Cryptophyceae and rhodophyceae; chemotaxonomy, phylogeny, and application

The biochemical compositions of seven strains of marine cryptomonad and a rhodophyte were determined in logarithmic phase batch (1.4 L flask) and semi-continuous (10 L carboy) culture. Lipid ranged from 13% to 28%, protein ranged from 53% to 68%, and carbohydrate ranged from 9% to 24% of the organic weight. The major lipid classes in the species examined were polar lipids (78-88% of total lipid). The major sterol in the Cryptophyceae and the Rhodophyceae was 24-methylcholesta-5,22E-dien-3beta-ol (62-99% of total sterols); which is also the major sterol in some diatoms and haptophytes. Smaller proportions of cholest-5-en-3beta-ol (1-17.7%) were also found in the Cryptophyceae. Most cryptomonads contained high proportions of the n-3 polyunsaturated fatty acids (PUFA), 18:3n-3 (20.7-29.9% of the total fatty acids), 18:4n-3 (12.5-30.2%), 20:5n-3 (7.6-13.2%) and 22:6n-3 (6.4-10.8%). However, the blue-green cryptomonad Chroomonas placoidea was characterized by a low proportion of 22:6n-3 (0.2% of total fatty acids), and a significant proportion of 22:5n-6 (4.5%), and the presence of 24-ethylcholesta-5,22E-dien-3beta-ol (35.5% of total sterols). The fatty acid composition of the rhodophyte Rhodosorus sp. was similar to those of the Cryptophyceae except for lower proportions of 18:4n-3 and lack of C21 and C22 PUFA. It is postulated that the primary endosymbiosis of a photosynthetic n-3 C18 PUFA-producing prokaryote and a eukaryotic host capable of chain elongation and desaturation of exogenous PUFA, resulted in the Rhodophyceae capable of producing n-3 C20 PUFA. The secondary endosymbiosis of a photosynthetic n-3 C20 PUFA-producing eukaryote (such as a Rhodosorus sp. like-rhodophyte) and a eukaryotic host capable of further chain elongation and desaturation, resulted in the Cryptophyceae being capable of producing n-3 C20 and C22 PUFA de novo. Selected isolates were examined further in feeding trials with juvenile Pacific oysters (Crassostrea gigas). Rhodomonas salina CS-24(containing elevated 22:6n-3) produced high growth rates in oysters; equivalent to the microalga commonly used in aquaculture, Isochrysis sp. (T.ISO).     

Incorporation of 14C-labelled polyunsaturated fatty acids by juvenile turbot, Scophthalmus maximus (L.) in vivo

The ability of juvenile turbot, Scophthalmus maximus (L.), to elongate and desaturate various polyunsaturated fatty acids (PUFA) was examined in relation to their lipid composition. Triacylglycerols were the most abundant lipid class present in the fish and phosphatidylcholine was the predominant phospholipid. In all lipid classes examined the levels of (n-3) PUFA exceeded that of (n-6) PUFA. 18C PUFA were minor components in comparison with 20:5(n-3) and 22:6(n-3). 20:4(n-6) was present in highest concentration in phosphatidylinositol in which it accounted for 16.9% of the fatty acids. When the fish were injected with either ¹⁴C-labelled 18:2(n-6), 18:3(n-3), 20:4(n-6), 20:5(n-3) or 22:6(n-3) the highest percentage recovery of radioactivity (69%) in body lipid was observed with 22:6(n-3). With all labelled substrates free fatty acids contained only a small proportion of the total recovered radioactivity whereas triacylglycerols were highly labelled. Phosphatidylcholine/sphingomyelin was the most highly labelled polar lipid fraction. With ¹⁴C-20:4(n-6) as injected substrate, 23.2% of the radioactivity recovered in total lipid was present in phosphatidylinositol in comparison with less than 6% with the other substrates. Only small proportions of radioactivity from ¹⁴C-18:2(n-6) and ¹⁴C-18:3(n-3) were recovered in the 20 and 22C fatty acids of triacylglycerols and total polar lipid. With ¹⁴C-20:5(n-3) as substrate, 27 and 33% of the total radioactivity recovered in the fatty acids of triacylglycerols and polar lipids respectively was present in 22C fatty acids. The corresponding values for ^l4C-20:4(n-6) as substrate were 19 and 18%. The results confirm the limited capacity of turbot to convert 18C PUFA to longer chain PUFA but demonstrate their ability to synthesize 22C PUFA from 20C PUFA. They also suggest a small but specific requirement for 20:4(n-6).     

