Fig. 3

Low temperature shifts the timing of formation of the cardiac cone.

(A) Lateral views of 22-ss wild-type (WT) and s1pr2^as10 mutant embryos raised at 28.5 or 22.5°C. (B) Time-lapse analyses of the medial migration of bilateral cardiomyocytes during the ~17–30-ss in Tg(cmlc2:EGFP, cmlc2:H2AFZmCherry)^cy13 transgenic fish (WT) or s1pr2^as10 mutant embryos raised at 28.5 or 22.5°C. Five WT or s1pr2^as10 mutant embryos were analyzed for each stage. The images outlined in red indicate the stage at which cardiac cone formation took place under each condition. (C) In situ hybridization of 19-ss wild-type (WT) or 26-ss s1pr2^as10 mutant embryos raised at 28.5°C or 22.5°C with a cmlc2 RNA probe. The number of embryos displaying cmlc2 staining/the total number of embryos analyzed is shown for each panel. (D) Different degrees of myocardial migration defects were observed in gata5 and bon morphants at 24 hpf. Class I (single heart tube), Class II (cardiomyocytes in close proximity but not in contact), and Class III (two separate hearts) defects are shown. (E) Percentages of each class of myocardial migration defects in 10 ng gata5-MO or bon-MO-injected embryos raised at 28.5 or 22.5°C. Scale bar = 100 μm. Statistical significance was determined using Student’s t-test. * indicates p<0.05.