Dinokurs
In the USA, chickens with dinosaur faces were created
American biologists have created chicken embryos with dinosaur faces, suppressing the development of proteins with which beaks are formed in the embryos. The experiment is reported in the journal Evolution (Bhullar et al., A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertical history), and the results of the study are briefly outlined by Nature News & Comment ('Dino-chickens' reveal how the beak was born).
The goal of the scientists was not to create mutants and not to resurrect dinosaurs using genetic engineering methods – they sought to understand how the process of turning muzzles into beaks in reptiles (future birds) was going on at the molecular level. It is known that the beak of lizards originated from two small bones (interjaw), elongated and joined into one structure.
Biologists led by Arhat Abzhanov from Harvard and Bhart-Anjan Bhullar from Chicago compared the development of embryos of modern birds and reptiles. It turned out that FGF and Wnt proteins are expressed differently in the body of these groups of animals: in reptiles they are active in two small areas of the fetus that turn into a muzzle, and in birds - in a wide band on a similar site.
To test this hypothesis, scientists injected chemicals into chicken embryos that block the activity of FGF and Wnt proteins. According to the research protocol approved by the university authorities, the mutant embryos were not brought to birth: changes in their anatomy were monitored in the last days of fetal development.
In some birds, the mandibular bones remained connected, in others – separate and short. Digital models of skulls showed that the bones in many of them turned out to be more similar to the cranial bones of the first birds (like archaeopteryx) and dinosaurs (such as velociraptor) than to the bones of ordinary chickens.
A frame from the video below
However, the identification of the genetic base of beaks is still far away: these can be both genes encoding FGF and Wnt, and genes of related biochemical reactions – as well as "regulating" DNA that affects gene expression.
Paleontologist Jack Horner, known for his project to grow dinosaurs from chickens, took Abzhanov and Bhullar's work with enthusiasm. Horner identified genetic mutations responsible for the disappearance of the tail in modern birds, but it has not yet been possible to influence them in practice (too many components are involved in the formation of the tail). Manipulation of proteins responsible for embryonic development seems to the paleontologist to be a very valuable method.
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14.05.2015