Exploring signatures of spatial cell type differentiation in Capsaspora owczarzaki, a close relative of animals

NAJLE, SEBASTIÁN R.; RUIZ-TRILLO, IÑAKI; SEBÁ-PEDRÓS, ARNAU; LINAS MAZUTIS

Roma

Congreso; VIII European Congress of Protistology - ISOP Joint Meeting; 2019

Federation of European Protistological Societies - International Society of Protistologists

Cell differentiation is a fundamental attribute of complex multicellular organisms, underpinning the functional specialization of cells and tissues during embryonic development. It has been proposed that animal multicellularity originated by a transition from temporal to spatial cell differentiation. However, it is not clear whether spatial cell-type differentiation is a consequence of multicellularity or if it was already present in the most recent common ancestor of animals. To elucidate this, we setup single-cell RNA-Seq in the filasterean amoeba Capsaspora owczarzaki, one of the closest unicellular relatives of animals. The temporal differentiation cycle of C. owczarzaki include a stage of aggregative multicellularity. These aggregates, composed from few hundred to tens of thousands of cells, are assumed to be without spatial cell differentiation. However, at the moment there was no molecular evidence proving that all the cells in the aggregates are identical. Preliminary analyses of differential gene expression at single-cell resolution showed an unexpected molecular heterogeneity in the individual cells forming the aggregates. The characterization of these putative cell-types, as well as the molecular mechanisms underlying programs of cell differentiation will allow us to better understand the origin of cell-type differentiation during the evolution of animal multicellularity.