Date of Award


Degree Type


Degree Name

Master of Science




Dr. Thomas Drysdale

Second Advisor

Dr. Sashko Damjanovski

Third Advisor

Dr. Robert Cumming


Cardiac morphogenesis requires coordination of cell morphogenesis but how this coordination is achieved is not well understood. The objective of this study is to elucidate the underlying mechanisms of heart tube formation in Xenopus laevis. I hypothesized that Shroom3, an actin binding protein needed for neural tube closure, is also used in heart tube formation. I demonstrate that Shroom3 is indeed necessary for heart tube formation. Without Shroom3 activity, hearts are shorter and fail to form a proper tube. In the forming heart tube, there is a basal movement of nuclei and cell thickening that requires Shroom activity. The apical actin accumulation and formation of apical microtubule populations, necessary for neural tube closure, are not observed in the myocardium. Therefore, I have identified Shroom3 as the key regulator of morphogenesis in the early heart and that the morphogenetic process is distinct from that seen in the neural tube.



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