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Investigation of Some Cell Morphology Using Phase Field Method

Senay Aras, Betul
http://rave.ohiolink.edu/etdc/view?acc_num=osu1503067908468122

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Mathematics.
In this thesis, we use phase field method to explore cell shape changes. Cell morphology is important for cell function although its role is not well understood. This dissertation consists of four chapters. In Chapter 1, we present a biological background and in Chapter 2, we present a mathematical background needed for the material presented in Chapter 3 and Chapter 4. In Chapter 3, we present a phase field model to study early invaginations observed on the cell surface and the role of eggshell in polarization, in the early life of a Caenorhabditis elegans (C. elegans) embryo. Intracellular polarization, where a cell specifies a spatial axis by segregation of specific factors, is a fundamental biological process. In the early embryo of the nematode worm C. elegans, polarization is often accompanied by deformations of the cortex. It has been suggested that the eggshell surrounding the early embryo plays a role in polarization, although its function is not understood. Here we develop a mathematical model which couples reaction-diffusion equations to a phase field model of the cell cortex and incorporates the eggshell to monitor cortical invaginations during the early development of the C. elegans embryo. We investigate the potential rigidity effect of the geometric constraint imposed by the presence and size of the eggshell on polarization dynamics. The actomyosin contractility on the cortex is described by a previously used reaction-diffusion model. ii The moving boundary is implicitly tracked by the phase field method. Asymmetric contraction of actomyosin is incorporated into the membrane tension energy. The membrane evolves according to the balance between the force by reorganization of cytoskeletal elements and the tension by the contractility of actomyosin at that time. Our model suggests that the geometric constraint of the eggshell is essential for proper polarization and the size of the eggshell also affects the dynamics of polarization. Therefore, we conclude that geometric constraint on a cell might affect the dynamics of a biochemical processes. Escherichia coli (EPEC) is a pathogen that adheres to epithelial cells, promoting cytoskeletal reorganization that results in membrane elongation and formation of a structure called a pedestal. In addition to providing attachment surfaces for EPEC, pedestals also allow intracellular surfing of EPEC on the cell surface. In Chapter 4, we present a two dimensional model employing the phase field method to study the mechanism behind elongation and translocation of pedestals. Like cell motility, protrusions are generated as a result of actin polymerization and nucleation is driven by Arp2/3 activity. We couple the evolution of the cell geometry with protein dynamics using a reaction diffusion model that tracks actin in both its monomeric and filamentous forms. We find that the thin elongated geometry of pedestals limits actin monomer availability and leads to oscillatory membrane velocity. We also conclude that actin polymerization at the tip of the pedestal, membrane elasticity and depolymerization at the bottom of the pedestal forms a sufficient mechanism for the translocation of the pedestals.
Ching-Shan Chou (Advisor)
Adriana Dawes (Advisor)
115 p.
Mathematics
pseudo-cleavage furrow, polarization, pedestals, EPEC

Recommended Citations

Citations

  • Senay Aras, B. (2017). Investigation of Some Cell Morphology Using Phase Field Method [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503067908468122

    APA Style (7th edition)

  • Senay Aras, Betul. Investigation of Some Cell Morphology Using Phase Field Method. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1503067908468122.

    MLA Style (8th edition)

  • Senay Aras, Betul. "Investigation of Some Cell Morphology Using Phase Field Method." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503067908468122

    Chicago Manual of Style (17th edition)

osu1503067908468122
434
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This open access ETD is published by The Ohio State University and OhioLINK.