untolerant cells grown anaerobically in the PL-unsupplemented media were ruptured. The cell membrane became alcohol-endurable in the anaerobic cultures with PL. Synthetic phospholipid promoted yeast growth and the fermentative activity, whereas a small amount of sterol ester enhanced the alcohoi-endurability. The supplementation of both lipids anaerobically induced physiological properties characteristic of the alcohol-tolerant cells.     

Lipids and fatty acids of two pelagic cottoid fishes (Comephorus spp) endemic to Lake Baikal

Matured females of two Lake Baikal endemic fish species, Comephorus baicalensis and Comephorus dybowski, have been investigated for lipid of the whole body and specific tissues (liver, muscles, ovaries), phospholipid classes and fatty acids of neutral and polar lipids. Total lipid in the body (38.9% fresh weight), liver (23.5%) and muscles (14.5%) of C. baicalensis were greater than those of C. dybowski (4.7, 8.7 and 2.6%, respectively); only their ovaries were similar (5.3 and 5.6% lipid, respectively). In both species, phosphatidylcholine and phosphatidylethanolamine were the major phospholipids, ranging from 60.7 to 75.1% of total phospholipid and 14.5–25.7%, respectively. In most cases, monounsaturated fatty acids (MUFA) were the major fatty acid group in C. baicalensis, whereas polyunsaturated fatty acids (PUFA) were the major group in C. dybowski. The MUFA 18:1(n-9) prevailed over other fatty acids in C. baicalensis and varied from 19% in polar lipids of muscles to 56.1% in neutral lipids of muscles. In polar lipid of C. dybowski, the PUFA 22:6(n-3) prevailed over other fatty acids in muscles and ovaries, while 16:0 dominated polar liver lipids and neutral lipids of all tissues. Other major fatty acids included 16:1(n-7), 18:1(n-7), and 20:5(n-3). Values of the (n-3)/(n-6) fatty acid ratio for neutral lipids of C. baicalensis (0.5–0.9) are well below the range of values characteristic either for marine or freshwater fish, while these values for polar lipids (1.6–1.8) are in the range typical of freshwater fish. Neutral lipid fatty acid ratios in C. dybowski (2.5–3.1) allow it to be assigned to freshwater fish, but polar lipids (2.8–3.7) leave it intermediary between freshwater and marine fish.     

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.     

Revealing the polar lipidome,pigment profiles,and antioxidant activity of the giant unicellular green alga,Acetabularia acetabulum

Marine algae are one of the most important sources of high-value compounds such as polar lipids, omega-3 fatty acids, photosynthetic pigments, or secondary metabolites with interesting features for different niche markets. Acetabularia acetabulum is a macroscopic green single-celled alga, with a single nucleus hosted in the rhizoid. This alga is one of the most studied dasycladalean species and represents an important model system in cell biology studies. However, its lipidome and pigment profile have been overlooked. Total lipid extracts were analyzed using hydrophilic interaction liquid chromatography-high resolution mass spectrometry (HILIC-HRMS), tandem mass spectrometry (MS/MS), and high-performance liquid chromatography (HPLC). The antioxidant capacity of lipid extracts was tested using DPPH and ABTS assays. Lipidomics identified 16 polar lipid classes, corresponding to glycolipids, betaine lipids, phospholipids, and sphingolipids, with a total of 191 lipid species, some of them recognized by their bioactivities. The most abundant polar lipids were glycolipids. Lipid classes less studied in algae were identified, such as diacylglyceryl-carboxyhydroxymethylcholine (DGCC) or hexosylceramide (HexCer). The pigment profile of A. acetabulum comprised carotenoids (17.19%), namely cis-neoxanthin, violaxanthin, lutein and β,β-carotene, and chlorophylls a and b (82.81%). A. acetabulum lipid extracts showed high antioxidant activity promoting a 50% inhibition (IC₅₀) with concentrations of 57.91 ± 1.20 μg · mL⁻¹ (438.18 ± 8.95 μmol Trolox · g⁻¹ lipid) in DPPH and 20.55 ± 0.60 μg · mL⁻¹ in ABTS assays (918.56 ± 27.55 μmol Trolox · g⁻¹ lipid). This study demonstrates the potential of A. acetabulum as a source of natural bioactive molecules and antioxidant compounds.     

