Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Aggregation of cloned mouse embryos improves survival rate


Scientists at the University of Pennsylvania have found a novel way to boost the paltry survival rate of cloned mammals: When two genetically identical cloned mouse embryos are combined, the aggregate embryo is considerably more likely to survive to birth.

A team from Penn’s School of Veterinary Medicine reports the results in the Oct. 1 issue of the European Molecular Biology Organization Journal.

"At the blastocyst stage, an early embryonic stage just prior to implantation, mouse clones typically have a much lower than normal number of cells," said corresponding author K. John McLaughlin, assistant professor of animal biology. "When we combined two clones at the four-cell stage, the embryos showed a remarkable improvement in viability, much greater than expected from the sum of their parts."

Despite the successful cloning of sheep, pigs, cats and most recently rats, mammalian cloning -- in which an ordinary cell’s nucleus is transferred to an egg whose nucleus has been removed -- remains remarkably inefficient. Of every 100 cloned mice, roughly one survives to birth.

The researchers found that when the clone hybrids were transferred back into the uteri of recipient mice, the survival rate jumped to 8 percent. The researchers even produced a litter of four cloned mouse pups, in stark contrast to the typical single pup born.

Cloning requires the precise genetic reprogramming of the nucleus inserted into an enucleated egg. This nucleus must abandon its former genetic program and adopt the genetic profile of an embryonic nucleus; failure to do so dooms the embryo.

"The paper provides a new insight into reprogramming following nuclear transfer," said Davor Solter, a developmental biologist at the Max-Planck Institute of Immunobiology who was not involved in this work. "It confirms indirectly that every cloned embryo is actually different and that reprogramming is random. It seems that two embryos which are epigenetically different can positively interact and complement each other leading to correct temporal and spatial gene expression. That this type of interaction can take place was not obvious and it could only be demonstrated by the described approach."

McLaughlin and his colleagues aren’t yet sure why the aggregation of cloned embryos boosts survival, although one theory is that the combination of two embryos helps compensate for genetic deficiencies in either.

"The genetic reprogramming of a cloned embryo never seems to occur with 100 percent accuracy," he said. "However, the group of genes that fails to reset properly differs in each individual embryo, meaning that each embryo that contributes to an aggregate can help mask the shortcomings of the other. By combining cloned embryos, you might end up with an embryo that’s 99 percent reprogrammed rather than just 90 percent."

When McLaughlin and colleagues cut wild-type mouse embryos in half, they found that the expression of key developmental genes was not affected, suggesting that the developmental deficiencies of cloned embryos are not due to low cell counts alone. They speculate that cells in a blastocyst may communicate in a way that is compromised in a smaller cloned embryo.

McLaughlin’s co-authors on the EMBO Journal paper include Michele Boiani, Sigrid Eckardt, N. Adrian Leu and Hans R. Schöler, all of Penn’s Center for Animal Transgenesis and Germ Cell Research. Their work was funded by the Marion Dilley and David George Jones Funds, the Commonwealth and General Assembly of Pennsylvania, the National Institutes of Health, the University of Pennsylvania Research Foundation and the United States Department of Agriculture.

Steve Bradt | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

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

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>