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Aug 29, 2007

Study Refutes Theory of How Adult Stem Cells Segregate DNA

  • Contrary to the belief that adult stem cells segregate their DNA in a nonrandom manner during cell division, University of Michigan (U-M) researchers discovered that blood-forming adult stem cells carry out DNA segregation in a random way.

    To test the nonrandom segration theory, or the immortal strand hypothesis, the U-M team administered a DNA-labeling substance called BrdU to mice for several days. Then they extracted the blood-forming stem cells to see how many of them retained BrdU.

    “What we found is that not many stem cells retained it,” says Sean Morrison, Ph.D., director of the Center for Stem Cell Biology at the U-M Life Sciences Institute. “In fact, what happened with the label was completely consistent with what you’d expect by random chromosome segregation and was completely inconsistent, in every context we looked, with the immortal strand model.”

    The experiments also revealed that BrdU is not the general-purpose stem-cell marker many researchers thought it was. By measuring stem cell purity among BrdU-retaining cells, they found it to be “a very insensitive and nonspecific marker,” they report.

    The paper will be published online August 29 in Nature.

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Scientifically Studying Ecstasy

MDMA (commonly known as the empathogen “ecstasy”) is classified as a Schedule 1 drug, which is reserved for compounds with no accepted medical use and a high abuse potential. Two researchers from Stanford, however, call for a rigorous scientific exploration of MDMA's effects to identify precisely how the drug works, the data from which could be used to develop therapeutic compounds.

Do you agree that ecstasy should be studied for its potential therapeutic benefits?

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