NEW YORK, April 11, 1997 (UPI) -- The hoopla greeting Dolly, the first successful clone of a mammal, may have made some people fear that armies of human clones were just around the corner.
But scientists close to the breakthrough say many unanswered questions about their one little lamb remain. Alan Colman, research director for PPL Therapeutics in Edinburgh, Scotland, says that scientists still don't know if genes from the 6-year-old mother will transmit age-related genetic weaknesses to the clone.
And although Dolly looks like a normal sheep -- albeit something of a ''self-made prima donna," Colman says, because of all the recent attention -- they still don't know if she is. They plan to try to answer one question, whether she can have lambs of her own, by breeding her soon. But, says Colman, even then, many other questions will remain.
''It's back to the drawing board. Let's try to understand the biology,'' says Colman.
At a biotechnology conference held Friday at Hunter College in New York, Colman said researchers still don't know if Dolly has shorter telomeres than the average lamb. Telomeres, genetic tags at the ends of chromosomes, are thought to control the aging of cells. If Dolly has inherited the telomeres of her 6-year-old mother, she may be growing old prematurely.
''The animal doesn't look old,'' he says, but studies are currently underway to find out if her telomeres are actually shorter.
They also don't know if Dolly will be more susceptible to tumors and other problems that arise in middle and old age. Another question is whether Dolly has one mother or two, because the researchers don't know yet if the host egg makes some genetic contribution.
In addition to the major genes in the nucleus, cells have small genetic structures, known as mitochondria, outside the nucleus. The mitochondria, which produce energy for the cell, may in some way alter the offspring.
Once scientists answer these questions, they hope to be able to use this technology to ultimately produce ''instant flocks'' of genetically identical animals. The advantage to this will come from combining cloning with transgenics, in which DNA is added to produce drugs for human diseases.
One such protein, from PPL's transgenics program, is now in clinical trials to treat cystic fibrosis. Cloning transgenic animals would eliminate a great deal of time, expense and guesswork of more conventional breeding methods, says Colman.
