Title: The coenocytic cycle of Sphaeroforma and the origins of animal development
Abstract: All animals evolved from a unicellular ancestor; however, the nature of this ancestor and the critical innovations that led to the emergence of multicellular animals remains unknown. Intriguingly, multiple lineages of the most closely related unicellular organisms already contain homologs of important animal developmental genes, and exhibit simple multicellular-like life cycles. Among these close unicellular relatives are ichthyosporeans, a lineage of unicellular protisis that form multinucleate cells (coenocytes). Due to its simple and tractable life cycle, which consists of synchronized coenocytic cycles followed by cellularization, an ichthyosporean Sphaeroforma arctica has emerged as a powerful model to address the relationship between the ichthyosporean life cycle and animal development. In this talk, I will present the description of the Sphaeroforma coenocytic cycle. I will show that during this life cycle, nuclear divisions are synchronized and occur in a clock like manner that is decoupled from the size of the cell. Furthermore, I will describe the transcriptional regulation of this coenocytic cycle, and show that the cellularization of the multinucleate cell generates a self-organized multicellular structure.
Andrej Ondracka is part of the Multicellgenome Lab