Description du sujet de thèse

Seed storage proteins play a central role in nutrient storage and are essential for seed development. These proteins undergo several physical transitions to a solid state within the seeds maturation and dehydration. Despite their biological importance, the structures formed by these proteins during development and germination are not well understood, limiting our knowledge of how seeds manage the storage and mobilization of nutrients. The proposed thesis project is part of the ANR MICROSEED project, whose aim is to study the assembly of plant storage proteins using concepts from condensed matter physics combined with microfluidic tools.

The aim of this thesis is to develop microfluidic chips incorporating hydrogel membranes to study protein solutions in nanoliter volumes. These chips will not only enable us to study the phase diagrams of model proteins under physiological conditions (pH, salinity), but also to mimic the dehydration / rehydration of a seed by osmotic compression. These experiments will enable us to probe the equation of state of model proteins, which links osmotic pressure to protein concentration. In parallel, we will seek to couple these microfluidic experiments with various in situ characterizations, such as X-ray scattering at small angles for the structure of protein solutions, or micro-rheology to probe viscosity locally.

Contexte de travail

The LOF “laboratory of the future” is a joint research unit affiliated with the CNRS, the University of Bordeaux and Syensqo (a chemical industry company dedicated to the development of advanced materials and specialty chemicals). LOF's vocation is to develop high-throughput methodologies such as microfluidics and robotics, in conjunction with R&D projects. Located in Pessac, the laboratory is part of a Solvay research and innovation center, and brings together a team of around twenty researchers from both academia and industry. The studies carried out by the LOF candidate will be of a fundamental nature with strong applicative potential, and will be carried out within the framework of an ANR project.

Contraintes et risques

The thesis will be carried out at LOF in Pessac (www.lof.cnrs.fr). Active collaborations are planned with INRAE (Nantes and Rennes) for the protein systems studied, and LGC (Toulouse) for experimental developments in X-ray scattering.