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Almeida, Maria Mafalda

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  • 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.
  • 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.