Comparison of fatty acid profiles of spawning and non-spawning Pacific herring, Clupea harengus pallasi

Crude lipid and fatty acid composition from liver, intestine, roe, milt and flesh of spawning and non-spawning Pacific herring (Clupea harengus pallasi) were examined to determine the relative effects of spawning on the nutritional value of herring. Depletion of lipid due to spawning condition was significant (P < 0.01) in all organ tissues and flesh of spawning herring. The lipid content ranged from an average of 1.9 to 3.4% (wet weight basis) in different organ tissues of spawning herring, to 10.5 to 16% in non-spawning fish. The fatty acid profile exhibited many differences in the relative distribution of individual fatty acids among organ tissues and between the two fish groups. Oleic acid (C18:1n-9), a major monounsaturated fatty acid (MUFA) found in all tissue lipids, decreased significantly (P < 0.01) in spawning fish. The two monoenes, C20:1n-9 and C22:1n-11, occurred at high concentrations in the flesh but at only minor proportion in the digestive organs and gonads. Spawning herring also had significantly (P < 0.01) higher polyunsaturated fatty acids (PUFA) content in the organ tissues, particularly in the milt and ovary, with docosahexaenoic acid (C22:6n-3, DHA) having the greatest proportion. Among the n-6 fatty acids, only C18:2n-6 and C20:4n-6 occurred at notable amounts and were present in higher proportions in spawning fish. We concluded that although relatively higher n-3 fatty acid content was found in the organ lipids of spawning herring, they are not an energy-dense prey food source due to the fact that both flesh and gonads contain a very low amount of lipid.     

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.     

Seasonal changes in lipid content and composition of the polychaete Nereis (Hediste) diversicolor

The lipid content and composition of Nereis (Hediste) diversicolor O. F. Müller (Annelida, Polychaeta, Nereidae) a mud-dwelling, intertidal errant polychaete in the Tagus estuary (Portugal), were examined on the monthly basis by lipid extraction, TLC and capillary GC. In this estuary, N. diversicolor is by far the dominant species among polychaeta and the main food item in the natural diet of several flatfishes. The biochemical elucidation of its lipid structure and distribution throughout the year, described in this study, provides information not only about the physiological role of lipids in the animal under consideration but also about dietary fatty acid requirements of some flatfishes in the wild and under laboratory conditions.The total lipid content varied between a maximum of 19.3% lyophilized dry weight in February (4.4% fresh weight) and a minimum of 6.6% in August (1.9% fresh weight). The major lipid classes were triacylglycerol, phospholipid, free sterol, free fatty acid, sterol ester/wax ester and alkyldiacylglycerol.The fatty acid composition was rather unsaturated with a 1:2 mean ratio of n-3: n-6. The major fatty acids were C160:0, C18:1n-9, C18:2n-6, and C20:5n-3; there were smaller amounts of C180:0, C18:1n-11, C18:1n-7, C18:3n-3, C20:1, C20:2n-6, C20:4n-6, C22:2, C22:5n-3, and many other fatty acids were detected at trace levels. The unsaturation ranged from 36.9 mg/g dry weight in summer to 107.4 mg/g in winter. An accumulation of fatty acids from plant origin was evident, in particular linoleic acid (C18:2n-6), which was quantitatively one of the major fatty acids throughout the year.     

Fatty acid compositional changes during the embryonic development of the swimming crab,Portunus pelagicus (Portunidae: Decapoda)

Abstract

The fatty acid composition, moisture, and total lipid of the eggs from the swimming crab, Portunus pelagicus, at three different embryonic stages (within 24 h, during the eye placode stage and the final heart beat stage), were measured. Results showed that the moisture and lipid content significantly increased and decreased (p < 0.05), respectively, as the stages progressed. The most prevalent fatty acids that were initially deposited included C16:0, C18:1n-9, and C18:0, while the most consumed fatty acids were C22:5n-6, C22:5n-3, and C20:1n-7. Among the major fatty acid groups, polyunsaturated fatty acids (PUFA) and long-chain PUFA (LC-PUFA) were consumed more than saturated fatty acids and significantly more (p < 0.05) than monounsaturated fatty acids (p < 0.05). Meanwhile, n-3 PUFA was deposited in significantly higher amounts (p < 0.05) than n-6 PUFA, but both were consumed at similar amounts at 43.4% and 41.3%, respectively. The relatively low amount of C20:5n-3 and C22:6n-3 consumption may indicate these fatty acids were conserved, while the essential fatty acids C18:3n-3 and C18:3n-6 were consumed at high amounts. These findings may have implications for broodstock nutrition in order to formulate a well-balanced diet.     

