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Reference : UMR7057-CARPHI-012
Workplace : PARIS 13
Date of publication : Thursday, June 3, 2021
Type of Contract : FTC Scientist
Contract Period : 12 months
Expected date of employment : 1 September 2021
Proportion of work : Full time
Remuneration : between 2728 and 3881 euros gross per month depending on experience
Desired level of education : 5-year university degree
Experience required : 1 to 4 years
The hydrostatic pressure in a cell surrounded by a cell-wall (plant, bacteria or fungi) is coined turgor pressure; it results from an inward osmotic flow. Turgor pressure plays a twofold role for plant cell-wall both putting it under tension and positively regulating its growth. The classic cell enlargement representation emerging from these studies is a cell wall metabolic loosening, followed by turgor-driven extension. Though turgor pressure is isotropic; cell growth is often anisotropic, intriguingly this growth anisotropy is strongly correlated with elastic strain anisotropy. For instance, cylindrical cells, growing axially, are elastically stiffer radially than longitudinaly; reinforcing microfibrils wounded around the cell play a major role to determine the anisotropy. In some cases, a slight inclination respective to the internode axis of the wounded microfibrils is associated to a spiralling movement of opposite chirality.
Infering growth from turgor pressure and cell-wall anisotropy is one of the great challenge for both theoretical and experimental plant mechanobiology: on the theoretical side deciding which is the right description of how turgor regulates cell-wall growth and on the experimental side providing clean data combining pressure measurements, elastic strain anisotropy and growth kinematic to help selecting these models. We aim to simultaneously tackle the experimental and theoretical challenges: developping numerical models as well as tractable experimental models for simutaneously control turgor, measure elastic and growth strains fields in single cells and primitive tissue constituted by few cells.
The successful candidate will be in charge of the non-modeling part of the project: controling internal turgor while monitoring growth strains of vegetal isolated cells and primitive tissue. She/he will be hosted in the Matière et Systèmes Complexe Laboratory (CNRS UMR 7057 and Paris University, Paris). She/he will be in constant interactions with modelers (physicist).
A plant physiologist or an experimental biophysicist interested by plant growth with a taste for interdisciplinarity. A preliminary training in pressure probe or patch clamp will be appreciated but is not mandatory.
The team, which associates Etienne Couturier and Julien Derr, has recently developed experimental setups to precisely monitor the growth kinematic of vegetal organs from the leaf scale to the characean internode scale, and theoretical tools to reverse engineer mechanical properties of cell- walled cells. The postdoc will also interact with other members of the lab: specialists of small force measurements (A. Asnacios, F. Heslot) and microinjection techniques for microscopy (N. Perieyras) as well as with the Mechanobiology Group of PIAF-Clermont-Ferrand ( B. Moulia, F. Hartmann).
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