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240 mya Protein Recreated


Call it "Triassic Park": with statistics, instead of amber-preserved DNA,
researchers at the Howard Hughes Medical Institute at The Rockefeller
University and Yale University recreated in the test tube a functional
pigment that would have characterized the eyes of archosaurs ("ruling
reptiles") and allowed these direct ancestors to dinosaurs to see in dim

The pigment, rhodopsin, was recreated based on the scientists "inferring"
its protein sequence.

Their findings, reported in the September issue of Molecular Biology and
Evolution, offer the first look at a protein that has not been seen in 240
million years, and pave the way for scientists to study how the structure
and function of vision pigments -- and ultimately other biologically
important molecules -- have changed over the course of evolutionary time. 
"Recreating the inferred visual pigments of the archosaur ancestors in the
laboratory should be a first step toward a better understanding what they
could see -- and not see," adds Sakmar, an HHMI associate investigator. 

In their journal paper, Sakmar and his colleagues report that archosaurs
may have had a class of visual pigments that would support dim-light
vision. "This is consistent with the intriguing though controversial
possibility that nocturnal, not diurnal, life histories may have been the
ancestral state in amniotes, which are birds, reptiles and mammals whose
embryos are protected with a fluid-filled sac," says Belinda S.W. Chang,
Ph.D., first author and research assistant professor at Rockefeller. "We
are doing further biochemical studies on this recreated pigment to clarify
this issue."