Mitigation solutions for the reproductive disorder of Senegalese sole cultivation – MITIGASOLE

Funder

Organizational Unit

Publications

The use of sand substrate modulates dominance behaviour and brain gene expression in a Flatfish Species

Publication . Almeida, Maria Mafalda; Cabrita, Elsa; Fatsini, Elvira

Physical complexity adds physical enrichment to rearing conditions. This enrichment promotes fish welfare and reduces detrimental characteristics that fish develop in captivity. Senegalese sole (Solea senegalensis) is an important species for European aquaculture, where it is reared in intensive conditions using fibreglass tanks. However, reproductive dysfunctions present in this species do not allow it to complete its life cycle in captivity. Recently, dominance behaviour has been studied to try to solve this problem. The present study aimed to assess the effect of sand as environmental enrichment in the dominance behaviour and brain mRNA abundance of Senegalese sole juveniles. Four tanks of sole (n = 48 fish in total) were established in two different environments (with and without sand). Juveniles were subjected to dominance tests of feeding and territoriality. Behaviours analysed by video recordings related to the distance from the food delivered and harassment behaviour towards other individuals (e.g., resting of the head on another individual). In both environments, dominant sole were the first to feed, displayed more head-resting behaviour and dominated the area close to the feeding point, where the events were reduced in fish maintained in the sand. mRNA expression related to differentiation of dopamine neurons (nr4a2) and regulation of maturation (fshra) were significantly upregulated in dominant fish in the sand environment compared to dominants maintained without sand. The use of an enriched environment may affect Senegalese sole dominance, enhance welfare and possibly advance future maturation.

2023-03-08Journal article

Open access

Testis transcriptomic analyses reveal the effects of an algae feed on sperm quality in senegalese sole during the breeding season

Publication . Félix de Azeredo Pinto e Melo, Francisca; Raposo de Magalhães, Cláudia; Marrero Alemán, Carlos; Duarte, Daniel Filipe Correia; Parente, Pedro; Fatsini Fernández, Elvira; Oliveira, Catarina; Cabrita, Elsa

The usage of dietary algae antioxidants to improve fish reproduction is under-explored, especially in terms of the male reproductive system. In this experiment, 6 % of a blended meal of Phaeodactylum tricornutum and Gracilaria gracilis was incorporated in Senegalese sole broodstock feed, to evaluate the effects on sperm quality of F1 males throughout the breeding season. For that, two groups of breeders were fed during 6 months with the control and algae diets (6 % of control wheat meal replaced with 6 % algae blend). Every 2 weeks, fish were sampled for sperm quality evaluation, which included spermatozoa motility (CASA system), lipid peroxidation (MDA quantification), cell viability, reactive oxygen species (ROS), apoptotic status (flow cytometer), and DNA fragmentation (Comet assay). On a final sampling, 6 fish per group were sacrificed to dissect gonadal tissue, extract RNA and perform an RNA sequencing (RNA-seq) for each treatment. Sperm quality variability was high during the breeding season, including within the same month, irrespective of the diet. Cell viability was approximately 80 % during the whole experiment. Nonetheless, in specific sampling points, algae-fed fish showed higher spermatozoa protection against oxidative processes: in the 1st sampling live cells without ROS (%) were 3 times higher than in control group; on the last two samplings, spermatozoa showed half of MDA content; and on the 3rd sampling had less DNA fragmentation. No differences were found regarding apoptotic status. At the end of the reproductive season, gonadal transcriptomic analysis revealed that algae-fed fish were lacking stimuli for sperm production, both in terms of quantity and quality. This fish group seemed to have lipid metabolism and antioxidant capacity enhanced by the diet but, at the same time, were facing a compensatory mechanism due to an unknown algae compound that might be disrupting DNA replication and spermatogenesis. Altogether, this study suggests that algae blends can be used in broodstock feeds for Senegalese sole, however further research is needed to understand how to use only the desirable bioactive compounds and thus obtain higher and consistent sperm quality throughout the breeding season.

2025-03Journal article

Open access

Cryopreservation did not affect spermatogonia global methylation profile in Senegalese sole (Solea senegalensis)

Publication . Almeida, Maria Mafalda; Cabrita, Elsa; Laizé, Vincent; Brionne, Aurélien; Labbé, Catherine; Fatsini Fernández, Elvira

Spermatogonia cryopreservation is a method to preserve valuable genomes from both maternal and paternal origin. The damage associated with the application of this technology on post-thaw cell quality is important to assess, including at the epigenetic level. This study aimed to assess post-thawed spermatogonia quality by evaluating alterations in plasma membrane integrity, DNA integrity (fragmentation and apoptosis), lipid peroxidation (malondialdehyde levels) and epigenetic modifications (DNA methylation profile). We observed that plasma membrane integrity (fresh 78.98 % f 5.66; cryopreserved 62.81 % f 3.25; P = 0.003) and DNA integrity (fresh 32.95% f 2.28; cryopreserved 37.28% f 1.87; P = 0.0026) were affected by cryopreservation, while no difference in lipid peroxidation was observed (fresh 1.13 % f 0.45; cryopreserved 0.91 % f 0.96; P = 0.701). While global levels of DNA methylation were unaffected by cryopreservation (fresh 82.80 % f 0.47; cryopreserved 83.32 % f 0.81; P = 0.745), some differentially methylated cytosines (DMC) were observed in cryopreserved versus fresh spermatogonia (156 DMC). This study showed that spermatogonia cryopreserved according to our protocol provides a good supply of undamaged cells for several applications. The significance of the few detected DMCs deserves further attention since it may affect gamete differentiation and epigenetic profile.

2025-03Journal article

Restricted access

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, Catarina

Enhancing 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.

2025-05Journal article

Open access