COMPLEX SYSTEMS SEMINAR<br>From Molecules to Development: Revealing Simple Rules of Biological Clocks</br>
Organisms from cyanobacteria through vertebrates make use of biochemical and genetic oscillators to drive repetitive processes like cell cycle progression and vertebrate somitogenesis. Despite the complexity and diversity of these oscillators, their core design is thought to be shared. Notably, most of them contain a core positive-plus-negative feedback architecture. Here we use the early embryonic mitotic cycles in *Xenopus* as a motivating example and discuss how the positive feedback functions as a bistable switch and the negative feedback as a time-delayed, digital switch (Yang and Ferrell, Nat Cell Biol, 2013; Ferrell, Tsai, and Yang, Cell, 2011). I will next discuss our ongoing and future research projects on essential biological clocks in early embryos. We employ mathematical modeling, microfluidic techniques, and optical imaging for a quantitative understanding of self-organizing behaviors of single cells and single molecules during early embryo development. Interested students are encouraged to contact me and to visit our webpage for more details.