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).     

Fatty acids from 11 marine macroalgae of the French Brittany coast

Four species of red marine algae (Rhodophyceae), five species of brown marine algae (Pheophyceae) and two species of green marine algae (Chlorophyceae) were examined for the fatty acid composition of the three lipid groups separated by silica gel column chromatography (neutral lipids, glycolipids, phospholipids). The four red algae had high contents of 16:0 and C20-polyunsaturated fatty acids (PUFA), 20:5n-3 ranging from 18 to 49% of the total fatty acid content and 20:4n-6 from 1.4 to 22.5%, these fatty acids were evenly distributed in all lipid groups. The five brown algae had high contents of 18:1n-9, 18:2n-6 and 18:3n-3 but low content of 20:5n-3. No precise trend was detected for the distribution of these fatty acids in the three lipid groups. The two green algae had high contents of 16:0, 18:1n-7 and 18:3n-3 and a very low content of PUFA. They contained also large amounts of 16:4n-3 together with 16:2n-6 and 16:3n-3. While 16:2n-6 was mainly found in phospholipids, 16:4n-3 was mainly distributed in neutral lipids and glycolipids.Porphyra umbilicalis represents the richest source of 20:5n-3 whileUndaria pinnatifida can be selected when a balanced mixture of (n-6) and (n-3) PUFA is required.Author for correspondence     

EFFECT OF NUTRIENT LIMITATION ON FATTY ACID AND LIPID CONTENT OF MARINE MICROALGAE1

Phaeodactylum tricornutum and Chaetoceros sp. (Badllariophyceae), Isochrysis galbana (clone T-Iso) and Pavlova lutheri (Prymnesiophyceae), Nannochloris atomus (Chlorophyceae), Tetraselmis sp. (Prasinophyceae), and Gymnodinum sp. (Dinophyceae) were cultured at different extents of nutrient-limited growth: 50 and 5% of μ_max. The lipid content of the algae was in the range 8.3–29.5% of dry matter and was generally higher in the Prymnesiophyceae than in the Prasinophyceae and the Chlorophyceae. Increasing extent of phosphorus limitation resulted in increased lipid content in the Bacillariophyceae and Prymnesiophyceae and decreased lipid content in the green flagellates N. atomus and Tetraselmis sp. The fatty acid composition of the algae showed taxonomic conformity, especially for the Bacillariophyceae, where the major fatty adds were 14:0, 16:0, 16:1, and 20:5n-3. These fatty acids were dominant also in the Prymnesiophyceae together with 22:6n-3. An exception was I. galbana, in which 18:1 was the major monounsaturated fatty add and 20:5n-3 was absent. The fatty acids of N. atomus and Tetraselmis sp. varied somewhat, but 16:0, 16:1, 18:1, 18:3n-3, and 20:5n-3 were most abundant. Gymnodinum sp. contained mainly 16:0, 18:4n-3, 20: 5n-3, and 22:6n-3. An increased level of nutrient limitation (probably phosphorus) resulted in a higher relative content of 16:0 and 18:1 and a lower relative content of 18:4n-3, 20:5n-3, and 22:6n-3. The nutrient limitation probably reduced the synthesis of n-3 polyunsaturated fatty acids.     

Effects of ambient temperature on lipid and fatty acid composition in the oviparous lizards, Phrynocephalus przewalskii

This study was designed to assess the effect of ambient temperature on lipid content, lipid classes and fatty acid compositions of heart, liver, muscle and brain in oviparous lizards, Phrynocephalus przewalskii, caught in the desert area of China. Significant differences could be observed in the contents of the total lipid and fatty acid compositions among different temperatures (4, 25 and 38 degrees C). The study showed that liver and muscle were principal sites of lipid storage. Triacylglycerol (TAG) mainly deposited in the liver, while phospholipids (PL) was identified as the predominant lipid class in the muscle and brain. Palmitic and stearic acid generally occupied the higher proportion in saturated fatty acids (SFA), while monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) consisted mainly of 16:1n-7, 18:1n-9, 18:2n-6, 18:3n-3, 20:4n-6 and 22:6n-3 regardless of tissue and temperature. These predominant fatty acids proportion fluctuations caused by temperature affected directly the ratio of unsaturated to saturated fatty acids. There was a tendency to increase the degree of unsaturation in the fatty acids of TAG and PL as environmental temperature dropped from 38 to 4 degrees C, although the different extent in different tissues. These results suggested that lipid characteristics of P. przewalskii tissues examined were influenced by ambient temperature.     

