Fig. 2
Hepatic transcriptome responses of Atlantic salmon exposed high temperature stress alone, or combined with hypoxia. a Results of Significance Analysis of Microarrays (SAM) with a False Discovery Rate (FDR) of < 5% (see Additional file 1). The top Venn diagram illustrates the total number of differentially expressed probes (DEPs) in salmon exposed to Warm & Normoxic (WN: 20 °C, 100% air saturation) or Warm & Hypoxic (WH: 20 °C, ~ 70% air sat.) conditions as compared to the Control group (CT: 12 °C, 100% air sat.) (n = 6 per treatment, N = 18 total). The bottom Venn diagram shows the corresponding number of DEPs that were up- or down-regulated. The overlapping areas represent shared DEPs between the WN and WH treatment groups. b Hierarchically clustered heat map based on 2894 DEPs (FDR < 5%) using Ward’s minimum variance method. Heatmap and dendrograms illustrate the clustering structure of 2894 SAM-identified DEPs for fish subjected to control conditions (CT), high temperature and normoxia (WN), or high temperature and hypoxia (WH). The integrated colour code shows up-regulated DEPs in red and down-regulated DEPs in blue, and represents normalized log2 ratios. c Principal Component Analysis (PCA) based on all detected 17,072 microarray probes of fish exposed to CT, WN and WH conditions; d PCA based on a common set of 1111 DEPs shared between the WN and WH treatment groups; e PCA based on 789 DEPs in the WN treatment group; f PCA based on 994 DEPs in the WH treatment group. Each PCA plot includes the three different treatment groups (CT, WN and WH), and is based on normalized log2 ratios. Ellipses denote the dispersion of variance with 95% confidence intervals around the the center of the distribution for each treatment group. The variance explained by the main Principal Components (PC-1 and PC-2) are indicated in percentage values next to the axes