We made very good progress in all aims and published some results.
Aim 1: As proposed, we systematically measured the protein degradation rates of human and mouse presomitic mesoderm cells, the cells that display the segmentation clock, by using the Stable Isotope Labeling by Amino acids in Cell culture (SILAC) method. We are now analyzing the data and testing the obtained hypotheses.
Aim 2: As proposed, we measured the metabolic rates (i.e. glycolysis rate and mitochondrial respiration rate) in presomitic mesoderm cells of six mammalian species. Even though both metabolic rates showed species-specific values, there was no correlation between the measured metabolic rates and the segmentation clock periods across species (Lazaro et al, Cell Stem Cell, 2023). These results do not support the idea that species-specific metabolic rates fully explain the species-specific developmental time. However, we also found that chemical inhibition of metabolism affects the segmentation clock periods in many species. Aim 3: We developed a novel human organoid that periodically forms somite-like structures (Sanaki-Matsumiya et al, Nat Commun, 2022). This human ‘somitoid’ also recapitulates the oscillation of the segmentation clock, providing an ideal platform to study developmental time and morphogenesis. We also expanded the number of species (e.g. rabbit, marmoset monkey, cattle and rhinoceros), setting up the ‘stem cell zoo’ in the lab. The comparison across six species enabled us to find several scaling laws of the segmentation clock (Lazaro et al, Cell Stem Cell, 2023).
Both somitoid paper and stem cell zoo paper were covered by several media, including Science Daily, Quanta magazine, and the Scientist.
