A stem cell zoo uncovers intracellular scaling of developmental tempo across mammals

Differential speeds in biochemical reactions have been proposed to be responsible for the differences in developmental tempo between mice and humans. However, the underlying mechanism controlling the species-specific kinetics remains to be determined. Using in vitro differentiation of pluripotent stem cells, we recapitulated the segmentation clocks of diverse mammalian species varying in body weight and taxa: marmoset, rabbit, cattle, and rhinoceros. Together with mouse and human, the segmentation clock periods of the six species did not scale with the animal body weight, but with the embryogenesis length. The biochemical kinetics of the core clock gene HES7 displayed clear scaling with the species-specific segmentation clock period. However, the cellular metabolic rates did not show an evident correlation. Instead, genes involving biochemical reactions showed an expression pattern that scales with the segmentation clock period. Altogether, our stem cell zoo uncovered general scaling laws governing species-specific developmental tempo. [Display omitted] •The segmentation clock of six mammals was recapitulated using pluripotent stem cells•The clock’s period does not scale with body weight, but with embryogenesis length•Biochemical reaction speeds scale with the segmentation clock period•The expression of genes involving biochemical reactions correlates with the period Lázaro et al. have investigated the mechanisms underlying the differences in developmental tempo by recapitulating in vitro the segmentation clock of six mammalian species. They reported that the speed of biochemical reactions and the expression of biochemical reaction genes scale with the segmentation clock period.