Dose-dependent hepatic transcriptional responses in Atlantic salmon (Salmo salar) exposed to sublethal doses of gamma radiation

To study the short term (48 h) hepatic transcriptional changes and identify potential modes of action, Atlantic salmon (Salmo salar) were exposed to 15 mGy, 70 mGy and 280 mGy external gamma radiation. A combination of high density (60 k) custom oligonucleotide salmonid microarray and quantitative real-time reverse transcription polymerase chain reaction (qPCR) was employed to perform gene expression analyses. Differentially expressed genes (DEGs) were determined using one-way analysis of variance (ANOVA) and Tukey posthoc tests. Functional enrichment analysis based on Gene Ontology (GO) was performed to link DEGs to their biological functions. The Salmo salar DEGs were further mapped to mammlian orthologs. By using ortholog DEGs, gene networks were built based on well-curated mammlian protein-protein interactions and pathways analyses were performed to link DEGs to specific toxicological/biological functions. The results obtained from microarray analysis were further verified using qPCR. Juvenile Atlantic salmon were exposed to external gamma radiation emitted from a cobalt-60 source for 48 h. Liver were sampled and used for gene expression analysis.