Developmental changes in synaptic membrane lipid composition and fluidity

Synaptic membrane enriched fractions were prepared from 7 and 14 day and adult cortical nerve endings. (a) The levels of synaptic membrane phosphatidylcholine decrease 19% during development while the levels of ethanolamine phosphoglycerides increase 21%. (b) On day 7, desmosterol accounts for 33% of the total membrane sterols. With maturity, the desmosterol disappears and the molar sterol/lipid P ratio increases 56%. (c) The fatty acid composition of the membranes change during development. 16:0 decreases 36% while 18:1 increases 49%. 16:1, a minor component of adult membranes, is found in significant quantities in pup membranes. 22:6 (n-3) increases 34% during development while 22:5 (n-6) decreases 59%. (d) The microviscosity of synaptic membranes, as measured by the fluorescence depolarization technique, increases during development. This effect is observed in both intact membranes and bilayers prepared from lipid extracts of the membrane.     

Effect of microalgal diets and commercial wheatgerm flours on the lipid profile of Ruditapes decussatus spat

The influence of both the lipid composition of microalgal diets and commercial flours on the lipid classes and fatty acids of Ruditapes decussatus spat was studied. These aspects of the nutritional value of the diets were discussed in relation to the growth of the spat. Four diets were tested; Diet A, composed of 100% of the daily food ration of microalgae; Diet B, composed of 100% of wheatgerm; Diet C, composed of 50% of microalgae and 50% of wheatgerm; and Diet D, composed of 25% of microalgae and 75% of wheatgerm. The microalgal cells present a higher lipid content than that for wheatgerm. Tahitian Isochrysis cells have phospholipids and triacylglycerols as majority lipids, whereas in the wheatgerm particles, the lipids more abundant are triacylglycerols. Fatty acid content was higher in the microalgal cells than in the wheatgerm particles. The n-3 fatty acids were the most abundant acids in the microalgae, whereas the n-6 fatty acids were in the wheatgerm. The n-3 PUFA were not detected in wheatgerm. Phospholipids were the main lipids present in the clam spat, followed by triacylglycerols. Other lipid classes, detected in significantly lower amounts, included free fatty acids, sterols, and sterol ester + waxes. The composition of fatty acids in the spat was influenced by the fatty acid composition of the diet. Highest spat growth rates were observed with those diets that present a higher phospholipid/triacylglycerol relation. A negative correlation in the relation n-6/n-3 vs. growth has also been observed, with better growth rates in diets with a lower ratio. If the fatty acid 20:5n-3 and 22:6n-3 considered "essential" for marine animals were not present in the diet, they were not present in the spat either. Desaturation and elongation capabilities of R. decussatus spat were also discussed.     

Effects of essential fatty acid deficiency and supplementation with docosahexaenoic acid (DHA; 22:6n-3) on cellular fatty acid compositions and fatty acyl desaturation in a cell culture model

