Lipid composition and utilization in developing eggs of two tropical marine caridean shrimps (Decapoda: Caridea: Alpheidae, Palaemonidae)

Changes in biomass and lipid biochemistry during egg development were studied in the tropical shrimps, Alpheus saxidomus and Palaemonetes schmitti, from Pacific Costa Rica. Freshly-laid eggs of P. schmitti were substantially smaller than those of A. saxidomus; dry mass decreased during embryogenesis in the former species but remained almost constant in the latter one. Water content of eggs close to hatching were similar among both species (roughly 75%). Newly-produced eggs of the two species contained ≈20% fatty acids per egg dry mass; a comparison with data concerning decapods inhabiting tropical and temperate waters revealed that eggs produced by shrimps inhabiting tropical waters tend to have a higher lipid egg content per dry mass than those from temperate regions. Major lipid classes in the eggs of both species were phospholipids and triacylglycerols which increased and decreased during the incubation period, respectively. The predominant fatty acids of P. schmitti eggs were 16:0, 20:5(n-3) and 22:6(n-3) whereas eggs of A. saxidomus showed high amounts of 16:0, 20:5(n-3) and 16:1(n-7), and remarkably low values of 22:6(n-3) fatty acid. Lipid utilization was more pronounced in P. schmitti; in A. saxidomus, eggs close to hatching still contained 70% of the initially deposited fatty acid content which may indicate an enhanced independence of the newly-hatched larvae on external energy resources. The observed differences may partially be related to different habitat preferences, however, the role of adaptation and phylogeny as determinants of egg lipid biochemistry in caridean shrimps remains to be clarified.     

Lipid,fatty acid and protein content of late larval to early juvenile stages of the western rock lobster,Panulirus cygnus

Lipid, fatty acid and protein content were determined individually on 7 phyllosomata, 69 clear pueruli, 286 pre-moult pueruli, and 86 juvenile western rock lobster (WRL) collected from four locations between the settlement seasons 2000 to 2006 to evaluate compositional changes during the non-feeding puerulus stage. Only the lipid content, particularly the phospholipids, decreased significantly with development. Protein declined sharply following moult to the juvenile. PL comprised between 86–94% of total lipid in all animals, and declined most between phyllosomata and clear pueruli (238.5 to 121.4 mg g^? 1 DW) (p < 0.001). Triacylglycerols were the only lipid to increase in absolute amounts with development, but declined 53% on average following moult to juvenile. This increase in TAG is likely due to the conversion of phospholipids to triacylglycerols. Monounsaturated fatty acids were the main energy form utilised during benthic development while polyunsaturated fatty acids showed a high degree of sparing. The n-3:n-6 fatty acid ratio of juveniles indicates that they may be approaching critically low levels of stored lipid energy reserves. Both protein, and lipid, declined sharply from the final puerulus phase to the juvenile confirming that a high energetic demand is required to fuel the moulting process.     

Fatty acid composition and incorporation of arachidonic acid into phospholipids of hemocytes from the tobacco hornworm Manduca sexta

The fatty acid compositions were determined for total lipids, triacylglycerols, phospholipids and four phospholipid fractions, including phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine/phosphatidylinositol (PS/PI) and cardiolipin (CA) obtained from hemocytes and cell-free serum from second day, fifth instar larvae of the tobacco hornworm Manduca sexta and the standard Manduca rearing medium. The hemocyte fatty acid profiles were considerably different from the profiles of the medium the insects were reared on and from the profiles of the cell-free serum. Hemocyte neutral lipids had lower proportions of polyunsaturated fatty acids than phospholipids. The fatty acid profiles of PC, PE, PS/PI and CA differ from each other and from the total lipid profiles, indicating selective fatty acid incorporation into hemocyte phospholipid species. Studies with radioactive arachidonic acid similarly indicated selective incorporation of polyunsaturated fatty acids into hemocyte lipids. Under our in vitro conditions, >40% of the total radioactivity was incorporated into hemocyte lipids. About 93% of the incorporated radioactivity was found in phospholipids. Within phospholipids. most of the radioactivity was associated with PC (46%), and less with PE (28%) and PS/PI (21%). Very little radioactivity was recovered in CA (0.9%).     

Comparative studies on the lipid composition of some digenetic trematodes.

