Microarray-predicted marker genes and molecular pathways indicating combined crowding and thermal stress in rainbow trout (Oncorhynchus mykiss)

Stress represents a major factor negatively affecting fish welfare in aquaculture. The objective of the present study was to identify and evaluate informative indicators for the welfare of rainbow trout Oncorhynchus mykiss exposed to (A) a critical water temperature of 27 °C and (B) acute crowding of 100 kg/m3 combined with water temperature of 27 °C. In order to make an approximate assessment of the overall condition, we determined health index, spleen-somatic index and haematocrit and recorded the blood concentrations of haemoglobin, cortisol and glucose of rainbow trout under challenging versus control conditions. Moreover, we analysed the transcriptomic profiles of the spleen of the two stress-treatment and the reference groups to identify gene sets, which are specific for temperature stress alone or combined temperature and crowding stress. Please see a diagram of treatments in the file Overall_design_diagram.pdf available at the foot of this record. Spleen transcriptomes from reference fish at 16C, fish given temperature stress at 27C and fish given temperature and crowding stress and 27C.