Use of liposomes to optimize the cryopreservation of ram semen

The success of cryopreservation is based on maintaining the functional integrity of cells, despite the stresses induced by the freezing/thawing processes. However, currently, some cells of interest are still poorly resistant to these stresses. In rams, for example, after freezing and insemination, spermatozoa are no longer able to travel up the female genital tract to fertilize the oocyte. One explanation could be linked to the lipid composition of sperm membranes, which makes them particularly sensitive to freezing. Our hypothesis is that the use of liposomes, innovative lipid nanovectors, acting at the level of the plasma membrane of cells, could promote their resistance to freezing. The objectives of the thesis are: 1) to acquire elements of understanding on the "lipid weaknesses" of ram spermatozoa and on its interactions with cryoprotectants (fluorescent labeling techniques in confocal microscopy); 2) to synthesize liposomes of optimized composition, specifically adapted to ram spermatozoa (modulation of the composition of the lipid bilayer of liposomes and encapsulation of antioxidant molecules); 3) to evaluate the cryoprotective effects of these liposomes in vitro (flow cytometry, heterologous In Vitro Fertilization) then in vivo, on different sheep breeds.

UPSP 2021.A104 - ICE (Cell-Environment Interactions) VetAgro Sup Veterinary Campus of Lyon.

Occasional travel for field experiments.

Master Degree in Biotechnologies or Biosciences.

Dedicated interest in Cell biology and strong scientific curiosity.

High motivation, reliability and initiative.