Special Section: THE BODY: From Baby Hatcheries To Xeroxing Human Beings

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Man may eventually be able to abandon sexual reproduction entirely. That startling and perhaps unwelcome possibility has been demonstrated by Dr. J.B. Gurdon of Britain's Oxford University. Taking an unfertilized egg cell from an African clawed frog, Gurdon destroyed its nucleus by ultraviolet radiation, replacing it with the nucleus of an intestinal cell from a tadpole of the same species. The egg, discovering that it had a full set of chromosomes, instead of the half set found in unfertilized eggs, responded by beginning to divide as if it had been normally fertilized. The result was a tadpole that was the genetic twin of the tadpole that provided the nucleus. Gurdon's experiment was also proof of what geneticists have long known: that all of the genetic information necessary to produce an organism is coded into the nucleus of every cell in that organism.

Man, say the scientists, could one day clone (from the Greek word for throng), or asexually reproduce himself, in the same way, creating thousands of virtually identical twins from a test tube full of cells carried through gestation by donor mothers or hatched in an artificial womb. Thus, the future could offer such phenomena as a police force cloned from the cells of J. Edgar Hoover, an invincible basketball team cloned from Lew Alcindor, or perhaps the colonization of the moon by astronauts cloned from a genetically sound specimen chosen by NASA officials. Using the same technique, a woman could even have a child cloned from one of her own cells. The child would inherit all its mother's characteristics including, of course, her sex.

Dramatic as cloning may be, it is overshadowed in significance by a technique that may well be practiced before the end of this century: genetic surgery, or correction of man's inherited imperfections at the level of the genes themselves. When molecular biologists learn to map the location of specific genes in human DNA strands, determine the genetic code of each and then create synthetic genes in the test tube, they will have the ability to perform genetic surgery.

Some molecular biologists envisage using laser beams to slice through DNA molecules at desired points, burning out faulty genes. These would then be replaced by segments of DNA tailored in the test tube to emulate a properly functioning gene and introduced into the body as artificial—and beneficial—viruses.

THE CONCEPT IS not as farfetched as it sounds. Real viruses are merely segments of DNA (or RNA) surrounded by largely-protein sheaths; they penetrate the cell nucleus (leaving their sheaths behind) and take over the cellular DNA.

The potential of the technique is already being tested by an international research team in the treatment of two children whose hereditary inability to produce the enzyme arginase had resulted in severe mental retardation. The team infected the youngsters with a natural virus, the Shope papilloma, which contains DNA that triggers arginase synthesis. Although the experiment is expected to produce no improvement in the children's mental condition, it may belatedly trigger the production of the missing enzyme and prove that viruses can carry beneficial messages to the cells.