GENETIC-ANALYSIS OF FIN FORMATION IN THE ZEBRAFISH, DANIO-RERIO

In the zebrafish, Danio rerio, a caudal and pectoral fin fold develop during embryogenesis. At larval stages the caudal fin fold is replaced by four different fins, the unpaired anal, dorsal and tail fins. In a ddition the paired pelvic fins are formed, We have identified a total of 118 mutations affecting larval fin formation, Mutations in 11 genes lead to abnormal morphology or degeneration of both caudal and pector al fin folds, Most mutants survive to adulthood and form a surprisingl y normal complement of adult fins, Mutations in nine genes result in a n increased or reduced size of the pectoral fins, Interestingly, in mu tants of one of these genes, dackel (dak), pectoral fin buds form init ially, but later the fin epithelium fails to expand, Expression of son ic hedgehog mRNA in the posterior mesenchyme of the pectoral fin bud i s initiated in dak embryos, but not maintained, Mutations in five othe r genes affect adult fin but not larval fin development, Two mutants, longfin (lof) and another longfin (alf) have generally longer fins. St ein und bein (sub) has reduced dorsal and pelvic fins, whereas finless (fls) and wanda (wan) mutants affect all adult fins, Finally, mutatio ns in four genes causing defects in embryonic skin formation will be b riefly reported.