Mots-Clés

interdisciplinary PhD project advanced light sheet imaging of live embryos

Description

VARIABILITY AND ROBUSTNESS          OF ASCIDIAN GASTRULATION

Funded 3-year PhD project

Tunicate lab, CRBM, Montpellier, France.

It is remarkable that embryos develop so reliably in spite of fluctuations in environmental parameters and of genetic variations.  The aim of this interdisciplinary PhD project, funded by an international ANR/NSF research grant, is to quantitatively study the robustness of animal embryonic trajectories to genetic and environmental perturbations.

The project will study embryos of a class of marine invertebrates, the ascidians, whose embryonic cell lineages and early embryonic morphologies have remained essentially identical since the group's emergence about 400 million years ago, suggesting that they are subject to very strong developmental or evolutionary constraints. Ascidian embryonic development is also robust to environmental perturbations of temperature and salinity. Surprisingly, this morphogenetic stability contrasts with the rapid genomic divergence between ascidian species.

The aim of our team, composed of biologists and computer scientists and with strong collaborations with physicists, is to understand the apparent paradox between robust and invariant morphogenesis and rapid genomic divergence. A short video highlights one of our recent works. We focus our analyses on a fundamental morphogenetic process: gastrulation.

This PhD project will seek to identify molecular and physical mechanisms that confer robustness of ascidian gastrulation to environmental, genetic, or geometric perturbations. For this, we will first describe how these perturbations affect the dynamic developmental trajectories of cells and seek to identify developmental checkpoints the embryos need to go through in order to build a functional larva. We will then use covariance analysis between geometric, mechanical and molecular features to identify functional developmental modules contributing to the robustness of ascidian embryogenesis.

These questions will be addressed experimentally by the selected PhD student, using embryological methods and advanced light sheet imaging of live embryos of the ascidian, Phallusia mammillata. The project will be carried out in the framework of a collaboration with the laboratories of Edwin Munro and Madhav Mani in Chicago, USA, and Atef Asnacios in Paris, France.

Candidates are expected to hold a Master degree by September 2022 and be highly motivated to work in an interdisciplinary environment at the crossroads of biology, computer science, applied mathematics and physics. Students coming from the fields of physics or computer science and eager to acquire experimental skills are welcome, as are experimental biologists willing to acquire theoretical and data analysis skills.

Interested young scientists should contact Patrick Lemaire by Email (patrick.lemaire@crbm.cnrs.fr).