Prof. Ebisuya explores why biological processes tend to occur more slowly in humans compared to mice. Her group studies species-specific biological tempo by using stem cells from a diverse range of animal species.
Research abstract:
While mechanisms of embryonic development are well conserved among mammals, the progression speed varies greatly across species. For example, the gestation period in humans is 9 months, while in mice it is 20 days, and in rhinoceroses, it extends to 1.5 years. To study such inter-species differences in biological tempo, my group uses the “stem cell zoo”, a collection of pluripotent stem cells from diverse mammals, including the human, mouse, and even rhinoceros. Using the stem cell zoo, we can recapitulate certain biological processes and their temporal dynamics. As a model system, we have recapitulated the segmentation clock, the oscillatory gene expression during early development, from the stem cell zoo. In human cells, the segmentation clock oscillates every 5 hours, whereas in mouse cells it oscillates every 2 hours, and in rhinoceros cells every 4 hours. We found that this oscillation period difference between species stems from species-specific kinetics in basic biochemical reactions, such as protein degradation - these reactions occur more slowly in human cells compared to mouse or rhinoceros cells. Currently, we are investigating the potential underlying causes behind the species-specific kinetics, including differences in cellular metabolism.
We are also exploring other examples of biological tempo, such as species-specific heart rates, to gain insights into tempo modulators across species.