Electronic Thesis and Dissertation Repository


Master of Science


Physiology and Pharmacology

Collaborative Specialization

Developmental Biology


Drysdale, Thomas A.


The transcription factor hand1 is expressed in the heart, lateral plate mesoderm (LPM) and neural crest cells during development. As Hand1-null mice die early in embryogenesis, identification of the precise role of Hand1 in development is difficult. In Xenopus, we observed that hand1 expression patterns correlates very closely with development of LPM derivatives, leading us to hypothesize that hand1 is required for normal LPM development. Using hand1 knockdown and overexpression models in Xenopus, development of LPM derivatives were assessed by whole mount in situ hybridization. I found that hand1 is required for proper heart morphogenesis. Furthermore, hand1 is required for the formation of a complex vasculature plexus within embryos, by maintaining early endothelial cell populations however Hand1 is not sufficient to induce endothelial cell differentiation. These findings confirm a conserved role of Hand1 in heart morphogenesis and suggest a new role for Hand1 in development of the vasculature plexus.