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[EN] Currently, microalgae are used in fish diets, but their long-term growth effect is unknown. In this experiment, juvenile seabream specimens were fed with microalgae-enriched diets for three months, and then transferred to a microalgae-free diet for 10 months to assess long-term effects up to commercial size (≈27 cm and ≈300 g). The juvenile diets contained Nannochloropsis gaditana at 2.5 or 5% inclusion levels, either raw (R2.5 and R5 groups) or cellulose-hydrolyzed (H2.5 and H5 groups). The body length and weight were measured in 75 fish group-1 at commercial stage. The size, number, and fibrillar density of white muscle fibers and the white muscle transverse area were measured in nine fish group-1 at commercial stage. The results showed the highest body weight in H5 at commercial stage. The white muscle transverse area and the white fibres hyperplasia and density also showed the highest values in H5, followed by H2.5. In contrast, the highest hypertrophy was observed in C and R2.5, being associated with the lowest muscle growth in both groups. These results showed a microalgae concentration-dependent effect in hydrolyzed diets as well as an advantageous effect of the hydrolyzed versus raw diets on the long-term growth of Sparus aurata., This research has been funded throughout the research projects of MINECO-FEDER (grant #RTI2018-096625-B-C33 and grant #RTI2018-096625-B-C31), and AquaTech4Feed (grant #PCI2020-112204) granted by AEI within the ERA-NET BioBlue COFUND.

[EN] Acquiring immunocompetence is essential in the development of fish embryos, as they are exposed to environmental pathogens even before they are fertilized. Despite the importance of the antimicrobial function as the first line of defense against foreign microorganisms, little knowledge is available about its role in larval development. In vertebrates, transgenerational immune priming influences the acquisition of immunocompetence of specimens, regulating the selective allocation of nongenetic resources to their progeny and modulating their development. In this work, we primed teleost European sea bass broodstock females with a viral protein expression vector in order to evaluate the innate immunity development of their offspring. Several antimicrobial functions, the pattern of expression of gene coding for different antimicrobial peptides (AMPs), and their protein levels, were evaluated in eggs and larvae during development. Our data determined the presence of antimicrobial proteins of maternal origin in eggs, and that female vaccination increases antimicrobial activities and the transcription and synthesis of AMPs during larval development., This work was supported by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe” or by the “European Union” [grants AGL2013-43588-P, AGL2016-74866-C3-1-R, PID2021-122287OB-C22 and PID2019-105522GB-I00], Fundación Séneca, Grupo de Excelencia de la Región de Murcia [grant 19883/GERM/15], the ThinkInAzul programme “plan complementario de I+D+I en ciencias marinas” through Next Generation European Funds, Instituto Español de Oceanografía [grant: NODAMED] and the National Commission for Scientific & Technological Research, Chile [grant FONDECYT N° 1191763]. Y.V.’s contracts were funded by a PhD grant from the Instituto Español de Oceanografía (IEO-CSIC) and a grant from the Banco Santander funding program, Becas Iberoamérica Santander Investigación.