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Zusammenfassung:
We are investigating processes shaping and decorating the fish body during juvenile development. The integument of the adult fish develops from embryonic structures derived from the neural crest or epidermal placodes. Scales are formed from dermal bones as well as fins are placodal in origin, while the three types of pigment cells from which the striped color pattern is formed, are derived from the neural crest. Many mutants affecting the adult shape and form have been collected in a large-scale screen for viable phenotypes performed as part of the EU integrated Project ZF Models. We identified the ectodysplasin (EDA) and the Fibroblast growth factor receptor 1 pathway as being required for scale formation. While the EDA pathway is specifically required late during juvenile development, FGFR1 has a vital role also in embryogenesis. We detected a teleost specific gene duplication of the fgfr1 gene. While both paralogs are active in embryonic development, only one copy is required for scale formation explaining the adult viable phenotype. Interestingly, the scaleless breeding form of the common carp, the mirror carp, carries either of two mutant alleles in the fgfr1 locus. Another focus of the laboratory is the formation of the melanophore stripes during juvenile development. This pattern derives from stem cells of neural crest origin and is dependent on pax7, nacre/mitfa, sparse/kit, and pfeffer/fms. As the target for selection during evolution are variations in adult rather than embryonic structures, our approach might serve to identify genes involved in the diversification of species during evolution.
