Evolution and Development of Metazoans

Group leader


We compare the genetic networks that regulate the developmental patterning of key aspects of the body plan across metazoans, in order to reconstruct the early stages of animal evolution. Our main model is the marine segmented worm Platynereis dumerilii. This annelid species is easily reared in the lab and amenable to most molecular genetic investigation techniques, including transgenesis. This is also a great model for live imaging.

Our main research axes:

  • Was the last common ancestor of bilaterian animals (Urbilateria) a segmented animal?
    We investigate the mechanisms responsible for segment formation in Platynereis. Some genes, such as engrailed, wingless or hedgehog play a similar role in Platynereis as in insects. We are investigating further the roles of the Wnt/β-catenin and Notch signalling pathways
  • What was the architecture of the nervous system like in Urbilateria?
    Striking similarities are found at the genetic level between the formation of nervous systems in vertebrates and Platynereis. By elucidating the mechanisms of nervous system patterning in an annelid, we hope we will be able to bridge the gap between protostomes and deuterostomes, to reconstitute ancestral characteristics and eventually to understand the origin of the complex nervous systems of vertebrates.
  • Did Urbilateria possess a blood circulatory system?
    Like most annelids, Platynereis has a closed vascular system. Oxygen is carried from gills to organs by haemoglobin dissolved in the blood. Blood flow is created by the local contractions of vessels. Do these similarities with the blood system of vertebrates indicate a common evolutionary origin? We are investigating the genes that pattern blood vessels and specify the hemogenic cells (that produce the blood haemoglobin).

This team is part of the Labex “Who am I?”

Keywords : Evolution, embryogenesis, segmentation, annelid, nervous system, vascular system, Platynereis, trochophore, teloblast, Evo-Devo, embryo imaging.

Selected Publications 

Özpolat BD, Handberg-Thorsager M, Vervoort M, Balavoine G. (2017) Cell lineage and cell cycling analyses of the 4d micromere using live imaging in the marine annelid Platynereis dumerilii. Elife. 6. pii: e30463.

Gazave E, Lemaitre Q, Balavoine G. (2017) The Notch pathway in the annelid Platynereis: Insights into chaetogenesis and neurogenesis processes. Open Biology, 7(2). pii: 160242.

Gazave E, Béhague J, Laplane L, Guillou A, Préau L, Demilly A, Balavoine G, Vervoort M. (2013) Posterior elongation in the annelid Platynereis dumerilii involves stem cells molecularly related to primordial germ cells. Dev Biol.382:246-67.

Janssen R, Le Gouar M, Pechmann M, Poulin F, Bolognesi R, Schwager EE, Hopfen C, Colbourne JK, Budd GE, Brown SJ, Prpic NM, Kosiol C, Vervoort M, Damen WG, Balavoine G & McGregor AP (2010) Conservation, loss, and redeployment of Wnt ligands in protostomes: implications for understanding the evolution of segment formation. BMC Evol Biol. 10, 374.

Dray N, Tessmar-Raible K, Le Gouar M, Vibert L, Christodoulou F, Schipany K, Guillou A, Zantke J, Snyman H, Béhague J, Vervoort M, Arendt D & Balavoine G. (2010) Hedgehog signaling regulates segment formation in the annelid Platynereis. Science329, 339-342.

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