Fig. 2

CreERT2 driver transgenes have predictable and consistent activity in pIGLET14a and pIGLET24b. Comparison of CreERT2-mediated recombination of Tol2-based drl:creERT2 and pIGLET-based lines p14a.drl:creERT2 and p24b.drl:creERT2 by crossing to the loxP reporter hsp70l:Switch and performing a 4-OHT induction series. Transgene and crossing schematics on top, lateral confocal views and anterior to the left. (A and B) Compared to the Tol2-based drl:creERT2 transgenic line, p14a.drl:creERT2 and p24b.drl:creERT2 show accurate lineage contribution dynamics at 56 hpf when treated with 4-OHT at shield stage and 12 ss (A and B). Note that with shield stage 4-OHT induction, drl-expressing cells contributed both to the LPM lineages (heart, pectoral fin, endothelial cells, kidney, mesothelia, blood, pharyngeal arch musculature, and macrophages) and a subset of paraxial mesoderm lineages (median fin fibroblasts and skeletal muscle). With 12 ss 4-OHT induction, LPM lineages are specifically traced with more mosaic labeling of heart, pectoral fin, and kidneys (A and B). Consistent with our p14a.drl:EGFP reporter lines, some neuronal lineage labeling is observed with p14a.drl:creERT2 when induced with 4-OHT at shield stage (yellow asterisk) (B). F2 heterozygous embryos are depicted (B). Scale bar, 200 ?m.