Yusufi A. N. K. &; Siddiqi A. H. 1976. Comparative studies on the lipid composition of some digenetic trematodes. International Journal for Parasitology6: 5–8. Neutral lipids and phospholipids of six digenetic trematodes, Cotylophoron cotylophorum, Gastrothylax crumenifer and Gigantocotyle explanatum from water buffalo, Echinostoma malayanum and Fasciolopsis buski from pig and Isoparorchis hypselobagri from cat-fish were analyzed. Total lipid concentrations in trematodes varied considerably irrespective of their hosts and habitats. While triglycerides were the major components in all species, considerable amounts of phospholipids and free fatty acids were present in all species. Cholesterol was minimum (4–9%) in more or less all species, except in F. buski, where cholesterol, phospholipids and triglycerides constituted 13–14% and free fatty acids around 7%. Among phospholipids, choline and ethanolamine phosphatides were major polar lipids. Sphingomyelin and cardiolipin were present as small fractions and lysophosphatidylcholine was evenly distributed among all the species (9–12%) except in F. buski, which contained a little higher content (15%).     

Lipid content and fatty acid composition of a marine-derived Trichoderma longibrachiatum strain cultured by agar surface and submerged fermentations

A marine-related Trichoderma longibrachiatum strain isolated from mussels in a farming shellfish area was investigated for total lipid (TL) production, total lipid fatty acids (TLFA), and phospholipid fatty acids (PLFA). Fungal biomass was produced from two different marine-like culture ways, on agar surface and submerged fermentations (ASF and SmF, respectively), allowing useful comparisons. ASF produced a rather higher biomass amount than SmF with similar TL content. All fatty acids (FA), identified by gas chromatography–mass spectrometry (GC–MS), were ranged from 14 to 30 carbon atoms. Similar FA compositions were found in TL and phospholipids (PL) from biomasses obtained by both fermentation systems, including oleic (up to 15.3% of total FA mixture for SmF, and 33.9% for ASF), linoleic (46.1% for SmF, and 40.3% for ASF) and palmitic (28.1% for SmF, and 19.1% for ASF) acids as major components. Regarding the most common FA, lipid class and FA profiles observed did not show marked differences with those available for some Trichoderma terrestrial species. Some 2-hydroxylated FA and a rather unusual series of C₁₈ unsaturated conjugated FA (CFA) were identified. In addition, fungal biomass production by ASF was found as an easy to operate process, especially for further screenings of marine-derived fungi.     

Comparative study on the fatty acid and lipid composition of four marine fish larvae

• 1.1. Fatty acid and lipid class composition were determined in larvae of four marine species: Atlantic halibut (Hippoglossus hippoglossus L.), plaice (Pleuronectes platessa), cod (Gadus morhua) and turbot (Scophthalmus maximus) at hatching and prior to first feeding.
• 2.2. Total fatty acid content decreased in the four species with up to 50% reduction in one of the halibut groups. Docosahexanaoic acid (22:6 n-3) was especially utilized.
• 3.3. Low lipid utilization was found in turbot in relation to the other three species.
• 4.4. Water environmental temperature may explain some of the differences in the fatty acid utilization and the source of metabolic energy between cold water species (halibut, cod, and plaice) and temperate species (turbot), in the period from hatching to prior to first feeding.
• 5.5. Relative amounts of neutral lipids and phospholipids were similar in plaice, cod and halibut, approximately 25% and 75% of total lipids, respectively, and were approximately constant during the yolk-sac stage. Neutral lipids were dominant for turbot at hatching, accounting for 53–55% of the total lipids, while phospholipids predominated prior to first feeding, being 56–59%.
• 6.6. Phosphatidylcholine was catabolized in halibut, plaice and cod but not in turbot, while phosphatidylethanolamine tended to be synthesized in all four species.

     

Lipids in plant tissue cultures. VI. Effect of temperature on the lipids of Brassica napus and Tropaeolum majus cultures

The lipid contents of callus cultures of rape (Brassica napus) and nasturtium (Tropaeolum majus) increase in response to decreasing the temperature, though to different degree. Irrespective of the incubation temperature the lipids in cultures of both plants contain as predominant classes steryl glycosides, esterified steryl glycosides, sterols, steryl esters and fatty acids and, as minor constituents, various proportions of triacylglycerols, phospholipids and several unidentified fractions.The ratio of phospholipids to triacylglycerols as well as the ratio of diacylglycerophosphorylethanolamines to dicylglycerophosphorylcholines increase with time both in rape cultures incubated at 30°C and in those kept at 5°C.The lipids in rape and nasturtium cultures grown at 30°C contain smaller proportions of polyunsaturated fatty acids than the lipids in cultures incubated at 5°C. Erucic acid, the major constituent fatty acid of the seed lipids, in both plants, occurs only in trace amounts in the lipids of callus cultures. In contrast, linoleic and linolenic acids, which occur only in traces in the seed lipids of nasturtium, are major constituent fatty acids in the lipids of callus cultures derived from seedlings of this plant.The levels of constituent polyunsaturated fatty acids in the diacylglycerophosphorylethanolamines and the diacylglycerophosphorylcholines increase with time whereas in the triacylglycerols only linolenic acid is slightly increased.     

