A recent study was published in "Neuron," that included maps of the X-chromosome inactivation. "They found a remarkable complexity to the pattern in which the chromosomes were switched on and off," according to Zimmer.
Females have two copies of the X-chromosome, each of which has different versions of the genes not found on the other. This allows for one or the other to be used in the cell, leading to more genetic diversity than males. If one of the genes has a weakness -- the other can be used.
"Females simply have access to realms of biology that males do not have," Huntington Willard, the director of Duke University's institute of Genome Sciences & Policy noted.
The recent published research led by Dr. Nathans showed illuminated maps of where different X-chromosomes were activated in various cells within the bodies of mice. Nathans "speculates that using chromosomes from both parents is especially useful in the nervous system. It could create more ways to process information. 'Diversity in the brain is the name of the game.'"
What shuts down the second X-chromosome? It's a number of molecules, led by what has been named the Xist.
Dr. Lee, a Howard Hughes Medical Institute investigator at Harvard Medical School, has found that when the Xist is inactivated and the second X-chromosome is allowed to be active, it creates extra proteins. These extra proteins can drive a cell to grow uncontrollably. This additional uncontrollable growth makes cancer is more likely.
Women's brains are created differently, on the molecular, cellular level. What does this mean? I'm not sure, but I'm fascinated. Now that we know Xist exists, maybe we can determine how it becomes inactive -- and ensure it remains inactive.
To me, this new research is both mind-blowing and potentially life-saving.