Lipid synthesized by micro‐algae grown in laboratory‐ and industrial‐scale bioreactors

Tetraselmis sp. and Nannochloropsis oculata, cultivated in industrial‐scale bioreactors, produced 2.33 and 2.44% w/w lipid (calculated as the sum of fatty acid methyl esters) in dry biomass, respectively. These lipids contained higher amounts of neutral lipids and glycolipids plus sphingolipids, than phospholipids. Lipids of Tetraselmis sp. were characterized by the presence of eicosapentaenoic acid (that was located mainly in phospholipids), and octadecatetraenoic acid (that was equally distributed among lipid fractions), while these fatty acids were completely absent in N. oculata lipids. Additionally, lipids produced by 16 newly isolated strains from Greek aquatic environments (cultivated in flask reactors) were studied. The highest percentage of lipids was found in Prorocentrum triestinum (3.69% w/w) while the lowest in Prymnesium parvum (0.47% w/w). Several strains produced lipids rich in eicosapentaenoic and docosahexaenoic acids. For instance, docosahexaenoic acid was found in high percentages in lipids of Amphidinium sp. S1, P. parvum, Prorocentrum minimum and P. triestinum, while lipids produced by Asterionella sp. (?) S2 contained eicosapentaenoic acid in high concentration. These lipids, containing ω‐3‐long‐chain polyunsaturated fatty acids, have important applications in the food and pharmaceutical industries and in aquaculture.     

Variability of Black and Caspian Sea sprat <Emphasis Type="Italic">Clupeonella cultriventris</Emphasis> (Clupeidae) growth in the contemporary range

The size and age composition of the population of Black and Caspian Sea sprat Clupeonella cultriventris, as well as the variation of the growth of fish in the reservoirs of the upper reaches of the Volga, are reported and a comparative analysis of group and individual variability of fish growth within the native (Caspian, Azov, and Black seas) and contemporary (formed due to invasion) ranges is presented. The degree of variability and the asymmetry of sprat body length distribution have been shown to increase under the conditions of large population sizes, deficit of food, and slow growth. Variability was also elevated near the borders of the range of the species, notwithstanding the abundance of food. It is shown that invasion of sea walnut comb jelly Mnemiopsis leydi into the Azov and Caspian Seas had so undermined feed base of sprat, that it is not only decreased its abundance and fecundity but also slowed growth of the fish.     

Fatty acid profile of the digestive gland and mantle in the bivalve Macoma balthica

• 1.1. Digestive gland and mantle fatty acids were studied in spring and summer in the bivalve Macoma balthica off the southern coast of Finland. The presence of lipids was also examined histochemically in various clam tissues.
• 2.2. the neutral lipid content of the digestive gland increased ca 4.5-fold during the annual growth period.
• 3.3. Neutral lipid fatty acids of the digestive gland, of which palmitoleic, eicosapentaenoic and palmitic acids were predominant, were clearly distinguished from phospho- and glycolipid fatty acids.
• 4.4. The degree of unsaturation of phospholipid fatty acids was higher in the cold season both in the digestive gland and mantle, mainly due to the titer of eicosapentaenoic acid.

     

Lipid, sterols and fatty acid composition of abyssal holothurians and ophiuroids from the North-East Pacific Ocean: food web implications

The lipid, fatty acid (FA), and sterol composition of two ophiuroids and four holothurians from the abyssal eastern North Pacific were analysed to assess their feeding habits and to ascertain their composition for use in a larger study to examine food web dynamics and trophic ecology. Holothurians were rich in phytosterols and algal derived FA such as docosahexaenoic acid and eicosapentaenoic suggesting tight trophic coupling to phytodetritus. Large proportions of stanols were found, probably a result of enteric bacteria but they may come from sterol metabolism in the holothurians themselves. Oneirophanta mutabilis was distinct with much higher levels of stanols and bacterially derived FA suggesting specific selection of bacteria rich detrital particles or the activity of enteric and integumental bacteria. The ophiuroids sterol and FA compositions differed greatly from the holothurians and reflected consumption of animal material in addition to phytodetritus. Large proportions of energy storage lipids suggested a sporadic food supply. Several unusual fatty acids were found in these abyssal echinoderms. Tetracosahexaenoic acid, 24:6omega3, in ophiuroids and 23:1 in holothurians may be good biomarkers for food web studies. We report the first occurrence of alphaOH 24:1 in holothurians with none detected in ophiuroids. Its function is presently unknown.     

