Pitx2 Patterning During Leucoraja erinacea Spiral Gut Development

Gut chirality, characterized by the twists and turns found within intestines, is formed through signals that arise during early embryogenesis. Errors in gut chirality increase the risk of volvulus, which can lead to bowel necrosis due to ischemia. 1 in 500 live births present with midgut volvulus, which is fatal if not treated. The highly conserved paired-like homeobox transcription factor Pitx2 is one of the initiating factors of chiral development, as it has been shown to condense the left side of the dorsal mesentery, initiating the first leftward tilt. The Chondrichthye L. erinacea has a spiral valve intestine exemplifying extreme organ chirality. I predict Pitx2 plays a role in forming the spiral during L. erinacea development. I cloned two regions of the  the L. erinacea Pitx2 gene, both had 90% nucleotide sequence identity, and 99% protein identity to Pitx2 genes of other animals. In situ hybridizations will be performed with RNA probes to observe where Pitx2 is active in the embryonic spiral valve. Visualizing the localization of Pitx2 during spiral formation will further elucidate the transcription factor’s role during chiral development. Uncovering the mechanism of how chirality is formed during embryogenesis will help illuminate the causes of chirality defects, and how to prevent such potentially fatal malformations.