Published on November 16, 2007

99 Percent similar but highly different

Scientists are closer to understand why although 99 per cent of the human and chimpanzee genes are identical, there are vast differences in the way the two look, behave, think and react to pathogens.

Professor Benjamin Blencowe and his team from the University of Toronto's
Centre for Cellular and Biomolecular Research have discovered possible new explanations for these differences. They have discovered significant differences in the way genetic material is spliced to create proteins by comparing brain and heart tissue from humans and chimpanzees.

“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,” said Blencowe. “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.”

Gene splicing involves cutting out part of the DNA in a gene and adding new DNA in its place to generate genetic messages that specify the production of proteins, the building material for the cells.

The process is entirely chemical with restriction enzymes used as chemical scalpel. Splicing can occur in alternative ways in the same genetic message to generate isoform proteins.
In this way, alternative splicing facilitates the synthesis of a greater variety of proteins.The new findings reveal that the alternative splicing process differs significantly between humans and chimpanzees.

“Identifying what makes us different can be very important to understanding why certain diseases affect one species and not the other,” said Blencowe.