Wednesday, November 2, 2011
Think your brain and genes are "special"?
“Essentially, we carry the same genes as mice". ”What distinguishes our brain is mRNA levels". The greatest changes occur before birth, and during midlife (50's to 70's).
From Science News/Laura Sanders, 10/28/11. "Human brains all work pretty much the same and use roughly the same genes in the same way to build and maintain the infrastructure that makes people who they are, two new studies show. And by charting the brain’s genetic activity from before birth to old age, the studies reveal that the brain continually remodels itself in predictable ways throughout life. In addition to uncovering details of how the brain grows and ages, the results may help scientists better understand what goes awry in brain disorders such as schizophrenia and autism.
.....In the studies, published in the Oct. 27 Nature, researchers focused not on DNA — virtually every cell’s raw genetic material is identical — but on when, where and for how long each gene is turned on over the course of a person’s life. To do this, the researchers measured levels of mRNA, a molecule whose appearance marks one of the first steps in executing the orders contained in a gene, in postmortem samples of donated brains that ranged in age from weeks after conception to old age.
.....These different patterns of mRNA levels distinguish the brain from a heart, for instance, and a human from a mouse, too, says Nenad Šestan of Yale University School of Medicine and coauthor of one of the studies. “Essentially, we carry the same genes as mice,” he says. “However, in us, these genes are up to something quite different.”
.....Both studies found lots of variation in gene behavior at different life stages, but one particular period stood out: The prenatal brain had massive changes in gene activity. Many genes there were pumping out big quantities of mRNA, and this production abruptly slowed after birth. “Prenatally, things are changing faster than they change at any other time,” says Carlo Colantuoni of the Lieber Institute for Brain Development at Johns Hopkins University Medical Center, and coauthor on one paper. “Things are happening fast in there.” Kleinman and his colleagues turned up a curious finding: Many of the genes that slow down right after birth show a surge of activity as a person gets older. “The biggest changes that are going on occur fetally,” he says. “And then they drop off until mid-life, and then in the 50s to 70s, expression changes pick up again and become quite dramatic.” Full article...
Posted by Kathy Meeh