Word: nutrient
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...reversing the normal genetic process in which DNA orders the production of "messenger" molecule RNA. Their enzyme permits RNA to manufacture the master molecule DNA. The Harvard team broke down rabbit hemoglobin and isolated its RNA. They then mixed this RNA with the Temin-Baltimore enzyme in a rich nutrient broth. They were thus able to trick the RNA into making the DNA from which it itself had been produced...
...chance that Mars may be the home of primitive living things something like bacteria, a soil sample in another chamber will be slightly moistened by a nutrient solution laced with carbon 14. The sample will be incubated, then tested to learn whether anything in the soil has consumed the nutrient and released waste gases containing the telltale carbon...
...fleas and algae flows back into the bottom tank, where it provides a full diet for the tilapia. Nothing is wasted: in the warm greenhouse space above the ponds, the new alchemists grow vegetables even in the dead of the New England winter. The plants are fertilized by the nutrient-laden fish water. To protect their harvests against bugs, the scientists have brought insect-eating frogs, spiders and chameleons instead of pesticides into the greenhouses...
There are also environmental costs in boosting food production. While nutrient input is essential for obtaining greater yields, fertilizers drain off from farm fields and into water supplies. There they cause "blooms" of aquatic plants that turn lakes into swamps, destroying fresh-water supplies. Similarly, clearing and planting virgin areas ruins wildlife habitats and upsets the delicate balance of life...
...test, a small sample of Martian soil will be partially submerged in a nutrient-rich solution (called "chicken soup" by the experimenters). If any Martian organisms grow in the broth and give off carbon dioxide or other common byproducts of respiration-like life processes, instruments will detect these chemicals. In another test, soil will be exposed to a nutrient containing radioactive carbon 14. If any microorganisms consume the nutrient and give off carbon-bearing gases as metabolic wastes, those wastes will be radioactively "tagged" and readily identified. Lastly, a Martian soil sample will be exposed to xenon "sunlight...