Viability of dietary substitution of live microalgae with dry Ulva rigida in broodstock conditioning of the Pacific oyster (Crassostrea gigas)

The current study evaluated the microalgae replacement by dry macroalgae (Ulva rigida) in the reproductive success and biochemical composition of the Pacific oyster (Crassostrea gigas) during broodstock conditioning. Five nutritional regimes were tested: 100% macroalgae (diet 1), 50% macroalgae+50% microalgae (diet 2), 25% macroalgae+75% microalgae (diet 3) and 100% microalgae (diet 4). An unfed group was used as a negative control. The microalgae blend was composed of 33% Isochrysis galbana and 67% diatoms (75% Skeletonema costatum+25% Chaetoceros calcitrans). Gonadal maturation was reflected in the physiological condition of the individuals. All treatments, except diet 1, showed an increase in condition index and were fully matured at the end of the trial, with the best physiological condition observed in oysters fed diet 3 and diet 4. Protein and total lipid content increased during the conditioning period, whereas glycogen content decreased. Oysters conditioned with diet 3 had higher protein and total lipid content and lower glycogen content than the other treatments. In addition, diet 3 showed the highest percentage of viable veliger larvae. The current study demonstrated that it is possible to replace 25% of microalgae with macroalgae in the broodstock conditioning, minimizing the operative cost in bivalve hatcheries. © 2018. Published by The Company of BiologistsThis work was supported by Project INNOVMAR-Innovation and Sustainability in the Management and Exploitation of Marine Resources [NORTE-01-0145-FEDER-000035] within the line ‘INSEAFOOD, Innovation and valorization of seafood products’, funded by the Northern Regional Operational Programme (NORTE2020) through the European Regional Development Fund. Postdoctoral fellowships were granted to authors T.G.T. [SFRH/BPD/89360/2012] and to author A.C.G. [ref. SFRH/ BPD/72777/2010], by Fundaçaõ para a Ciência e a Tecnologia (Portugal), under the auspices of ESF and Portuguese funds. Z.E.M. is grateful to the project [UID/QUI/ 50006/2013-POCI/01/0145/FEDER/007265] with support from Fundaçaõ para a Ciência e a Tecnologia/MEC through national funds and co-financed by European Regional Development Fund, under the Partnership Agreement PT2020. This work was partially supported by POCI-01-0145-FEDER-006939 [Laboratory for Process Engineering, Environment, Biotechnology and Energy—UID/EQU/00511/2013], funded by the European Regional Development Fund, through COMPETE2020— Programa Operacional Competitividade e Internacionalizaçaõ and by national funds via Fundaçaõ para a Ciência e a Tecnologia, through project NORTE-01-0145-FEDER-000005—LEPABE-2-ECO-INNOVATION, supported by NORTE 2020, under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund

Expression of LC-PUFA metabolism genes in juvenile tambaqui (Colossoma macropomum) fed different dietary lipid source and levels

Trabajo presentado en el 3rd AquaImprove Aquaculture Research Workshop, celebrado en Oporto Portugal, el 18 de diciembre de 2018Fish oil (FO) is an important aquaculture fish feed ingredient, but its limited natural supply has fostered the search for new lipid sources. The current study evaluated the capacity of tambaqui (Colossoma macropomum), one of the most produced fish species in Brazil, to biosynthesize long-chain polyunsaturated fatty acids (LC-PUFA) from dietary plant oil sources. To the best of our knowledge, little information is available about the effects of dietary vegetable oil (VO) levels on hepatic lipid metabolism in tambaqui. The current study evaluated the effects of different dietary lipid source and levels on the gene expression of key enzymes involved in LC-PUFA metabolism in juvenile tambaqui. Fish (IBW: 8.61 ± 1.38g) were fed for 9 weeks with four diets (FO5%, FO10%, VO5% and VO10%) and the gene expression of fads2, elovl5 and elovl2 were carried out in liver and brain tissues. The expression of fads2 and elovl5 in liver were upregulated when the fish were fed by the VO diets. It is plausible to infer that fish fed VO diet have more LA (18:2n–6) and LNA (18:3n–3) available for LC-PUFA biosynthesis. In addition, brain fads2 and elovl2 expression was up-regulated, with the higher activity of elovl2 in the brain suggesting its important role in the biosynthesis of docosahexaenoic acid (DHA). In conclusion, the elongation and desaturation of C18 substrates are active processes for the production of LC-PUFA in tambaqui, when it is fed with a VO source in replacement of FO, showing that the tambaqui has the innate ability to biosynthesize LC-PUFA from C18 VO, thus satisfying its lipid essentiality for normal growth and developmentPeer reviewe

Protective effects of seaweed supplemented diet on antioxidant and immune responses in European seabass (Dicentrarchus labrax) subjected to bacterial infection

