A toolbox to study epidermal cell types in zebrafish.

Epithelia provide a crucial protective barrier for our organs and are also the sites where the majority of carcinomas form. Most studies on epithelia and carcinomas use cell culture or organisms where high-resolution live imaging is inaccessible without invasive techniques. Here, we introduce the developing zebrafish epidermis as an excellent in vivo model system for studying a living epithelium. We developed tools to fluorescently tag specific epithelial cell types and express genes in a mosaic fashion using five Gal4 lines identified from an enhancer trap screen. When crossed to a variety of UAS effector lines, we can now track, ablate or monitor single cells at sub-cellular resolution. Using photo-cleavable morpholino oligonucleotides that target gal4, we can also express genes in a mosaic fashion at specific times during development. Together, this system provides an excellent in vivo alternative to tissue culture cells, without the intrinsic concerns of culture conditions or transformation, and enables the investigation of distinct cell types within living epithelial tissues.