Related Experiment Video
Updated: Feb 14, 2026
05:59
Application of the DNA-Specific Stain Methyl Green in the Fluorescent Labeling of Embryos
Published on: May 2, 2015
14.7K
Placeholder Nucleosomes Underlie Germline-to-Embryo DNA Methylation Reprogramming
Patrick J Murphy1, Shan Fu Wu1, Cody R James1
1Howard Hughes Medical Institute, Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
Cell
|February 20, 2018
Summary
Placeholder nucleosomes, containing histone H2A variant H2A.Z(FV) and H3K4me1, prevent DNA methylation in zebrafish embryos. This epigenetic mechanism controls gene activation or repression during early development and inheritance.
Area of Science:
- Developmental Biology
- Epigenetics
- Genomics
Background:
- Epigenetic marks guide the germline-to-embryo transition, impacting stem cell programming and inheritance.
- In zebrafish, DNA methylation is established in quiescent embryos, with paternal patterns maintained and maternal patterns reprogrammed.
- Understanding the mechanisms controlling these epigenetic changes is crucial for developmental biology.
Purpose of the Study:
- To elucidate the mechanism by which DNA methylation patterns are programmed during the zebrafish germline-to-embryo transition.
- To identify the role of specific nucleosomes in regulating DNA methylation and gene expression.
- To investigate the consequences of perturbing these epigenetic marks.
Main Methods:
- Chromatin immunoprecipitation (ChIP) to identify nucleosome occupancy and histone modifications.
- DNA methylation analysis to assess genome-wide methylation patterns.
- Functional assays to study the effects of nucleosome perturbations on gene expression and DNA methylation.
Main Results:
- "Placeholder" nucleosomes, containing H2A.Z(FV) and H3K4me1, occupy DNA methylation-free regions in sperm and cleavage embryos.
- These nucleosomes are found at promoters of housekeeping and early embryonic genes.
- Loss of Placeholder leads to DNA methylation accumulation, while its gain causes hypomethylation and aberrant gene activation.
Conclusions:
- Placeholder nucleosomes actively deter DNA methylation during quiescent developmental stages.
- This mechanism poises parental genes for either activation or repression at the onset of transcription.
- Placeholder nucleosomes are key regulators of epigenetic reprogramming and gene expression during early zebrafish development.
Related Concept Videos
02:33The Nucleosome
19.0K
DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside the nucleus is astonishing. It is organized into several sequentially higher levels of compaction to fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
19.0K
02:33The Nucleosome
5.2K
5.2K
01:19The Nucleosome
4.3K
Human DNA is almost two meters long. However, it is compressed inside a tiny nucleus measuring only a few microns in diameter. To make this degree of compaction possible, DNA is organized into several sequential levels so that it can fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
4.3K
02:54Nucleosome Remodeling
11.3K
Nucleosomes are the basic units of chromatin compaction. Each nucleosome consists of the DNA bound tightly around a histone core, which makes the DNA inaccessible to DNA binding proteins such as DNA polymerase and RNA polymerase. Hence, the fundamental problem is to ensure access to DNA when appropriate, despite the compact and protective chromatin structure.
Nucleosome remodeling complex
Eukaryotic cells have specialized enzymes called ATP-dependent nucleosome remodeling enzymes. These enzymes...
Nucleosome remodeling complex
Eukaryotic cells have specialized enzymes called ATP-dependent nucleosome remodeling enzymes. These enzymes...
11.3K
02:10The Nucleosome Core Particle
14.6K
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
14.6K
01:12The Nucleosome Core Particle
2.4K
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
2.4K