European seabass (Dicentrarchus labrax) production is often hampered by bacterial infections such as photobacteriosis caused by Photobacterium damselae subsp. piscicida (Phdp). Since diet can impact fish immunity, this work investigated the effect of dietary supplementation of 5% Gracilaria sp. aqueous extract (GRA) on seabass antioxidant capacity and resistance against Phdp. After infection, mortality was delayed in fish fed GRA, which also revealed increased lysozyme activity levels, as well as decreased lipid peroxidation, suggesting higher antioxidant capacity than in fish fed a control diet. Dietary GRA induced a down-regulation of hepatic stress-responsive heat shock proteins (grp-78, grp-170, grp-94, grp-75), while bacterial infection caused a down-regulation in antioxidant genes (prdx4 and mn-sod). Diet and infection interaction down-regulated the transcription levels of genes associated with oxidative stress response (prdx5 and gpx4) in liver. In head-kidney, GRA led to an up-regulation of genes associated with inflammation (il34, ccr9, cd33) and a down-regulation of genes related to cytokine signalling (mif, il1b, defb, a2m, myd88). Additionally, bacterial infection up-regulated immunoglobulins production (IgMs) and down-regulated the transcription of the antimicrobial peptide leap2 in head kidney. Overall, we found that GRA supplementation modulated seabass resistance to Phdp infection.This study is part of M.J. Peixoto PhD thesis. This work has received funding from the European Union’s Horizon 2020 research and innovation program under the TNA programme (project ID AE040085) within AQUAEXCEL2020 project (652831) to RF, LJM and ROAO for accessing to IATS-CSIC facilities

Physiopathological responses of sole (Solea senegalensis) subjected to bacterial infection and handling stress after probiotic treatment with autochthonous bacteria

This study aimed to evaluate the protective effects of four autochthonous bacteria isolated from juvenile sole (Solea senegalensis) intestine as dietary probiotic supplement against bacterial pathogen infection and handling/transport stressors. Growth performance and immune responses were evaluated after 85 days of feeding trial. Sole (IBW=16.07 ± 0.11 g) were fed six experimental diets, a control diet (CTRL, without the dietary probiotic supplementation), and five diets supplemented with probiotic bacteria: PB1 (Shewanella hafniensis), PB2 (Enterococcus raffinosus), PB3 (Shewanella hafniensis + Arthrobacter soli), PB4 (Pseudomonas protegens + Arthrobacter soli) and PB5 (Shewanella hafniensis + Arthrobacter soli + Enterococcus raffinosus). All bacteria were selected based on their in vitro antimicrobial activity. After the growth trial, fish were submitted to a stress factor (transport) and then each dietary group was divided in two additional groups: non-infected (placebo) and infected with Photobacterium damselae subsp. piscicida. Immune and antioxidant responses were evaluated at day 10 post-infection. In infection trial A, fish were infected on the same day of transport, whereas in trial B fish were infected after a 7-day recovery from the transport stress. At the end of the feeding trial, fish fed with PB2 and PB4 showed lower final body weight when compared with the other dietary groups. Respiratory burst activity and nitric oxide production were not affected by probiotic supplementation. Fish fed with PB5 presented lower peroxidase activity compared to CTRL. Lysozyme and alternative complement pathway activity (ACH50) showed no significant differences between treatments. The innate immune responses were significantly affected after handling stress and bacterial infection. In trial A, the ACH50 levels of infected fish were significantly lower than the placebo groups. On the other hand, in trial B fish infected with Pdp demonstrated higher ACH50 levels when compared to placebos. Peroxidase levels were strongly modulated by bacterial infection and handling stress. In trials A and B, infection had a clear downgrade effect in peroxidase levels. Lipid peroxidation, catalase, glutathione S-transferase and glutathione reductase were altered by both bacterial infection and transport. Overall, dietary probiotic supplementation did not influence growth performance of sole. The immune and oxidative defenses of sole responded differently to infection depending on the probiotic and the synergy between pathogen infection and transport.info:eu-repo/semantics/publishedVersio

Regulation of gene expression associated with LC-PUFA metabolism in juvenile tambaqui (Colossoma macropomum) fed different dietary oil sources

Given the ecological unsustainability of using fish oil (FO) as the main source of long-chain polyunsaturated fatty acids (LC-PUFA), the investigation of alternative dietary LC-PUFA sources is crucial for aquaculture. Tambaqui (Colossoma macropomum) is a valuable economic aquaculture resource in Brazil, capable of endogenously elongating and desaturating linoleic (LA; 18:2n-6) and α-linolenic (ALA; 18:3n-3) acids to longer and physiologically vital LC-PUFA. Yet, it is unclear how this pathway is regulated by different oil sources in tambaqui. Thus, we designed an experiment with 2 different oil diets (fish oil—FO and vegetable oil—VO) at 2 different concentrations (5% or 10%) to investigate the molecular regulation of fatty acid biosynthesis in this species. We observed no differences in survival, body weight gain (BWG) and feed conversion ratio between the treatments. Gene expression analysis shows that fads2 and elovl5 are up-regulated in liver, while fads2 and elovl2 are up-regulated in brain of tambaqui fed with VO. The transcription factors pparβb and pparγ are also up-regulated in the brain by VO diet, when compared to FO diet. The VO diet also contributed to the biosynthesis of LC-PUFA in liver and specifically DHA in the brain. Overall, our approach shows that lipid metabolism-relevant genes are regulated by different dietary lipid sources.This study was supported by CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico – Brazil and by COMPETE 2020, Portugal 2020, by the European Union through the ERDF, grant number 031342, by FCT through national funds (PTDC/ CTA-AMB/31342/2017)

Elongases from fatty acids of amazon fish tambaqui (Colossoma macropomum)

Trabajo presentado en la International Conference on Aquaculture & Marine Biology, celebrada en Roma (Italia) del 25 al 27 de junio de 2018Peer reviewe