Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How to make chromosomes from DNA

29.07.2015

Restoration of DNA structure shown to be prerequisite

Researchers at the University of Tokyo have discovered a long-overlooked process important for converting a long, string-like DNA molecule into a chromosome. This finding gives us a better understanding of the mechanism of how cells store safely genetic material, DNA.


*Model of condensin function revealed by the present study. © 2015 Takashi Sutani

DNA molecules are long, string-like polymers storing the genetic information of life and, in a cell, are tightly packed into structures called chromosomes. Formation of chromosomes in a dividing cell is required for faithful transmission of information in DNA to daughter cells. The condensin complex is known to play an essential role in assembling chromosomes, but it remains unknown how condensin is involved in folding of DNA molecules.

Researchers at the University of Tokyo, including Assistant Professor Takashi Sutani, Professor Katsuhiko Shirahige (Institute of Molecular and Cellular Biosciences) and Ph.D student Toyonori Sakata (Graduate School of Agricultural and Life Sciences), isolated from cells and analyzed DNA segments to which condensin binds, and revealed that condensin is associated with single-stranded DNA (ssDNA) which is produced by unwinding of the DNA double-helix.

By measuring the amount of ssDNA using an ssDNA binding protein, they found that ssDNA regions existed at expressed genes and were produced by gene expression (or transcription), and that ssDNA amount was further increased in condensin-deficient cells.

They also discovered that chromosome segregation defects in mutant cells that showed lowered levels of condensin function were largely rescued by transcription inhibition. They therefore concluded that ssDNA is produced by unwinding of double-stranded DNA during transcription, that ssDNA is detrimental to assembling chromosomes, and that condensin restores unwound ssDNA segments to double-stranded DNA.

“It was widely believed that unwound DNA segments return spontaneously to canonical double-helical DNA, but this study has revealed that restoration of double-stranded DNA is actively regulated and is important for cell survival. It has also demonstrated for the first time that the presence of ssDNA impedes chromosome organization, providing insight into the mechanism of chromosome formation,” says Assistant Professor Sutani.

This work was conducted in collaboration with the research group of Dr. Tatsuya Hirano (Chief Scientist at RIKEN Institute, Japan).

Image*
Condensin recognizes unwound DNA segments produced by gene expression and restores them to double-stranded DNA. This function proved to be a prerequisite for making chromosomes from DNA.

Paper
Takashi Sutani, Toyonori Sakata, Ryuichiro Nakato, Koji Masuda, Mai Ishibashi, Daisuke Yamashita, Yutaka Suzuki, Tatsuya Hirano, Masashige Bando & Katsuhiko Shirahige, "Condensin targets and reduces unwound DNA structure associated with transcription in mitotic chromosome condensation", Nature Communications Online Edition: 2015/7/23 (Japan time), doi: 10.1038/ncomms8815.


Associated links
UTokyo Research article

Euan McKay | ResearchSea
Further information:
http://www.researchsea.com

Further reports about: DNA DNA molecules DNA segments Hirano Takashi chromosomes double-stranded DNA

More articles from Life Sciences:

nachricht New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego

nachricht Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Novel 3-D printing technique yields high-performance composites

16.01.2018 | Materials Sciences

New application for acoustics helps estimate marine life populations

16.01.2018 | Life Sciences

Fast-tracking T cell therapies with immune-mimicking biomaterials

16.01.2018 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>