Changes in lipid class and fatty acid composition during development in white seabream (Diplodus sargus) eggs and larvae

To establish the changes which occur during embryogenesis and early larvae development, eggs, yolk-sac larvae (one day old larvae) and absorbed yolk-sac larvae (three day old larvae) of white sea bream were examined for lipid class and fatty acid composition. The development was characterized by a decrease in all lipid classes with the exception of phosphatidylserine (PS) and fatty free acids (FFA) which increased, and sphingomyelin (SM) which remained unchanged. The changes observed in lipid class content and the decrease in fatty acids in total lipid (TL) reflect the utilization and mobilization of lipids during both embryogenesis and early larvae development. Fluctuations in the relative composition of fatty acids in phosphatidylcholine (PC) during development suggest a selective bulk uptake and catabolism of fatty acids in this lipid class. Unlike PC, catabolism of triacylglycerol (TG) fatty acid appears to be non-selective. During development, the decrease in levels of polyunsaturated fatty acids (PUFA) eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA) in total lipid denotes their utilization as energy substrate by Diplodus sargus larvae.     

Specificity of fatty acid composition of highly migratory fish. A comparison of docosahexaenoic acid content in total lipids extracted in various organs of bonito (Euthynnus pelamis)

Fatty acid composition of lipids in various organs of the bonito (Euthynnus pelamis), a typical species within the tuna species, caught in the sea off the Pacific coast of Japan, was determined by gas-liquid chromatography. The major fatty acids of all organs examined were palmitic acid (16:0), palmitoleic acid (16:1), oleic acid (18:1), icosapentaenoic acid (20:5), and docosahexaenoic acid (22:6). 22:6 (DHA) was the dominant fatty acid accounting for 25% or more of the total fatty acids in all organs of the bonito, caught in the sea off the Japanese coast.     

Effect of season on the fatty acid composition and free amino acid content of the sardine Sardinops melanostictus

The purpose of this study was to clarify the seasonal variation of fatty acid composition and free amino acid content in the Japanese sardine (Sardinops melanostictus) from the sea of Hyuga-Nada, and the relationship between the fatty acid composition of this sardine and that of plankton in the area. The lipid content of sardines at the sea of Hyuga-Nada was low in February (1.8%) and high (7.2%) from July to September. The major fatty acids in the total lipids from sardine were myristic acid (14:0), palmitic acid (16:0), stearic acid (18:0), palmitoleic acid (16:1 n-7), oleic acid (18:1 n-9), eicosapentaenoic acid (20:5 n-3), and docosahexaenoic acid (22:6 n-3). The characteristics of the fatty acids isolated from sardines in July were similar to those from plankton in the same season. This reflects the deposition of plankton fatty acids in sardine depot fat. The season of high free histidine content in the ordinary meat corresponded with that of high lipid content. These results suggested that both the fatty acid composition of sardines and the high concentrations of certain amino acids in free form are influenced by the intake and seasonal variation of composition of plankton.     

Metabolism of n-3 polyunsaturated fatty acids and modification of phospholipids in cultured rabbit aortic smooth muscle cells

