Surprisingly, disrupting warts kinases in S. rosetta caused a very animal-like phenotype: giant rosettes colonies!

This suggests the molecular pathways that control multicellular development in animals and choanos might be more conserved than we expected...

When rosettes reach a critical size, cells undergo a 'jamming transition', pressure becomes unsustainable - and rosettes split into two. In other words: a limiting quantity of ECM sets rosette size and shape.

Now for the biological story: when it detects certain bacteria, the choanoflagellate S. rosetta undergoes serial cell division to develop into a swimming sphere of cells aptly named "rosette", which evokes (mutatis mutandis) a morula stage embryo.

Gliding is conserved in at least 2 choano species we looked at (C. flexa and S. rosetta). We don't know in which natural context it is deployed, but we think it is likely to be involved in interactions with surfaces such as biofilms...

Most striking, in some instances of spontaneous flagellar detachment, the flagellum can glide on its own - mercilessly leaving the cell body behind, stabbing it on the way if need be (don't do this at home).

In this new study, @maitefreired.bsky.social has shown that moderate confinement activates *yet another* mode of motility: choanos straighten their flagellum, and start moving over the substrate at pretty high speed (~1 µm/sec) without any visible cell deformation. They glide!