Molecular responses to toxicological stressors: Profiling microRNAs in wild Atlantic salmon (Salmo salar) exposed to acidic aluminum-rich water

• Published in: Aquatic toxicology Vol. 138-139; pp. 98 - 104
• Main Authors: Kure, Elin H., Sæbø, Mona, Stangeland, Astrid M., Hamfjord, Julian, Hytterød, Sigurd, Heggenes, Jan, Lydersen, Espen
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.08.2013
• Subjects: Acid-aluminum water; aluminum; Aluminum - toxicity; Animals; Atlantic salmon; Base Sequence; bioinformatics; Biomarkers - metabolism; Blood Glucose; blood plasma; Carbon Dioxide - blood; catecholamines; Chlorides - blood; cortisol; Danio rerio; fish; gene expression regulation; Gene Expression Regulation - drug effects; genome; Hematocrit; High throughput sequencing; High-Throughput Nucleotide Sequencing; Hydrogen-Ion Concentration; hypoxia; ions; microRNA; microRNA responses; MicroRNAs - genetics; MicroRNAs - metabolism; Molecular Sequence Data; muscle tissues; Muscle, Skeletal - drug effects; Muscle, Skeletal - metabolism; physiological response; Salmo salar; Salmo salar - genetics; Salmo salar - metabolism; Sodium - blood; Toxicological stress; Water Pollutants, Chemical - toxicity; Atlantic salmon; Acid-aluminum water; High throughput sequencing; Salmo salar; microRNA responses; Toxicological stress
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2013.04.004

•Young Atlantic salmon (Salmo salar) were exposed for 3 days to acidic water (pH≈5.6) with inorganic aluminum (100μgL−1).•Besides loss of plasma ions and hypoxia, significant changes in muscle tissue miRNA expression were documented.•The identified differential expressed miRNAs may have potential as biomarkers in fish.•To get more information on regulatory pathways, the miRNA data need to be aligned to the genome reference of S. salar, when this becomes available. Atlantic salmon (Salmo salar) is among the most sensitive organisms toward acidic, aluminum exposure. Main documented responses to this type of stress are a combination of hypoxia and loss of blood plasma ions. Physiological responses to stress in fish are often grouped into primary, secondary and tertiary responses, where the above mentioned effects are secondary responses, while primary responses include endocrine changes as measurable levels of catecholamines and corticosteroids. In this study we have exposed young (14 months) Atlantic salmon to acid/Al water (pH≈5.6, Ali≈80μgL−1) for 3 days, and obtained clear and consistent decrease of Na+ and Cl− ions, and increases of glucose in blood plasma, hematocrit and PCO2 in blood. We did not measure plasma cortisol (primary response compound), but analyzed effects on microRNA level (miRNA) in muscle tissue, as this may represent initial markers of primary stress responses. miRNAs regulate diverse biological processes, many are evolutionarily conserved, and hundreds have been identified in various animals, although only in a few fish species. We used a novel high-throughput sequencing (RNA-Seq) method to identify miRNAs in Atlantic salmon and specific miRNAs as potential early markers for stress. A total of 18 miRNAs were significantly differentially expressed (FDR<0.1) in exposed compared to control fish, four down-regulated and 14 up-regulated. An unsupervised hierarchical clustering of significant miRNAs revealed two clusters representing exposed and non-exposed individuals. Utilizing the genome of the zebrafish and bioinformatic tools, we identified 224 unique miRNAs in the Atlantic salmon samples sequenced. Additional laboratory studies focusing on function, stress dose-responses and temporal expression of the identified miRNAs will facilitate their use as initial markers for stress responses.