The metabolism of the linolenic acid family (n-3) of fatty acids, e.g., linolenic, eicosapentaenoic, and docosahexaenoic acids, in cultured smooth muscle cells from rabbit aorta was compared to the metabolism of linoleic and arachidonic acids. There was a time-dependent uptake of these fatty acids into cells for 16 hr (arachidonic greater than docosahexaenoic, linoleic, eicosapentaenoic greater than linolenic), and the acids were incorporated mainly into phospholipids and triglycerides. Eicosapentaenoic and arachidonic acids were incorporated more into phosphatidylethanolamine and phosphatidylinositol plus phosphatidylserine and less into phosphatidylcholine than linolenic and linoleic acids. Docosahexaenoic acid was incorporated into phosphatidylethanolamine more than linolenic and linoleic acids and into phosphatidylinositol plus phosphatidylserine less than eicosapentaenoic and arachidonic acids. Added linolenic acid accumulated mainly in phosphatidylcholine and did not decrease the arachidonic acid content of any phospholipid subfraction. Elongation-desaturation metabolites of linoleic acid did not accumulate. Cells treated with eicosapentaenoic acid accumulated both eicosapentaenoic and docosapentaenoic acids mainly in phosphatidylethanolamine and the arachidonic acid content was decreased. Added docosahexaenoic acid accumulated mainly in phosphatidylethanolamine and decreased the content of both arachidonic and oleic acids. The following conclusions are drawn from these results. The three n-3 fatty acids are utilized differently in phospholipids. The arachidonic acid content of phospholipids is reduced by eicosapentaenoic and docosahexaenoic acids, but not by linolenic acid. Smooth muscle cells have little or no desaturase activity, but have significant elongation activity for polyunsaturated fatty acids.     

Changes in Arachidonic Acid Levels and Formation and in Lipid Synthesis in the Human Neuroblastoma SK-N-BE During Retinoic Acid-Induced Differentiation

Abstract: We observed that retinoic acid, which differentiates the human neuroblastoma SK-N-BE into mature neurons, induced an elevation in levels of polyunsaturated fatty acids, especially arachidonic acid (20:4 n-6). This effect was not induced by phorbol myristate acetate, another differentiating agent. We then explored the effects of retinoic acid on the formation of arachidonic acid and of docosahexaenoic acid from precursors and on the de novo lipid synthesis from acetate at various stages of differentiation, which was assessed by morphological (cell number and neurite outgrowth) and biochemical (protein content and thymidine incorporation) criteria. At 3 days of incubation with retinoic acid, in the n-6 series, total conversion of linoleic acid, especially to 20:3 n-6, was elevated, in association with preferential incorporation of acetate into phospholipids; in contrast, at 8 days, synthesis of 20-carbon polyunsaturated fatty acids declined, in association with enhanced incorporation in triglycerides. In the n-3 series, eicosapentaenoic acid was converted to docosahexaenoic acid in SK-N-BE, but the conversion was not affected by retinoic acid. During the early stage of neuronal differentiation, therefore, enhanced production of 20-carbon polyunsaturated fatty acids from their precursors occurred, and newly formed fatty acids were preferentially incorporated in phospholipids, possibly in association with membrane deposition. When differentiation was completed, arachidonic acid formation and incorporation of acetate in phospholipids and cholesterol declined with enhanced labeling of storage lipids.     

Changes in the Fatty Acid Composition of Hepatopancreas of the Mollusk Mytilus trossulus Fed on Microalgae

The influence of diet on the fatty acid composition of the hepatopancreas of Mytilus trossulus was studied. Three groups of mollusks were fed monocultures of the microalgae Phaeodactylum tricornutum, Chaetoceros muelleri (Bacillariophyceae), and Nannochloropsis sp. (Eustigmatophyceae) for 10 days. After 10 days, the proportion of polyunsaturated fatty acids, mainly eicosapentaenoic and docosahexaenoic, increased in the total lipids of the hepatopancreas in all mollusk groups. The content of saturated fatty acids in the mussel tissues decreased and was not dependent on the amount in the algal diet. Toward the end of the experiment, the fatty acid composition of the hepatopancreas of mussels was similar irrespective of the fatty acid composition of their food. The fatty acid analysis of M. trossulus feces suggests a selective assimilation by mussels of predominantly the n-3 polyunsaturated fatty acids. The role of fatty acid metabolism in M. trossulus is discussed.     