The desaturation of [1-(14)C] 18:3n-3 to docosahexaenoic acid (DHA; 22:6n-3) is enhanced in an essential fatty acid deficient cell line (EPC-EFAD) in comparison with the parent cell line (EPC) from carp. In the present study, the effects of DHA on lipid and fatty acid compositions, and the metabolism of [1-(14)C]18:3n-3 were investigated in EPC-EFAD cells in comparison with EPC cells. DHA supplementation had only relatively minor effects on lipid content and lipid class compositions in both EPC and EPC-EFAD cells, but significantly increased the amount of DHA, 22:5n-3, eicosapentaenoic acid (EPA; 20:5n-3), total n-3 polyunsaturated fatty acids (PUFA), total PUFA and saturated fatty acids in total lipid and total polar lipid in both cell lines. Retroconversion of supplemental DHA to EPA was significantly greater in EPC cells. Monounsaturated fatty acids, n-9 and n-6PUFA were all decreased in total lipid and total polar lipid in both cell lines by DHA supplementation. The incorporation of [1-(14)C]18:3n-3 was greater into EPC-EFAD compared to EPC cells but DHA had no effect on the incorporation of [1-(14)C]18:3n-3 in either cell line. In contrast, the conversion of [1-(14)C]18:3n-3 to tetraenes, pentaenes and total desaturation products was similar in the two cell lines and was significantly reduced by DHA supplementation in both cell lines. However, the production of DHA from [1-(14)C]18:3n-3 was significantly greater in EPC-EFAD cells compared to EPC cells and, whereas DHA supplementation had no effect on the production of DHA from [1-(14)C]18:3n-3 in EPC cells, DHA supplementation significantly reduced the production of DHA from [1-(14)C] 18:3n-3 in EPC-EFAD cells. Greater production of DHA in EPC-EFAD cells could be a direct result of significantly lower levels of end-product DHA in these cells' lipids compared to EPC cells. Consistent with this, the suppression of DHA production upon DHA supplementation was associated with increased cellular and membrane DHA concentrations in EPC-EFAD cells. However, an increase in cellular DHA content to similar levels failed to suppress DHA production in DHA-supplemented EPC cells. A possible explanation is that greatly increased levels of EPA, derived from retroconversion of the added DHA, acts to offset the suppression of the pathway by DHA by stimulating conversion of EPA to DHA in DHA-supplemented EPC cells.     

Biochemical composition during growth and starvation of early larval stages of cultured spiny lobster (Jasus edwardsii) phyllosoma

We examined biochemical changes accompanying feeding and starvation from hatch to Stage VI (day 74 after hatch) in spiny lobster, Jasus edwardsii, phyllosoma larvae. Larval dry weights (dw) increased 17-fold from hatch (80+/-1 microg) to Stage VI (1415+/-44 microg). Larvae starved for 6-11 days at Stages II, IV and VI were 14-40% lighter than their fed counterparts fed enriched Artemia. The increases and losses in total dry weight during feeding and starvation were associated with changes in the content of protein (constituting 31.4-41.7% of dw) and carbohydrate (constituting 2.6-5.3% of dw), while larger changes in lipid content indicated its greater importance as an energy substrate. Lipid content increased from 7.9% of dw at hatch to its highest of 12.5% at Stage IV, but declined by 50% or more during starvation. This suggests that protein, carbohydrate and lipid are all important energy stores, although lipids are catabolized at a greater rate during food deprivation. The principal lipid class was polar lipid (PL; 79-92% of total lipid), followed by sterol (ST; 6-20%), with triacylglycerol and other lipid classes at <2%. PL were catabolized and ST were conserved during starvation. Changes in the fatty acid (FA) profile had mostly occurred before the first moult at day 8 after hatch, with gradual changes thereafter to Stage VI, reflecting their abundance in the Artemia diet. There was some conservation of the major essential FAs, 20:4n-6, 20:5n-3, 22:6n-3, and the FA profile showed large gains in the C(18) polyunsaturated FA, 18:1n-9, 18:2n-6. Ascorbic acid content increased 10-fold from hatch to the end of Stage I (36 and 333 microgg(-1) dw, respectively), while the content at the end of Stage II was higher in fed than that in starved larvae (439 and 174 microgg(-1) dw, respectively). Our study will assist in the development of alternatives to nutritionally incomplete diets, such as live ongrown Artemia, to meet the requirements of phyllosoma in culture.     

