Fig. 1

In adult zebrafish, stress stimulates cortisol secretion and activates GCR signalling. (a) Adult zebrafish were exposed to different stressors. (b) Whole-body cortisol levels are shown as a dot plot. Each dot represents the value obtained for one fish. The dash indicates the mean value of each group (N e 10 fish; ***p < 0.001). H.S., heat shock; Caf, caffeine, Crow, crowding. (c) Live heart dissected from Tg(GCRE::EGFP) fish display GFP in the ventricle. (d,d2) Immunofluorescence analysis of Tg(GCRE::EGFP) heart section demonstrates a colocalization between tropomyosin and GFP. However, this transgenic reporter is not ubiquitously expressed in adult tissues. (e,f) Fluorescent images of the same transgenic animal Tg(GCRE::EGFP) reveal an enhanced glucocorticoid receptor (GCR) transcriptional activity in the whole body at 8 days after 1 h of daily crowding, as compared to the state before stress. (e2,f2) Converted images of the GFP signal into a grey scale using Image J software for quantification of fluorescence. (g) Graph showing the mean converted fluorescence values obtained for three different fish before and after the period with daily acute stress exposure. **p < 0.01. Scale bars: (c) 1 mm, (d) 100 µm and (e) 10 mm.