Applied Math Seminar — Leif Zinn-Brooks (HMC/Scripps)

Title: Circadian Rhythms in Multinucleate Cells

Abstract:

Circadian rhythms are among the most researched cellular processes, but limited work has been done on how these rhythms are coordinated between nuclei in multinucleate cells. I’ll analyze a mathematical model for circadian oscillations in a multinucleate cell, motivated by mRNA and protein data from the filamentous fungus Neurospora crassa. Stochastic simulations of this model illuminate the importance of mRNA-protein phase separation, in which mRNAs are kept close to the nucleus in which they were transcribed, while proteins can diffuse freely across the cell. This phase separation allows for a robust oscillator to be assembled with very low mRNA counts. I’ll also discuss how the labor of transcribing mRNAs is divided between nuclei, both when nuclei are evenly spaced across the cell and when they are not. Division of this labor can be regulated by controlling the amount of cytoplasmic volume available to each nucleus. Our results indicate that there is potential for emergent organization and extreme mRNA efficiency in multinucleate cells.