Chemical characterisation of eggs from deep-sea sharks

The chemical characterisation and nutritional value of eggs from the five deep-sea sharks leafscale gulper shark (Centrophorus squamosus), greater lantern shark (Etmopterus princeps), longnose velvet dogfish (Centroscymnus crepidater), Portuguese dogfish (Centroscymnus coelolepis) and black dogfish (Centrocyllium fabricii) captured at Hatton Bank in the North Atlantic were examined. The chemical composition was quite similar for all the eggs studied. The dominant fatty acid in all the eggs was the monounsaturated fatty acid C18:1, which varied from 27-39%. The eggs had a relatively high content of C16:0 (13.0-18.5%) and C22:6n-3 (10.3-15.1%). The two main lipid classes in the eggs were triacylglycerols (36-55%) and phospholipids (34-41%). The eggs had high amounts of vitamin A and E. The shark eggs were particularly rich in the amino acids aspartic acid, glutamic acid, leucine and arginine.     

Fatty Acid Composition of Endoneurium and Perineurium from Adult Rat Sciatic Nerve

Reports on lipid composition of peripheral nervous system have generally been restricted to the saturated fatty acids of the endoneurium. In this work we attempt to determine the fatty acid composition of the different lipid classes in both endo- and perineurium from sciatic nerve microdissection on adult rats. Unsaturated fatty acids were found to make up around 60% of total fatty acids in samples of endoneurium and perineurium, with monounsaturated fatty acids forming 40-50% of total unsaturated fatty acid content. Although the same fatty acids were present in both tissues there was a striking difference in C 18:1 (n-9) and C 18:2 (n-6) ratio between endoneurium and perineurium, which is particularly rich in linoleic acid. The nonpolar perineurial lipids were found to be richest in linoleic acid. Phospholipids were present in the perineurium, and they contained high proportions of saturated and medium-chain monounsaturated fatty acids.     

Liver and muscle fatty acid composition of mature and immature rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) fed two different diets

Fatty acid composition of liver and muscle tissues of immature and mature Oncorhynchus mykiss fed on two different diets were determined. Fatty acid analyses were carried out by gas chromatography. Palmitic acid (C16:0), oleic acid (C18:1 n-9), linoleic acid (C18:2 n-6) and docosahexaenoic acid (C22:6 n-3) were the major components in both liver and muscle tissues of immature and mature rainbow trout of both sexes. The amounts of C22:6 n-3 were higher in the liver (29.04 ± 0.06 − 27.41 ± 0.17%) and muscle (13.05 ± 0.40 − 11.37 ± 0.21%) of immature fish than in mature fish and depended on the composition of the diet. Results of this study show that fatty acid composition in fish tissues can considerably vary, depending on the age of fish and their diet. Thus more detailed studies are necessary on the influence of diet on immature and mature fish fatty acid composition. The age and diet of fish consumed may also be important for human health.     

Lipid classes and fatty acid composition of rotifers (Brachionus plicatilis) fed two algal diets