Characterizations of Phospholipids from Paramecium tetraurelia Cells and Cilia*,†

Phospholipids from Paramecium tetraurelia strains 51s and d,95 cultures and isolated cilia were characterized. The following classes of phospholipids were identified in whole cell lipids: the 1-alkyl-2–acylglyceryl and the 1,2–diacylglyceryl forms of phosphonylethanolamine, phosphorylethanolamine. and phosphorylcholine; cardiolipin: ceramide aminoethylphosphonate and 5 other sphingolipids: phosphatidylserine; phosphatidylinositol; and lyso derivatives of the major glycerophospholipids. Cilia lipids were rich in ether lipids, phosphonolipids. and sphingolipids. Net lipid biosynthesis did not occur, as determined by the weight of lipids extracted from culture medium compared with the weight of lipids extracted from culture medium and ciliates after 7 days of growth. Total lipids/cell decreased with culture age. changes in the neutral lipid fraction accounting for the major decrease. Phospholipid class distributions changed with culture age—the glyceryl phosphorylethanolamine and choline content of cells decreased, while the glyceryl ohosphonylethanolamine content remained relatively constant: hence, the ratio of phosphonolipids to total phospholipids increased. All fatty acids observed in total lipids from cells and cilia were also present in the glycerophospholipids. Total lipids from cilia contained a greater percent of polyunsaturated fatty acid than those of whole cells. Whole cells and cilia glyceryl phosphonolipids contained up to 93% eicosatetraenoic plus eicosapentaenoic fatty acids. The enrichment of phosphonolipids in cilia accounted for most of the polyunsaturated fatty acid enrichment observed in cilia total lipids. The fatty acid composition of all major whole cell glycerophospholipid classes changed dramatically with culture age, while only small changes occurred in cilia glycerophospholipid fatty acids.     

Fatty acid composition and lipid content in the copepod <Emphasis Type="Italic">Limnocalanus macrurus</Emphasis> during summer in the southern Bothnian Sea

The lipid reserves and occurrence of the cold-stenothermic, omnivorous copepod Limnocalanus macrurus were studied in the Bothnian Sea (northern Baltic Sea) during spring and summer 2013–2014 with a special emphasis on the fatty acid composition of adults and their potential food. The individual total wax ester (WE) content, determined from the size of oil sacs in the prosoma, ranged on average from 1.3 to 2.6 µg, and showed a decreasing trend towards September. Lipids were dominated by fatty acids 16:0, 18:1(n-9), 18:2(n-6), 20:5(n-3) and 22:6(n-6), forming 56–61% of total fatty acids in June–September. Decreasing abundance of adults and reduction of the lipid storage implied that during summer adults suffered from starvation and, as a result, became eliminated from the population. The lipid content and dietary fatty acid markers suggested that in May, adult L. macrurus utilized the phytoplankton bloom, consisting mainly of diatoms and dinoflagellates, but later, during July–September, consumed either algae or heterotrophic organisms sinking from upper water layers or crustaceans inhabiting the same deeper water layers as L. macrurus. In the face of the climate change, the rising temperatures may force L. macrurus permanently to deeper water levels. If also the food resources are limited, we conclude that the summer season may act as a bottleneck limiting the propagation of L. macrurus and having implications further along the food web.     

Nutritional status and intermediate chain-length fatty acids influence the conservation of essential fatty acids in the milk of northern Nigerian women

The milk of 89 women in northern Nigeria was analyzed for the fatty acid composition of the total milk lipids, and assessed for the effect nutritional status has on the conservation of essential and non-essential fatty acids when the proportions of C(10)-C(14)fatty acids are increased. The women were stratified on the basis of their body mass index, and calculations were made to estimate the effects of a 3.3-fold increase in the proportion of C(10)-C(14)fatty acids on the proportion of alpha-linolenic acid, docosahexaenoic acid, linoleic acid and arachidonic in total milk lipids. In the well-nourished group (group III, body mass index >23 kg/m(2)), the critical n-3 and n-6 fatty acids were not conserved, while in poorly nourished women (group I, body mass index <19 kg/m(2)), marked conservation of alpha-linolenic acid, docosahexaenoic acid, arachidonic acid, and palmitic acid was seen. Poor nutritional status of the mother appears to promote selective retention of critical essential and non-essential fatty acids in the milk lipid fraction.     

