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- Epigenetics in aquaculture - the last frontierPublication . Granada, Luana; Lemos, Marco; Cabral, Henrique; Bossier, Peter; Novais, SaraAquaculture production is expanding rapidly around the world. To tackle rising production and species diversity issues, innovations in the field of aquaculture feeds, breeding, disease management and other improvements must be addressed. In this framework, the study of epigenetic mechanisms behind different aquaculture rearing processes presents great opportunities. The transcriptional impact of epigenetic modifications, triggered by environmental stimuli, has been shown to influence the organism’s phenotype. Therefore, understanding the environmental-induced epigenetic markers related to disease resistance or other economically important traits will allow the establishment of favourable breeding conditions with increased economical revenue. Several studies have shown epigenetic effects in various species, induced by different rearing conditions, with benefits for the organisms and evidences for heritability of the acquired adaptive phenotypic traits across generations, making these studies even more relevant in a production context. These studies have demonstrated the great potential of epigenetics to positively induce disease resistance, stress tolerance and attain better sex ratios in the aquatic organism. Also, in the field of nutritional epigenetics, the possibility of early nutritional programming to improve the performance of broodstock or even the long-term performance of their progeny has been suggested. In sum, an increased understanding of epigenetic mechanisms in economically important species, and the epigenetic markers leading to the most favourable phenotypic traits, will contribute to the expansion of economically viable commercial aquaculture industries. The major epigenetic mechanisms and respective analysis methods, as well as the state of the art and potential applications in aquaculture, are addressed in this review.
- Effect of three diets on the growth and fatty acid profile of the common ragworm Hediste diversicolor (O.F. Müller, 1776)Publication . Santos, António; Granada, Luana; Baptista, Teresa; Anjos, Catarina; Simões, Tiago; Tecelão, Carla; Fidalgo E Costa, Pedro; Costa, José Lino; Pombo, AnaThe polychaete Hediste diversicolor has a high physiological tolerance to extreme environmental factors, being easily farmed and reproduced in different types of conditions. Both in the field and under laboratory conditions, this worm can feed on different types of food. In order to highlight the potential of H. diversicolor for aquaculture, specific growth rate (SGR), daily growth rate (DGR), survival rate and fatty acid profile of juvenile worms, fed with three different diets, were assessed. The experiments were conducted using juvenile polychaete from a controlled reproduction with wild adults. H. diversicolor individuals were fed with two commercial diets, seabream dry feed (Aquagold) and semi-wet pellets for reared sole (Moist Sole), and with a non-processed diet consisting on mackerel's fillets (Trachurus trachurus). Juveniles fed with Aquagold had the highest final individual weight (0.89 ± 0.10 g). The SGR was higher in H. diversicolor fed with Aquagold and Moist Sole, (6.49 ± 0.30% d−1 and 6.54 ± 0.06% d−1, respectively. The highest DGR was observed for juveniles fed with Aquagold (0.146 ± 0.02 g d−1). The survival rate of ragworms under different treatments ranged from 96 to 100%. Regarding the protein content, the Moist Sole diet provided the highest percentage of protein in the reared worms (8.87%). Results showed that the total fat content of the diets was reflected in the fat content of the reared worms. The Moist Sole diet treatment had the highest fat content (2.25%) and individuals fed with seabream dry feed showed similar results (2.18%), while the lowest percentage was observed for the mackerel diet (0.85%). According to the fatty acid profile, the major fatty acids found in the juveniles fed with the three different diets were palmitic (C 16:0), with a higher value in the individuals fed with mackerel's fillets. Oleic (C 18:1 n9), eicosapentaenoic (C 20:5 n3), docosahexaenoic (C 22:6 n3) and stearic (C 18:0) acids presented high values in H. diversicolor fed with all the experimental diets. Statement of Relevance: The common ragworm Hediste diversicolor is a potential high quality fatty acids source for reared fish and shrimp. Previous studies suggested that diet could be a relevant factor affecting the fatty acid composition of this polychaete (Luis and Passos, 1995). This study aimed to assess the effect of different diets on growth and survival of common ragworms juveniles (H. diversicolor), as well as the fatty acid profile and protein content in their tissues, aiming to find an appropriate diet to be used in commercial aquaculture.
- Differences in mechanisms of stress tolerance induction between strains of monogonont rotifer Brachionus sp.Publication . Granada, Luana; Fonseca, Vanessa; Bossier, Peter; Novais, SaraAquaculture production is an important food source for human consumption worldwide, benefiting from methodologies that enable the development of advantageous phenotypic traits and, consequently, the reduction of biological and economic losses. Organisms exposed to environmental stimuli at early life stages can undergo molecular responses associated to increased tolerance to abiotic and biotic stressors. Rotifer Brachionus sp. has been crucial for the development of sustainable aquaculture practices, since it is used as first live food for several species’ larvae, allowing a stable production of aquatic seedling. Moreover, it has been used as model organism in several research fields, due to characteristics such as short life cycle and ease of handling. For these reasons, two strains of B. koreanus were used in this thesis to understand the potential of heat stress in early stages of development to induce tolerance to several environmental stressors later in life, and to study possible molecular mechanisms involved in this phenotypic alteration. Although genetically and morphologically identical, MRS10 and IBA3 strains showed differences in several life parameters and in tolerance to various stressors. Overall, the non-lethal heat shock (NLHS) conditions determined in this thesis proved to successfully induce tolerance to heat stress, high salinity, hydrogen peroxide, and cadmium chloride in rotifers. Induced thermotolerance was concomitant with up-regulation of several hsp genes and increased production of HSP70, whilst epigenetic alterations showed to have a major role in the development of cross-tolerance mediated by NLHS, with up-regulation of genes related to histone H3 modifications, and increased levels of total acetylation of histone H3. This thesis demonstrated the potential of Brachionus sp. as model organism to study molecular mechanisms underlying induced tolerance, and of NLHS as promising method to improve culture conditions of rotifers, with clear advantages for the aquaculture sector.
- Insight into aquaculture's potential of marine annelid worms and ecological concerns: a reviewPublication . Pombo, Ana; Baptista, Teresa; Granada, Luana; Ferreira, Susana; Gonçalves, Sílvia C.; Anjos, Catarina; Sá, Erica; Chainho, Paula; Cancela Da Fonseca, Luís; Fidalgo E Costa, Pedro; Costa, José LinoPolychaetes are marine annelid worms that can contribute to aquaculture diversification. Its culture has been viable, and commercially attempted, but intensive production has progressed only in few countries around the world. In the countries with no production, marine polychaetes are imported or harvested. A strong and sustained research investment provided to a better understanding of the nutritional requirements and reproduction of some species. Recent studies showed new technical improvements, which can lead to an important progress in productivity and give a new impetus to the polychaete production. Some marine worm species were identified as good candidates for integrated multitrophic aquaculture. The development of cost-effective aquaculture techniques for marine annelid worms is essential to ensure a balance between commercial interests and the preservation of ecosystems. The influence of polychaete aquaculture on the environment and vice versa raise important concerns related to ecological security and sustainability of this activity. This review focus on the main technical improvements and advances that have been made in areas as diverse as: aquaculture potential of polychaetes, reared species, main species used worldwide, and highlights biological and ecological concerns, important challenges and recommendations.