Takashi Mikawa — Professor, University of California San Francisco School of Medicine Cardiovascular Research Institute 

Research summary: Developmental regulation of organogenesis

Title: An apoptosis-mediated barrier at the midline patterns ipsilateral gastrulation in the amniote.

Abstract: Bilaterality is a major body plan in metazoan phyla. Cells either of the left or right side of bilaterians rarely cross the midline body plane throughout life as evidenced by a naturally occurring mutation, condition of Gynandroph. It has been a longstanding mystery how this evolutionally conserved ipsicaterlaity in the Bilaterians. We show that a caspase-3 dependent programmed death plays a crucial role for the ipsilaterlarity in the amniotes. Using the developing chick embryo as a model, we found that cell death along the midline of the primitive streak, a conduit of amniote gastrulation, prevents contralateral cellular ingression. Suppression  of Caspase-3 removes the midline cell death program and allows gastrulation cells to ingress into the contralateral side of the body. These results highlight an active role of cell death to establish a barrier  that underlie the morphogenetic organization of patterning in avians.

Host: Julie Kuhlman