The effect of temperature on the growth and lipid composition of the extremely halophilic coccus,Sarcina marina

Sarcina marina (NCMB 778) grew over the temperature range 20–45°C but no growth was recorded at 15°C or 50°C. At the optimum growth temperature of 34°C the doubling time was 14.5 h.The major polar lipid components, tentatively identified as the diether analogues of phosphatidyl glycerophosphate (PGP), phosphatidyl glycerol (PG), diglycosyl diglyceride (DGD) and triglycosyl diglyceride (TGD), and the major neutral lipid components, tentatively identified as squalene, dihydrosqualene, tetrahydrosqualene, vitamin MK8, geranyl geraniol and di-O-phytanyl glycerol, are identical to those found in other extremely halophilic rods and cocci.The total lipid content varied with growth conditions from 0.6 – 3.2% of the dry cell weight, polar lipids accounted for between 94.3 and 83.6% of the total lipid, the remainder being neutral lipid.In response to both the transition from exponential to stationary phase and a reduction of 14°C in growth temperature, batch cultures showed: (i) an increase in total lipid content; (ii) a decrease in PG and (iii) an increase in PGP. Specific responses to the temperature decrease were (i) increased total lipid content; (ii) no decrease in neutral lipids in stationary phase; (iii) marked reduction in PG and (iv) raised DGD. (i) and (ii) could be mechanisms for increasing membrane fluidity.In common with all other extreme halophiles investigated the alkyl side chains of S. marina polar lipids were identified as the phytanyl (3R, 7R, 11R, 15-tetramethylhexadecyl) group. Its structure did not appear to vary with temperature so that the normal mechanisms for modifying the structure of lipid alkyl side chains to modulate membrane fluidity in response to temperature changes probably does not occur in this group of microorganisms.     

Extraction and composition of polar lipids from the archaebacterium, Methanobacterium thermoautotrophicum: effective extraction of tetraether lipids by an acidified solvent

The usual Bligh and Dyer method could extract only a small part of the lipids of Methanobacterium thermoautotrophicum. When the water in the solvent was replaced by 5% trichloroacetic acid, the lipid recovery reached the maximum level, which was 6 times higher than that by the former method. The use of HCl (2 M) or disruption of cells was also effective but prolonged extraction with the HCl-containing solvent caused degradation of some phosphoglycolipids. Twenty-three spots of polar lipids were detected on a thin-layer chromatogram of the total lipid. These were 10 phospholipids (18%), 6 aminophospholipids (17%), 3 aminophosphoglycolipids (15%), 2 phosphoglycolipids (31%), and 2 glycolipids (19%). The predominant polar lipids were a highly polar phosphoglycolipid (PGL1, 30%) and a glycolipid (GL1a, 16%). The other major lipids included an aminophospholipid (PNL1a, 9%), and an aminophosphoglycolipid (PNGL1, 7%). The complete structure determination of PNL1a, GL1a, and PNGL1 is described in the accompanying paper. Acetolysis of the total lipids followed by acid methanolysis was required for the complete cleavage of polar head groups, releasing core residues of diphytanyl glycerol diether (C20 diether) and dibiphytanyl diglycerol tetraether (C40 tetraether). A densitometric assay of a thin-layer chromatogram showed that the ratio of C20 diether and C40 tetraether was 1:14. GLC analysis of alkyl chlorides prepared from the total lipid by BCl3 treatment showed that phytanyl (C20), biphytanyl (C40), and unidentified alkyl chains accounted for 10, 83, and 7 mol% of the total alkyl chains, respectively. Strong acid hydrolysis of the macromolecular residue obtained after lipid extraction gave a significant amount of C40 tetraether, which had probably been bound covalently to other substances in the cells.     

