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The high mortalities observed during Octopus vulgaris paralarvae culture have been associated with a nutritional imbalance, with long-chain polyunsaturated fatty acids (LC-PUFA) appearing to have a critical role. In order to determine the in vivo capability of O. vulgaris hatchlings to incorporate and metabolise unsaturated fatty acids (FA), hatchlings were incubated in flat-bottom 6-well tissue culture plates at a density of 90 hatchlings/well in 10 mL of seawater (36‰). Incubations were performed with gentle stirring at 21 °C for 6 h with 0.2 μCi (0.3 μM) of [1 -14C]-labelled FA including 18:1n - 9, 18:2n - 6, 18:3n - 3, 20:4n - 6 (ARA), 20:5n - 3 (EPA) or 22:6n - 3 (DHA), which were added directly to the seawater as their potassium salts bound to bovine serum albumin (BSA). A control treatment without [1 -14C]FA was also assessed. O. vulgaris hatchlings not only possessed the ability to incorporate FA bound to BSA, but also to esterify them into phospholipid, with marked specificity. [1 -14C]DHA and [1 -14C]C18 FA substrates were mainly esterified into phosphatidylcholine, while [1 -14C]ARA and [1 -14C]EPA were esterified into phosphatidylethanolamine. The majority of radioactivity from [1 -14C]FA incorporated into hatchling total lipid was recovered as unmodified FA with elongation being the only metabolism detected. Of the FA investigated, [1 -14C]ARA was the most efficiently incorporated into hatchling lipids, but it was also the least modified FA. The fact that no desaturation activity was recorded towards the FA tested in this experiment may indicate that the nutritional requirements of O. vulgaris hatchlings in terms of FA are highly specific and LC-PUFA must be considered essential dietary nutrients. [ABSTRACT FROM AUTHOR]

Abstract: A crude cell extract from Agrobacterium radiobacter was encapsulated in calcium-alginate capsules for the synthesis of p-hydroxyphenylglicine (p-HPG). The effect of the encapsulation process on the two enzymatic activities involved on the p-HPG synthesis was studied. The encapsulation process was optimised with regard to alginate concentration and ratio extract:alginate. The encapsulation efficiency was around a 60% and the derivatives showed a p-HPG synthesis yield of around a 50%. The optimum temperature was 55°C and the activation energy (E a) of the whole process was 4.4kcal/mol. The biocatalyst could be used six times without any activity loss. [Copyright &y& Elsevier]

The capacity to biosynthesise long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA) depends upon the complement and function of key enzymes commonly known as fatty acyl desaturases and elongases. The presence of a Δ5/Δ6 desaturase enabling the biosynthesis of docosahexaenoic acid (22:6n-3, DHA) through the "Sprecher pathway" has been reported in Chelon labrosus. Research in other teleosts have demonstrated that LC-PUFA biosynthesis can be modulated by diet and ambient salinity. The present study aimed to assess the combined effects of partial dietary replacement of fish oil (FO) by vegetable oil (VO) and reduced ambient salinity (35 ppt vs 20 ppt) on the fatty acid composition of muscle, enterocytes and hepatocytes of C. labrosus juveniles. Moreover, the enzymatic activity over radiolabelled [1-14C] 18:3n-3 (α-linolenic acid, ALA) and [1-14C] 20:5n-3 (eicosapentaenoic acid, EPA) to biosynthesise n-3 LC-PUFA in hepatocytes and enterocytes, and the gene regulation of the C. labrosus fatty acid desaturase-2 (fads2) and elongation of very long chain fatty acids protein 5 (elovl5) in liver and intestine was also investigated. Recovery of radiolabelled products including stearidonic acid (18:4n-3, SDA), 20:5n-3, tetracosahexaenoic acid (24:6n-3, THA) and 22:6n-3 in all treatments except FO35-fish, provided compelling evidence that a complete pathway enabling the biosynthesis of EPA and DHA from ALA is present and active in C. labrosus. Low salinity conditions upregulated fads2 in hepatocytes and elovl5 in both cell types, regardless of dietary composition. Interestingly, FO20-fish showed the highest amount of n-3 LC-PUFA in muscle, while no differences in VO-fish reared at both salinities were found. These results demonstrate a compensatory capacity of C. labrosus to biosynthesise n-3 LC-PUFA under reduced dietary supply, and emphasise the potential of low salinity conditions to stimulate this pathway in euryhaline fish. [Display omitted] • Dietary regulation of the LC-PUFA biosynthesis is possible in Chelon labrosus. • Overexpression of fads2 and elovl5 shows the role of salinity in LC-PUFA production. • Low salinity is a convenient strategy to produce DHA enriched specimens. [ABSTRACT FROM AUTHOR]

The bioactivities of chitooligosaccharides are markedly influenced by the degree of acetylation, degree of polymerization or molecular weight and pattern of acetylation. Thus, it is crucial to identify reproducible processes that will give rise to well-defined chitooligosaccharides and establish methods for their posterior physicochemical characterization in order to advance in the knowledge of their bioactivity. Chitooligosaccharides were prepared by two different processes. The first used chitosanase enzymatic hydrolysis and the second consisted of a two-step procedure based on chemical hydrolysis followed by chitosanase hydrolysis. Chitooligosaccharides produced in the second process were composed of 63 % of fully deacetylated sequences and inhibited the growth of Escherichia coli and Listeria monocytogenes . Better antibacterial activity was found for those obtained in the first process composed of 27 % of fully deacetylated sequences. Therefore, a low percentage of free amino groups and the presence of acetylated sequences are necessary in these molecules to exert good antibacterial capacity. [ABSTRACT FROM AUTHOR]