iiinova — where your digital self keeps evolving

Jonas Neipel

@neipel.bsky.social

Theoretical biophysicists in Grill and Jülicher labs. (MPI-CBG, MPI-PKS Dresden) Interested in anything from genome regulation to developmental biology, currently focusing on left-right symmetry breaking and shape/curvature/ geometry sensing.

Posts Replies Media

Jonas Neipel @neipel.bsky.social · 20/07/2025

(3/10) Jerome found cells moving to the left around the node, repositioning a Shh domain to the left, but what makes them do that?

110

Jonas Neipel @neipel.bsky.social · 20/07/2025

(9/10)  In conclusion, we give a mechanical perspective on how the node organises avian development: mechanical coupling of tissue layers allows for the generation of an active chiral torque dipole to break embryonic L/R symmetry. How is this achieved on a cell scale? Stay tuned!

110

Jonas Neipel @neipel.bsky.social · 20/07/2025

(8/10) But now comes the really striking result: She found that replacing the meso-/endo tissue with a vitel. membrane is sufficient to restore node rotation. So, you simply need some mech. substrate. sustaining a counter-torque such that the node can drive its own rotation.

100

Jonas Neipel @neipel.bsky.social · 20/07/2025

(7/10)  But, what is the substrate? Is it the underlying meso-/endoderm?  Here come the crazy experiments by Julia: She used an eye-brow to remove the meso-/endo showing that it’s required for node rotation. Notably, meso-/endo grows back yielding a delayed and reduced node rotation.

110

Jonas Neipel @neipel.bsky.social · 20/07/2025

(6/10) So, the following picture following mechanical picture of avian L/R sym. break. emerges: actomyosin-activity generates cell-scale torque dipoles that propel the rotation of node and surrounding epiblast with respect to some rigid substrate.

100

Jonas Neipel @neipel.bsky.social · 20/07/2025

(5/10) But is the node really capable of making itself rotate? Lasercuts by Julia show yes, providing maybe the first direct evidence for a tissue-scale active chiral torque. Also, we show that the apparent torque is actomyosin-dependent, consistent with previous observations by Jerome.

100

Jonas Neipel @neipel.bsky.social · 20/07/2025

(4/10) We quantified these chiral tissue flows in 25 quail embryos and inferred forces using a fluid model, suggesting a torque of 6μNμm is generated locally at the node.

132