Meeting Abstract
During development, bilaterian organisms are patterned along the left-right axis. While the TGFβ-family member, Nodal, is thought to play a highly conserved role in this process, the impact of other signaling mechanisms on this process is poorly characterized. To better understand what other signaling pathways contribute to asymmetric organogenesis, we employ the tunicate Ciona intestinalis. We have found that the Ciona heart and gut-tube are positioned on the right side of developing juveniles. Asymmetric positioning of these organs is first observed during larval stages. Intriguingly, we show that while nodal signaling is crucial for proper gut asymmetry, it is dispensable for heart asymmetry in larva. Through inhibitor experiments, we have found that H+/K+-ATPase dependent ion flux is necessary for proper heart and gut positioning in both larvae and juveniles. Based on our findings, we hypothesize a model where ion flux and ciliary flow act through a feed-forward mechanism to direct heart and gut asymmetries. These results provide the groundwork for future studies pinpointing the mechanisms underlying left-right patterning in vertebrates.
