Meeting Abstract

P1.129  Friday, Jan. 4  The zebrafish as a model for the evolution and development of breeding tubercles in fishes RODRIGUEZ, A.M.*; HAWKINS, M.B.; STOCK, D.W.; Univ. of Colorado, Boulder; Harvard University, Cambridge, MA; Univ. of Colorado, Boulder alexandra.rodriguez@Colorado.edu

Breeding tubercles are multicellular, keratinized epidermal projections thought to serve a variety of functions in fishes, including facilitating contact between individuals during spawning, as well as defending nests or territories. They are found in members of four relatively distantly-related orders of fishes, suggesting multiple independent origins. In addition, they frequently differ in size, number, and location among even closely-related species. The development of breeding tubercles has been little studied, and despite their presence in the zebrafish (Danio rerio), they have received virtually no mention in this model system. We have begun characterizing the distribution and development of breeding tubercles in the zebrafish with the goal of identifying the developmental genetic mechanisms involved in their origin and diversification. We found tubercles to be present on pectoral fin rays of males, but not females. Both sexes exhibited tubercles on fleshy pads at the tip of the lower jaw and in rows along each ramus. Additional tubercles on the lower jaw, dorsal surface of the head, and operculum exhibited sexual dimorphism that appeared to differ among strains. The first tubercles to appear during development were in the location of the lower jaw pads before the latter were apparent. In the zebrafish and other members of the genus Danio, these pads are supported by a projection from the dentary bone; we found that this projection appears at virtually the same time as the overlying tubercles. Finally, we have begun examining breeding tubercles in adult-viable mutants and have found to date that ectodysplasin signaling is necessary for their development.