PhD Thesis (M/F) - "Morphogenesis of the sea urchin skeleton microstructure."

Job Description

Thesis Subject

The microstructure of the skeleton built by sea urchins, called stereom, is an impressive example of complexity and self-organization. This structure is a micro-porous meshwork made of calcite, which bears a particular saddle-shape curvature signature which confers it optimal mechanical properties. In the present thesis project we explore the hypothesis that curvature is not only a remarkable emergent feature of the growth process but also a key organising factor in its morphogenesis. In particular, we will investigate how such a curvature-growth interaction may be mediated by the cytoskeleton as suggested by very recent experimental observations. We will use two model systems which are the growth of the juvenile shell plates and the regeneration of adult spines in the sea urchin Paracentrotus lividus. We will monitor the interaction between skeleton and cytoskeleton using confocal microscopy on fixed specimen, and in vivo, in control conditions and under pharmacological treatments perturbing the cytoskeleton organisation. By the use of network and 3D analysis we will quantify the spatial and temporal organisation of the skeleton and the cytoskeleton. This analysis will allow us to produce a database to compare with the predictions of a growth model coupling the geometry of the growing skeleton and the spatial organisation of the cytoskeleton.

Profile and skills :
- Image analysis and computer programming (Python, Fiji)
- Confocal microscopy
- Physical modelling (pde, phase field, linear stability analysis)
- Immunochemistry

Your Work Environment

Work environment :
This is a highly interdisciplinary project at the interface between Physics and Biology. The PhD thesis will be directed by Giulio Facchini at the Matière et Systèmes Complexes (MSC) laboratory in Paris and co-supervised by Jenifer Croce at the Laboratory of Développemental Biology (LBDV) of Villefranche-sur-mer. The candidate will rely on the expertise of G. Facchini with problems of curvature-driven growth, and the characterisation of 3D complex structures in self-organised systems and on the thoughtful knowledge of sea urchin husbandry and development offered by J. Croce.
A considerable part of the PhD thesis will be devoted to experiments, (specimen manipulation, immunochemistry, microscopy) including some that will necessarily take place in LBDV. Conversely, a complementary part devoted to image analysis and modelling will take place mainly in MSC. The candidate will then be working and living at two different locations for several months. The specific working plan will be organised together with the director and the co-supervisor.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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