Liver triacylglycerols and free fatty acids in streptozotocin-induced diabetic rats have atypical n-6 and n-3 pattern

In diabetes there is a decrease in membrane arachidonic (AA) and docosahexaenoic (DHA) acids and a concomitant increase in linoleic (LA) and alpha-linolenic (ALA) acids. This metabolic perturbation is thought to be due to impaired activity of Delta(6)- and Delta(5)-desaturases. Triacylglycerols are the major lipid pool in plasma and liver tissue and have a significant influence on fatty acid composition of membrane and circulating phospholipids. Data on the distribution of n-6 and n-3 polyunsaturated fatty acids of triacylglycerols in diabetes are sparse. We investigated whether streptozotocin-induced diabetes in Sprague-Dawley rats alters fatty acid composition of triacylglycerols and free fatty acids of liver tissue. The animals were fed a breeding diet prior to mating, during pregnancy and lactation. On days 1-2 of pregnancy, diabetes was induced in 10 of the 25 rats. Liver was obtained at post partum day 16 for analysis. Relative levels of LA (P=0.03), dihomo-gamma-linolenic acid (DHGLA) (P=0.02), AA (P=0.049), total n-6 (P=0.02), ALA (P=0.013), eicosapentaenoic acid (EPA) (P=0.004), docosapentaenoic acid (22:5n-3, DPA) (P=0.013), DHA (P=0.033), n-3 metabolites (P=0.015) and total n-3 (P=0.011) were significantly higher in the triacylglycerols of the diabetics compared with the controls. Similarly, liver free fatty acids of the diabetics had higher levels of LA (P=0.0001), DHGLA (P=0.001), AA (P=0.001), n-6 metabolites (P=0.002), total n-6 (P=0.0001), ALA (P=0.003), EPA (P=0.015), docosapentaenoic (22:5n-3, P=0.003), DHA (P=0.002), n-3 metabolites (P=0.005) and total n-3 (P=0.001). We conclude that impaired activity of desaturases and/or long chain acyl-CoA synthetase could not explain the higher levels of AA, DHA and n-6 and n-3 metabolites in the diabetics. This seems to be consistent with an alteration in the regulatory mechanism, which directs incorporation of polyunsaturated fatty acids either into triacylglycerols or phospholipids.     

Polyunsaturated fatty acids in maternal plasma and in breast milk

In order to explain processes underlying the transfer of fatty acids from the maternal compartment into human milk, the lipid content and the fatty acid composition of maternal plasma and milk have been analyzed in breastfeeding mothers at 1 day and 3 months of lactation.The rise in milk lipids occurring during the study period was concomitant with a fall in plasma total fat content, mainly due to the decrease of triglycerides. Significant correlations between plasma and milk fatty acids at the two time points were observed only for linoleic (LA, 18:2 n-6) and (alpha;-linolenic acid (alpha LNA, 18:3 n-3), while for arachidonic (AA, 20:4 n-6) and docosahexaenoic acid (DHA, 22:6 n-3) correlations were found only at one day and 3 months, respectively.These data suggest that levels of the n-6 and n-3 18C polyunsaturated fatty acids in milk are closely dependent on their concentrations in maternal plasma, in turn related with the dietary intake, while the accumulation of AA and DHA in milk is the result of a sequence of transfer and metabolic processes.     

Comparison of bloodstream fatty acid composition from African-American women at gestation, delivery, and postpartum

