Egg Lipid Research Articles

Relation between lipid and fatty acid composition of eggs and larval survival in white pacific shrimp (Penaeus vannamei, Boone, 1931)

In this study, lipid classes and fatty acid composition were determinedin eggs of P. vannamei as a function of survival to zoeaIII stage. Spawns were reared individually to zoea III and grouped, accordingtotheir final survival to this larval stage, into spawns of high and lowsurvival.Eggs of individual spawns were analyzed for lipid and fatty acid composition ofneutral and polar lipids and the results were then grouped according tosurvivalto zoea III. The lipids within each group (high and low survival to zoea III)were pooled for the separation of phospholipids and the analysis of their fattyacid composition.Higher levels of triglycerides, carotenoids, and linoleic (18:2n-6) acid ineggs were associated with improved survival to zoea III. Linoleic acid washigher in spawns from the high survival group in both neutral and polarfractions and in most of the phospholipid classes analyzed. Docosahexanoic acid(DHA) was not related to survival to zoea, probably because its content washighenough (> 15% of total fatty acids) to satisfy embryo and early larvaldevelopment needs. A high content of eicosapentaenoic acid (EPA) was found inphosphatidylethanolamine, lysophosphatidylethanolamine, phosphatidylserine, andphosphatidylinositol compared to other phospholipid classes, suggesting aspecific role of EPA in these lipids. These results describe the specificphospholipid composition of penaeid eggs and could (potentially) be used aspredictive indicators of larval quality for research and production purposes.

Isomers of Conjugated Linoleic Acid (CLA) Are Incorporated into Egg Yolk Lipids by CLA-Fed Laying Hens

This study was designed to determine the amount of conjugated linoleic acid (CLA) incorporated into egg lipids after dietary CLA supplementation. Single Comb White Leghorn laying hens (n = 40; 28 wk old) were randomly assigned to four treatments of varying CLA levels (0, 0.01, 0.5 and 1 g CLA/kg diet). Eggs were collected daily for 36 d. Feed consumption and body weight were monitored. CLA content of egg yolk lipid was analyzed by gas-liquid chromatography. Birds fed 0.5 and 1.0 g CLA/kg feed had significantly more CLA in the egg yolk lipid vs. control and 0.01 g CLA/kg diet groups after 7 d (P < 0.0004). Incorporation of CLA into egg lipid was highest on d 24 and 36. CLA enrichment in egg lipid in the 1.0 g CLA/kg diet group was similar to that in ruminant animal food products, approximately 3 mg CLA/g fat.

SEA TURTLES AS BIOLOGICAL TRANSPORTERS OF NUTRIENTS AND ENERGY FROM MARINE TO TERRESTRIAL ECOSYSTEMS

Our study quantified the nutrients and energy introduced into the nesting beach at Melbourne Beach, Florida, from distant foraging grounds by loggerhead sea turtles, Caretta caretta. The fate of eggs deposited into 97 nests was determined by monitoring nests throughout incubation. The organic matter, energy, lipid, nitrogen, and phosphorus content of fresh eggs, eggs at successive stages of development, hatchlings, and hatching remains were determined. From these analyses, we estimated the flow of energy and nutrients introduced into the 14 305 nests (∼1.6 × 106 eggs) deposited in a 21-km stretch of Melbourne Beach in 1996. We quantified the amount of energy and nutrients incorporated into each of four pathways: ingested by nest predators; consumed by detritivores, decomposers, and plants; lost as metabolic heat or gases during embryological development and hatching; or returned to the ocean as hatchlings. Each nest introduced a mean of 688 g of organic matter, 18 724 kJ of energy, 151 g of lipids, 72 g of nitrogen, and 6.5 g of phosphorus into the beach. Twenty-five percent of the organic matter, 27% of the energy, 34% of the lipids, 29% of the nitrogen, and 39% of the phosphorus introduced into the nests returned to the ocean as hatchlings. Quantities of energy and nutrients transported by the turtles are comparable to quantities moved by other important biological transporters. Human activities have substantially altered the quantity of energy and nutrients transported, and the distribution of those nutrients on the beach. By introducing nutrients into beach ecosystems, sea turtles may help maintain stable dune systems that are critical to their reproductive success.