Exceptional long-term starvation ability and sites of lipid storage of the Arctic pteropod <Emphasis Type="Italic">Clione limacina</Emphasis>

The Arctic pteropod Clione limacina was collected in Kongsfjorden, Svalbard, in mid June 2004, to study the lipid metabolism within the sites of lipid storage structures during long-term starvation. Animals survived in an aquarium without any food for nearly 1 year (356 days). Size, number of lipid droplets, dry and lipid mass, lipid class and fatty acid compositions of C. limacina were determined and separately analysed for the digestive gland and the remaining integument. During the starvation period, animals shrunk from 22.4 to 12 mm in length on average, and the number of lipid droplets decreased from 1,600 to 1,000 per animal. Dry mass (DM) and total lipid mass both dropped by about 80% from day 200 to the end. The lipid content as percentage DM of the total organism did not decrease significantly ranging from 43.8 to 32.3%DM. The lipid content of the trunk was moderate with about 20%DM. The digestive gland was very rich in lipids with more than 70%DM throughout the experiment and is the major site of lipid metabolism and storage. Triacylglycerols (TAG) decreased, in the total organism, from high initial levels of 62.6 to 43% of total lipid at the end. In contrast, the proportions of 1-O-alkyldiacylglycerols [diacylglycerol ethers (DAGE)] remained almost constant, varying between 20.4 and 28.4%. In the digestive gland, TAG ranged from 60.3 to 64.8% and DAGE from 23.6 to 32.2% from day 200 to the end of the experiment. TAG and DAGE of the trunk were most likely located in the lipid droplets and were almost depleted at the end of starvation. Besides their function as lipid deposit DAGE may also act as protecting substance against bacterial and fungal infections. During the first 200 days of starvation, the fatty acid compositions showed only small variations. Thereafter, fatty acids typical for storage lipids decreased in all body compartments. In adaptation to long periods of food scarcity, C. limacina has evolved various strategies as body shrinkage, utilisation of body constituents not essential for survival, a very low metabolism and slow lipid consumption.     

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.     

Effect of UV stress on the fatty acid and lipid class composition in two marine microalgae <Emphasis Type="Italic">Pavlova lutheri</Emphasis> (Pavlovophyceae) and <Emphasis Type="Italic">Odontella aurita</Emphasis> (Bacillariophyceae)

Polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA), are abundantly synthesized by some phytoplankton species and play a key role in the marine food chain. However, they are generally considered to be sensitive to oxidation by UV radiation (UV-R). In order to investigate the effect of UV-R on the lipid composition of two marine microalgae, Pavlova lutheri and Odontella aurita, they were exposed to a combination of UVA-R and UVB-R with a total UV-R daily dose of 110 kJ m⁻². Chlorophyll a, photochemical efficiency, and lipid composition were then determined on days 3, 5, and 8 of UV-R exposure. In P. lutheri, exposure to UV-R treatment led to a decrease in the proportions of PUFAs, such as EPA and DHA, especially into structural lipids (glycolipids and phospholipids). Our findings reveal a reduction of 20% in EPA levels and 16% in DHA levels, after 8 days of UV-R treatment. In O. aurita, exposure to UV-R did not change the fatty acid composition of the total lipids and lipid fractions of the cells. EPA levels remained high (27–28% of total lipids) during the 8 days of treatment. Consequently, the n-3 fatty acid content of P. lutheri was altered which highlights the sensitivity of this species to UV-R, whereas the results obtained for O. aurita suggest a more UV-R resistance. As a result, in latitude countries with medium UV-R level, outdoor “race-way” culture of O. aurita could yield a high-EPA algal biomass, whatever the seasonal variations in UV-R.     

