MUTATIONS AFFECTING PIGMENTATION AND SHAPE OF THE ADULT ZEBRAFISH

Mutations causing a visible phenotype in the adult serve as valuable v isible genetic markers in multicellular genetic model organisms such a s Drosophila melanogaster, Caenorhabditis elegans and Arabidopsis thal iana. In a large scale screen for mutations affecting early developmen t of the zebrafish, we identified a number of mutations that are homoz ygous viable or semiviable. Here we describe viable mutations which pr oduce visible phenotypes in the adult fish. These predominantly affect the fins and pigmentation, but also the eyes and body length of the a dult. A number of dominant mutations caused visible phenotypes in the adult fish, Mutations in three genes, long fin, another long fin and w anda affected fin formation in the adult. Four mutations were found to cause a dominant reduction of the overall body length in the adult. T he adult pigment pattern was found to be changed by dominant mutations in wanda, asterix, obelix, leopard, salz and pfeffer. Among the reces sive mutations producing visible phenotypes in the homozygous adult, a group of mutations that failed to produce melanin was assayed for tyr osinase activity. Mutations in sandy produced embryos that failed to e xpress tyrosinase activity. These are potentially useful for using tyr osinase as a marker for the generation of transgenic lines of zebrafis h.