Tracing Nutrient Allocation to Reproduction With Stable Isotopes: A Preliminary Investigation Using Colonial Waterbirds of Great Slave Lake

AbstractWe investigated the use of stable-isotope analysis as a direct means of tracing allocation of endogenous protein and lipid reserves to reproduction in five gulls (Larus canus, L. delawarensis, L. californicus, L. argentatus, L. philadelphia), four terns (Sterna caspia, S. hirundo, S. paradisaea, Chlidonias niger), and one jaeger (Stercorarius parasiticus) breeding on Great Slave Lake (GSL) in the Northwest Territories. Our approach was based on assumptions that (1) body tissues of birds just arriving at GSL from their assumed marine-associated wintering habitats would have stable-isotope ratios more enriched than those of birds in equilibrium with the local GSL foodweb, and (2) mobilization of these reserves to reproduction could be traced by the isotopic measurement of egg macronutrients. As predicted, the pectoral muscle of six species of arriving birds was more enriched in 13C (x̄ = −21.5‰) and 15N (x̄ = 12.7‰) than was that of postbreeding birds (13C, x̄ = −23.5‰; 15N, x̄ = 9.9‰) or hatching-year birds raised at GSL (13C, x̄ = −24.3‰; 15N, x̄ = 9.0‰). Abdominal fat of arriving Herring Gulls and Mew Gulls was more enriched in 13C (x̄ = −19.7‰) than the fat of other species (x̄ = −23.4‰), indicating lipids of marine origin. We compared isotope values of the local GSL foodweb with dietary values predicted from isotope measurements of egg macronutrients if diets were entirely derived at GSL. Isotopic analysis of lipid-free egg yolk, yolk lipid, and shell carbonate suggested that for most species, little if any endogenous protein reserves were used for reproduction, with the possible exception of Caspian Terns, whose egg protein and egg lipid values, and Common Terns, whose egg protein values, were more enriched in 13C than those of the other species. Although endogenous nutrient reserves likely were important to birds during migration and the initial settling period at GSL, local food supplies were adequate to provide nutrients for reproduction.

Discrimination of wild and domestic origin of sturgeon ova based on lipids and fatty acid analysis

This study was designed to discriminate different origins of sturgeon eggs (wild or domestic) based on their biochemical composition. Fatty acid profiles of neutral and phospholipid fractions of three populations of white sturgeon, Acipenser transmontanus (two domestic and one wild) and one population of wild lake sturgeon Acipenser fulvescens ova lipids were analyzed. Palmitic acid (16:0) was the dominant saturated fatty acid in both neutral and phospholipid fractions of egg lipids regardless of species or population origin. Levels of palmitoleic (16:1 n−7) and docosahexaenoic (22:6 n−3) acids were species specific irrespective of fish origin. Palmitoleic acid was found at a significantly ( P<0.05) higher level in lake sturgeon egg neutral lipids than in white sturgeon. The opposite was the case for 22:6 n−3. Other fatty acids, such as stearic (18:0) and oleic (18:1 n−9) acids, were origin specific rather than species specific. Stearic acid was found at significantly lower levels in wild fish egg neutral lipids than in domesticated fish ova, whereas 18:1 n−9 showed the opposite trend. Phospholipid fatty acids were much less variable between species and among populations. We demonstrated that sturgeons' environment, thus their diet along with species specific characteristic life history (i.e., freshwater or marine origin) play an important role and markedly influence fatty acid composition of their eggs. Thus, egg fatty acid profile can be a viable tool in discrimination of different sturgeon populations with respect to caviar source and can ultimately be used to protect endangered wild populations of sturgeon.

Annual cycle of plasma lipids in captive reared striped bass: effects of environmental conditions and reproductive cycle.

