CBSE NEWS

Haussler lab research listed among Discover Magazine's top 100 science stories of 2006

Tuesday, January 9, 2007
Written by Branwyn Wagman

Research from David Haussler’s laboratory made the list of “top 100 science stories of 2006, published by Discover Magazine. Story number 58, “Why we are not chimps,” recapped the discovery of an RNA gene called HAR1 that has undergone accelerated evolutionary change in humans and is active during a critical stage in brain development. Evidence suggests that this gene may play a role in the development of the cerebral cortex and may even help explain the dramatic expansion of this part of the brain during human evolution.

The discovery arose from a bioinformatic analysis conducted by Katherine Pollard, who was then a postdoc working in the Haussler lab. The analysis showed that HAR1 is essentially the same in all mammals except humans. There were only two differences between the chicken and chimp genomes in HAR1's sequence of 118 bases (bases are subunits of DNA, the As, Cs, Ts, and Gs that spell out the genetic code)

This similarity means the DNA sequence remained unchanged over hundreds of millions of years of evolutionary history, an indication that it performs a biologically important function. But sometime after the human lineage diverged from its last common ancestor with chimpanzees 5 to 7 million years ago, HAR1 began to change rather dramatically.

We found 18 differences between chimps and humans, which is an incredible amount of change to have happened in a few million years," Pollard said.

Once additional laboratory work confirmed the HAR1 gene’s activity in the developing brain, the findings were published as an article in Nature in September of 2006.

In addition to Haussler and Pollard (now at UC Davis), the coauthors of the Nature paper include Pierre Vanderhaeghen, Nelle Lambert, Marie-Alexandra Lambot, and Sandra Coppens of the Institute for Interdisciplinary Research (IRIBHM) at the University of Brussels; Sofie Salama, Jakob Pedersen, Sol Katzman, Bryan King, Courtney Onodera, Adam Siepel (now at Cornell University), and Andrew Kern of UCSC's CBSE; Colette Dehay of the Université Claude Bernard Lyon, France; and Haller Igel and Manuel Ares of UCSC's Center for Molecular Biology of RNA and Department of Molecular, Cell, and Developmental Biology.