Meeting Abstract
Embryonic organizers are signaling centers that coordinate developmental events within an embryo. Localized to either an individual cell or group of cells, embryonic organizing activity induces the specification of other cells in the embryo and can influence formation of the body axes. In the spiralian Capitella teleta, previous cell deletion studies have shown that organizing activity is localized to a single cell, 2d, and this cell induces the formation of the dorsal-ventral and left-right axes. In this study, we attempt to identify the signaling pathway responsible for the organizing activity of 2d. Embryos at stages when organizing activity is occurring were exposed to various small molecule inhibitors, raised to larval stages, and scored for axial anomalies analogous. Our results show that interference with the TGF beta signaling pathway through a short 3 hour exposure to the inhibitor SB431542 results in larvae that lack bilateral symmetry and a detectable dorsal-ventral axis. However, interference with the BMP signaling pathway through exposure to the inhibitor dorsomorphin dihydrochloride does not initially appear to play a role in 2d’s specification of the dorsal-ventral or the left-right axe¬is. These results differ from a recent report that in the gastropod Ilyanassa, a member of a sister clade to Capitella, BMP signaling is crucial for dorsal-ventral axis patterning. These and further investigations will shed light on the identity of the 2d signaling pathway involved with Capitella axes formation, and contribute to our understanding of how changes in developmental programs lead to evolution of body plans.
