It has now been proven that chimpanzees are the closest living relatives to humans on this planet with genomes that are almost 99% identical to our own. But if we really are that closely related on paper, what are the causes of the vastly different structural, behavioural, and mental variations that occur between the two species? With the help of innovative new research from the University of Toronto's Centre for Cellular and Biomolecular Research, potential new explanations to this conundrum have finally been uncovered. In performing several comparisons between the heart and brain tissue extracted from humans and chimpanzees, University of Toronto Professor Benjamin Blencowe and his team, including graduate student researcher John Calarco, have discovered considerable differences in the way mRNA is spliced during protein production (ScienceDaily, 2007).
"It's clear that humans are very different from chimpanzees on several levels, but we wanted to find out if it could be the splicing process that accounts for some of these fundamental differences," says Blencowe, a professor with
the Banting and Best Department of Medical Research and Department of Molecular Genetics (ScienceDaily, 2007).
"The surprising thing we found was that six to eight per cent of the alternative splicing events we looked at were showing differences, which is quite significant. And those genes that showed differences in splicing are associated with a range of important processes, including susceptibility to certain diseases" (ScienceDaily, 2007).
mRNA splicing is the process of protein production that occurs following the transcription phase of protein production in which the primary RNA transcript is modified before leaving the nucleus to be translated by a ribosome. This process of modification involves the attachment of a splicesome, formed from several ribozymes and protein molecules, to the pre-mRNA molecule which then removes the non-coding portions of RNA called introns and splices together the two adjacent exons. The variation that comes about from this process is determined by a function called alternative RNA splicing, in which different sections of the genetic code are treated as exons during RNA splicing, thus allowing many different proteins to be created from the same gene. The new findings have confirmed that this rocess of exon recognition differs significantly between humans and chimpanzees, thus creating some of the major differences between the two species.
The study, which has now made its appearance in the Journal of Genes and Development, is likely to have positive implications for the future study of disease in chimpanzees and humans. This study is one of the essential steps in identifying and understanding why different diseases will have large effects one species and not the other.
http://www.sciencedaily.com/releases/2007/11/071114151513.htm
http://www.mukto-mona.com/Articles/jaffor/evolution080306.htm
University of Toronto (2007, November 15). Humans And Chimps Differ At Level Of Gene Splicing. ScienceDaily. Retrieved April 15, 2008, from http://www.sciencedaily.com /releases/2007/11/071114151513.htm
By: Thomas Bennett, 41761902
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