Researchers have taken cloning technology one step further by getting eggs from a cow to accept genes from other species - sheep, pigs, rats and even primates, one level away from man.
Using the same technology that created Dolly the sheep, the world's first adult mammal clone, University of Wisconsin-Madison researchers took cow eggs, stripped them of their genetic material and got them to grow and start functioning with new DNA from other species.They created 70 such inter-species embryos and grew them to a 60-to-120-cell stage that is considered viable for implantation. The researchers have made six or seven attempts at pregnancy so far, but none has succeeded.
But the findings suggest many potential uses. Among them: creating animal organs for human transplantation, getting animals to produce antibiotics or other useful substances, preserving endangered species and propagating commercially valuable animals such as racehorses or prized cows.
The work was to be reported Monday in Boston at a meeting of the International Embryo Transfer Society.
It was done in the lab of noted genetics researcher Neal First, a UW professor of animal science, at the suggestion of UW staff scientist Tanja Dominko.
UW's work "is a starting point" to creating cross-species cloned animals, said Jorge Piedrahita, an embryologist and sheep cloning researcher at Texas A&M University, adding, "It's going to be quite a bit of work to get it from where it's at (now) to a viable pregnancy."
"The potential is there," First said. "If we had offspring, it would have been a reality."
John Van Blerkom, a professor of molecular biology at the University of Colorado, said the work revealed "a fundamentally important biological finding."
"The egg doesn't care what kind of nucleus it is" that is inserted, he said. Once its own DNA has been removed, it will grow and take instructions from whatever new DNA has been added, he said.
This is akin to taking an entire factory of workers who have been making one product a certain way, giving them a new boss and telling them to make something entirely different. In biological terms, getting the egg of one species to be ruled by another species' DNA is like teaching a fish to fly.