Advancing Epigenetics Towards Systems Biology

What is chromatin, euchromatin and heterochromatin?

Chromatin is the molecular substance of a chromosome. It consists of a complex of DNA, RNA and protein in eukaryotic cells. Frequently, people encounter pictures of chromosomes which have a striped pattern of stronger and lighter staining. What are these chromosome bands? Do they represent genes? No, they do not necessarily represent genes nor do they automatically correspond to stretches lacking genes. Chromosomes often presented to the public are most highly compacted metaphase chromosomes or the giant chromosomes (i.e. polytene chromosome) of Drosophila larvae from salivary gland cells. The latter are made up of about 2000 DNA double strands arranged parallel to each other. A single band of a Drosophila giant chromosome can contain about 50.000 nucleotides in a row. But what makes its staining different to an adjacent band? What we see as dark bands is a consequence of an increased concentration of DNA within variably, compacted chromatin that differs in staining on average every 50 kb. But there is also a gradient of diverse higher order degrees of compaction. Further, in the life of a chromosome it alters its appearance. During the so-called interphase it is relaxed with a lot of open chromatin (see FAQ 7). During this phase, some entire chromosomes but mostly only parts thereof retain a strong staining. These subnuclear features are known since the early days of cytology. In 1928, Heitz introducd for them the term 'heterochromatin'. Euchromatin, on the other hand, is highly decondensed chromatin. Chromosomal regions in the genome which lack high numbers of genes are normally compacted in heterochromatin while chromosomal regions with high concentrations of transcribed genes are part of relaxed euchromatin. But these patterns change during development depending on the pattern of particular epigenetic tags present in the chromatin (see FAQ 8).

Wed, Oct 16th 2019- Fri, Oct 18th 2019

The Asia Epigenome Meeting is an annual event that rotates in South Korea, Japan, China, Taiwan, Singapore and India. It is to engage world leading scientists and outstanding Asia researchers to promo...

Wed, Nov 20th 2019- Sat, Nov 23rd 2019

Metabolism and Epigenetics are intricately linked, playing a key role in development, cancer, immune signaling and aging. This symposium brings together world-leading researchers exploring this nexus....


EpiGeneSys Final
Meeting in Paris

Thur. 11 February 2016 - Sat. 13 February 2016

More than 280 scientists attended the fifth Annual Meeting of EpiGeneSys. The conference kicked off with a talk by coordinator Geneviève Almouzni, Director of the Research Center at the Institut Curie, highlighting the achievements of the network over more than five years...

Maison des océans - Paris Read more


The Non-Coding Genome ...

December 3-4 th, 2015

The last training workshop of the EpiGeneSys network

Hotel Mediterraneo - Rome, Italy Read more

Paris / TriRhena Chromatin Club

July 9th, 2015

...exciting talks and network with members of the Chromatin community!

... An EpiGeneSys TAB workshop

June 11st-12nd , 2015

... learn about current approaches to single cell epigenetics and to meet up and network with...

Montpellier, FranceRead more

Latest publications


The Histone Acetyltransferase Mst2 Protects Active Chromatin from Epigenetic Silencing by Acetylating the Ubiquitin Ligase Brl1.

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Proliferation Drives Aging-Related Functional Decline in a Subpopulation of the Hematopoietic Stem Cell Compartment.

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The impact of rare and low-frequency genetic variants in common disease.

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