Extracellular vesicles (EVs) are nanometer-scale lipid bilayer-enveloped spherical vesicles that carry a wide range of bioactive molecules, like proteins, lipids, enzymes, and nucleic acids (RNA and DNA). They are actively released by various cells and can be found in biofluids like urine, blood, saliva, cerebral spinal fluid, and seminal plasma. EVs play a vital role in cell-to-cell communication and various biological processes . Notably, miRNAs contained in EVs are believed to impact the reproductive process in various species, including fish. In the case of Senegalese sole (Solea senegalensis) , a promising aquaculture species, its reproduction cycle is not fully controlled and relies on wild broodstock. Under cultured conditions, the male progeny of wild broodstock often exhibit reproductive behavioural dysfunctions, producing limited and poor-quality sperm or sometimes failing to engage in courtship for egg fertilization .
To overcome these challenges, we have conducted a feeding trial utilizing control diets and diets supplemented with algae to improve their reproductive performance and sperm quality . After 6 months , we collected blood plasma and isolated EVs based on their size (~30-1000 nm), employing size-exclusion chromatography with qEV 70 nm Gen2 single columns from Izon ( Figure 1) . Subsequently, t hese EVs were characterized by measuring their concentration and size using t unable r esistive p ulse s ensing in the Exoid (Izon). Finally , we extracted total RNA from the samples and prepared small RNA libraries to characterize and identify specific miRNAs associated with antioxidant activity that may serve as molecular markers for assessing sperm quality in Senegalese sole.
The findings of this study are expected to have significant implications for enhancing the reproductive success of Senegalese sole in the cultured industry.
Acknowledgement: This work was funded by the BREEDFLAT project (EEA and Norway Grants, ref. PT-INNOVATION-0080).