Genetic comparisons between humans and other animals have identified a gene that may help in making humans unique. Intriguingly, the gene is expressed during the embryonic development of the neocortex, the site of many of the brain's most sophisticated processes.
Researchers led by David Haussler initially found the genetic sequence by comparing the human genome with those of the chimp, mouse and rat in a bid to find regions that have evolved particularly rapidly since we diverged from these other species, and which might, therefore, have been key players in shaping human evolution.
Now, as they report in a paper published online by Nature (Vol. 442, No. 7104, 17 August 2006), they have found that this genetic region contains a gene, called HAR1F, which is expressed during brain growth before birth. The gene, which produces an RNA molecule rather than a protein, is expressed in cells called Cajal-Retzius neurons during the crucial period of 7 to 19 weeks of gestation, when many of the nerve cells of the neocortex are establishing their functions within the brain.
David Haussler (Howard Hughes Medical Institute and University of California, Santa Cruz, CA, USA)
Chris P. Ponting (University of Oxford, Oxford, UK)
(C) Nature press release.
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