The effect of radish plant rotation around a vertical axis on leaf morphology and lipid composition

The effects of radish (Raphanus sativus L. var. radicula D.C., cv. Rozovo-krasnyi s belym konchikom) plant clockwise rotation (2 rpm) around the vertical axis during their growth on growth parameters and also on the composition and content of polar lipids (PL) and neutral lipids (NL) in plant leaves and fatty acids included in them were studied. Rotation in the plane of the Earth’s magnetic field horizontal component did not affect the number of leaves but declined their total mass by 25%. However, a reduction of the root mass was observed only at elevated temperature. Rotation reduced the ratio of PL to NL by 1.5–2.0 times as compared with control, decreasing the content of such PL as glycoand phospholipids and increasing the content of NL, triacylglycerols and free sterols. Among glycolipids, the content of monogalactosyldiacylglycerols and digalactosyldiacylglycerols was reduced in comparison with stationary control, and among phospholipids the content of phosphatidylcholin was reduced by ∼50%. The ratio of phospholipids to sterols was reduced more than by 30%, indirectly indicating the decreased fluidity of the lipid bilayer of membranes; the ratio PL/NL was reduced as well, indicating an acceleration of age-dependent changes in the rotated plants. Rotation increased the content of linolenic acid and reduced the contents of oleic and erucic acids, thus increasing the index of fatty acid desaturation. We concluded that radish plant clockwise rotation around the vertical axis is an unfavorable factor inducing the appearance of the signs of premature senescence.     

The scheduling of spawning with the moult cycle in Northern krill (Crustacea: Euphausiacea): a strategy for allocating lipids to reproduction

Summary

Euphausiids moult and grow throughout their life, which implies sharing of resources between growth and reproduction for adult krill. In the Northern krill, Meganyctiphanes norvegica (M. Sars), female krill produce eggs cyclically. Spawning moult cycles alternate with vitellogenic moult cycles for lipid yolk accumulation. Histology shows that lipids are associated with the R cells of the digestive gland in both sexes, with the yolk platelets of mature oocytes and with the fat body cell membranes and blood lacunae in reproducing females. Mature female krill can have a total lipid content twice as high as males, mostly due to accumulation in the ovary, the fat body and the haemolymph. In contrast, in males, as well as in non-reproducing females, the highest percentage of lipids is found in the digestive gland and the haemolymph. In Meganyctiphanes norvegica, the most abundant lipid fractions are polar lipids and triglycerides, the latter being relatively low in reproducing female gonad and fat body. Triglycerides are believed to be a pure energy source and polar lipids are essential for membrane development in embryos. The fatty acid content and composition of the triglyceride and polar lipid fractions in females are different from males, related to both reproductive and dietary processes. Higher levels of polyunsaturated fatty acids (PUFA) in the polar lipid fraction were found in reproductive females. During the non-reproductive season, the converse was found, indicating the specific role PUFA and other fatty acids play in growth and egg production. Adaptive processes linked to reproduction were studied comparatively in three populations of the Northern krill—Clyde Sea (W, Scotland), Kattegat (E, Denmark), Ligurian Sea (Mediterranean)—all differing considerably in climatic and trophic conditions. Such adjustments in lipid synthesis and storage are viewed as reproductive strategies developed by the Northern krill in response to different environmental conditions.     

