Effects of dietary eicosapentaenoic acid on growth, survival, pigmentation and fatty acid composition in Senegal sole (Solea senegalensis) larvae during the Artemia feeding period

We examined the effect of dietary eicosapentaenoic acid (20:5n-3, EPA) on growth, survival, pigmentation and fatty acid composition of Senegal sole larvae using a dose-response design. From 3 to 40 days post hatch (dph), larvae were fed live food that had been enriched using one of four experimental emulsions containing graduated concentrations of EPA and constant docosahexaenoic acid (22:6n-3, DHA) and arachidonic acid (20:4n-6, ARA). Proportions of EPA in the enriched Artemia nauplii were described as “nil” (EPA-N, 0.5% total fatty acids, TFA), “low” (EPA-L, 10.7% TFA), “medium” (EPA-M, 20.3% TFA) or “high” (EPA-H, 29.5% TFA). Significant differences among dietary treatments in larval length were observed at 25, 30 and 40 dph, and in dry weight at 30 and 40 dph, although no significant correlation could be found between dietary EPA content and growth. The stage of eye migration at 17 and 25 dph was significantly affected by dietary levels of EPA. Significantly lower survival was observed in fish fed EPA-H enriched nauplii. A significantly lower percentage of fish fed EPA-N (82.7%) and EPA-L (82.9%) diets were normally pigmented compared to the fish fed EPA-M (98.1%) and EPA-H (99.4%) enriched nauplii. Tissue fatty acid concentrations reflected the corresponding dietary composition. Arachidonic and docosahexaenoic acid levels in all the tissues examined were inversely related to dietary EPA. There was an increase in the proportion of docosapentaenoic acid (22:5n-3, DPA) in the tissues relative to the diet, which is indicative of chain elongation of EPA. This work concluded that Senegal sole larvae have a very low EPA requirement during the live feeding period

Cultured fish cells metabolize octadecapentaenoic acid (all-cis delta3,6,9,12,15–18∶5) to octadecatetraenoic acid (all-cis delta6,9,12,15–18∶4) via its 2-trans intermediate (trans delta2, all-cis delta6,9,12,15–18∶5)

Octadecapentaenoic acid (all-cis Δ3,6,9,12,15-18:5; 18:5n-3) is an unusual fatty acid found in marine dinophytes, haptophytes and prasinophytes. It is not present at higher trophic levels in the marine food web but its metabolism by animals ingesting algae is unknown. Here we studied the metabolism of 18:5n-3 in cell lines derived from turbot (Scophthalmus maximus), gilthead sea bream (Sparus aurata) and Atlantic salmon (Salmo salar). Cells were incubated in the presence of approximately 1 μM [U-14C] 18:5n-3 methyl ester or [U-14C] 18:4n-3 (octadecatetraenoic acid; all-cis Δ6,9,12,15-18:4) methyl ester, both derived from the alga Isochrysis galbana grown in H14CO3, and also with 25 μM unlabelled 18:5n-3 or 18:4n-3. Cells were also incubated with 25 μM trans Δ2, all-cis Δ6,9,12,15-18:5 (2-trans 18:5n-3) produced by alkaline isomerization of 18:5n-3 chemically synthesized from docosahexaenoic acid (all-cis Δ4,7,10,13,16,19-22:6; 22:6n-3). Radio- and mass analyses of total fatty acids extracted from cells incubated with 18:5n-3 were consistent with this fatty acid being rapidly metabolized to 18:4n-3 which was then elongated and further desaturated to eicosatetraenoic acid (all-cis Δ8,11,14,17,19-20:4; 20:4n-3) and eicosapentaenoic acid (all-cis Δ5,8,11,14,17-20:5; 20:5n-3). Similar mass increases of 18:4n-3 and its elongation and further desaturation products occurred in cells incubated with 18:5n-3 or 2-trans 18:5n-3. We conclude that 18:5n-3 is readily converted biochemically to 18:4n-3 via a 2-trans 18:5n-3 intermediate generated by a Δ3,Δ2-enoyl-CoA-isomerase acting on 18:5n-3. Thus, 2-trans 18:5n-3 is implicated as a common intermediate in the β-oxidation of both 18:5n-3 and 18:4n-3

Dietary arachidonic acid alters tissue fatty acid profile, whole body eicosanoid production and resistance to hypersaline challenge in larvae of the temperate marine fish, striped trumpeter (Latris lineata)

We determined the effect of dietary arachidonic acid (20:4n-6, ARA) on tissue ratios of ARA/eicosapentaenoic acid (20:5n-3, EPA) and subsequent whole body production of the eicosanoids, prostaglandin F-2 alpha (PGF(2 alpha)) and E-2 (PGE(2)) in the marine larvae of striped trumpeter, Latris lineata. Larvae were also subjected to a hypersaline challenge (55 ppt) with an aim to determine possible relationships between tissue fatty acid profiles, prostanoid production, and their tolerance to osmotic challenge. From 5 to 23 days post-hatch (dph) larvae were fed live food, rotifers (Brachionus plicatilis), that had been enriched with one of five experimental emulsions containing increasing concentrations of ARA and constant EPA and 22:6n-3 (docosahexaenoic acid, DHA). Final ARA concentrations in the rotifers were 1.33, 3.57, 6.21, 8.21 and 11.22 mg g(-1) DM. Larval growth and survival was unaffected by dietary ARA. Tissue fatty acid concentrations generally corresponded with dietary fatty acids and final tissue ratios of ARA/EPA ranged from 0.9 to 4.9. At 18 and 23 dph whole body concentrations of PGF(2 alpha) and PGE(2) generally increased as more dietary ARA was provided in a dose-response manner, and a significant elevation in both PGF(2 alpha) and PGE(2) in larvae fed the highest dietary ARA concentration was recorded at 23 dph compared to larvae receiving the lowest concentration. At 18 dph, the highest cumulative inactivity following a hypersaline challenge occurred in larvae fed 8.21 or 11.22 mg ARA g(-1) DM, which was significantly greater than those receiving 3.57 mg ARA g(-1) DM. At 23 dph no relationship between inactivity of larvae subjected to a hypersaline challenge to dietary ARA was evident. In summary, dietary ARA altered tissue ARA/EPA ratios, prostanoid production and resistance to a hypersaline challenge in larval striped trumpeter. While increasing dietary ARA generally resulted in elevation of prostanoids as well as increasing the number of inactive larvae following a hypersaline challenge at 18 dph, similar trends between prostanoids and larval inactivity were not evident at 23 dph, suggesting the exact mechanisms and relationships between eicosanoids and larval osmoregulation warrants further investigation. Nevertheless the study provides preliminary data on the effect of dietary ARA on the prostaglandin production in marine fish larvae

Effect of the intermolecular thermal motions on the tail of the electronic density of states in polyacene crystals

The thermal fluctuation of the intermolecular hopping integral in the series of polyacene crystals (naphthalene, anthracene, tetracene, pentacene) was evaluated computationally using a combined molecular dynamics and quantum chemistry approach. It was shown that these large fluctuations can manifest themselves in a temperature-dependent relatively broad tail of the density of states extending from the valence band into the gap. It was also shown that this tail accounts for a large fraction of all states in the valence band and therefore it may be essential for accurately describing the charge transport and optical properties