ABS 044: Investigating the Role of Endoderm Contractility in Avian Foregut and Heart Tube Morphogenesis

Emily Garcia ¹ , Olivia Powell ² , Nandan Nerurkar ²

¹ Neuroscience & Behavior, Barnard College, New York, NY
² Biomedical Engineering, Columbia University, New York, NY

Van Wickle (2025) Volume 1, ABS044

Introduction: The process by which the early embryo becomes a fully functional organism with many interconnected networks of organs and tissues is called morphogenesis [1]. Following gastrulation, during which the endoderm, mesoderm, and ectoderm ingress from the epiblast, the foregut is formed from the posterior movement of the head fold [2]. Simultaneously, the precardiac cells in the underlying mesoderm fold bilaterally towards the midline of the embryo and fuse to create the heart tube [3]. Literature suggests that both processes of foregut formation and heart tube formation are interconnected and influence each other. The aim of this study is to further investigate the relationship between foregut elongation and heart tube fusion. Through studying the effect of DeAct-SpvB, an enzyme that induces the disassembly of actin, on the endoderm of chick embryos at various stages, we found that heart tube morphogenesis requires endoderm actomyosin contractility until stage HH9. Our findings provide new insights into the intertissue coordination that drives early heart tube development.

Methods: Fertilized eggs were incubated for 33 hours at 37 ℃ before embryos were transferred onto paper rings to maintain structural tension, following methods adapted from Chapman et al. (2001). Electroporation was employed to introduce DNA or mRNA into endodermal cells, enabling targeted genetic manipulation. Protein localization was visualized using immunostaining, which involved tagging specific proteins with fluorescently labeled antibodies, as described in Khlefa et al. (2023).

Discussion: The data suggests that embryos require endodermal actin for heart tube fusion prior to HH stage 9+. Embryos electroporated with DeAct prior to the onset of heart fusion developed improperly looped heart tubes (n=6), or lacked heart tubes entirely (n=7).

Results: Ongoing efforts aim to electroporate the precardiac mesoderm with DeAct to investigate the specific role of mesodermal contractility in heart tube and foregut morphogenesis.