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 New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>