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- Cutting-Edge methods in Teleost and Chondrichthyan reproductive biologyPublication . Mechaly, Alejandro S.; Awruch, Cynthia; Cabrita, Elsa; Costas, Benjamín; Fernandes, Jorge M.O.; Gallego, Victor; Hirt-Chabbert, Jorge; Konstantinidis, Ioannis ; Oliveira, Catarina; Ramos Júdez, Sandra; Ramos-Pinto, Lourenço ; Fatsini Fernández, ElviraReproduction is a fundamental biological process for producing offspring and ensuring the continuation of the species. With nearly 35,000 fish species worldwide exhibiting a very diverse range of reproductive systems and strategies, the study of fish reproduction is a significant challenge. Research into various fish reproductive models is driven by their use in human biomedical applications, improving the diversification and sustainability of aquaculture species, and developing strategies for biodiversity conservation. These models must be approached from an animal ethics perspective, considering the welfare of the species under study and applying the 3Rs principle (Replacement, Reduction and Refinement). This principle focusses on replacing animals with alternative methods wherever possible, reducing the number of animals used and refining procedures to minimize suffering. While destructive sampling of wild aquatic species should be minimized, the need remains to provide information on reproduction as an important parameter for delineating management and conservation programs. One of the practices that helps reduce and replace the use of animal testing is the scientific study of individuals obtained through bycatch. This is the case for some chondrichthyans, and endangered fish species included in conservation programs. Regarding fish species that are kept under human care (commonly called captivity), studies on reproduction are essential to improve well-being and increase production of farmed species. Research on fish reproduction requires expanding basic knowledge of broodstock management tools, such as gamete quality assessment, reproductive behavior studies, the use of hormone therapies to stimulate reproduction, and the development of non-lethal or less invasive methods using body fluids (e.g., mucus, seminal plasma, blood plasma, or urine) to study reproductive status, as well as novel markers from state-of-the-art omics research. This review describes a multidisciplinary approach that includes the aforementioned reproductive management tools, indicators of welfare, and next-generation sequencing techniques using samples collected by minimally invasive methods.
- The use of egg quality parameters to evaluate the effect of a diet supplemented with algae and antioxidants in turbot (Scophthalmus maximus)Publication . Ramos Júdez, Sandra; Fatsini Fernández, Elvira; Marrero Alemán, Carlos; García-Pichel, Candela; Parente, Pedro; Medina, D.; Castro, C.; Cabrita, Elsa; Oliveira, CatarinaEnhancing egg quality can be achieved by improving breeders’ diet through the antioxidant content, as oxidative stress could adversely affect egg quality. Micro- and macroalgae species are natural sources of antioxidants and other essential nutrients that can be incorporated in fish feeds. In this study the quality of Scophthalmus maximus eggs were compared between breeders fed a commercial (non-supplemented) diet and those fed a diet enriched with 5 % Arthrospira platensis and 1 % of the iodine-rich Laminaria digitata, further fortified with antioxidants (astaxanthin, vit. C and E) (supplemented diet). Several egg parameters were evaluated. Hierarchical clustering of all the egg batches grouped them into two main categories: higher (≥ 50 % buoyancy) and lower-quality eggs (≤ 30 % buoyancy). The expression of transcripts related to egg quality (ctsz, ccna2), oxidative response (nrf2, cat), and apoptosis (bax, casp3a) was also measured in batches categorized by quality, as well as in higher-quality batches from females fed the commercial versus supplemented diet. Eggs of higher quality (greater buoyancy), regardless of females’ diet, had significantly higher total antioxidant status (TAS) levels (P < 0.05), suggesting TAS as an egg quality marker. The expression of ccna2 was upregulated, while ctsz showed almost no expression in higher-quality eggs but was down-regulated in lower-quality eggs, highlighting their potential as markers of egg quality in turbot. Higher-quality eggs from females fed the supplemented diet exhibited higher TAS, lower superoxide dismutase activity, and an upregulation of nrf2 compared to higher-quality eggs from non supplemented females. This suggests a more efficient cellular mechanism to restore oxidative homeostasis. Supplementing the diet increased the likelihood of achieving ≥80 % buoyant eggs and overall cumulative egg production, contributing to more effective and sustainable turbot farming.