DNA sequences that are maintained across species over the course of their evolution are said to be conserved. A portion of these conserved sequences shows a particularly high level of similarity across species, indicating that a process is at work, called purifying selection, in which changes in the DNA are rejected. Previously, scientists assumed that purifying selection maintains most regulatory regions in the genomes of animals because these regions are involved in important biological functions. However, recent research has shown that many of the DNA segments bound by proteins that can influence gene expression are not under strong purifying selection.
To find out if the DNA segments bound by GATA1 are capable of regulating genes, the scientists investigated the extent to which they could trigger the expression of a gene after introducing GATA1-bound DNA segments into red blood cells. The scientists cut these GATA1-bound DNA segments out of the mouse's genome and reintroduced them into mouse red blood cells along with a gene from a firefly that is responsible for the insect's ability to produce light. The team's goal was to determine if GATA1 would bind to the regulatory regions and turn on the activity of the firefly gene.
"We wanted to know if the level of gene activity would change and, if it did change, how much it would change," said Hardison. The team found that 52 percent of the GATA1-bound regions increased gene activity two-fold and that 28 percent of the regions increased gene activity three-fold. "We think that some o
'/>"/>
| Contact: Barbara K. Kennedy science@psu.edu 814-863-4682 Penn State Source:Eurekalert |