Scientists have suppressed a gene during the embryonic development of chickens to see if they can make their feathers more like those of dinosaurs. This image shows feather buds on day 12 of incubation. (Image credit: © Rory Cooper & Michel Milinkovitch (CC BY))
By interfering with a key gene, the researchers were able to make chicken feathers more dinosaur-like, but the effects were short-lived.
In a recent study, scientists silenced a gene during embryonic growth to transform chicken feathers into more primitive structures, similar to the simple tubular protofeathers thought to have first appeared on dinosaur ancestors in the Early Triassic period 250 million years ago.
They succeeded – but only temporarily. The broods showed delays in feather development and bare patches when hatched, but after a few weeks their plumage returned to normal for birds.
The study is part of a larger effort to understand how and why feathers evolved. Scientists previously changed the same gene to make chickens' scaly feet feathery, but reversing feather evolution has proven more difficult.
“Our experiments show that while temporary interference with the development of leg scales can permanently transform them into feathers, it is much more difficult to permanently alter feather development itself,” explained senior author Michel Milinkovitch, a professor of genetics and evolution at the University of Geneva. “It is clear that evolution has shaped a network of interacting genes that has become extremely robust, ensuring that feathers develop correctly even under significant genetic or environmental changes.”
That the researchers were unable to create permanently feathered, dinosaur-like chickens doesn’t detract from the success of the study. Milinkovic and his co-author Rory Cooper, now a research fellow at the University of Sheffield in the UK, demonstrated the importance of a particular gene, whimsically named “Sonic Hedgehog,” in the evolution of feathers. By interfering with this gene, the researchers were able to temporarily disrupt the process of feather formation.
Modifying the Sonic Hedgehog gene can alter various aspects of development in chickens. For example, temporarily boosting the gene can permanently transform scales on the legs into feathers. But researchers have found that it is much harder to disrupt the development of the feathers themselves.
The first feathers weren't the complex, branched structures of today's feathers. They were individual tubes that resembled tiny drinking straws. To understand how evolution transformed everything from soft down to colorful peacock feathers from these simple forms,
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