The temporal order in which segments of the genome are duplicated is referred to as the replication timing (RT) program. RT is
established in each cell cycle coincident with the repositioning and anchorage of chromosomes in early G1. In general, segments that
replicate in early S are organized into transcriptionally permissive chromatin, and segments that replicate in late S are assembled into
repressive chromatin. During human embryonic stem cell (hESC) differentiation, segments of the genome undergo changes in RT, which are
accompanied by changes in chromatin compartments, and transcriptional activity. Determining the order these changes occur during hESC
differentiation required defining cell cycle parameters for hESCs. First, we demonstrate that the fluorescence ubiquitination cell
cycle indicator (Fucci) system is incapable of demarcating G1/S cell cycle transitions. Instead, we employed a combination of fluorescent
PCNA to monitor S phase progression, cytokinesis to demarcate mitosis, and fluorescent nucleotides to label early and late replicating DNA
and track 3D organization. We find that re-localization and anchorage of chromosomes were completed prior to the onset of S phase, even in
the context of an abbreviated G1 phase. Furthermore, we find that single hESCs preferentially differentiate from G1. We show changes in RT
are remarkably coincident with transcription; although, neither is sufficient for the other to occur. We also show changes in RT accompany
cell commitment during the first cell cycle and precede changes in chromatin compartments. Finally, we find that in hESCs, domains that
switch from early to late replication interact more frequently with late replicating chromatin, suggesting hESCs may be poised to quickly
repress early to late switching domains upon stimulation. / A Dissertation submitted to the Department of Biological Science in partial fulfillment of the
requirements for the degree of Doctor of Philosophy. / Summer Semester 2016. / July 18, 2016. / Includes bibliographical references. / David Gilbert, Professor Directing Dissertation; Timothy Megraw, University Representative; Hank
Bass, Committee Member; Brian Chadwick, Committee Member; Jonathan Dennis, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_405643 |
| Contributors | Wilson, Korey (authoraut), Gilbert, David M. (professor directing dissertation), Megraw, Timothy (university representative), Bass, Hank W. (committee member), Chadwick, Brian P. (committee member), Dennis, Jonathan Hancock (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Biological Science (degree granting departmentdgg) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource (88 pages), computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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