Swiss scientists have genetically engineered a golden rice that produces extra vitamin A and could help save the lives of millions of children. Ingo Potrykus of the Swiss Federal Institute of Technology in Zurich says 300 grams of the new variety may yield a day's requirement of the vitamin. Dr. Potrykus's team transferred not a single gene but an entire genetic pathway for producing beta carotene -- the precursor of vitamin A -- into the rice plant. Health experts estimate that 124 million children worldwide are deficient in vitamin A, which can make them susceptible to blindness and such diseases as measles and diarrhea. About two million children die each year because of inadequate nutrition.