Biological activities of lipid components ofLeptospira interrogans serovarcopenhageni avirulent strain Shibaura

The gas chromatogram showed that the polar lipids (PL) extracted fromLeptospira interrogans serovarcopenhageni avirulent strain Shibaura consisted mainly of palmitic acid, palmitoleic acid, and oleic acid, and that the free fatty acids (FFA) from the strain contained oleic acid at a concentration as high as 67.5%. The intracutaneous injection of FFA induced much stronger edematous and vascular permeability reactions in guinea pigs than did that of PL. In addition, O ₂ ^– generation of polymorphonuclear leukocytes in vitro was enhanced with FFA to much greater extent than with PL.Among the FFA, oleic acid caused the strongest biological activities such as edematous reaction, vascular permeability reaction, O ₂ ^– -generating activity, and hemolytic activity. It is, therefore, very likely that oleic acid may play an important role in toxicities of leptospiral lipids.     

Betaine lipids in chlorarachniophytes

Evolving from the endosymbiosis of a green algal cell by a filose amoeba or amoeboflagellate, the chimearic chlorarachniophytes combine unique features retained from both of their ancestral units. They have preserved from the endosymbiont only the nucleomorph and chloroplast. Four strains from three genera of this algal class were studied to identify a set of non‐phosphorous‐containing polar lipids and their associated fatty acids using the techniques of positive‐ion electrospray ionization/mass spectrometry (ESI/MS) and electrospray ionization/mass spectrometry/mass spectrometry (ESI/MS/MS). Fourteen non‐phosphorous‐containing polar lipids, classified as betaine lipids were primarily identified as forms of diacylglyceryl‐N,N,N‐trimethylhomoserine (DGTS) and its structural isomer diaclyglycerylhydroxymethyl‐N,N,N‐trimethyl‐β‐alanine (DGTA). Though the number of forms of DGTA and DGTA were roughly equal, DGTS composed more of the polar lipid portion present in three of the strains tested, while the fourth, Lotharella globosa, was dominated by forms of DGTA. In addition, a lipid tentatively identified as diacylglycerylcarboxyhydroxymethylcholine (DGCC) was observed twice in minor amounts. The polar lipid‐associated fatty acids of the aforementioned algal strains generally included dodecanoic acid (12:0), tetradecanoic acid (14:0), hexadecanoic acid (16:0), octadecanoic acid (18:0), octadecenoic acid (18:1), and eicosapentaenoic acid [20:5(n‐3)]. The differences in betaine lipid content among the species studied may allow for further conclusions to be drawn regarding the taxonomy of chlorarachniophytes.     

EFFECT OF GROWTH AND LIGHT/DARK CYCLES ON DIATOM LIPID CONTENT AND COMPOSITION1

Total extractable lipid (TEL) and lipid composition were studied throughout the growth cycle in three freshwater diatoms-Cyclotella meneghiniana Kütz., Melosira varians C. A. Ag., and Stephanodiscus binderanus (Kütz.) Krieg under three light regimes (16:8 h LD, 20:4 h LD, and 12:12 h LD) at 20°C. Two of the diatoms demonstrated strong daylength preferences for growth; C. meneghiniana grew best under long-day (20: 4-h LD) conditions, whereas S. binderanus grew best under short-day (12:12-h LD) conditions. The lipid composition of the diatoms was similar throughout the growth cycle. Aged (2-month-old) cells were high in total lipid and triacylglycerols. Before the onset of active growth and during the early part of active growth, there was a reduction in total neutral lipids, primarily triacylglycerols, and an increase in all polar lipids, including chlorophyll a, acetone-mobile polar lipids, and phospholipids. While cell numbers were still increasing, triacylglycerols increased and polar lipids decreased to levels near those found in aged cultures, Results suggest that increased triacylglycerol content of freshwater diatoms is not necessarily indicative of senescent populations.     

