It has been four years since Dolly, the cloned sheep, put a reassuringly sweet face on the new era of Frankenstein biology. You would think with all the cloning, genetic engineering, and general monkeying around scientists have done since then, they would have produced at least one grotesque monster. Instead, the mutants just keep getting cuter.
Enter ANDi, the most adorable member of the biotechnology petting zoo yet. ANDi (the name stands for "inserted DNA" backwards) is mostly monkey, rhesus macaque to be precise. But nestled somewhere in his chromosomes is a short stretch of DNA that makes him part jellyfish, too. His birth announcement, made last week in the journal Science, removes what little doubt was left that genetic engineering isn't just for mice and soybeans. As the world's first "transgenic" monkey, ANDi is living proof that the technique can work on our closest biological relatives--and therefore on us.
As disarming as he may appear, ANDi raises more questions than he answers. Scientifically, the experiment demonstrates just how technically difficult it is to do genetic manipulation in higher animals. At the same time, even a preliminary advance with our genetic next of kin ignites all the ethical concerns about tinkering with human DNA and the prospect of designer babies.
Like all of us, ANDi started out as an unfertilized egg. A team of scientists at the Oregon Health Sciences University used a modified virus to carry the jellyfish gene into monkey eggs, which were then injected with sperm and implanted in surrogate mothers. The gene itself is just an easy-to-spot marker used by biologists to test new procedures. But, says team leader Gerald Schatten, now that they've shown the technique works, "We can use the same method to insert almost any gene we want." That would be a boon to researchers hunting for cures for everything from blindness to Parkinson's disease, who currently use genetically modified mice for their work.
Of mice and men. As useful as those lesser critters are, sometimes the differences between mice and humans are too great to make them useful tools for researching human disease. Only primates have a monthly menstrual cycle, for example, which can have important impacts on breast and ovarian cancer. Rodents also lack a macula, the part of the eye's retina that is lost in macular degeneration, the leading cause of blindness in the United States. Perhaps most significant, rodent brains are just too simple to show the subtle effects of psychiatric and neurodegenerative diseases such as schizophrenia and Alzheimer's.
Still, you don't have to be an animal-rights activist to balk at the thought of tinkering with the genetic makeup of complex, social animals like monkeys. "You have to consider how great the benefit to humanity will be," says neurogeneticist Carolee Barlow of the Salk Institute in San Diego. "If you can use monkeys to cure a disease, you'll be helping people who have no other options. But you have to remember that anything you do with a monkey affects it as a being. They deserve the best life we can give them."
No comments:
Post a Comment