Fatty acid composition and lipid synthesis in developing safflower seeds

Linoleic acid predominated in every lipid class during the whole period of seed development of safflower, while linolenic acid decreased with increasing maturation and it was not detected in mature seeds. Just before the initiation of triacylglycerol accumulation, the fatty acid composition of triacylglycerols changed more rapidly than those of phospholipids and glycolipids. Saturated fatty acids tended to accumulate at the 1- and 3-positions of the glycerol molecule and the more highly unsaturated acids at the 2-position. The fatty acid compositions at the 1- and 3-positions were similar in all cases investigated, but in none of the triacylglycerols was the distribution completely symmetrical. The positional distribution of linolenic acid in triacylglycerols prepared from the immature seeds 2 days after flowering and from the leaves was unusual; in spite of its highest degree of unsaturation, it was preferentially esterified at the 1- and 3-positions. When triacylglycerol was most rapidly accumulated (14–18 days after flowering), the incorporation of acetate-[U- ¹⁴C] into total lipids was also maximum and dienoic fatty acids were the principal acids labelled. Diacylglycerols and compound lipids reached the highest rate of synthesis 15 days after flowering, and then a maximum incorporation into triacylglycerol occurred 18 days after flowering. Incubation temperature affected the synthesis of individual lipid classes. Triacylglycerol was more rapidly synthesized at 32° than at 10°, while diacylglycerols and compound lipids were accumulated under the low-temperature condition. A rise of incubation temperature caused a depression in dienoic acid synthesis.     

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     

Fatty acid and lipid analysis of the house cricket,Acheta domesticus

The fatty acid content and composition of the house cricket Acheta domesticus have been investigated in entire insects at different developmental stages and in selected organs of male and female adults. We have also determined the fatty acid composition of the various lipid classes within extracts of the organs of adult female insects. Fatty acids were analysed by capillary gas chromatography or mass spectrometry as their methyl esters (FAMEs) after direct transesterification of insect material or separated lipid classes.The major esterified fatty acids in all extracts were palmitate (C_16:0), stearate (C_18:0), oleate (C_18:1) and linoleate (C_18:2). Levels of esterified fatty acid varied considerably between organs but the fatty acid compositions showed only small variations. The levels of polyunsaturated fatty acids of the C₁₈ series were considerably higher in phospholipid fractions than in other lipid classes. Triacylglycerols formed the major lipid class in ovaries, fat-body and newly-laid eggs, whereas diacylglycerols and phospholipid predominate in the haemolymph. Triacylglycerols, phospholipids, diacylglycerols and free fatty acids were all found in significant amounts in the gut tissue.     

Lipid and fatty acid profile of Perna viridis, green mussel (Mollusca: Bivalvia) in different areas of the Eastern Venezuela and the West Coast of Trinidad

The species Perna viridis is a highly consumed species, which fast growth makes it an interesting aquaculture alternative for Venezuelan and Trinidad coasts. With the aim to contribute with its nutritional value information, this study analyzed lipid and fatty acid contents from samples taken in five locations from Eastern Venezuela and three from Trinidad West Coast. Total lipids were extracted and quantified, from a pooled sample of 100 organisms per location, by standard gravimetric methods, and their identification and quantification was done by TLC/FID (Iatroscan system). Furthermore, the esterified fatty acids of total lipid, phospholipids and triacylglycerols were identified and quantified by gas chromatography. Eastern Venezuela samples from Los Cedros, La Brea and Chaguaramas showed the highest total lipid values of 7.92, 7.74 and 7.53, respectively, and the minimum values were obtained for La Restinga (6.08%). Among lipid composition, Chacopata samples showed the lowest phospholipid concentration (48.86%) and the maximum values for cholesterol (38.87%) and triacylglycerols (12.26%); besides, La Esmeralda and Rio Caribe samples exhibited maximum phospholipids (88.71 and 84.93 respectively) and minimum cholesterol (6.50 and 4.42%) concentrations. Saturated fatty acids represented between 15.04% and 65.55% within total lipid extracts, with maximum and minimum values for La Esmeralda and Chacopata, respectively. Polyunsaturated results resulted between 7.80 and 37.18%, with higher values in La Brea and lower values in La Esmeralda. For phospholipids, saturated fatty acids concentrations varied between 38.81 and 48.68% for Chaguaramas and Chacopata samples, respectively. In the case of polyunsaturated fatty acids, these varied between non detected and 34.51%, with high concentrations in Los Cedros (27.97%) and Chaguaramas (34.51%) samples. For the triacylglycerols, the saturated fatty acids composition oscillated between 14.27 and 53.80% with low concentrations for Chacopata and high concentration for La Restinga; the polyunsaturated fatty acids were between 4.66 and 35.55% with lower values for Chacopata and higher values for Chaguaramas samples. P. viridis is recommended for human being consumption, according to the high content of unsaturated fatty acids found for this species.     

