Project title: Sensing mechanical forces during epithelial remodeling in the Placozoan Trichoplax adhaerens.

Type of rotation: Master 1 (2 Months)

Supervisors: Andrea PASINI and Elsa BAZELLIERES

Concept and Objectives

Epithelia are cohesive sheets of apico-basally polarized cells that constitute the most common and evolutionarily most ancient tissues. While the biochemical signals that control epithelial establishment and maintenance have been the object of innumerable studies, the mechanical forces involved in these processes are a more recent field of investigation. Our project aims at laying the foundations for a quantitative study of the mechanical forces involved in epithelial movements and wound healing in a very simple animal, the Placozoan Trichoplax adhaerens. T. adhaerens is a small marine animal basically constituted of an epithelial bilayer and showing very high morphological plasticity and wound healing abilities (Armon et al, 2018; Srivastava et al., 2008). The project will involve adapting to T. adhaerens an experimental approach already successfully established in the host lab. Briefly, standardised fluorescent deformable polyacrylamide (PAAM) beads will be inserted by microinjection (Traber N. et al, 2019) or micromanipulation within the intact or mechanically wounded epithelium of live T. adhaerens. The beads will allow tracking and quantification of the epithelial movements during normal T. adhaerens migration or during the wound healing process. In addition, measuring how the perfectly spherical PAAM beads are deformed during these processes will allow the quantification of the mechanical forces at play (Girardo S. et al., 2018). The M1 student will learn micromanipulation, live confocal imaging, immunofluorescence and quantitative modelling techniques.

References

Armon S. et al., (2018) PNAS, 115, e10333
Srivastava M. et al., (2008) Nature 454, 955
Girardo S. et al., J. Mater. Chem. B, 2018,6, 6245-6261
Traber N. et al., Sci Rep. 2019; 9: 17031.