THE AEQUOREA-VICTORIA GREEN FLUORESCENT PROTEIN CAN BE USED AS A REPORTER IN LIVE ZEBRAFISH EMBRYOS

The green fluorescent protein (GFP) from the cnidarian Aequorea victor ia is capable of producing fluorescence without an exogenously added s ubstrate. Here we demonstrate that a cDNA for GFP driven by a Xenopus elongation factor 1 alpha enhancer-promoter can confer fluorescence up on live zebrafish embryos, either as an injected plasmid or as a trans gene after passage through the germline. When injected into zebrafish embryos at the one-cell stage, this construct starts to express detect able GEP after about 4 hr of development at 28 degrees C, about 1 hr a fter the midblastula transition fluorescence can be observed in cells of many tissue types in the embryo for at least 3 weeks after injectio n. We used three different expression constructs, each employing a mod ified ef1 alpha enhancer-promoter, to generate 12 transgenic lines. Ei ght of the 12 lines, including 5 of 5 derived from one construct with an intron, express detectable fluorescence in the F1 and, where tested , in the F2 generation. Most expressing lines showed very similar expr ession patterns. Generally, fluorescence is not seen in the transgenic embryos before 20 hr postfertilization, at which point it appears uni formly throughout the embryo. fluorescence is most visible between 24- 36 hr, and it becomes less visible after this, except that in many lin es strong fluorescence remains visible in the eye for at least 5 days. A single inherited copy of the transgene is sufficient to produce det ectable fluorescence in hemizygous F1 and F2 embryos. (C) 1995 Academi c Press, Inc.