Our aim was to examine the docosahexaenoic acid (DHA; 22:6n-3) status of pregnant African-American women reporting to the antenatal clinic at Wayne State University in a longitudinal study design. Fatty acid compositions of plasma and erythrocyte total lipid extracts were determined and food frequency surveys were administered at 24 weeks of gestation, delivery, and 3 months postpartum for participants (n = 157). DHA (mean +/- SD) in the estimated total circulating plasma was similar at gestation (384 +/- 162 mg) and delivery (372 +/- 155 mg) but was significantly lower at 3 months postpartum (178 +/- 81 mg). The relative weight percentage of DHA and docosapentaenoic acid n-6 (DPAn-6; 22:5n-6) decreased postpartum, whereas their respective metabolic precursors, eicosapentaenoic acid (EPA; 20:5n-3) and arachidonic acid (AA; 20:4n-6), increased. Similar results were found in erythrocytes. Dietary intake of DHA throughout the study was estimated at 68 +/- 75 mg/day. The relative amounts of circulating DHA and DPAn-6 were increased during pregnancy compared with 3 months postpartum, possibly via increased synthesis from EPA and AA. The low dietary intake and blood levels of DHA in this population compared with others may not support optimal fetal DHA accretion and subsequent neural development.     

Seasonal changes in lipid classes and fatty acid composition in the digestive gland of Pecten maximus

Seasonal variations in lipid classes and fatty acid composition of triacylglycerols and phospholipids in the digestive gland of Pecten maximus were studied over a period of 16 months. Acylglycerols predominated (19-77% of total lipids), in accordance with the role of the digestive gland as an organ for lipid storage in scallops. Seasonal variations were mainly seen in the acylglycerol content, while phospholipids (2.5-10.0% of total lipids) and sterols (1.9-7.4% of total lipids) showed only minor changes. The most abundant fatty acids were 14:0, 16:0, 18:0, 16:1(n-7), 18:1(n-9), 18:1(n-7), 18:4(n-3), 20:5(n-3) and 22:6(n-3) and these showed similar seasonal profiles in both, triacylglycerol and phospholipid fractions. In contrast to the phospholipid fraction, the triacylglycerol fraction contained more 20:5(n-3) than 22:6(n-3). In three phospholipid samples we noted a high percentage of a 22-2-non-methylene-interrupted fatty acid, previously described to have a structural role in several bivalve species. The main polyunsaturated fatty acids displayed important seasonal variations parallel to those of the acylglycerols, suggesting good nutritional conditions. A positive correlation existed between the level of saturated fatty acids and temperature, whereas the levels of polyunsaturated fatty acids correlated negatively with temperature.     

Lipids of the Green Alga BotryococcusCultured in a Batch Mode

The lipid fraction of the green alga Botryococcuscultured in a batch mode was found to contain polar lipids (more than 50% of the total lipids), di- and triacylglycerols, sterols and their esters, free fatty acids, and hydrocarbons. In aging culture, the content of polar lipids somewhat decreased and that of triacylglycerols increased by more than four times. The content of hydrocarbons in the algal biomass did not exceed 0.9% and depended little on the culture age. Intracellular lipids contained saturated and unsaturated (mono-, di-, and trienoic) fatty acids. The maximum content of C_{16 : 3}and -C_{18 : 3}fatty acids (up to 35% of the total fatty acids) was detected in the phase of active growth. The extracellular and intracellular lipids of the alga differed in the proportion of particular lipids and in the fatty acid pattern.     

Long chain polyunsaturated fatty acid production and partitioning to triacylglycerols in four microalgae

Gas chromatographic profiling of fatty acids was performed during the growth cycle of four marine microalgae in order to establish which, if any, of these could act as a reliable source of genes for the metabolic engineering of long chain polyunsaturated fatty acid (LC-PUFA) synthesis in alternative production systems. A high-throughput column based method for extraction of triacylglycerols (TAGs) was used to establish how much and at what stage in the growth phase LC-PUFAs partition to storage lipid in the different species. Differences in the time course of production and incorporation of docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) into TAGs were found in the marine microalgae Nannochloropsis oculata (Eustigmatophyceae), Phaeodactylum tricornutum and Thalassiosira pseudonana (Bacillariophyceae), and the Haptophyte Pavlova lutheri. Differences were not only observed between species but also during the different phases of growth within a species. A much higher percentage of the total cellular EPA was partitioned to TAGs in stationary phase cells of N. oculata compared to P. tricornutum. Although P. tricornutum produces DHA it does not partition it to TAGs. Both T. pseudonana and P. lutheri produce EPA and DHA and partition these to TAGs during the stationary phase of growth. These two species are therefore good candidates for further biochemical and molecular analysis, in order to understand and manipulate the processes that are responsible for the incorporation of LC-PUFAs into storage oils.     

