Scientists have managed to edit the genome of domestic chickens so that in the future they may be able to lay eggs from different breeds. It is hoped that this could then be used to produce common hens that will be able to give birth to genetically pure rare breeds at risk of disappearing forever.
These are quite surprisingly the first gene-edited birds ever produced in Europe. The genetic modification of birds has lagged significantly behind that of mammals, due mainly to the complexity of birds' eggs. This means that the production of the sterile hens through altering the gene responsible for the production of the individual’s germ line is an important step forward. The research is published in the journal Development.
It leads to the very real possibility of inserting germ line cells from other breeds of chickens into the developing sterile embryo while it is still inside the egg, so that when it hatches, the bird would go on to lay eggs from the transplanted breed. This would also require that the surrogate hen being inseminated with sperm is from the same breed that its eggs belong to, but this is done regularly with many domestic birds anyway, although it should also be possible to create male birds with semen from other breeds.
In 2010, researchers in Dubai reportedly manipulated male chickens to produce the sperm from vulnerable Houbara bustards, a game bird that is popularly hunted in the Middle East. The semen from these cockerels was then taken and used to artificially inseminate female bustards, and produced healthy, genetically pure Houbara bustards.
Whether or not this technique could be used to get common chickens to become surrogate mothers to rare and endangered, but unrelated species is yet to be seen. It is unlikely, for example, that the hens would be able to give birth to eagle chicks, but it could lead to other more closely related species being used to boost the populations of birds struggling to breed.
But the main use for this technology would be to preserve the genetic diversity of chickens. As the most populous domestic animal, chickens are a vital creature. With threats such as bird flu that have the potential to wipe out entire populations, the preservation of rare breeds that may harbor genetic variation could be invaluable, in a similar way to how scientists are creating seed banks to preserve crop varieties that could be used to increase plant diversity in the future.
To do this, researchers have created the "frozen aviary", and this latest study means that it will be possible to freeze germ line cells rather than whole eggs, increasing dramatically the potential for them to be successfully revived in the future and inserted into the modified hens.