Chromatin-based memory of prolonged cold exposure in Arabidopsis thaliana

Berry, Scott (2015) Chromatin-based memory of prolonged cold exposure in Arabidopsis thaliana. Doctoral thesis, University of East Anglia.

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All living organisms contain genes. Turning these genes on and off at
the appropriate times controls much of an organism’s development and
its responses to environmental conditions. In recent years, chromatin
has emerged as an important player in orchestrating gene regulation.
This thesis focuses on the role of chromatin in the maintenance of gene
expression states and their inheritance through cell division.
FLOWERING LOCUS C (FLC) in the plant Arabidopsis thaliana is repressed
by the prolonged cold of winter, and repression is maintained
in subsequent warm conditions. The molecular complexes involved in
modulating FLC chromatin are vital for FLC regulation and are conserved
among plants and animals, making FLC a paradigmatic system
for understanding of the role of chromatin in gene regulation.
After cold, FLC chromatin adopts a distinct configuration. In this
study, experiments are used to show that this local chromatin ‘state’
instructs its own inheritance through cell division in growing plants.
Thus, memory of winter cold is stored in the chromatin of the FLC gene.
Mathematical models developed in this work focus on understanding
how chromatin states are maintained and also re-established after
DNA replication. Minimal models are used to investigate if a particular
set of interactions between chromatin and chromatin-modifiers can
give rise to the qualitative behaviours, and quantitative results that are
observed experimentally. Models developed here make predictions for
the FLC system, and more generally show how cis and trans determinants
of gene expression can be integrated by chromatin.
The role of transcription in determining chromatin states is also examined
experimentally by studying the chromatin-associated protein
LHP1. LHP1 is required for FLC repression and binds to modified
histones associated with repressed FLC chromatin. In this work, it is
shown that LHP1 also binds RNA and that this is important for its in
vivo function.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Jackie Webb
Date Deposited: 03 May 2016 15:11
Last Modified: 28 Feb 2017 01:38

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