Figure 1.—

Variegated expression of UAS-regulated GFP in zebrafish larvae. (A) Representative larva carrying unique insertions of the gene/enhancer trap vector designated by c numbers. For a given insertion, sibling F₂ larvae express gfp either in a pattern similar to the F₁ generation (GFP^high, left panels) or in a smaller subset of cells within this pattern (GFP^low, right panels). Larvae were imaged at 3 dpf. (B) Fluorescent labeling of the forebrain, midbrain, and hindbrain (r5–6, arrowhead) of c269 GFP^high larvae at 2 dpf. (C) GFP^low c269 sibling larvae show significantly fewer GFP-labeled cells, which are restricted to within the c269 GFP^high pattern of expression. (D) Corresponding images of GFP (top) and mCherry (bottom) fluorescence in c269 GFP^high, GFP^low, and GFP^off larvae carrying a newly integrated UAS:mCherry transgene at 2 dpf. Irrespective of the extent of GFP expression, mCherry labeling recapitulates the complete c269 GFP^high expression pattern.