Could surrogate chickens save other birds from extinction?

The chicken or the egg: If a research team achieves their goal, this eternal question may be answered for some poultry breeds.

Researchers working toward a science fiction version of the cuckoo's reproductive strategy may have just taken a leap forward.

Some species of cuckoos, ducks, honeyguides, and other birds lay their eggs in other birds' nests so others will inadvertently adopt their young in what is called intraspecific brood parasitism. Scientists think they could harness such a concept to help save rare bird breeds from endangerment and extinction by boosting their population sizes, but their process would start much earlier: with surrogate birds developing other birds' eggs.

Now, researchers say they have created ideal surrogate chickens: hens that do not lay their own eggs. Although these chickens could not produce their own chicks, they were otherwise healthy, the research team reports in a paper published last week in the journal Development.

"These chickens are a first step in saving and protecting rare poultry breeds from loss in order to preserve future biodiversity of our poultry from both economic and climate stresses," said the leader of the research team, Mike McGrew of the University of Edinburgh's Roslin Institute, in a press release.

To develop these egg-less surrogate chickens, Dr. McGrew and his team harnessed new genetic editing techniques. Using a tool called TALEN, the scientists deleted a section of the chicken's DNA known to be crucial for bird fertility. 

The gene they targeted, called DDX4, helps generate primordial germ cells, the specialized cells that ultimately develop eggs. The idea is that by halting the surrogate chicken's own primordial germ cell production, scientists would have an opening to implant the primordial germ cells from other bird breeds. 

Although this step of the process – the implantation – has yet to be done, the idea is that the chicken would lay the egg as if it was its own.

Though it may sound far-fetched, the idea is feasible, at least theoretically, says F. Abel Ponce de León, a professor of genomics and molecular genetics at the University of Minnesota who was not involved in the research.

"The experiment is well designed and conclusions are well supported by the data," Dr. Ponce de León tells The Christian Science Monitor in an interview. However, the idea that implantation could become a tool for conservation of species is "only speculation until the proper experiments are done."