FP7-PEOPLE-2012-IEF PEMDEEV-GAN 329024

The objective of PEMDEEV is to investigate endomesoderm development in the priapulid species Priapulus caudatus in unprecedented detail. I will generate a thorough fate map during cleavage in P. caudatus, which will allow me to identify single blastomeres and trace forward their lineage into the final body plan of the embryo. With this, I will understand how the endomesoderm is formed and how it is related to the primary embryonic axis. I will achieve this objective by using 3D-time lapse microscopy (4D-microscopy) and cell tracking of single blastomeres by microinjection of fluorescent dyes. Next, I will focus on the molecular specification and differentiation of the cells giving rise to the endomesoderm in P. caudatus. I will identify evolutionary conserved genes involved in endomesoderm development using preliminary data of the ongoing genome-sequencing project. I will then apply recently established molecular methods by the host research group, such as antibody labeling, wholemount in situ hybridization in embryos and drug treatments, to characterize the expression and function of these genes during priapulid development. I will also set up novel experimental techniques, such as morpholino and siRNA microinjection, to generate loss/gain of function embryos, which will unequivocally determine the role of each particular gene in development. The results derived from PEMDEEV will shed light into the emergence of the ecdysozoan body plan and the diversification of the endomesoderm in metazoans. The implementation of PEMDEEV will result in the characterization of the fate map of P. caudatus and the cellular mechanisms that form the endomesoderm in this conservatively evolving ecdysozoan. These outcomes will help to reconstruct the evolution of early developmental modes and cell types in ecdysozoans and bilaterians. The proposed project will also define the role of developmental pathways and gene regulatory.