Browsing by Author "Valdés, Juan Antonio"

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    Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive Stages
    (2025) Cortés, Raúl; Cristián A. Valenzuela; Johnson, Andrés; Valenzuela, Ariel; Valdés, Juan Antonio; Escobar Aguirre, Sebastian Gonzalo
    Melanosis, or melanized focal changes (MFCs), is a significant issue in the Atlantic salmon (Salmo salar) farming industry, causing economic losses due to fillet downgrading. Nevertheless, molecular mechanisms underlying melanosis remain poorly understood, particularly in Chilean aquaculture. This study aimed to characterize transcriptional regulation associated with melanogenesis and inflammation in salmon muscle tissues exhibiting melanosis. Samples were collected from fish at three productive stages, all with MFCs in muscle in common: freshwater at two different origins and accumulated thermal units “ATUs” (300 ATUs post-antibiotic overdose, “Security”; 600 ATUs post-vaccination, “Vaccination”) and seawater harvest (“Harvest”). Gene expression analysis by qPCR targeted melanogenesis-related genes (mitf, tyr, and dct) and immune markers (arg2, inos2, and il-1β). Results revealed significant transcriptional modulation in freshwater samples, including downregulation of mitf, upregulation of dct, and changes in immune-related genes (arg2 and inos2). In contrast, seawater (“Harvest”) samples showed significant upregulation of tyr and dct, but no significant immune gene modulation. These findings indicate distinct molecular responses depending on the MFCs’ development stage, emphasizing early stages as critical points for intervention. Unlike recent studies, which have predominantly focused on samples from the harvest stage, this work uniquely integrates results from both the freshwater phase and the harvest stage.
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    High temperature induces oxidative damage, immune modulation, and atrophy in the gills and skeletal muscle of the teleost fish black cusk-eel (Genypterus maculatus)
    (2025) Becerra, Sofía; Arriagada-Solimano M.; Escobar Aguirre, Sebastián Gonzalo; Palomino, Jaime; Aedo, Jorge; Estrada, Juan Manuel; Barra Valdebenito, Verónica; Zuloaga, Rodrigo; Valdés, Juan Antonio; Dettleff, Phillip
    The high temperature associated with heat waves is a relevant abiotic factor that could impact the biology of teleost fish. The innate immune response, muscular growth, and oxidative stress status are relevant functions in fish tissues that could be affected by increased temperature. In this study, black cusk-eel (Genypterus maculatus) juveniles were subjected to increased temperature, to experimentally replicate heat waves registered from the South Pacific Ocean for five days. The results showed that thermal stress modulated the immune response in gills, with up-regulation of antibacterial peptides, pro-inflammatory cytokines, and Toll-like receptors genes, including hepcidin, gzma, tnfa, cxcl8, and tlr5, with no effect on complement system genes. In skeletal muscle, high temperature triggered atrophy-related gene expression, with up-regulation of foxo1, foxo3, fbxo32, murf1, and atg16l. Increased temperature also generated an up-regulation of transcripts encoding heat shock protein (hsp60 and hsp70) in gills and skeletal muscle, generating oxidative stress in both tissues, with increased expression of the antioxidant genes sod1 and gpx1 in gills and skeletal muscle, respectively, with oxidative damage observed at the DNA level (AP sites), protein (carbonyl content), and lipoperoxidation (HNE content) in both tissues. The present study shows that short-term increases in temperature like those observed in heat waves could affect the immune response in gills, induced atrophy in skeletal muscle, and generate oxidative stress in a teleost species important for Chilean aquaculture diversification, information relevant under the context of climate change scenario.