Rotifers (Brachionus plicatilis), maintained on baker's yeast, were fed for 24h upon two algal diets, Isochrysis galbana (diet A) and Isochrysis galbana + Nannochloropsis gaditana (diet B). (These algal diets were selected for their potential use as essential fatty acid (EFA) boosters, taking into account the requirements of fish larvae). The effect of these algal diets on total lipid content, lipid classes and fatty acid composition was studied. The total lipid content increased after feeding upon both diets but no significant differences were found between the two types. Neutral lipid and polar lipid contents increased and a positive correlation was observed between the neutral lipids content of rotifers and that of the food supplied. However, the content of polar lipids in rotifers did not depend upon that of the diet. The increase in neutral lipid content was found to be higher in rotifers fed upon diet B, compared to diet A which increased the phospholipid content. Non-enriched rotifers contained only small amounts of polyenoic fatty acids, i.e. 18:3n-6, 18:3n-3, 20:4n-6, 20:5n-3 and 22:6n-3, the contents of which increased significantly by feeding both diets. The EFA composition (20:4n-6, 20:5n-3 and 22:6n-3) of neutral lipids and phopholipids in rotifers reflected the EFA composition of each diet. Diet B-fed rotifers had the highest content in 20:4n-6 and 20:5n-3, whereas rotifers fed diet A and the highest 22:6n-3 content. The mixed diet I. galbana + N. gaditana enhanced substantially the composition of lipid classes i.e. neutral lipids and of n-3 PUFA of rotifers in comparison with Isochrysis or yeast diets.     

Dietary fatty acids modulate liver mitochondrial cardiolipin content and its fatty acid composition in rats with non alcoholic fatty liver disease

No data are reported on changes in mitochondrial membrane phospholipids in non-alcoholic fatty liver disease. We determined the content of mitochondrial membrane phospholipids from rats with non alcoholic liver steatosis, with a particular attention for cardiolipin (CL) content and its fatty acid composition, and their relation with the activity of the mitochondrial respiratory chain complexes. Different dietary fatty acid patterns leading to steatosis were explored. With high-fat diet, moderate macrosteatosis was observed and the liver mitochondrial phospholipid class distribution and CL fatty acids composition were modified. Indeed, both CL content and its C18:2n-6 content were increased with liver steatosis. Moreover, mitochondrial ATP synthase activity was positively correlated to the total CL content in liver phospholipid and to CL C18:2n-6 content while other complexes activity were negatively correlated to total CL content and/or CL C18:2n-6 content of liver mitochondria. The lard-rich diet increased liver CL synthase gene expression while the fish oil-rich diet increased the (n-3) polyunsaturated fatty acids content in CL. Thus, the diet may be a significant determinant of both the phospholipid class content and the fatty acid composition of liver mitochondrial membrane, and the activities of some of the respiratory chain complex enzymes may be influenced by dietary lipid amount in particular via modification of the CL content and fatty acid composition in phospholipid.     

Changes in fatty acid composition of Mytilus galloprovincialis (Lmk) fed on microalgal and wheat germ diets

Dietary fatty acid incorporation and changes in various lipid and phospholipid classes in the mussel Mytilus galloprovincialis subjected to three different dietary regimens were analysed and compared. Group A was unfed; group B received a diet consisting of 100% Thalassiosira weissflogii, exhibiting the typical fatty acid composition of diatoms, and group C received a diet consisting of 100% wheat germ conferring a 18:2:n-6 abundance. Biochemical analyses of diets and mussels were carried out at the beginning and at the end of the 30-day experimental period. Starvation and T. weissflogii based diet poorly affected mussel growth and fatty acid composition which remained unchanged. On the contrary, the wheat germ-based diet increased the condition index and deeply affected the fatty acid profile of all lipid and phospholipid classes. The high dietary 18:2n-6 level drastically reduced tissue content of 20:4n-6, 20:5n-3 and 22:6n-3. The biosynthesis of Non Methylene Interrupted (NMI) dienoic fatty acid appeared to be insensitive to the high input of 16:1n-7 and 18:1n-9 respectively from diet B and C, and to the PUFA shortage of diet C. Nevertheless the two NMI trienoic derivatives, 20:3Δ5,11,14 and 22:3Δ7,13 16, were found higher in C with respect to other groups, presumably due to the high 18:2n-6 content of this diet.     

Fatty Acid Composition of Algae from Habitats with Varying Amounts of Illumination

The fatty acid (FA) composition of algae Ulva fenestrata (Chlorophyta), Costaria costata (Phaeophyta), and Grateloupia turuturu (Rhodophyta) differed in their illumination habitats (shaded grotto and bright light). It was found that the light intensity affect the lipid content and fatty acid (FA) ratios in the algae. In the shaded places, the content of polyunsaturated FAs of the (n-3) series in U. fenestrate and of the (n-3) and (n-6) series, except 18 : 2, in C. costata are higher than at bright light, whereas in G. turuturu, the content of 20 : 5n-3 acids in that instance was lower. The lipid content was 2.5–3.6 times higher in the algae at low light intensity. The content variation of algal lipid components apparently was related to adaptive response of these plants to illumination condition.     

