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-----Original Message----- From: Kathleen Cochran <[log in to unmask]> Sent: Sunday, March 29, 2009 12:00 AM To: [log in to unmask] Subject: Re: Therapeutic Cloning gets boost This sounds like very good news. Kathleen 2009/3/27 rayilynlee <[log in to unmask]> > Therapeutic Cloning Gets A Boost With New Research Findings > > ScienceDaily (Mar. 26, 2009) - Germ cells, the cells which give rise to a > mammal's sperm or eggs, exhibit a five to ten-fold lower rate of spontaneous > point mutations than adult somatic cells, which give rise to the body's > remaining cell types, tissues and organs. Despite their comparatively higher > mutation rates, however, adult somatic cells are used as the donor cells in > a cloning process called somatic cell nuclear transfer (SCNT). This made > researchers wonder if cloning by SCNT leads to progeny with more mutations > than their naturally conceived counterparts. Also, would cloned fetuses > receive DNA programming predisposing them to develop mutations faster than > natural fetuses of the same age? > Those scenarios are simply not likely, say researchers at The University of > Texas at San Antonio, The University of Texas Health Science Center at San > Antonio and The University of Hawaii at Honolulu's John A. Burns School of > Medicine. The team, which spent more than five years analyzing mutation > rates and types in cloned Big BlueŽ mouse fetuses recently published its > findings in the online Early Edition of the Proceedings of the National > Academy of Sciences in a paper titled "Epigenetic regulation of genetic > integrity is reprogrammed during cloning." > > The paper offers the first direct demonstration that cloning does not lead > to an increase in the frequency of point mutations. > > John McCarrey, professor of cellular and molecular biology at UTSA and the > study's principal investigator, suggests a "bottleneck effect" is partially > responsible for the observations his team recorded. "To create a cloned > fetus by somatic cell nuclear transfer, only one adult somatic cell -- one > donor cell -- is needed," he explains. "Because a random cell population > exhibits a low mutation rate overall and only one cell from that population > is used for cloning, the likelihood is remote that the cell chosen to be > cloned will transfer a genetic mutation to its cloned offspring. Therefore, > the bottleneck effect limits the transfer of mutations from donor cells to > cloned offspring." > > Not only did the researchers find that SCNT does not lead to an increase in > the frequency of point mutations in cloned mice, the team also found that > naturally conceived fetuses and cloned fetuses that are the same age have > similar rates of spontaneous mutation development. They attribute this > finding to epigenetic reprogramming. > > It is known in the scientific community that germ cells contain an > epigenome, a programmed state of the genome, that keeps mutation rates low. > They suggest this type of epigenome is found in germ cells because those > cells are responsible for contributing genetic information to subsequent > generations. Adult somatic cells (the donor cells in SCNT) have higher > mutation rates and less stringent epigenetic programming to avoid mutations > than germ cells, but offspring produced from somatic cells by cloning have > mutation rates similar to those in offspring produced by natural > reproduction, suggesting that the epigenome of an adult somatic cell is > reprogrammed during cloning to maintain the genetic integrity of that cell's > progeny. > > Journal reference: > Patricia Murphey, Yukiko Yamazaki, C. Alex McMahan, Christi A. Walter, > Ryuzo Yanagimachi, and John R. McCarrey. Epigenetic regulation of genetic > integrity is reprogrammed during cloning. Proceedings of the National > Academy of Sciences, 2009; 106 (12): 4731 DOI: 10.1073/pnas.0900687106 > Adapted from materials provided by University of Texas at San Antonio, via > EurekAlert!, a service of AAAS. > > Rayilyn Brown > Director AZNPF > Arizona Chapter National Parkinson Foundation > [log in to unmask] > ---------------------------------------------------------------------- > To sign-off Parkinsn send a message to: mailto: > [log in to unmask] > In the body of the message put: signoff parkinsn > ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn