Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive Stages

Melanosis, or melanized focal changes (MFCs), is a significant issue in the Atlantic salmon (<i>Salmo salar</i>) farming industry, causing economic losses due to fillet downgrading. Nevertheless, molecular mechanisms underlying melanosis remain poorly understood, particularly in Chilean...

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Main Authors: Raúl Cortés, Cristián A. Valenzuela, Andrés Johnson, Ariel Valenzuela, Juan Antonio Valdés, Sebastián Escobar-Aguirre
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Fishes
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Online Access:https://www.mdpi.com/2410-3888/10/7/302
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author Raúl Cortés
Cristián A. Valenzuela
Andrés Johnson
Ariel Valenzuela
Juan Antonio Valdés
Sebastián Escobar-Aguirre
author_facet Raúl Cortés
Cristián A. Valenzuela
Andrés Johnson
Ariel Valenzuela
Juan Antonio Valdés
Sebastián Escobar-Aguirre
author_sort Raúl Cortés
collection DOAJ
description Melanosis, or melanized focal changes (MFCs), is a significant issue in the Atlantic salmon (<i>Salmo salar</i>) 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 (<i>mitf</i>, <i>tyr</i>, and <i>dct</i>) and immune markers (<i>arg2</i>, <i>inos2</i>, and <i>il-1β</i>). Results revealed significant transcriptional modulation in freshwater samples, including downregulation of <i>mitf,</i> upregulation of <i>dct</i>, and changes in immune-related genes (<i>arg2</i> and <i>inos2</i>). In contrast, seawater (“Harvest”) samples showed significant upregulation of <i>tyr</i> and <i>dct</i>, 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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spelling doaj-art-89548cdfec964bad8d3d162993d3609a2025-08-20T03:08:05ZengMDPI AGFishes2410-38882025-06-0110730210.3390/fishes10070302Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive StagesRaúl Cortés0Cristián A. Valenzuela1Andrés Johnson2Ariel Valenzuela3Juan Antonio Valdés4Sebastián Escobar-Aguirre5Laboratorio Biología Molecular Marina, Facultad de Agronomía y Sistemas Naturales, Pontificia Universidad Católica de Chile, Santiago 7820436, ChileGrupo de Marcadores Inmunológicos, Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso 2374631, ChileLaboratorio Biología Molecular Marina, Facultad de Agronomía y Sistemas Naturales, Pontificia Universidad Católica de Chile, Santiago 7820436, ChileLaboratorio de Piscicultura y Patología Acuática, Departamento Oceanografía, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción 4070386, ChileLaboratorio de Biotecnología Molecular, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago 8370035, ChileLaboratorio Biología Molecular Marina, Facultad de Agronomía y Sistemas Naturales, Pontificia Universidad Católica de Chile, Santiago 7820436, ChileMelanosis, or melanized focal changes (MFCs), is a significant issue in the Atlantic salmon (<i>Salmo salar</i>) 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 (<i>mitf</i>, <i>tyr</i>, and <i>dct</i>) and immune markers (<i>arg2</i>, <i>inos2</i>, and <i>il-1β</i>). Results revealed significant transcriptional modulation in freshwater samples, including downregulation of <i>mitf,</i> upregulation of <i>dct</i>, and changes in immune-related genes (<i>arg2</i> and <i>inos2</i>). In contrast, seawater (“Harvest”) samples showed significant upregulation of <i>tyr</i> and <i>dct</i>, 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.https://www.mdpi.com/2410-3888/10/7/302melanosistranscriptional regulationAtlantic salmonChilefreshwater and seawater stage
spellingShingle Raúl Cortés
Cristián A. Valenzuela
Andrés Johnson
Ariel Valenzuela
Juan Antonio Valdés
Sebastián Escobar-Aguirre
Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive Stages
Fishes
melanosis
transcriptional regulation
Atlantic salmon
Chile
freshwater and seawater stage
title Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive Stages
title_full Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive Stages
title_fullStr Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive Stages
title_full_unstemmed Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive Stages
title_short Expression Conditions of Melanogenic Enzymes and Immune Molecular Markers in Atlantic Salmon Muscle During Different Productive Stages
title_sort expression conditions of melanogenic enzymes and immune molecular markers in atlantic salmon muscle during different productive stages
topic melanosis
transcriptional regulation
Atlantic salmon
Chile
freshwater and seawater stage
url https://www.mdpi.com/2410-3888/10/7/302
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