Overview of pME-BrainbowTEC and application in developing zebrafish spinal cord.

(A) Schematic of pME-BrainbowTEC. (B) No recombination, loxP recombination or lox2272 recombination lead to distinct fluorophore expression. (C) Schematic of LR recombination reaction used to create UAS:BrainbowTEC. (D) Possible fluorophore combinations and resulting observed color from three copy expression of UAS:BrainbowTEC. (E) Experimental design for UAS:BrainbowTEC labeling of motoneurons in developing zebrafish spinal cords. Fish carrying multiple copies of UAS:BrainbowTEC were crossed with a dual inducible-Cre and motoneuron-specific GAL4 driver line (mnx1:GAL4; hsp70l:Cre). Embryos were heat-shocked at 7 hours post fertilization (hpf) to induce Cre expression for lox recombination of genomic UAS:BrainbowTEC copies, then imaged at 48 hpf. (F) Representative fluorescent confocal microscope image for GFP, tdTomato, and E2Crimson in 48 hpf zebrafish embryo showing neuronal cell bodies in the spinal cord and motor axons within several adjacent somites. Inset shows neuronal cell bodies in the spinal cord.