Our lab has chosen to investigate a new molecular animal model, the marine annelid Platynereis dumerilii. Genomic resources and molecular techniques have been generated that make it a model marine invertebrate for ocean biology and for organismal systems biology. Platynereis is amenable to high-throughput imaging techniques and functional interference approaches (first genetic knock-out lines have been generated).
With the recent development of the PrImR (Profiling by Image Registration) resource, it is the first animal model for which gene expression profiling data can be obtained in cellular resolution for the whole organism. We have discovered that the Platynereis’ brain harbours sensory-associative brain parts and a neurosecretory brain centre that correspond to the vertebrate pallium and hypothalamus respectively – findings that revolutionise our understanding of brain evolution.
The clear picture is emerging that the Platynereis brain harbours many cell types so far known only for the vertebrates, but in a much more simple and different overall arrangement. To broaden our comparative approach, we study two other model species (amphioxus and Nematostella), representing distinct divisions of the animal kingdom: chordates and cnidarians. Amphioxus has a very simple brain uniting invertebrate- and vertebrate-like features.
The Nematostella nervous system is very simple and thus represents a good proxy for a very early stage of nervous system evolution. We are also exploring population genetics and the variability of development and differention in different habitats by using strains of Platynereis and amphioxus collected during the Tara Oceans expedition.
The scientific activities of the Tara Oceans expedition, led by EMBL senior scientist Eric Karsenti, present an unprecedented effort that resulted in 35,000 samples containing millions of small organism collected in more than 210 ocean stations, chosen for their climatic significance or biodiversity.