Liver and heart mitochondria obtained from Adelie penguin (Pygoscelis adeliae) offers high resistance to lipid peroxidation

Lipid peroxidation is generally thought to be a major mechanism of cell injury in aerobic organisms subjected to oxidative stress. All cellular membranes are especially vulnerable to oxidation due to their high concentration of polyunsaturated fatty acids. However, birds have special adaptations for preventing membrane damage caused by reactive oxygen species. This study examines fatty acid profiles and susceptibility to lipid peroxidation in liver and heart mitochondria obtained from Adelie penguin (Pygoscelis adeliae). The saturated fatty acids in these organelles represent approximately 40-50% of total fatty acids whereas the polyunsaturated fatty acid composition was highly distinctive, characterized by almost equal amounts of 18:2 n-6; 20:4 n-6 and 22:6 n-3 in liver mitochondria, and a higher proportion of 18:2 n-6 compared to 20:4 n-6 and 22:6 n-3 in heart mitochondria. The concentration of total unsaturated fatty acids of liver and heart mitochondria was approximately 50% and 60%, respectively, with a prevalence of oleic acid C18:1 n9. The rate C20:4 n6/C18:2 n6 and the unsaturation index was similar in liver and heart mitochondria; 104.33 +/- 6.73 and 100.09 +/- 3.07, respectively. Light emission originating from these organelles showed no statistically significant differences and the polyunsaturated fatty acid profiles did not change during the lipid peroxidation process.     

BIOCHEMICAL COMPOSITION AND FATTY ACID CONTENT OF FILAMENTOUS NITROGEN-FIXING CYANOBACTERIA

The biochemical composition and fatty acid content of twelve strains of filamentous, heterocystous, nitrogen-fixing cyanobacteria have been determined. When grown under diazotrophic conditions, protein, carbohydrate, lipid, and nucleic acids comprised 37–52%, 16–38%, 8–13%, and 8–11% of the dry weight, respectively. The presence of a combined nitrogen source resulted in an increase in the protein content of the cells and a decrease in the levels of lipids and carbohydrates, although biomass productivity was not affected significantly. Biochemical composition also changed during culture growth, with the highest levels of proteins and lipids occurring as the culture entered stationary phase, whereas the highest levels of carbohydrate and nucleic acids were found during the exponential phase. Total fatty acid levels in the strains assayed ranged between 3 and 5.7% of the dry weight. With regard to fatty acid composition, all strains showed high levels of polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SAFAs), with values of 24–45% and 31–52% of total fatty acids, respectively, whereas the levels of monounsaturated fatty acids (MUFAs) were in general lower (11– 32%). Palmitic acid (16:0) was the most prevalent SAFA, whereas palmitoleic (16:1n- 7) and oleic acid (18:1n-9) were the most abundant MUFAs in all the strains. Among PUFAs, γ-linolenic acid (GLA, 18:3n-6) was present at high levels (18% of total fatty acids) in Nostoc sp. (Chile) and at lower levels (3.6% of total fatty acids) in Anabaenopsis sp. The presence of GLA has not been previously reported in these genera of cyanobacteria. The rest of the strains exhibited high levels (12–35% of total fatty acids) of α-linolenic acid (ALA, 18:3n-3). Linoleic acid (18:2n-6) was also present at a substantial level in most of the strains. Eicosapentaenoic acid (EPA, 20:5n-3) was also detected in Nostoc sp. (Albufera). Some filamentous nitrogen-fixing cyanobacteria therefore represent potential sources of commercially interesting fatty acids.     

