Browsing by Author "Martins, Dulce Alves"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Alternative sources of n-3 long-chain polyunsaturated fatty acids in marine microalgaePublication . Martins, Dulce Alves; Custodio, Luisa; Barreira, Luísa; Pereira, Hugo; Ben-Hamadou, Radhouan; Varela, João; Abu-Salah, Khalid M.The main source of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) in human nutrition is currently seafood, especially oily fish. Nonetheless, due to cultural or individual preferences, convenience, geographic location, or awareness of risks associated to fatty fish consumption, the intake of fatty fish is far from supplying the recommended dietary levels. The end result observed in most western countries is not only a low supply of n-3 LC-PUFA, but also an unbalance towards the intake of n-6 fatty acids, resulting mostly from the consumption of vegetable oils. Awareness of the benefits of LC-PUFA in human health has led to the use of fish oils as food supplements. However, there is a need to explore alternatives sources of LC-PUFA, especially those of microbial origin. Microalgae species with potential to accumulate lipids in high amounts and to present elevated levels of n-3 LC-PUFA are known in marine phytoplankton. This review focuses on sources of n-3 LC-PUFA, namely eicosapentaenoic and docosahexaenoic acids, in marine microalgae, as alternatives to fish oils. Based on current literature, examples of marketed products and potentially new species for commercial exploitation are presented.
- A balanced dietary amino acid profile improves amino acid retention in post-larval Senegalese sole (Solea senegalensis)Publication . Aragão, C.; Conceição, L. E. C.; Martins, Dulce Alves; Rønnestad, I.; Gomes, E.; Dinis, Maria TeresaThe rearing of most marine fish larvae still relies on live food. Dietary amino acid (AA) imbalances when using live food in the larval rearing of flatfishes have been suggested. The aim of this study was to test if dietary AA supplementation affects AA metabolism in Senegalese sole (Solea senegalensis) post-larvae. This was done by tube-feeding Artemia-fed sole with a dipeptide solution containing two potential limiting AA (leucine and phenylalanine), in order to supplement the larval gut content and to balance the dietary AA profile.
- Cortisol response to air exposure in Solea senegalensis post-larvae is affected by dietary arachidonic acid-to-eicosapentaenoic acid ratioPublication . Martins, Dulce Alves; Engrola, S.; Morais, S.; Bandarra, N.; Coutinho, J.; Yúfera, M.; Conceição, L. E. C.An experiment was conducted in order to evaluate the effects of feeding frozen Artemia diets differing in arachidonic acid-to-eicosapentaenoic acid ratios (ARA/EPA) on growth, survival and stress coping ability of Senegalese sole post-larvae (19–31 days after hatch). Two experimental diets presenting high (‘High’; 3.0) or low (‘Low’; 0.7) ARA/EPA ratios were tested under two rearing conditions: undisturbed (C) and stressed by a 2-min air exposure every two days (S). Growth, survival and basal cortisol levels were similar between groups indicating that independently of dietary ARA/EPA ratios, fish were able to cope with the repeated stress imposed. Also, cortisol levels at 3 h past air exposure were determined in all groups at the end of the experiment. Among fish fed the ‘Low’ diet, Cgroups seemed to present a quicker recovery from the acute stress (basal-like levels) than S groups. Repeated stress effects were not apparent in fish fed the ‘High’ diet and, relative to basal levels, twofold higher cortisol concentrations were detected at 3 h, in both C and S groups. This study suggests the importance of ARA in steroidogenesis regulation and the modulatory role of EPA in this process. Despite the tolerance to a wide range of dietary ARA/EPA as indicated by growth and survival results, acute stress coping response may be more efficient in Senegalese sole post-larvae fed low ARA/EPA ratios and, under these particular conditions, a faster recovery of cortisol to basal values could be indicative of rearing conditions (undisturbed vs. repeatedly stressed).