Protein, lipid and fatty acid concentrations in plasma of eight male and eight female six year old captive striped bass (Morone saxatilis) were monitored monthly over the course of two reproductive cycles as part of an effort to investigate the time course of lipid class mobilization and subsequent deposition in gonads. Total protein levels (44.2 ± 0.67 mg ml−1, range 20.6–86.4) showed seasonal fluctuation, but did not vary with sex. Total lipid concentrations in the plasma of both males (17.7 ± 0.61 mg ml−1) and females (14.1 ± 0.64 mg ml−1) showed seasonal fluctuations with the lowest levels in late Spring during spawning. Plasma lipids in females were significantly (p < 0.0001) lower than those of the males except during early ovarian secondary growth. Analysis of the lipid class composition revealed that the decrease in plasma lipid concentrations in females prior to spawning is primarily due to a decrease of up to 50% in the phospholipid content of the plasma relative to males. Striped bass vitellogenin was found to contain approximately 20% lipid by weight with nearly 80% of the lipid being phosphatidyl choline (PC). Vitellogenin levels previously measured in these individuals were highest during the winter months and decreased in the 2 months prior to spawning. Although mature striped bass oocytes are rich in wax esters, no wax esters or fatty alcohols were found in the plasma. Analysis of the fatty acyl composition of separated lipid classes suggests that PC is the primary carrier of the essential (n=3) fatty acids 22:6 (DHA) and 20:5 (EPA) to the gonads. Fatty acid analysis of the lipids associated with vitellogenin revealed that levels of essential fatty acids were low relative to vitellogenin-borne lipids from other teleosts. The lack of detectable wax esters in plasma lipids of female striped bass suggests that these abundant lipids in mature eggs are synthesized within the oocytes.

Measures of egg quality in induced spawns of the Asian sea bass, Lates calcarifer Bloch.

The egg morphometry and lipid and protein components were determined in induced spawns (n=14) of the sea bass, Lates calcarifer, to identify measures of egg quality. Based on fertilization and hatching rates, the spawns were classified either in Group I, (zero fertilization) or Group II (where fertilization and hatching occurred). The egg morphometry did not differ between the two groups (p > 0.05). The total lipid was higher in Group II than in Group I, although the difference was not significant (p > 0.05). The EPA and linoleic acid were significantly higher in Group II (p 0.05). Proline, glycine, p-ethanolamine, and aspartic acid were significantly higher in Group II (p < 0.05), while tyrosine and glutamic acid were significantly higher in Group I (p < 0.05). Phosphoserine and fertilization rate were positively correlated (p < 0.03; r=0.60), as well as aspartic acid and hatching rate (p < 0.05; r=0.54). Arginine was negatively correlated with fertilization rate (p < 0.03; r=−0.61) and the percentage of normal zygotes (p < 0.03; r=−0.63). Serine was inversely correlated with yolk volume of the newly-hatched larvae (p < 0.03; r=−0.77). The moisture content of the eggs, which was significantly higher in Group II than in Group I (p < 0.03), was directly correlated with the FAAs:protein ratio (p < 0.03; r=0.76). The present results reveal egg components that may be used as quality measures in induced spawns of sea bass, a euryhaline teleost that spawn pelagic eggs containing an oil globule.

Effects of acidic pH and phytoplankton on survival and condition of Bosmina longirostris and Daphnia pulex

The effects of pH, algal composition and algal biomass on abundance, size, reproduction and condition of Daphnia pulex and Bosmina longirostris were tested in a field experiment using water and natural phytoplankton assemblages from a circumneutral (pH 6.43) and a moderately acidic (pH 5.75) lake in south-central Ontario. Both species were affected by pH and phytoplankton composition, with decreased egg production, lipid reserves, body size or abundance in treatments containing algae and/or water from the more acidic lake compared to treatments containing water and phytoplankton from the circumneutral lake. This result was unexpected for Bosmina, which often increases in relative and/or absolute abundance in acidified lakes. The negative effect of acidic conditions on Bosmina suggests that the population increase observed in most acidified lakes is not due to a positive response to low pH or ambient phytoplankton, but to altered biotic interactions possibly involving reduced competition.

TRACING NUTRIENT ALLOCATION TO REPRODUCTION WITH STABLE ISOTOPES: A PRELIMINARY INVESTIGATION USING COLONIAL WATERBIRDS OF GREAT SLAVE LAKE

