VERENA RUPRECHT (left) and PHILIPP NIETHAMMER (right)
“But they all use the word ‘multicellularity’ when they really mean ‘animal’—since there are no unicellular animals, and since multicellularity, genuine multicellularity, details of multicellularity, are known in protists, bacteria and all the major groups of life. . . . Some bacteria like Gomphosphaeria are always multicellular in all stages of development. . . . They [zoologists] play with 1/5th of the deck in biology. They belong to a thought style I don’t share.“—Lynn Margulis in a 2009 conversation with me excerpted from The Altenberg 16: An Exposé of the Evolution Industry
What could be lovelier on a rare day in June than a tea & mechano-plasticity early embryo lecture on Manhattan’s East River. Cell biologist Philipp Niethammer’s laboratory hosted last week’s gathering at Sloan Kettering Institute (SKI) presenting Verena Ruprecht and her work in quantitative cell biology; Ruprecht is group leader of the cell & developmental biology program at Barcelona’s Centre for Genomic Regulation. She was honored by EMBO (European Molecular Biology Organization) with a Young Investigator Award in 2020.
Prior to the lecture Ruprecht told me that she sometimes collaborates with another EMBO Young Investigator, who I’ve interviewed on this page: Jean-Léon Maître at Institute Curie in Paris, leading the charge there into the mechanics of mammalian morphogenesis. France is one of the important centers of mechanobiology research.
The SKI room was packed, with some of the younger academics in jeans on the floor sitting next to the table of cookies. Ruprecht kept the lecture moving showing four-dimensional image analysis of zebrafish cell dynamics.
The morphodynamic migration of cells and cell content is a kind of amoeboid ballet in its formations and deformations.
The SKI event was a reminder that as microscopy gets more and more sophisticated the investigation into embryogenesis becomes increasingly intriguing. For multiscale imaging, Ruprecht relies on Advanced Fluorescence Microscopy, which enables the observation and quantification of evolutionary dynamics playing out in living cells, its organelles and sub-organelles by collecting emitted fluorescent light.
And with the recent introduction of Expansion Microscopy (ExM), investigations on the nanoscale should become easier. The nanoscale is where the challenge lies in mechanobiology, according to physical virologist Bogdan Dragnea.
Dragnea told me several years ago during a conversation for my book Darwin Overthrown: Hello Mechanobiology that it’s the mix of mechanics, thermodynamics and quantum mechanics in the region of 10 to 100 nanometers “that’s going to be extremely interesting”.
Ruprecht during the SKI talk made the point that unicellular choanoflagellates (or as Lynn Margulis would say, so-called unicellular)—thought to be the closest living relative to animals—can display a similar amoeboid blebbing dynamic to that of animals. Choanoflagellates can go into an amoeboid-like crawling mode, particularly if confined, by withdrawing their flagella. Ruprecht termed this crawl an “ancient” mechanism.
Detlev Arendt et al. in a 2015 Royal Society paper mention “the possibility that cell crawling and flagellar swimming both predate the divergence of the choanoflagellates and animal lineage.”
Choanoflagellates swim with and eat bacteria, are bacteriovores. A decade ago, University of California, Berkeley scientists Nicole King and Rosie Alegado (now at U. Hawaii) revealed that bacteria can trigger choanoflagellate morphogenesis, nudge the organism to reproduce and form a rosette colony via contact with a bacterial fatty acid/lipid molecule, a sulfonolipid. And according to Nicole King’s National Academy of Sciences biosketch (she became an NAS member in 2022)–her Berkeley lab has recently identified a choanoflagellate that “harbors a bacterial community.”
With Ruprecht’s reference to choanoflagettes, I was also reminded of my conversation several years ago with Royal Society Leeuwenhoek Medalist Jeffery Errington regarding his research on L-form bacteria.
L-forms are wall-deficient and reproduce by non-binary fission via membrane tubulation and blebbing. They generate blob-shaped descendants. Errington, now at the University of Sydney, thinks L-forms were extensive in early evolution.
Errington told me that it’s simple geometry to transform a walled bacterium into an L-form. It’s a matter of excess membrane, which results in deformation of the cell. You drive changes by increasing surface area. Some walled bacteria like E-coli, he said, can be coaxed into a wall-less state through osmotic pressure and they can then return to a walled state.
Errington said further “the ability to change between the two states begins to seem quite a general property of bacteria, which to me suggests that this is a very ancient trait that’s been retained by modern bacteria. . . . [S]imilar triggers to those that will turn a Gram-positive bacterium [i.e., with a single thick peptidoglycan wall] like Bacillus subtilis into an L-form will also convert E. coli into the L-form state. And these two species of bacteria are separated by about a billion years of evolution.”
It was good to be in the room with evolution scientists for an hour or so thinking about Deep Time rather than Deep State, even if they were too young to remember Omni magazine.
I do wish the Simons Foundation would rethink its mask-wearing requirement when its public lectures resume in the fall; the mask policy is keeping many interested from attending.
OSCILLATIONS 