A 2 months internship proposal by the DEEVA team.
Generating molecular markers for developmental studies in the ascidian Clavelina lepadiformis.
Ascidians are marine invertebrates that belong to the vertebrate sister group. This diverse group of 3,000 species is characterized by a conserved, fast and stereotyped embryonic development with very few cells. By contrast, their genomes are highly divergent with a fast rate of evolution and extensive rearrangements. Since ascidians are good models for functional genomics they offer an excellent opportunity to probe the diversification of developmental mechanisms 1.
We have studied the gene regulatory network that controls peripheral nervous system formation in the ascidian Ciona intestinalis; and have started to probe the modifications that have occurred in other species 2–4. Our team, being located at the marine station of Banyuls-sur-mer, benefits from the access to a variety of ascidian species that cover the different ascidian families. We have developed the embryological methods, transcriptomic and genomic resources for several species 5,6.
Clavelina lepadiformis is an iconic local species that belongs to Aplosoubranchia, one of the 3 orders of ascidians that includes only colonial species and whose embryonic development has been poorly studied. The student will combine molecular biology and embryology to participate in a pioneering work aiming at establishing Clavelina as a tractable model organism for molecular embryology by generating markers. The student will thus determine, by in situ hybridization, the expression patterns of developmental regulators during the embryogenesis of Clavelina.
1. Lemaire, P. Evolutionary crossroads in developmental biology: the tunicates. Development 138, 2143–52 (2011).
2. Pasini, A. et al. Formation of the Ascidian Epidermal Sensory Neurons: Insights into the Origin of the Chordate Peripheral Nervous System. PLoS Biol 4, e225 (2006).
3. Coulcher, J. F. et al. Conservation of peripheral nervous system formation mechanisms in divergent ascidian embryos. eLife 9, e59157 (2020).
4. Chowdhury, R. et al. Highly distinct genetic programs for peripheral nervous system formation in chordates. BMC Biol 20, 1–25 (2022).
5. Darras, S. En masse DNA Electroporation for in vivo Transcriptional Assay in Ascidian Embryos. Bio-protocol 11, e4160 (2021).
6. Daric, V., Lanoizelet, M., Mayeur, H., Leblond, C. & Darras, S. Genomic Resources and Annotations for a Colonial Ascidian, the Light-Bulb Sea Squirt Clavelina lepadiformis. Genome Biology and Evolution 16, evae038 (2024).
