The next question that they asked was if the human and chimp elements have sequence differences, why do they still function similarly. They took the chimp version, placed it in an identical construct in mice and found that the human and chimp sequences have very different expression properties.
"Our results led us to believe that HACNS1 has contributed to uniquely human aspects of digit and limb patterning," Rubin said. "We suspect the gain of function in HACNS1 may have influenced the evolution of these or other human limb features by altering the expression of nearby genes during limb development."
The researchers have yet to define the precise molecular mechanism by which the substitutions in HACNS1 confer the human expression patterns. "To get a more complete picture of our HACNS1 factors into human morphological evolution will require additional studies," Rubin said.
"If this really is deterministic, you should see some type of change. But it will be a long, hard path forward," according to Rubin.
|Contact: David Gilbert|
DOE/Joint Genome Institute