Lipid composition of deep-sea hydrothermal vent tubeworm Riftia pachyptila, crabs Munidopsis subsquamosa and Bythograea thermydron, mussels Bathymodiolus sp. and limpets Lepetodrilus spp

Lipid composition was determined for hydrothermal vent species collected by the Deep Submergence Vehicle ALVIN from chimneys at 2,500 m depth on the East Pacific Rise. These are the first lipid biomarker studies for most of these species. Lipid content was low and dominated by polar lipid in the vestimentiferan tubeworm Riftia pachyptila, mussels Bathymodiolus sp. and limpets Lepetodrilus spp. The galatheid (Munidopsis subsquamosa) and most brachyuran adult (Bythograea thermydron) crabs were characterized by higher storage lipid (triacylglycerol). Total polyunsaturated fatty acids were similar in R. pachyptila plume and body, but higher in the posterior part of the soft body, which had more docosahexaenoic acid (2-5% of total FA) compared to the anterior and plume (< or =0.3%). Two sulphur-oxidizing bacterial markers, 16:1(n-7)c and 18:1(n-7)c, were high in R. pachyptila and mussel (up to 23%), but lower in both crab species (4-17%). R. pachyptila had greater nonmethylene interrupted diunsaturated fatty acids (8-13%) than all other species (2-8%). R. pachyptila may desaturate and elongate 18:1(n-7)c to obtain essential polyunsaturated fatty acids 20:5(n-3) and 20:4(n-6). The sterol composition of R. pachyptila included similar amounts of cholesterol and desmosterol, whereas the other species had a more diverse sterol composition. These differences in lipids, fatty acids and sterols reflect diverse nutritional strategies and possibly temperature regimes in these species.     

Lipids and sterols of Pinus sylvestris L. sapwood and heartwood

Summary The lipid and sterol content and composition of three lipid fractions (free fatty acids/ sterols, triacylglycerols and sterol/triterpenoid esters) extracted from three stem discs of Pinus sylvestris were assessed to investigate metabolic changes related to heartwood formation. The wood was separated into (1) cambial zone, (2) outer sapwood, (3) inner sapwood, (4) transition zone, (5) outer heartwood and 6) inner heart-wood. The fractions were separated by thin-layer chromatography (TLC) and analysed by gas-liquid chromatography (GLC). The amount of fatty acids of sapwood triacylglycerols was about 1.5% (dry wt.) but a large reduction occurred in the transition zone. In contrast, noticeable amounts of free fatty acids were present only in the heart-wood. The most important fatty acids in the sapwood fractions were 16:0, 18:0, 18:1, 18:2 (the dominant fatty acid in all fractions), 18:3 and 20:3. Together 18:1 and 18:2 formed about 70% of the total triacylglycerol fatty acids. Of the sterol/ triterpenoid esters, 18:2 and 18:3 were predominant. The fatty acid composition of all fractions changed in the transition zone. The sterols found were sitosterol, stigmastanol, campesterol and campestanol. The amount of sterol esters increased towards the heartwood, and the amount of free sterols was lowest in the inner sapwood. Sitosterol was the dominant sterol in both free sterols and sterol esters.     