We investigated the use of stable-isotope analysis as a direct means of tracing allocation of endogenous protein and lipid reserves to reproduction in five gulls (Larus canus, L. delawarensis, L. californicus, L. argentatus, L. philadelphia), four terns (Sterna caspia, S. hirundo, S. paradisaea, Chlidonias niger), and one jaeger (Stercorarius parasiticus) breeding on Great Slave Lake (GSL) in the Northwest Territories. Our approach was based on assumptions that (1) body tissues of birds just arriving at GSL from their assumed marine-associated wintering habitats would have stable-isotope ratios more enriched than those of birds in equilibrium with the local GSL foodweb, and (2) mobilization of these reserves to reproduction could be traced by the isotopic measurement of egg macronutrients. As predicted, the pectoral muscle of six species of arriving birds was more enriched in 13C (x̄ = −21.5‰) and 15N (x̄ = 12.7‰) than was that of postbreeding birds (13C, x̄ = −23.5‰; 15N, x̄ = 9.9‰) or hatching-year birds raised at GSL (13C, x̄ = −24.3‰; 15N, x̄ = 9.0‰). Abdominal fat of arriving Herring Gulls and Mew Gulls was more enriched in 13C (x̄ = −19.7‰) than the fat of other species (x̄ = −23.4‰), indicating lipids of marine origin. We compared isotope values of the local GSL foodweb with dietary values predicted from isotope measurements of egg macronutrients if diets were entirely derived at GSL. Isotopic analysis of lipid-free egg yolk, yolk lipid, and shell carbonate suggested that for most species, little if any endogenous protein reserves were used for reproduction, with the possible exception of Caspian Terns, whose egg protein and egg lipid values, and Common Terns, whose egg protein values, were more enriched in 13C than those of the other species. Although endogenous nutrient reserves likely were important to birds during migration and the initial settling period at GSL, local food supplies were adequate to provide nutrients for reproduction.

Placental nutrition in the viviparous lizardNiveoscincus metallicus: the influence of placental type

The ion, energy, lipid, nitrogen and fat-soluble vitamin contents of freshly ovulated eggs and neonates of the viviparous lizard Niveoscincus metallicus were measured to quantify uptake of nutrients across the placenta. This species is particularly interesting because it has a chorio-allantoic placenta that is intermediate in complexity compared to viviparous species that have been the focus of other studies. Newly ovulated eggs have a wet mass of 79.6+/-4.6 mg and a dry mass of 41.8+/-2.8 mg, compared to the neonates that have a wet mass of 224.2+/-8.2 mg and dry mass of 37.9+/-1.2 mg. Thus, there is no significant net uptake of dry matter across the placenta. Neonates have significantly less lipid (6.2+/-0.4 mg) than eggs (12.7+/-0.5 mg), but no significant difference in nitrogen (4.1+/-0.3 mg) compared to eggs (4.5+/-0.2 mg). Energy densities reflect the protein and lipid composition and the relative dry masses of the eggs and neonates. There is significantly more energy (1029.1+/-80.0 J) in the egg than in the neonate (858.2+/-38.6 J). The increase in the ash content of the neonates (2.9+/-0.2 mg) compared to fresh eggs (2.1+/-0.3 mg) was not significant, even though there was an approximately threefold increase in the amount of sodium (0.11+/-0.01 mg in neonates, 0.34+/-0.01 mg in eggs) and potassium (0.12+/-0.017 in neonates, 0.40+/-0.01 mg in eggs) in neonates compared to eggs. There was no significant uptake of calcium and magnesium during development. The egg lipids consisted of triacylglycerol (66.7+/-2.3 %), phospholipid (18.9+/-0.7 %), cholesteryl ester (4.9+/-1.6 %) and free cholesterol (5.6+/-1.5 %). The egg phospholipid contained comparatively high proportions of arachidonic and eicosapentanoic acids but low levels of docosahexaenoic acid (DHA), whereas the phospholipid of the neonate was greatly enriched in DHA. In the egg, the predominant vitamin E was (&agr;)-tocopherol (62.6+/-3.4 mg g(-)(1)), although there was some (&ggr;)-tocotrienol (3.5+/-0.3 mg g(-)(1)), and vitamin A was present (1.5+/-0.2 mg g(-)(1)). The ratio of neonate dry mass to egg dry mass of N. metallicus (0.91) lies between that of species with type I (0.78) and type III (1.70) chorio-allantoic placentae, confirming our conclusion that the placenta of N. metallicus is functionally intermediate, as well as intermediate in complexity, between these other two types.

