Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

On the trail of the epigenetic code

12.10.2010
Test system on Drosophila should provide the key to histone function. The genetic inherited material DNA was long viewed as the sole bearer of hereditary information.

The function of its packaging proteins, the histones, was believed to be exclusively structural. Additional genetic information can be stored, however, and passed on to subsequent generations through chemical changes in the DNA or histones.

Scientists from the Max Planck Institute for Biophysical Chemistry in Göttingen have succeeded in creating an experimental system for testing the function of such chemical histone modifications and their influence on the organism. Chemical modifications to the histones may constitute an "epigenetic histone code" that complements the genetic code and decides whether the information from certain regions of the DNA is used or suppressed. (EMBO reports, November 1, 2010, advance online publication)

How do you get a two-metre-long DNA thread into the cell nucleus? By winding it into a ball, of course! The DNA is wound around proteins known as histones, becoming 50,000 times shorter as a result. Other proteins then aggregate on it to form chromatin and, finally, the chromosomes. The latter are the product of an ingenious packaging trick. The five types of histones (H1, H2A, H2B, H3 und H4) fulfil even more tasks, however, and this is what makes them so fascinating. Histones can have small chemical attachments, such as acetyl, methyl and phosphate groups, in different places. These cause the opening of the chromatin, for example, and hence enable the genetic information to be read. Conversely, certain areas of the DNA molecule can be deactivated and rendered unreadable through other modifications, such as the binding of proteins. Scientists refer to this process as "gene silencing". "The histone modifications can intervene in the control of gene activity in this way and, as a result, complement the genetic code," explains Herbert Jäckle, Director of the Max Planck Institute for Biophysical Chemistry in Göttingen.

Every time a cell divides, this modification pattern of the histones is inherited by the daughter cells. The scientists assume that this epigenetic inheritance is controlled by a cell-specific or organ-specific "histone code". "This decides whether the cell machinery has access to the DNA-coded genes or whether the access is blocked," says Jäckle. The scientists would very much like to crack this code: for the production of the histones, hundreds of gene copies are stored in the genome of higher organisms. Therefore, up until now, it appeared to be impossible to switch off these gene copies and replace them with genetically-modified histone variants. Researchers could only create a test system if they managed to do this: if these variants lack certain docking sites, for example for chemical groups, certain modifications to the histones could be prevented and it would then be possible to investigate the extent to which the absence of these modifications leads to diagnosable defects in the organism.

The Max Planck researchers in Göttingen have now succeeded in developing a new method for researching the function of all histone modifications. The cell biologists removed all of the histone genes from the genome of the fruit fly Drosophila melanogaster. As a result, the cells could no longer divide. As occurs with normal cell division, the organism’s genome is still doubled through DNA synthesis but the cell then remains at a standstill in the division cycle and the organism dies. The situation normalises progressively, however, with the increasing number of copies of the four histone genes produced: "Flies with twelve copies of the histone gene cluster ultimately survive and are capable of reproducing," explains Jäckle’s colleague and project leader Alf Herzig.

It had already been established for multicellular organisms that several copies of the histone gene are required for the organism to survive. However, the results obtained by the researchers also indicate that the cell realises during division that histones are lacking, and the division of the cell is then halted despite the fact that DNA has already been doubled - as is the case during all cell division processes. "Communication paths clearly exist between the histone production process and the cell division machinery," says Ufuk Günesdogan, a doctoral student in the department. Most importantly, the researchers now have a test system at their disposal into which histone variants can be channelled for the gradual experimental examination of the function of histone modification and, ultimately, the histone code in the organism. It can only be a matter of time now until the code is finally cracked.

Michael Frewin | alfa
Further information:
http://goto.mpg.de/mpg/news/20101011/

More articles from Life Sciences:

nachricht Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>