Chlorosome lipids from Chlorobium tepidum: characterization and quantification of polar lipids and wax esters

We have extracted polar lipids and waxes from isolated chlorosomes from the green sulfur bacterium Chlorobium tepidum and determined the fatty acid composition of each lipid class. Polar lipids amounted to 4.8 mol per 100 mol bacteriochlorophyll in the chlorosomes, while non-polar lipids (waxes) were present at a ratio of 5.9 mol per 100 mol bacteriochlorophyll. Glycolipids constitute 60 % of the polar lipids while phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, and an aminoglycosphingolipid make up respectively 15, 3, 8 and 12 %. A novel glycolipid was identified as a rhamnose derivative of monogalactosyldiacylglycerol, while the other major glycolipid was monogalactosyldiacylglycerol. Tetradecanoic acid was the major fatty acid in the aminoglycosphingolipid, while the other polar lipids contained predominantly hexandecanoic acid. The chlorosome waxes are esters of unbranched fatty acids and fatty alcohols with 14 or 16 carbon atoms, joined to form molecules with between 28 and 32 carbon atoms. The stoichiometry between lipids and bacteriochlorophyll suggests that much of the chlorosome surface is covered by protein.     

Biodegradation of solar by Candida guilliermondii strain 1

Summary Candida guilliermondii strain 1 was grown on solar as a sole carbon source for 14 days, and the lipid classes were investigated. The yeast showed high affinity towards hydrocarbons of short chain length, and within 6 days the cellular lipid classes represented 39.69%, 27.50%, 15.35%, 2.23%, 16.20% of hydrocarbons, neutral lipids, free fatty acids, sterols and polar lipids respectively. Undecanoic and hexadecanoic acids were the major fatty acids of the cellular neutral lipids and oleic acid was the major component of the polar lipids.     

Regulation of lipid metabolism in the snow alga Chlamydomonas nivalis in response to NaCl stress: An integrated analysis by cytomic and lipidomic approaches

The cultures of the snow alga Chlamydomonas nivalis in the exponential phage were stressed by NaCl (up to 1.5%) for 0～48 h, followed by Nile Red staining-based cytomic analysis (flow cytometry and confocal laser scanning microscopy). The fluorescent intensities of total lipids, and neutral and polar lipids increased to the maximum within 7 h in the NaCl stressed cells with the highest increase in total lipids by 2-fold (0.75%-NaCl for 7 h), the highest increase in neutral lipids by 68-fold (1%-NaCl for 7 h) and the highest increase in polar lipids by 10-fold (1.25%-NaCl for 5 h), respectively. Seven types and 22 kinds of polar lipid molecules were selected and identified as biomarkers by UPLC/Q-TOF-MS-based lipidomic analysis, which demonstrated differences in total lipids between the stress group (0.75%-NaCl for 7 h) and the control. The biological roles of the biomarkers in the alga under NaCl stress were discussed. The integrated approach based on “omics” technologies developed in the present work is validated as a powerful tool to successfully reveal the regulation of lipid metabolism in microalgae in response to stress stimulation.     

The Effect of Seasonal Shifts in Temperature on the Lipid Composition of Marine Macrophytes

The comparative study of lipid composition was carried out in four species of marine algae, Ahnfeltia tobuchiensis, Laminaria japonica, Sargassum pallidum, and Ulva fenestrata, as well as a higher plant grass wrack (Zostera marina). Plants were collected in the Japan Sea in spring at 2.9 and 5.5°C and in summer at 23°C. The main lipid components of membranes were determined, and the general patterns of the ratio of phospholipids (PL), glycolipids (GL), betaine (BL), and neutral (NL) lipids were discerned. The relative content of NL in all species (except A. tobuchiensis) was higher in summer. The level of triacylglycerols was as high as 18–37%. The content of individual classes of PL and GL varied between the spring and summer samples, the relative content of PL being higher in spring. In most species, the ratio of PL to GL decreased in summer. The content of free sterols did not depend on the season. The molar ratios of phosphatidylcholine and diacylglycerol-o-(hydroxymethyl)-(N,N,N-trimethyl)homoserine to free sterols varied from 0.9 to 1.7. The seasonal changes of lipid composition were apparently related to macrophyte adaptation to water temperature and to biology of their development.