Differences in egg lipid and antioxidant composition between wild and captive pheasants and geese

The aim of this study was to assess the differences in yolk lipid composition of pheasants and geese between birds maintained in captivity on commercial grain-based diets and their counterparts in the wild which are free to select their diets from the environment. The most striking difference was that the proportion of α-linolenic acid (18:3n-3) was far greater in all yolk lipid classes [triacylglycerol (TAG), phospholipid (PL), cholesteryl ester (CE)] of the wild birds than in the captive birds of both species. For example, in yolk TAG, the level (wt.% of total fatty acids) of 18:3n-3 was only 1.6% in eggs of captive pheasants compared with 27.9% in eggs of the wild birds. The proportions of 18:3n-3 in yolk TAG of housed, free-range and feral geese were 0.6, 6.6 and 19.3% respectively. It is suggested that these differences arise from the predominance of linoleic acid (18:2n-6) as the major polyunsaturate in the commercial grain-based feeds whereas geese and pheasants in the wild consume grasses and green shoots in which 18:3n-3 is the main fatty acid. The concentrations of vitamin E and carotenoids in the yolks of the free-range and feral geese were much greater than in those of the housed geese. Thus the developing embryos of pheasants and geese in the wild will have access to far higher levels of n-3 polyunsaturates and lipid-soluble antioxidants compared with embryos of the housed birds.

Placental transfer of nutrients during gestation in the viviparous lizard, Pseudemoia spenceri

Energy, ionic, protein and lipid contents and fatty acid profiles for the major lipid classes of freshly ovulated eggs and neonates of the viviparous lizard, Pseudemoia spenceri, were measured. Litter size is 1.7 ± 0.1, with larger females producing larger neonates. Placentotrophy results in approximately 23% more dry matter in the neonates than in the fresh egg. The increase in the quantity of protein and lipid during development is not significant and is reflected in the similarity of energy densities of eggs and neonates. As a percentage of dry matter, neonates have slightly lower proportions of lipid and protein than eggs because of significant uptake of ash, calcium, potassium and sodium, but not of magnesium, across the placenta. The amounts of triacylglycerol and phospholipid are not significantly different between the egg and the neonate, but neonates contain significantly more cholesterol and cholesteryl ester. The amounts of the major fatty acids, palmitic and oleic acids, recovered from the total lipids of the neonate do not differ significantly from the amounts present in the egg lipids, but the neonates contain significantly less linoleic and α-linolenic acids and more palmitoleic, stearic and arachidonic acids than the eggs. The amount of docosahexaenoic acid recovered from the lipids of the neonate is 2.6-times greater than the amount initially present in the egg. P. spenceri has a relatively larger egg and a smaller reliance on placentotrophy than other species in the same genus, all of which have a similar placental morphology. Nevertheless, the pattern of embryonic nutrition includes both obligative and facultative placentotrophy. All the major components of yolk of oviparous species are present in eggs of P. spenceri, but most are augmented during development by placental transfer.

Development of broodstock diets for the European Sea Bass ( Dicentrarchus labrax) with special emphasis on the importance of n−3 and n−6 highly unsaturated fatty acid to reproductive performance

Commercially fabricated diets allow greater control over the composition of biochemical components and reduce the risks of disease introduction, which are significant concerns when using the wet fish diets commonly used for most farmed marine broodstocks. However, satisfying the dietary lipid requirements of marine broodstock using artificial diets has proved difficult, particularly with respect to their highly unsaturated fatty acid (HUFA) composition. Two groups of mature sea bass, each divided between three replicated tanks, were fed two dry pelleted diets over a 2-year period, encompassing two spawning seasons. The first diet contained a good quality Northern Hemisphere meal and oil; the second differed only in the source of oil, which was substituted with tuna orbital oil (TOO). The use of TOO in the dry pelleted formulation allowed the manipulation of n−3 and n−6 HUFA in the resulting eggs, specifically arachidonic acid (20:4 n−6; AA), eicosapentaenoic acid (20:5 n−3; EPA) and docosahexaenoic acid (22:6 n−3; DHA). The results showed that dietary manipulation of these HUFA could improve levels and ratios of AA, EPA and DHA which were transferred to the resulting eggs with improvements in early survival and hatching success repeated over successive spawning seasons. The dry diet containing TOO facilitated comparable reproductive performance to the wet fish diet ( Boops boops) which has previously been considered the most effective broodstock diet. The improvements in reproductive performance are discussed in relation to the proportion of these HUFA with respect to each other in total egg lipid and the phospholipid classes phosphatidylcholine (PC), phosphatidylinositol (PI) and phosphatidylethanolamine (PE) and to their potential impact on eicosanoid formation. Finally, this study has shown that a commercially fabricated diet can be successfully used as sensitive investigative tool for aquaculture research.

