Meeting Abstract
P1.69 Monday, Jan. 4 Disruption of hedgehog signaling during different developmental stages in zebrafish reveals discrete cranial features potentially affected by regulation of hedgehog during evolution ESTEVA-SANDERS, A*; HERNANDEZ, LP; George Washington University; George Washington University aees001@gwmail.gwu.edu
Hedgehog signaling has been shown to play an important role in proper craniofacial development. While the role of this signaling pathway in early embryonic development in zebrafish has been well documented, its role in later larval development has not been as well investigated. We have examined the role of Hedgehog (hh)-signaling on the development of the neurocranium and viscerocranium in the zebrafish. Cyclopamine, a pharmacological agent known to block all hh signaling, was administered to embryonic and larval zebrafish. Different treatment times (12 hours post fertilization [hpf], 24, 36, 48, 60, and 72 hpf) were used to determine the role of hh signaling during different developmental time points. When embryos were treated at the earlier time points (12, 24hpf), the treated zebrafish did not develop branchial cartilages suggesting that hh-signaling is necessary for branchial arch differentiation. Later treatment times showed reduced growth of all pharyngeal cartilages as compared with controls. Moreover, experiments with later treatment times revealed that structures that had developed normally prior to treatment with cyclopamine were not maintained once hh signaling was blocked. These findings suggest that the hh-pathway is not only important in differentiation of branchial arches, it is also important for the growth and maintenance of the pharyngeal cartilages. Surprisingly, growth of the second pharyngeal cartilage, the hyoid, did not show significantly reduced growth. These findings suggest that a different genetic pathway may control hyoid growth. The potential role of hh signaling in the regulation of cranial shape and size during the course of evolution will be discussed.