Biochemical Heterogeneity of the Lipid Status of the Prespawn Eggs of Pink Salmon <Emphasis Type="Italic">Oncorhynchus gorbuscha</Emphasis> (Walbaum 1792) (Varzuga River,White Sea basin)

A comparative analysis of lipid and fatty acids contents in certain portions of female gonads—head, central, and caudal—of the prespawned pink salmon Oncorhynchus gorbusha has been performed. Heterogeneity of the lipid status of eggs located in certain portions of ovaries has been found: in the head portion, a high level of physiologically important eicosapentaenoic 20:5(n-3) and docosahexaenoic 22:6(n-3) fatty acids has been registered, which coincided with a higher intensity of lipid metabolism evidenced by higher ratio of 16:0/18:1(n-9); the central portion is characterized by a low level of total lipids due to phospholipids (including phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin) and cholesterol; in the caudal portion, a high amount of certain phospholipids (phosphatidylcholine, phosphatidylethanolamine, lysophosphatidylcholine, sphingomyelin, and phosphatidylinositol) has been found. Such heterogeneity in certain portions of ovaries indicates asynchronous biochemical processes in oocytes of these portions that finally affects fertilization, growth and development of embryos, and further differentiation of the young fish.     

Variations of lipid and fatty acid contents during the reproductive cycle of the anthozoan <Emphasis Type="Italic">Renilla koellikeri</Emphasis>

Lipid and fatty acid contents were monitored in the sea pansy Renilla koellikeri during its reproductive cycle. The fluctuations of lipids and fatty acids were closely related to sexual development and gonads represented the principal site of lipid storage in the colony. Between April and May, fatty acids and lipids greatly accumulated just prior to spawning. The subsequent decrease of lipid and fatty acid contents in June probably resulted from loss due to spawning. Fatty acid composition was assessed for the whole animal and was compared between male and female gonads, and between gonads and somatic tissues. Arachidonic acid (AA) was the principal fatty acid in the whole colony followed by palmitic acid and eicosapentaenoic acid (EPA). The examination of fatty acid variations in gonads showed that EPA and AA were highly incorporated in eggs during the month preceding spawning, whereas in the same period, EPA was the only fatty acid to accumulate in spermatophores. The differences of fatty acid levels observed in gonads reflected sex differences observed in colonies. The seasonal variations of the omega6/omega3 ratio of the colonies were largely influenced by EPA and AA, and appeared as a reliable indicator of the sexual maturity of the sea pansy.     

N-3 polyunsaturated fatty acid supplementation alters inositol phosphate metabolism and protein kinase C activity in adult porcine cardiac myocytes

Several mechanisms have been proposed to explain the anti-arrhythmic effects of n-3 polyunsaturated fatty acids. One mechanism is the effect of modifying cell membrane phospholipid and their subsequent effect on intracellular cell signaling via the second messengers, Ins(1,4,5)P(3) and diacylglycerol. Isolated cardiac myocytes from adult pig hearts were used to investigate the effect of n-3 polyunsaturated fatty acids, eicosapentaenoic acid and docosahexaenoic acid, on the inositol phosphate metabolism and protein kinase C activity. Adult porcine cardiac myocytes were grown in media supplemented with 400 μM arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. After 24 hr, fatty acid analyses of total lipids by TLC in supplemented cells showed that eicosapentaenoic acid and docosahexaenoic acid were selectively incorporated into the phosphatidylinositol fraction. In the diacylglycerol fraction, there was a small incorporation of both eicosapentaenoic acid and docosahexaenoic acid but it was not significantly different from that of controls. To study the effect of membrane phospholipid modification on the phospholipase C mediated inositol lipid cycle, cardiac myocytes were labeled with 4μCi/ml myo-[2-(3)H]Ins for 48 hr. After stimulation with epinephrine and phenylephrine (alpha-receptor agonist) the water soluble [(3)H]Ins products were separated by chromatography on Dowex AG 1-X8 and measured by scintillation counting. After stimulation, the levels of [(3)H]Ins(1,4,5)P(3) and [(3)H]Ins(1,3,4,5)P(4) in eicosapentaenoic acid and docosahexaenoic acid supplemented myocytes were significantly reduced (P < 0.05) compared to arachidonic acid supplemented myocytes. Similarly, eicosapentaenoic acid and docosahexaenoic acid supplemented cells had reduced levels of protein kinase C activity after stimulation compared to arachidonic acid supplemented cells. From these experiments, it is evident that n-3 PUFA supplementation modulates intracellular cell signaling suggesting a possible anti-arrhythmic mechanism.