The Chilean scallop Argopecten purpuratus (Lamarck, 1819): II. manipulation of the fatty acid composition and lipid content of the eggs via lipid supplementation of the broodstock diet

Dietary supplementation with lipid emulsions during broodstock conditioning of Argopecten purpuratus was used to manipulate the fatty acid composition of the eggs. The scallops were fed a mixed algal diet either alone (Al) or supplemented with an emulsion rich in ethyl esters of docosahexaenoic acid (DHA; Al+EmDHA) or eicosapentaenoic acid (EPA; Al+EmEPA) at a concentration of 50% lipids per algal dry weight (DW). The longer induction period and the lower fecundity in scallops fed solely on algae indicated a higher food value for the lipid-supplemented diet compared to the non-supplemented diet. Lipid supplementation resulted in a significant increase of the total lipid content (mg/g DW) of the eggs. The fatty acid quality of the diet had no significant effect on the fatty acid profile of the polar lipids. However, the supplementation of the DHA-rich emulsion resulted in a significant increase of the DHA level (% of total fatty acids) in the total and neutral lipids of the eggs compared to eggs from scallops fed solely algae. The absolute DHA content (mg/g DW) increased by 47%. The EPA level in the total and neutral lipids of eggs from broodstock supplemented with EmEPA was significantly higher than in eggs from scallops fed Al+EmDHA but no significant differences were detected with eggs from the non-supplemented diet (Al). The absolute EPA concentration in eggs from scallops fed Al+EmEPA was, respectively, 19 and 17% higher than in eggs from broodstock fed, respectively, solely algae (Al) or Al+EmDHA. The results illustrated that fatty acids, supplied as emulsified ethyl esters, could be ingested and assimilated by adult A. purpuratus and were at least partially allocated to the eggs.

Simple and rapid extraction method of total egg lipids for determining organochlorine pesticides in the egg

A simple and rapid extraction method of total egg lipids for determination of organochlorine pesticides (OCPs) in the egg was developed. After being mixed with anhydrous sodium sulphate, the extraction of lipids in egg yolk was performed using n-hexane–acetonitrile (2:1, v/v). Troublesome emulsions did not occur. Using the present method, an average of 3.03 g of egg lipids was collected from 10 g of egg yolk. Compared with classical methods, the present method is handy; needs much shorter analysis time and less requirement of solvents and has higher efficiency of egg lipid extraction and higher recoveries of OCPs.

Fatty acid and carotenoid composition of eggs from two nonanadromous Atlantic salmon stocks of cultured and wild origin

Two Swedish landlocked (nonanadromous) salmon (Salmo salar) stocks were investigated with the aim of characterising their egg fatty acid (FA) and carotenoid profiles. Fish from one of the stocks were also cultured over the past few decades as part of the Swedish program for genetic preservation, allowing a comparison between the eggs from females on a diet based on lipids of limnic (natural food chain) origin and eggs from females fed an artificial diet of marine origin. No significant differences in the FA profile of the phospholipid (PL) or triacylglycerol (TAG) fraction were found between the two wild stocks. The content of EPA (20:5n-3, eicosapentaenoic acid) in PL fraction was significantly higher in eggs from cultured females (13.0%) compared with eggs from both wild stocks (5.7 and 6.4%). Further, in PL fraction, AA (20:4n-6, arachidonic acid) levels in these eggs were significantly lower (2.4% versus 6.7 and 6.2%). The AA content of the TAG fraction differed greatly between wild (4.4 and 4.9%) and cultured (1.2%) eggs, whereas this fraction showed almost no corresponding difference in EPA content. The level of DHA (22:6n-3, docosahexaenoic acid) did not differ between the two wild stocks or between wild and cultured fish. This was in spite of widely different levels of DHA in the diet. The composition of carotenoids was altered in the cultured eggs which had a higher proportion and higher content (1.16 μ g egg−1) of astaxanthin than the wild eggs (0.56 and 0.62 μg egg−1, respectively). Hatching success varied markedly between wild (>95%) and cultured fish (40–75%). We conclude that changes in the lipid source in the diet of female salmon during gonadal maturation will alter the egg fatty acid composition with an increased risk of disturbances in embryonic development as a consequence. Further, the lack of any difference between wild and cultured females in terms of their egg DHA content indicates that there is a strong genetic influence on levels of this fatty acid in salmon eggs.