Total lipid and fatty acid compositions of <Emphasis Type="Italic">Lertha sheppardi</Emphasis> (Neuroptera: Nemopteridae) during its main life stages

Total lipid and the fatty acid compositions of phospholipid and triacylglycerol fractions, prepared from eggs, 3^rd instars of larvae, pupae, male and female adults of Lertha sheppardi, were analyzed by gas chromatography and gas chromatography-mass spectrometry. The effect of diet (adults’ nutrition) on fatty acid composition of L. sheppardi adults was also investigated. Total lipid of L. sheppardi considerably increased in adults compared with immature stages. There was a significant decrease in total lipid level in larval stage in contrast with egg stage. Qualitative analysis revealed the presence of 14 fatty acids during all stages. The major components were C16 and C18 saturated and unsaturated components which are ubiquitous to most animal species. In addition to these components, one odd-chain (C17:0) and prostaglandin precursor fatty acids were found. The fatty acid profiles of phospholipids and triacylglycerols were substantially different. In phospholipid fraction, monounsaturated fatty acids were the major proportion of fatty acids in both sex of adults and pupae, whereas polyunsaturated fatty acids were the most dominant fatty acids in eggs and 3^rd instars. Results of triacylglycerol fraction revealed that fatty acid composition of eggs had higher level of C16:1, C18:0 and C18:3n-3 content than that of 3^rd instars and pupae, which suggests accumulation of energetic and structural reserve materials during embryonic development. At more advanced developmental stages, mainly in adult females, the amount of C16:1 increased once again, which may be related to the need for accumulation of sufficient energy and of carbon reservoir in the developing new vitellum. Percentages of C18:1 were significantly high in adult stages compared to other stages. These findings indicate that the accumulation and consumption of fatty acids fluctuate through different development stages. Diet did not effect the fatty acid composition of L. sheppardi adults.     

Lipid content and composition of the Antarctic lamellibranch, Laternula elliptica (King & Broderip) (Anomalodesmata: Laternulidae), in King George Island during an austral summer

Total lipid content, lipid classes and fatty acid composition were studied in various tissues of the Antarctic clam Laternula elliptica in an early austral summer. A histological examination of the gonads revealed that most of the clams examined were spawning or ready to spawn. Lipid content was highest in gills (14.9% of tissue dry weight), followed by gonads (10.9%) and digestive glands (9.9%), and averaged 8.2% for the soft tissues. The overall lipid contents were relatively low compared to temperate bivalves at a similar reproductive stage. Lipid class composition in the total lipid of L. elliptica was quite similar to those of most marine bivalves at lower latitudes, being dominated by triacylglycerols (19.3–41.4% of total lipids) and phospholipids (18.9–28.3%) in most of the organs. Large amounts of triacylglycerol deposits in non-reproductive tissues, particularly in siphon and gill, indicate a potential role of lipid as maintenance energy reserve, although the low lipid contents suggest that lipid may not serve as an energy reserve for any food-limited periods. Fatty acid composition in L. elliptica was also typical of marine bivalves with predominance of 16:0 (26%) and 20:5n-3 (18%) acids. Total fatty acids from the soft tissues showed a moderate level of unsaturation (50.6%), and about 35% of the total fatty acids were polyunsaturated. These values were not significantly different from, or even lower than those of marine bivalves in warmer waters. However, the content of 20:5n-3 (18.2% of total fatty acids), which dominated n-3 polyunsaturated fatty acids, was similar to those reported for other marine bivalve species in temperate waters. The fatty acid composition of L. elliptica reflected dietary input of some microalgal species. The nanoflagellates Cryptomonas spp., which were reportedly rich in 16:0, 18:3n-3 and 20:5n-3, predominated in the water column during the present investigation. Accepted: 19 June 1999     

The effect of low temperature on fatty acid composition and tocopherols of the red microalga, <Emphasis Type="Italic">Porphyridium cruentum</Emphasis>

Porphyridium cruentum was grown in 10 L batch culture at 18°C, pH 8.0 and 28‰ salinity. The cells were harvested in the stationary phase and the fatty acid composition analysed by GC and tocopherol content by HPLC. A total of 14 fatty acids were identified including saturated fatty acids (13:0, 14:0, 14:0 iso, 15:0, 16:0, 16:0iso) and monounsaturated fatty acids (MUFAs; 16:1(n-7), 18:1(n-7), 18:1(n-9). Polyunsaturated fatty acids (PUFAs) were the predominant fatty acids detected, reaching 43.7% of total fatty acids in the stationary phase of culture. Among the PUFAs, eicosapentaenoic acid (EPA, 20:5(n-3)) was dominant (25.4%), followed by 12.8% arachidonic acid (AA, 20:4(n-6)). α-Tocopherol and γ-tocopherol contents were 55.2 μg g⁻¹ dry weight and 51.3 μg g⁻¹ dry weight respectively.