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【bio-news】人脑进化的相关基因（Human brain devel
Altered RNA may help tell the story of how human brains evolved from chimps
变化了的RNA或许帮助了解人类大脑是如何从黑猩猩的大脑进化而来的。
http://www.the-scientist.com/news/display/24326/
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An RNA gene may help unlock the mystery of the evolution of the human brain, according to a report in Nature. By comparing the human genome with the genome of the chimpanzee, the study's authors identified a region that showed the most dramatic shift from chimps to humans, and is expressed by cells that play a role in cortical development -- suggesting that it may help explain what makes the human brain unique.
根据《Nature》报导， 一种RNA基因或许可以帮助我们揭开人类大脑进化的奥秘。在比较人类和黑猩猩的基因组时，这项研究的作者找到了两者间一个有显著不同的基因片段，而此片段的功能表达显示其在大脑皮层的发育方面有一定的作用――暗示这可能有助于解释是什么使人类大脑会如此的独特。
Because the chimpanzee brain is about a third of the size of the human brain, changes in brain development could be key to understanding the evolution of humans. There is a "tantalizing possibility" that this pinpointed gene is involved in that process, study author David Haussler from the University of California, Santa Cruz, told The Scientist.
因为黑猩猩的大脑中仅有人脑的的三分之一大小，大脑发育的发展演变可能是了解人类进化的关键。研究作者，来自Santa Cruz，University of California,的David Haussler告诉 《The Scientist》说："非常可能"，这一特殊基因参与了这个过程。
"One of the great mysteries is how did we come to be so different from our ancestors," Haussler added. "Certainly there are molecular changes in our DNA that have evolved to make our species unique."
“我们现在演变得如此地与我们的祖先不同，是一个巨大的奥秘”Haussler补充道：“当然, 其中也有DNA分子的变化，才使人类进化成了如此独特的物种”
The human genome has undergone an estimated 15 million changes since evolving from our common ancestor with chimpanzees, and researchers are sifting through these changes to understand which are fundamental for human evolution. Many people have focused their search on the protein-coding regions of the human genome to identify important changes. But the great majority of genome alterations -- approximately 99% -- fall within areas that don't code for proteins.
从我们与黑猩猩的共同祖先开始，在进化过程中，人类基因估计发生了1500万个改变。而研究人员正通过筛选, 以了解这些变化中哪些对人类进化至关重要。很多人都着重于研究人类基因组的蛋白编码区域以求发现重大改变。 但绝大多数的基因组改变――约99%――发生在属于非蛋白质编码区域。
As a result, Haussler and his team chose to look at the entire human genome, using an advanced computational screen to search for areas of the genome which experienced few changes between other species, but dramatic differences between chimps and humans. But with approximately three billion bases in the human genome, random drift was a problem, said Haussler. "We had to have something that was more extreme than what you would get in billions of random tries."
因此，Haussler及其团队选择查看整个人类基因，利用先进的计算机系统筛选，来寻找基因组中某些在其他物种中因他物种而有些许不同，而在黑猩猩与人类之间有巨大改变的区域。对大约有30亿个碱基的人类基因组来说，随机漂移是一个问题。Haussler说。“与其进行上亿次的随机尝试，我们必须有一些更多的非常规方法（extreme？help......）
It was a long shot, he said, but the technique identified 49 regions of the human genome that experienced a significant increase in genetic alterations, relative to chimpanzees. Of those regions, HAR1 (human accelerated region 1) showed the most dramatic shift, experiencing 18 changes between humans and chimpanzees, but only two changes between chimpanzees and chickens -- a possible sign that the gene evolved a special function in humans.
长远来看，他说，但在遗传学变化中，已经通过技术鉴定，发现比较黑猩猩，人类基因组在49个区域有明显增加。 在这些区域中，最显着的改变在HAR1区（人类加速区域 1)，人类与黑猩猩之间共有18个改变，但是黑猩猩和鸡之间只有两个改变――表明可能，此基因的进化产生了人类某一特殊功能。
The team went on to characterize HAR1 and found that it was part of an RNA gene. In situ hybridization experiments on human embryonic brain sections revealed that this gene is expressed in Cajal Retzius neurons, which previous studies have found play a role in cortical development by regulating expression of the protein, reelin. When the team looked at reelin localization, they found that reelin and the HAR1 RNA are co-expressed in very specific regions of the brain at particular gestation times.
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作者:admin@医学,生命科学 2011-01-29 05:14
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