Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cells reprogram in 24 hours

19.04.2002


Erasing molecular memory of parents could shed light on clones.

Cells naturally wipe out the mark of their parents in 24 hours, say cloning experts. Exactly how may begin to explain the way that animal clones and stem cells are reprogrammed. Not all genes are born equal. In mammals, some genes are imprinted - cells switch on only the copy inherited from mum or dad, not both. This sex stamp must be erased and rewritten in sperm and egg cells, however, so they are correctly labelled as male or female when they fuse to form the next generation.

The deletion occurs in as little as a day, Fumitoshi Ishino of the Tokyo Institute of Technology in Yokohama, Japan, and his team have now shown. Even as an embryo is growing, the cells destined to form its ovaries and testes are scrubbing out established patterns of gene activity1.



The finding begins to unravel how cells overwrite their history, explains Azim Surani of the Wellcome/CRC Institute in Cambridge, UK. This is something researchers working on cloning and stem cells long to find out. "Any information we get is bound to be helpful," says Surani.

Programming skills

Hours after fertilisation sperm and egg overwrite their DNA with instructions for making an embryo - imprints remain intact. Cloned mammals are thought to die early or suffer ill health partly because this reprogramming is incomplete; in clones made from some cell types, imprinting is upset as a result.

Some of the cell machinery that erases imprints may also do reprogramming, says Wolf Reik, who studies these phenomena at the Babraham Institute in Cambridge, UK. "I’m sure there are going to be parallels."

Once found, the molecules involved might be harnessed to improve the efficiency of cloning. Similarly, adult stem cells might be better persuaded to rewrite their normal instructions and generate unusual cell types.

But cloning researcher Rudolf Jaenisch of the Whitehead Institute in Cambridge, Massachusetts, is not convinced that the two processes - removing imprinting and reprogramming - are comparable. He says that cloning shortcuts the natural process.

Wipe out

Ishino’s team believe that, under the right conditions, the imprint on a donor cell’s DNA is carried unaffected into the clone. They used this to test when nuclear imprinting is erased in a growing embryo.

The group made clones from the cells in mice embryos that give rise to ovary and testes. They took the cells at different stages of embryo development. Cells taken after imprinting had been erased gave rise to clones that died very young, they found. Clones from cells that still had some imprinting lasted longer.

Midway through an embryo’s growth, genes lose their sex bias and switch into a default state in a day, the researchers conclude. Chemical gags are removed from genes one by one, to make the activity of both copies equal. The speed suggests that the imprinting pattern is actively wiped out, says Reik, rather than being lost passively over many cell divisions.

The experiments also add to growing evidence that embryos cannot survive without correct imprinting. "Clones that have no parental information do not develop to term," says Ishino. Similarly, embryos carrying two copies of either the mother or father’s genes cannot survive.

References
  1. Lee, J. Erasing genomic impinting memory in mouse clone embryos produced from day 11.5 primordial germ cells. Development, 129, 1807 - 1817, (2002).


HELEN PEARSON | © Nature News Service

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>