Cellular guidance by chemical or physical signals is essential for many life processes and usually relies on sophisticated biological processes that are still partially elucidated. Microfluidic experiments and mechanical modeling has revealed that the choice for cells to orient themselves against or in the direction of a flow can result from a simple physical bias. They have worked with keratocytes, cells that form the scale of fishes, and whose morphology is characterized by broad flat “front” and a compact protruding front “back”. A simplified model of a cell with a hemispherical back and a flat rectangular front allows to quantitatively calculate the forces that the flow exerts on each edge. The resulting force stabilizes the cells with a large rear edge against the flow, like a roly-poly that stays upright because of its heavy bottom edge. The researchers’ model successfully predicted the experimentally observed orientation for each cell without adjusting parameter. It is an elegant example where a characterized biological behavior does not result from specialized molecular sensors and a complex cascade of internal biosignals to reorient the cell, but from a simple passive physical bias.
A– Keratocytes descending a flow, the white arrow indicates the direction of the stream. B– Cell morphology seen in 3D by confocal microscopy, with a bulbous back edge and a flat, thin front edge. C– Cell modeling with a hemisphere at the back (red) and a flat rectangle at the front (brown) D– The torques resulting from flow on cell front (red arrow) and cell front (brown arrow) stabilize upstream orientation of cell with larger rear edge, like the torque resulting from gravity stabilizes the standing position of roly-poly toys with large bottom edge.
We are pleased to welcome for two months Andrzej Kubiak, a visiting post-doc from the Jagiellonian University in Polland. Andrzej’s is mainly interested in hematopoietic stem cells and will be collaborating with Pierre-Henri Puech on an application of single-cell force spectroscopy to investigate adhesion within the bone marrow.
The BioPhysImmuno IRP project aims to continue a successful collaboration started through a CNRS Projet International de Coopération Scientifique (PICS) project (20218-2021) between two complementary laboratories, one located in Mexico and one in France. The project has been launched with Pierre-Henri Puech acting as coordinator!
Our PhD student Chandrasekar SUBRAMANI NARAYANA presented a poster entitled “Deep Learning Based Counting & Localization of Phage Under TIRF Microscopy” at the conference organized by the Institute Imaging Marseille this September!
Our PhD students participated in the Physics of Living Matter conference organized in Marseille this year which was followed by PLM 16 II at Cambridge! Valentine Seveau gave a talk, while Ismahene Mesbah, Rémy Torro and Beatriz Diaz Bello presented their posters!
We welcome Florian Dupuy, our new INSERM engineering assistant. Florian has had extensive experience at the Cochin Insitiute in the parasitology team Biology of Plasmodium Transmission, where he put to use his cellular and molecular biology skills to decipher the plasmodium parasite’s interactions with host cells, a critical step towards finding antimalarial drugs.
Florian will deploy his valued experience in the many projects of LAI for years to come.
Each year, the CNRS awards talented women and men, support staff in research, whose creativity, mastery and innovative flair, contributes to pushing knowledge and to the excellence of French research, with the “médaille de cristal” (crystal medal) 🏅.
Lama Awada, Farah Mustapha, and Pierre-Henri Puech presented their posters at one of the most anticipated conferences of the year in Siena, Italy. In addition, Lama was awarded the EFIS-EJI grant which is dedicated to young scientists who produced abstracts of outstanding quality!