IƱaki Ruiz-Trillo & Elena Casacuberta, Institut de Biologia Evolutiva (CSIC-UPF)

UNICELLULAR HOLOZOANS

Models for Understanding Animal Origins and Cell Biological Questions

The Question(s)

Unicellular holozoans are key taxa to address both evolutionary and cell biological questions. To start with, and given their key phylogenetic position as the closest unicellular relatives to animals, these organisms are crucial to provide clues into the evolutionary origin of many genes, pathways and regulatory mechanisms that later on were essential for animal multicellularity and animal development. In particular, they can provide answers on the specific genetic mechanisms that were responsible for animal origins. Because they have complex genomes and life stages, they are also key to understand some cell biological features, such as cell aggregation, the regulation and deployment of different cell morphologies, or the coenocyte development.
We believe in advancing in several organisms in parallel to be able to perform useful and more fruitful comparative analyses. Thus, we are developing new genetic tools in different taxa to create a functional platform of newly treatable organisms in this part of the eukaryotic tree of life.

The Model

We are developing several model organisms among three different lineages (Filasterea, Ichthyosporea, and Corallochytrea). Specifically, we are working with: 1) Capsaspora owczarzaki, a filasterean amoeba with the capacity to form multicellular structures by cell aggregation; 2) Creolimax fragrantissima, a marine ichthyosporean with a coenocyte development and amoebas; 3) Abeoforma whisleri, a marine ichthyosporean with a complex life cycle that comprises cell stages with different morphologies and behaviours, including a coenocyte; and 4) Corallochytrium limacisporum, a corallochytrean with the capacity to go to either into a clonal or coenocyte development. The genome and transcriptome are available for all of those.