Thank you 😀

Thanks PAvel!!! 😊

Thanks Andre!!! 😊

#devbio #crystals #SizeandShape #zebrafish :)

Of course, this could not be possible without incredible support from @mpi-cbg.de and @poldresden.bsky.social, and their great facilities! 😊

In case you’re curious, we do have quite a few new experiments, compared to our preprint, here: www.biorxiv.org/content/10.1...

Mechanistically, our work shows that purine diversity and availability inside the zebrafish iridosome is key to form anisotropic crystal lattices, explaining the zebrafish distinct functional crystal shapes.

Macroscopically, b-axis anisotropy is controlled by the ratio of guanine-to-hypoxanthine in the iridosome, without affecting the other axes. At the atomic level, the extent of the anisotropy depends entirely on the type, number, and strength of the hydrogen bonds within the crystal lattice.

Then, by performing comparative genetic analyses in vivo (new mutants and transgenics!) and reproducing such conditions in silico (Monte Carlo simulations!), we found that the zebrafish crystals’ in-plane hydrogen bond molecular structure is the main determinant for the observed crystal anisotropy.

Using confocal live imaging of reflection, cryoFIB-SEM, and novel morphometric analysis pipelines, we show that intracellular crystal growth favors the b-axis, producing their characteristic anisotropic shape.

In brief, this is a story about subcellular size and shape! Many organisms self-organize crystals, for functions like vision, pigmentation, and metabolite storage. In zebrafish, iridophores concentrate guanine (yes, think DNA!) and other purines in membrane-bound organelles, the iridosomes.

It was a great pleasure to write this with Lucas Ribas, the first phD student from our lab :) more to come soon!