Meeting Abstract

P1.4  Jan. 4  The role of hedgehog signaling during craniofacial development in larval zebrafish. O’QUIN, C.T.*; GROSS, J.S.; HERNANDEZ, L.P.; George Washington University, Washington, DC ctoquin@gwu.edu

Hedgehog signaling has been shown to play an important role in the proper growth and development of a number of embryonic tissues. Indeed, the role of hedgehog signaling during embryonic development has been examined in a number of model species, however its role later in larval development has not been as extensively studied. We have examined the effect of disabling the Hedgehog (hh)-signaling pathway on the development of the viscerocranium in the zebrafish, Danio rerio. We hypothesized that hh-signaling is extremely important in the proper growth and development of the viscerocranium. Zebrafish embryos and larvae were treated with Cyclopamine (CyA) a pharmacological agent that blocks hh-signaling. Different treatment times (36 hours post fertilization [hpf], 48 hpf, 60 hpf, 72 hpf, 96 hpf) were used to determine the effects of disabling hh signaling at different points in development. Our results indicate that when embryos were treated at the earlier time points (36hpf, 48hpf), the CyA-treated zebrafish did not develop all branchial cartilages suggesting that hh-signaling is necessary for branchial arch differentiation. Our results also showed a significant lack of growth in the mandible and branchial arches as compared with wild-type zebrafish at later treatment times. These findings suggest that the hh-pathway is not only important in branchial arch differentiation, but is also important for the growth of the mandible and branchial cartilages. Surprisingly, blocking the hh-pathway did not have a significant effect on the growth of the hyoid. These findings suggest that a different genetic pathway likely controls hyoid growth.