Lipid and fatty acid composition of the fat body during the female reproductive cycle of Labidura riparia (Insecta Dermaptera)

During the reproductive cycle of the female Labidura riparia, cytological observations show cyclical modifications of lipid droplets in the periovarian adipocyte. Fat body lipids and their constitutive fatty acids are analyzed. The lipids are predominantly triacylglycerols, which increase after adult ecdysis during vitellogenic and non-vitellogenic periods. Small amounts of diacylglycerols and phospholipids are found. Diacylglycerols increase during vitellogenesis and decrease during the non-vitellogenic period. Cytological modifications of lipid droplets are probably related to diacylglycerol fluctuations. Gas-liquid chromatography of fatty acid methyl esters shows oleic acid to be the predominant fatty acid in total lipids and triacylglycerols; unsaturated acids are approximately twice as abundant as saturated acids all along the reproductive cycle. Fatty acid composition of diacylglycerols and phospholipids differs from triacylglycerols and total lipids composition. Palmitic, stearic, oleic and linoleic acids represent the major fatty acids; their relative amounts vary during the different periods of the reproductive cycle. The correlations between fat body lipid changes and ovarian development were discussed and compared with observations made on other insect species. Accepted: 23 April 1997     

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.     

Changes in fatty acid composition of the lipid classes in developing oil palm mesocarp

During fruit development of oil palm (Elaeis guineensis) oil deposition in the mesocarp startedca12–13 weeks after flowering (WAF) and continued until the fruit ripened at 20 WAF. Over the next 1–2 weeks oil continued to be deposited but the fruit became loose and readily detached from the bunch. The lipids extracted at this stage contained over 50 % free fatty acids andca6%, polar lipids. The major fatty acids in the storage triacylglycerols were 16:0,18:1 and 18:2. The fatty acid composition of the neutral lipid classes and polar lipids during oil deposition were similar except that the latter also contained a high proportion of 18:3. Longer chain acids (20:3 and 22:0) were detected in certain lipid classes at 8 and 12 WAF.     

Encapsulation of Aspidogaster conchicola (Trematoda: Aspidogastrea) by unionid mussels

Of 334 mussel specimens representing 13 species, 143 individuals of seven species were found infected with Aspidogaster conchicola; encapsulation of worms was seen in six molluscan species. Encapsulated worms were most abundant anterior to the pericardium and were surrounded by inner fibroblastic and outer fibrocytic/fibrous walls, with occasional adjoining compressed host connective tissues. The inner wall contained acid mucins and phospholipids, while the outer wall contained reticulum fibers, neutral mucins, and phospholipids. Capsule structure was compared to the molluscan encapsulation classification system of T. C. Cheng and E. Rifkin (1970, Amer. Fish. Soc. Spec. Pub., No. 5, pp. 443–496) and to G. B. Pauley and C. D. Becker's (1968, J. Parasitol., 54, 917–920) account of A. conchicola encapsulation. Capsule contents included living or moribund adult worms, viable eggs or empty egg shells produced by disintegrated worms, juveniles hatched from eggs deposited by encapsulated adults, and host cells of which “brown cells” were most abundant. Because of the high frequency of encapsulated moribund worms observed in this study (more than 60%), we infer that this host reaction probably contributed to the parasite's death. Worm eggs individually encapsulated by hemocytes in hemal spaces also were observed. Life cycle implications of juvenile A. conchicola within digestive gland diverticula are discussed.     

