“Latest Stem Cells News”

Researchers have created mammalian cells containing a single set of chromosomes in research funded by the Wellcome Trust and EMBO. The technique should allow scientists to better establish the relationships between genes and their function.

Mammal cells usually contain two sets of chromosomes – one set inherited from the mother and one from the father. The genetic information contained in these chromosome sets helps determine how our bodies develop. Changes in this genetic code can lead to or increase the risk of developing disease.

To understand how our genes function, scientists manipulate the genes in animal models – such as the fruit fly, zebrafish and mice – and observe the effects of these changes. However, as each cell contains two copies of each chromosome, determining the link between a genetic change and its physical effect – or ‘phenotype’ – is immensely complex.

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For decades, biology textbooks have been clear – our traits are the product of our genes. But a new study by Yale University researchers published Dec. 26 in Nature Genetics suggests another mechanism can regulate variations of traits even in genetically identical individuals.

A particular type of RNA works in concert with a common protein to protect organisms from harmful genetic variations without the help of genes, reports Haifan Lin, director of the Yale Stem Cell Center, professor of cell biology and genetics and senior author of the paper.

“This mechanism may help explain how ordinary cells such as fibroblasts can be converted to stem cells and why some cancers develop at random,” Lin said.

The theory that factors other than genes are responsible for an organism’s traits, or phenotype, has been around for almost 70 years but has only gained steam in the past decade. For instance, cloned animals are often born with different colors than the animals that are the source of their DNA. But what causes these changes remained unclear.

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UC San Diego scientists have dramatically improved the success rate of genetically modifying human embryonic stem cells. This advance brings the promise of better treatment of genetic diseases.
The new approach works in 20 percent of embryonic stem cells, compared to less than 1 percent treated with standard methods, said Yang Xu, a UCSD professor of biology, who led the study, assisted by Hoseok Song and Sun-Ku Chung, postdoctoral fellows in his lab.

The study was published Thursday in the journal Cell Stem Cell.
Some genetic diseases can’t be studied adequately in animals, Xu said, so the ability to produce human cells with the diseases will be of great help. For example, drugs to treat the diseases can be tested in the genetically modified cells, he said.

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