Composition of lipids, fatty acids and sterols in Okinawan corals

A survey of lipid composition was made for 15 cnidarians from Okinawa, Japan. Eleven zooxanthellate scleractinian corals, an azooxanthellate scleractinian coral Tubastrea sp., a soft coral Lobophytum crassum, a hydroid coral Millepora murrayi and a sea anemone Boloceroides sp. were examined to elucidate the total lipid content, fatty acid composition for each lipid class and sterol composition. All specimens contained monoalkyldiacylglycerol which migrated between the triacylglycerols and esters on thin layer chromatography (TLC). Analysis by high performance thin layer chromatography (HPTLC) and Gas chromatography-mass spectrometry (GC-MS) revealed that these cnidarians were rich in wax ester and triacylglycerol, and that palmitic acid (16:0) was the most abundant fatty acid component of these lipid classes, followed by stearic (18:0) and oleic (18:1, n-9) acid in order of concentration. Of 11 sterols separated, four sterols were identified. It is suggested that sterol composition may be more useful for the biochemical classification of these cnidarians than fatty acid composition.     

EFFECTS OF HARVEST STAGE AND LIGHT ON THE BIOCHEMICAL COMPOSITION OF THE DIATOM THALASSIOSIRA PSEUDONANA1

The marine diatom Thalassiosira pseudonana (Hustedt, clone 3H) Hasle and Heimdal was cultured under three different light regimes: 100 μmol photon · m^?2· s^?1 on 12:12 h light : dark (L:D) cycles; 50 μmol photon · m^?2· s^?2 on 24:0 h L:D; and 100 μmol photon · m^?2· s^?1 on 24:0 h L:D. It was harvested during logarithmic and stationary phases for analysis of biochemical composition. Across the different light regimes, protein (as % of organic weight) was highest in cells during logarithmic phase, whereas carbohydrate and lipid were highest during stationary phase. Carbohydrate concentrations were most affected by the different light regimes; cells grown under 12:12 h L:D contained 37–44% of the carbohydrate of cells grown under 24:0 h L:D. Cells in logarithmic phase had high proportions of polar lipids (79 to 89% of total lipid) and low triacylglycerol (≤10% of total lipid). Cells in stationary phase contained less polar lipid (48 to 57% of total lipid) and more triacylglycerol (22 to 45% of total lipid). The fatty acid composition of logarithmic phase cells grown under 24:0 h L:D were similar, but the 100 μmol photon · m^?2· s^?1 (12:12 h L:D) cells at the same stage contained a higher proportion of polyunsaturated fatty acids (PUFAs) and a lower proportion of saturated and monounsaturated fatty acids due to different levels of 16:0, 16:1(n-7), 16:4(n-1), 18:4(n-3), and 20:5(n-3). With the onset of stationary phase, cells grown at 100 μmol photon · m^?2· s^?1 (both 12:12 and 24:0 h L:D) increased in proportions of saturated and monounsaturated fatty adds and decreased in PUFAs. Concentrations (% organic or dry weight) of 14:0, 16:0, 16:1(n-7), 20:5(n-3), and 22:6(n-3) increased in cells of all cultures during stationary phase. The amino acid compositions of cells were similar irrespective of harvest stage and light regime. For mariculture, the recommended light regime for culturing T. pseudonana will depend on the nutritional requirements of the animal to which the alga is fed. For rapidly growing bivalve mollusc larvae, stationary-phase cultures grown under a 24:0 h L:D regime may provide more energy by virtue of their higher percentage of carbohydrate and high proportions and concentrations of energy-rich saturated fatty acids.     

Eicosapentaenoic acid and docosahexaenoic acid effects on tumour mitochondrial metabolism, acyl CoA metabolism and cell proliferation

