Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Viable and fertile fruit flies in the absence of histone H3.3

13.11.2012
Histones – proteins that package DNA – affect cell function differently than previously assumed: the cell doesn’t need the histone H3.3 to read genes. Molecular biologists from the University of Zurich demonstrate that fruit flies can develop and reproduce in the absence of this histone. Additionally, cell division works without a histone modification previously deemed crucial.

Histones are proteins that are found in the cell’s nucleus, where they are present in complexes with DNA and are presumed to play a regulatory role in all processes that take place on the DNA. These processes include transcription, namely RNA synthesis, and the duplication of DNA during cell division.


Drosophila wing imaginal disc: Non-stained cells, areas in black, can not modify their histone H3 at the lysin. But the cells can divide and read genes. Dark blue represents non-mutant cells, cyan represents the modification at the lysin.

Picture: UZH

Until now, the function of the individual histones in the various processes could only be determined indirectly. Molecular biologists Konrad Basler and Martina Hödl from the University of Zurich for the first time directly studied the function of two histones and one histone modification – with surprising results: Viable and fertile organisms develop in the absence of the histone known as H3.3. Additionally a particular histone modification was believed to be crucial for the activation of gene transcription.

However, the researchers were able to demonstrate that this is also not the case. The established models for the role and function of histones and their modifications during the transcription and cell-division need to be revised.

Fertile fruit flies despite lack of histone H3.3

For their study, Basler and his postdoctoral student Hödl used the fruit fly Drosophila melanogaster, the genome of which has been fully decoded. In an initial experiment, the scientists switched the two histone variants H3.2 and H3.3 in the cells. In normal (i.e. non-manipulated) cells, histone H3.2 is only expressed in one specific phase of the cell cycle, the so-called S phase. Histone H3.3, however, is always expressed. Consequently, it was assumed that histone H3.3 plays a key role in transcription, especially in reading genes. Thus, the general consensus was that RNA synthesis would be restricted in the absence of histone H3.3. “In our experiment, under lab conditions viable and fertile fruit flies could develop from cells that do not have any H3.3,” explains Hödl, summing up the result that turns the previous understanding on its head. “Organisms also begin to develop from cells without H3.2 but these died in the first larval stage,” Hödl continues.

Genes are switched on and off without histone modification

Histones are modified by different enzymes at different points in the protein. In a second experiment, Basler and Hödl examined the importance of modifications of the fourth amino acid of the protein, a lysine. Modification of this lysine is thought to play a key role in activating and deactivating the transcription of the gene. To test this, the scientists replaced the lysine with non-modifiable amino acids in all the histone H3 genes. The result was another big surprise. “Cells without this specific histone modification are able to divide normally,” explains Basler before adding: “However, they do so considerably more slowly than cells that have not been modified.” Therefore, the modification of this lysine is not essential for the activation of the genes.

The results show that the activation of genes and the inheritance of the ability to activate genes work differently than previously assumed. Clearly, the structure of the transcription process is extremely robust. According to Basler, the role of this common histone modification for cell function has been overestimated in recent years.

Literature:
Martina Hödl, Konrad Basler, Transcription in the Absence of Histone H3.2 and H3K4 Methylation. Current Biology. November 8, 2012. http://dx.doi.org/10.1016/j.cub.2012.10.008
Contact:
Dr. Martina Hödl
Institute of Molecular Life Sciences
University of Zurich
Tel. +41 44 635 31 15
E-Mail martina.hoedl@imls.uzh.ch

Nathalie Huber | Universität Zürich
Further information:
http://www.uzh.ch

More articles from Life Sciences:

nachricht New type of photosynthesis discovered
17.06.2018 | Imperial College London

nachricht New ID pictures of conducting polymers discover a surprise ABBA fan
17.06.2018 | University of Warwick

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

Im Focus: Water is not the same as water

Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.

From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

A sprinkle of platinum nanoparticles onto graphene makes brain probes more sensitive

15.06.2018 | Materials Sciences

100 % Organic Farming in Bhutan – a Realistic Target?

15.06.2018 | Ecology, The Environment and Conservation

Perovskite-silicon solar cell research collaboration hits 25.2% efficiency

15.06.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>