Biology Reference
In-Depth Information
CHAPTER THREE
Epigenetic Marking of the
Zebrafish Developmental
Program
Ingrid S. Andersen *
, , Leif C. Lindeman *
, , Andrew H. Reiner *
, ,
Olga Østrup *
, ,1
* Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of
Oslo, Oslo, Norway
Norwegian Center for Stem Cell Research, University of Oslo, Oslo, Norway
BasAM, Norwegian School of Veterinary Science, Oslo, Norway
1 Corresponding author: e-mail address: philc@medisin.uio.no
, , Håvard Aanes , Peter Aleström , Philippe Collas *
Contents
1.
Introduction: Setting the Stage for the Zebrafish Developmental Gene
Expression Program
86
2. Turning on Gene Expression at the MZT
87
3. DNA Methylation Changes During the MZT
91
3.1 Expression of DNA methyltransferases in zebrafish embryos
92
3.2 Dynamics of DNA methylation through the MZT
93
3.3 A relationship between DNA methylation and transcriptional repression?
95
4. Developmental Gene Expression Prepatterning by DNA Hypomethylation
95
5. Prepatterning Developmental Gene Expression by Modified Histones Before ZGA
97
5.1 Histone methylation marks of promoters and enhancers
97
5.2 Dynamic occupancy of the embryonic genome by histone marks during
development through the MBT
99
6. Developmental Epigenetic Fate Map Through the MBT: A Path to Multivalency?
103
7. Transgenerational Inheritance or De Novo Deposition of Embryonic Epigenetic
Marks? Two Models
105
8. Conclusions and Perspectives
106
References
107
Abstract
A characteristic of anamniote development is a relatively long period of embryonic cell
divisions in the absence of on-going transcription. In zebrafish, this period lasts for 10 cell
cycles, or 3-h postfertilization, after which zygotic genome activation (ZGA) takes place
during themidblastula transition. How the embryo establishes transcriptional competence
and how ZGA is spatially and temporally regulated have not been examined until recently.
We review here recent data on the transitions in DNA methylation and posttranslational
histone modifications occurring during early zebrafish development, as the embryo
 
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