In order to investigate the effects of high-fat diets rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), Wistar rats bearing subcutaneous implants of the Walker 256 tumour were fed pelleted chow containing low DHA/EPA or high DHA/EPA. The presence of n-3 polyunsaturated fatty acids (PUFAs) led to a marked suppression (35-46%) of tumour growth over a 12 day period. Both the whole tumour homogenate and the Percoll-purified mitochondrial fraction presented significant changes in fatty acid composition. The levels of EPA increased in both n-3 dietary groups while the levels of DHA increased only in the high DHA/EPA group, in comparison with the control chow-fed group. The presence of n-3 PUFAs led to an increase in mitochondrial acyl CoA synthetase activity, but neither the cytoplasmic acyl CoA content nor the n-3 fatty acid composition of the cytoplasmic acyl CoAs was altered by the diet. The content of thiobarbituric acid-reactive substances (TBARS) was increased in the low DHA/EPA group but was unchanged in the high DHA/EPA group. In vitro studies with the Walker 256 cell line showed a 46% decrease in cell growth in the presence of either EPA or DHA which was accompanied by a large decrease in the measured mitochondrial membrane potential. The TBARS content was increased only in the EPA-exposed cells. Cell cycle analysis identified a decrease in G0-G1 phase cells and an increase in G2-M phase cells and apoptotic cells, for both EPA and DHA-exposed cells. The data show that the presence of n-3 PUFAs in the diet is able to significantly after the growth rate of the Walker 256 tumour. The involvement of changes in mitochondrial membrane composition and membrane potential have been indicated for both EPA and DHA, while changes in lipid peroxidation have been identified in the presence of EPA but not of DHA.     

Fatty acid incorporation is decreased in astrocytes cultured from alpha-synuclein gene-ablated mice

Because alpha-synuclein may function as a fatty acid binding protein, we measured fatty acid incorporation into astrocytes isolated from wild-type and alpha-synuclein gene-ablated mice. alpha-Synuclein deficiency decreased palmitic acid (16:0) incorporation 31% and arachidonic acid [20:4 (n-6)] incorporation 39%, whereas 22:6 (n-3) incorporation was unaffected. In neutral lipids, fatty acid targeting of 20:4 (n-6) and 22:6 (n-3) (docosahexaenoic acid) to the neutral lipid fraction was increased 1.7-fold and 1.6-fold, respectively, with an increase in each of the major neutral lipids. This was consistent with a 3.4- to 3.8-fold increase in cholesteryl ester and triacylglycerol mass. In the phospholipid fraction, alpha-synuclein deficiency decreased 16:0 esterification 39% and 20:4 (n-6) esterification 43% and decreased the distribution of these fatty acids, including 22:6 (n-3), into this lipid pool. alpha-Synuclein gene-ablation significantly decreased the trafficking of these fatty acids to phosphatidylinositol. This observation is consistent with changes in phospholipid fatty acid composition in the alpha-synuclein-deficient astrocytes, including decreased 22:6 (n-3) content in the four major phospholipid classes. In summary, these studies demonstrate that alpha-synuclein deficiency significantly disrupted astrocyte fatty acid uptake and trafficking, with a marked increase in fatty acid trafficking to cholesteryl esters and triacylglycerols and decreased trafficking to phospholipids, including phosphatidylinositol.     

n-3 Deficient and docosahexaenoic acid-enriched diets during critical periods of the developing prenatal rat brain.

The last period of the intrauterine life in the rat (embryonic day 17 to 21, ED17-ED21) is demarcated by an increase in brain and body weight and active neuronogenesis. During this period, a rapid accumulation of DHA (22:6 n-3), unparalleled to other fatty acids, takes place. The details of DHA rapid acquisition in the fetal brain were investigated after imposing a diet deficient in n-3 fatty acids (FA) as of ED1 and subsequently examining the distribution of DHA in major brain phospholipid (PL) classes on ED20, having added on ED15 a triglyceride (TG) mixture enriched up to 43% with DHA. The n-3 deficiency maintained for 19 days resulted at ED20 in more than 30% reduction of DHA in PL, which was counterbalanced by an increase of docosapentaenoic acid (DPA, 22:5 n-6). No effect on body weight, nor major changes in PL composition or other FA in fetal brain PL were observed. Feeding dams a DHA-TG diet on ED15 induced an immediate increase of DHA in maternal liver PL, followed by a subsequent increase of DHA in fetal liver PL, as well as in fetal brain PL.Thus the content of fetal brain DHA in n-3 deficient embryos could be restored within 48 hours. Dietary manipulation of fetal tissues is a rapid phenomenon and can be used to enrich DHA at critical periods of development in utero.