Liposomal Influenza Vaccine

Very large academic studies in the US have established that influenza A and B vaccines (mainly subunit preparations) prevent hospitalisations and deaths in ‘at risk’ groups such as the elderly. Greater confidence in vaccine efficacy has resulted in the use of increased amounts of the vaccines in Europe and the US. In the UK, a record 8 million vaccine doses were manufactured during 1998. However, currently available vaccines induce protection in 70 to 80%, rather than 100%, of patients. Antigenic drift of the haemagglutinin (H) and neuraminidase (N) antigens affects the immunogenicity of influenza vaccines, but even with a good antigenic match between vaccine and virus, there is margin for improvement. Also, some elderly persons, fortunately in a minority, are ‘nonrespondent’ to certain viral strains. It is important to evaluate the data for liposomal influenza vaccine against this background. Liposomes are lipid particles that can serve as delivery systems and adjuvants for antigens. They are biodegradable if composed of phospholipids. In the case of liposomal influenza vaccine, the liposomes (or so-called ‘virosomes’) are novel structures of liposome bilayers into which are inserted influenza H and N antigens; the vaccine has a similar appearance to an influenza virus. Obviously the current studies with the novel liposomal influenza vaccine are still limited with respect to the number of patients who have received the vaccine, but the data look solid and significant. I was particularly impressed with the immune response to a single dose of the liposomal vaccine in children, who would often be unprimed to influenza. Similarly, I appreciated the comparison with whole virus vaccine which is often a good immunogen but which unfortunately also induces unwanted systemic responses, particularly in children. It would seem that by removal of viral egg lipids and RNA and nucleoprotein and matrix proteins, followed by reconstitution of H and N into liposomes, the immunogenicity of liposomal influenza vaccine is improved compared with conventional influenza vaccines, but without the adverse effects of whole virus vaccines. The scientific progress of the new liposomal vaccine will be followed with acute interest. ▲ GUEST COMMENTARY BioDrugs 1999 Feb; 11 (2): 145-146 1173-8804/99/0002-0145/$01.00/0

Influence de l'état physique sur l'ionisation gamma de lipides d'uf

Egg lipid irradiation, in solid or liquid state, does not change the nature of radioinduced hydrocarbons but only they quantities. Moreover the ratio between yields in solid and in liquid state is independent from the hydrocarbon.

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.

The effect of egg fatty acid concentrations on embryo viability in wild and domesticated walleye ( Stizostedion vitreum)

Eggs from three distinct populations of walleye Stizostedion vitreum, one domesticated (London State Fish Hatchery) and two wild (Lake Erie and Salt Fork Reservoir), were compared in terms of total lipid content and fatty acid profiles (phospholipids and neutral lipids). The concentrations of total lipids in eggs from domesticated broodstock were significantly lower (8.6 ± 1.0 % of wet weight) than those of both wild populations (13.3 ± 0.9 % and 10.9 ± 0.6 % of wet weight for Lake Erie and Salt Fork Reservoir, respectively). The profiles of fatty acids in egg lipids differed significantly among the three investigated populations. Domesticated females fed a formulated diet produced eggs containing significantly higher levels of linoleic acid (18:2n-6), characteristic of plant lipids. However, arachidonic acid (20:4n-6), was at significantly higher levels in eggs of wild walleye stocks. Although eicosapentaenoic acid (20:5n-3) was detected at significantly higher levels in eggs from Lake Erie walleye, docosahexaenoic acid (22:6n-3), the most abundant in polar lipids, was found at similar levels in eggs of all three populations. Survival of walleye embryos was correlated with the concentrations of polyunsaturated long chain fatty acids. Our data suggest that deficiency in n-3 fatty acids might be associated with impaired development of walleye, and thus poor larval and juvenile viability.