Meeting Abstract

P1.49  Tuesday, Jan. 4  The effects of cyclopamine disruption of the hedgehog pathway on early morphogenesis of musculoskeletal structures of the branchial arches ESTEVA-SANDERS, A*; HERNANDEZ, LP; George Washington University aees001@gwmail.gwu.edu

Hedgehog signaling has been shown to severely affect the normal development of craniofacial features in the zebrafish. While much work has examined the role of hedgehog on the neurocranium and first two arches, less work has examined the role of this pathway on proper development of the branchial arches. Cyclopamine, a pharmacological agent known to block all hedgehog signaling, was administered to embryonic zebrafish. Different treatment times (12, 24, and 36 hours post fertilization [hpf]) were used to determine the role of hedgehog signaling during different developmental time points. Zebrafish were placed in cyclopamine at different developmental stages and allowed to develop until different end points. When embryos were treated at 12 and 24hpf the treated zebrafish never developed branchial cartilages suggesting that hedgehog signaling is necessary for branchial cartilage differentiation. Those treated at 36hpf developed the first branchial arches only. We investigated not only the role of this signaling pathway in very early embryonic development of zebrafish cartilage but also the effect of this missing cartilage on proper pharyngeal muscle development. Specifically we investigated what happens to the developing branchial arch musculature when the branchial cartilages fail to form. We will first present wildtype development of the branchial cartilages and adjacent muscles and then present the effect of hedgehog signaling on this musculoskeletal development. These findings suggest that the hedgehog pathway is not only important in differentiation of branchial arches, but also affects proper development of the adjacent pharyngeal musculature.