Chemical manipulation of dental patterning in Malawi cichlids
Bloomquist, Ryan F.
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A dynamic model for odontogenesis is lacking. Cichlids serve as superior organisms for studies in tooth development because of diversity in tooth shape, size, number, number of rows, all of which undergo continuous replacement, as well as the possession of a second set of toothed jaws, within the posterior pharynx. Through in situ hybridization we have characterized basic patterns of odontogenesis in cichlids that are conserved throughout vertebrates. We have used the teratogens cyclopamine and SU5402 to reduce the function of Shh and Fgf protein, respectively with a time and dose dependence. Cyclopamine trials indicate that Shh is necessary to pattern the dentition and that its expression in the first tooth is essential, as is its interaction with tooth spacing genes in the initiation of a periodic pattern mechanism. Members of the Fgf family are required for proper replacement cycles, possibly through stem cell interactions.