Fig. 3

Conditional CreER^T2-mediated recombination in Tg(mbpa:mCherry-T2A-CreER^T2) in 5-dpf larvae. A: Schematic representation of treatments applied to achieve conditional CreER^T2-mediated recombination with the temperature-inducible, Cre-dependent reporter line Tg(hsp70l:loxP-DsRed-loxP-EGFP). B: Scheme of the ligand-dependent recombination event in double-transgenic Tg(mbpa:mCherry-T2A-CreER^T2), Tg(hsp70:loxP-DsRed-stop-loxP-EGFP) larvae. Application of TAM results in Tg(hsp70: loxP-EGFP) in mbpa-expressing cells. C: Lateral view of a 7-dpf larva after 4-OHT treatment and heat shock. Recombination is indicated by a switch from red to green fluorescence in cells in the hindbrain and spinal cord. Scale bar, 200 µm. D,E: Higher magnification of the areas indicated by white boxes in C showing EGFP-expressing oligodendrocytes. F: Dorsal view of the hindbrain with EGFP fluorescence in presumptive oligodendrocyte cell bodies (arrowhead) and processes (arrow). Scale bar, 100 µm. G,H: Recombination can also be observed in Schwann cells myelinating the anterior and posterior lateral lines (arrowheads) Scale bar, 200 µm. I: Recombination only ever occurred in larvae treated with 4-OHT and HS, but never in control siblings treated with ethanol and HS. Scale bar, 200 µm. J: Asterisks mark auto fluorescence from yolk and pigmentation. Scale bar, 200 µm.