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Collective synchronization of coupled self-orgnanizing mouse embryonic oscillators

Ho, Christine

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Please note: Access restricted to Repository staff only until 19 December 2020.
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[img] PDF, English
Please note: Access restricted to Repository staff only until 19 December 2020.
Login+Download (2MB) | Terms of use

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Abstract

Synchronization abounds in nature at different scale and biological context: fireflies flash in sync, neurons fire together. Synchronization is the ability to coordinate events to operate in unison. It requires objects to sense and communicate with each other. This interaction is called coupling. How synchronization and coupling are achieved in nature are subject of intense studies. One remarkable case of synchronization has been observed during the formation of the body axis in vertebrates. In vertebrates, the segmented vertebral column is established during somitogenesis at the embryonic stages. Somites form rhythmically, for example in mouse with a period of about 2 hours. This process is associated with the oscillatory activity of genes involved in Notch, Wnt and Fgf signalling pathways along the pre somitic mesoderm (PSM) tissue. Interestingly, in vitro randomization assays including tissue dissociation and re-aggregation, PSM cells spontaneously re-synchronize and self-organize into several miniature emergent PSM structures (ePSM). Thus, a randomized ensemble of genetic oscillators with different frequencies and phases establish synchrony and form ordered oscillating patterns. Although the requirement for Notch signalling pathway for synchronization is known, the general rules of coupling remain elusive. To describe synchronization between coupled biological oscillators, Kuramoto in 1979 provided a model based on phase difference coupling. This model assumes that synchronization is continuous and driven by the phase difference between weakly coupled oscillators. This Kuramoto model is widely used to study synchronization phenomena, including PSM oscillations . However, theoretical predictions regarding the collective phase synchronization have not been tested experimentally yet. We developed a novel experimental strategy to quantitatively challenge the Kuramoto model, particularly in regard to its prediction of how the collective phase is determined. While the Kuramoto model predicts that the collective phase is equal to phase average of input oscillators, our results suggest that the collective phase is dictated by one phase of input oscillators. Combined with other results, our experimental findings do not match Kuramoto model predictions. I discuss future experimental strategies to test alternative models for PSM synchronization.

Item Type: Dissertation
Supervisor: Aulehla, Dr. Alexander
Place of Publication: Heidelberg
Date of thesis defense: 28 November 2019
Date Deposited: 08 Jan 2020 10:54
Date: 2020
Faculties / Institutes: The Faculty of Bio Sciences > Dean's Office of the Faculty of Bio Sciences
Subjects: 570 Life sciences
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