Lipase in lipid bodies of cotyledons of rape and mustard seedlings

Lipolytic activity was absent in the crude cotyledon extract of ungerminated rapeseed (Brassica napm L. var. Dwarf Essex), and increased to a peak at day 4 in seedling growth, concomitant with the decrease in total lipids. About 50% of the lipase activity was recovered in the lipid bodies isolated from the cotyledon extract by flotation centrifugation. Isolated lipid bodies underwent autolysis of internal triacylglycerols resulting in the release of fatty acids. After the triacylglycerols in isolated lipid bodies had been extracted with diethyl ether, the lipase was recovered in the remaining membrane fraction. The lipase had a maximal activity at pH 6.5 on trierucin, trilinolein, or endogenous triacylglycerols, and at pH 8.0 on N-methylindoxylmyristate. The lipase was most active on trierucin and trilinolein, and hydrolyzed the related di- and monoacylglycerols at lower rates. There was little enhancement of the lipase activity in the presence of NaCl, CaCl₂, or detergents, and detergents in general reduced the activity. The hydrolysis of trierucin was linear until about 50% of the trierucin had been converted to erucic acid, and there was little accumulation of dierucin and monoerucin. Lipase extracted from lipid bodies isolated from germinated rapeseed of the variety Tower, which contains little or no erucic acids in the storage triacylglycerols, also had the highest activities on trierucin and trilinolein. A comparative study on mustard seed (Brassica juncea) revealed that the mustard lipase possessed characteristics very similar to those of the rapeseed lipase.     

Phospholipid metabolism following fertilization in sea urchin eggs and embryos.

Phospholipid metabolism during early development was examined in the sea urchins Stronglyocentrotus purpuratus and Lytechinus pictus. Transport of ³H-choline was stimulated fivefold following fertilization in both species. However, the actual percent incorporation of labeled precursors into phospholipids from the TCA soluble pool did not change at fertilization. There was a slight increase in transport of ¹⁴C-ethanolamine at fertilization but again there was no change in its percent incorporation into phospholipids. When eggs were preloaded with ³H-choline or ¹⁴C-ethanolamine and fertilized, the eggs or embryos showed similar patterns of incorporation into phospholipids. There was no significant change in the percent phosphorylation of choline in fertilized or unfertilized eggs.An investigation was made of the activity of choline kinase, the first enzyme in the biosynthesis of phosphatidylcholine. This enzyme was found to have similar activities in fertilized and unfertilized eggs using a variety of homogenization media. The activity of choline kinase was found to decrease slightly in activity at fertilization and reach a maximum activity by gastrula.These results indicate that there is no activation of phospholipid synthesis at fertilization of sea urchin eggs. Apparent increased incorporation actually reflects increased transport of precursors and not de novo synthesis.     

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.     

Lipolysis post mortem in North Atlantic krill

• 1.1. Three common species of North Atlantic krill, Meganyctiphanes norvegica (M. Sars), Thysanoessa inermis (Krøyer) and T. raschii (M. Sars), have been stored at 0°C post mortem, and the lipolytic activity followed by measuring changes in the lipid composition during storage.
• 2.2. Both phosphoglycerides and triacylglycerols were subjected to extensive hydrolysis with the formation of free fatty acids in all krill species examined, whereas wax esters, constituting a considerable proportion of the lipids in the Thysanoessa species, were not hydrolysed at all.
• 3.3. In M. norvegica the triacylglycerols and phosphoglycerides were hydrolysed at similar rates, whereas in T. inermis and T. raschii the phosphoglycerides were hydrolysed most rapidly.
• 4.4. For all krill species examined, the rate of production of free fatty acids was nearly constant during the initial phase of storage, and subsequently declined on prolonged storage.
• 5.5. At the end of the storage period of 16–24 days, the free fatty acids constituted about 35% of the total lipid in M. norvegica, and about 50% in the Thysanoessa species.
• 6.6. The rate of production of free fatty acids was about the same in all the three species of krill and seemed to be independent of the total lipid content.

     

Ontogenetic change in the lipid and fatty acid composition of scleractinian coral larvae

Some scleractinian coral larvae have an extraordinary capacity to delay metamorphosis, and this is reflected in the large geographic range of many species. Coral eggs typically contain a high proportion of wax esters, which have been hypothesized to provide a source of energy for long-distance dispersal. To better understand the role of lipids in the dispersal of broadcast spawning coral larvae, ontogenetic changes in the lipid and fatty acid composition of Goniastrea retiformis were measured from the eggs until larvae were 30 days old. Egg biomass was 78.8 ± 0.5% lipids, 86.3 ± 0.2% of which were wax esters, 9.3 ± 0.0% polar lipids, 4.1 ± 0.2% sterols, and 0.3 ± 0.1% triacylglycerols. The biomass of wax esters declined significantly through time, while polar lipids, sterols and triacylglycerols remained relatively constant, suggesting that wax esters are the prime source of energy for development. The most prevalent fatty acid in the eggs was palmitic acid, a marker of the dinoflagellate Symbiodinium, highlighting the importance of symbiosis in coral reproductive ecology. The proportion of polyunsaturated fatty acids declined through time, suggesting that they are essential for larval development. Interestingly, triacylglycerols are only abundant in the propagules that contain Symbiodinium, suggesting important differences in the energetic of dispersal among species with vertical and horizontal transmission of symbionts.