Meeting Abstract

135.5  Monday, Jan. 7  Silurana (Xenopus) tropicalis as a model system for the evolution of odontogenesis GRIECO, TM; University of California, Berkeley grieco@berkeley.edu

The highly conserved developmental mechanisms of odontogenesis illuminate the ways in which vertebrates have created highly adaptive and morphologically variable phenotypes from similar genetic underpinnings. The frog model Silurana (Xenopus) tropicalis, with its expanding genetic and genomic potential along with the large amount of comparative data derived from Xenopus laevis, provides a system to test hypotheses of tooth developmental mechanism function and evolution. I discuss how S. tropicalis lends itself to comparison across vertebrates when used with our extensive knowledge of mouse and fish tooth development, and how comparison between frogs allows us to understand what happens to the conserved mechanisms of odontogenesis when faced with a life history containing a prolonged, specialized larval stage. I use data from histological sections and gene expression during first generation tooth initiation to describe odontogenesis in tadpoles. First-generation teeth appear laterally before they appear medially, but alternation as reported by other researchers has been difficult to visualize in this study population. I consider evidence from these time series as it bears on hypotheses of dental patterning and initiation across vertebrates and within animals with late-developing dentitions.