DAVIDSON, B. J.; LEVINE, M.; Univ. of California, Berkeley: Chordate CPR: Resuscitating the exploration of chordate heart evolution

The most primitive chordate heart is found in the tunicates. Although rudimentary in structure, the tunicate heart is similar to vertebrate hearts in morphogenesis and embryological origins. Recent research has characterized many of the essential genes which regulate vertebrate heart development. However, attempts to characterize the fundamental interactions between these genes has been difficult as there are multiple copies of each gene, often with overlapping functions. The genome of the tunicate Ciona intestinalis has recently been sequenced. Ciona possesses only one copy of many vertebrate heart regulatory orthologs. Here we present our initial research into heart development in Ciona intestinalis. We are employing modern techniques to revise early 20th century descriptions of the morphogenesis of the ascidian heart. Additionally, we have begun to characterize the expression and regulation of Ciona genes orthologous to key vertebrate heart development genes such as NKX-2.5, GATA4 and d-HAND.