Word: fraenkel
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Dates: during 1960-1969
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Akira Tsugita and Dr. Heinz Fraenkel-Conrat. both of the University of California at Berkeley, tell this week how they pinned a specific chemical change in a virus to a change in the code...
Chemical Mutation. Tsugita and Fra«n-kel-Conrat worked with TMU, a virus that causes mosaic disease in tobacco plants. TMU's structure is extremely simple. All it has is a core of coiled-up RNA surrounded by a cylindrical jacket made of protein molecules. Tsugita and Fraenkel-Conrat first stripped off the jacket by use of a protein-dissolving chemical. Then they treated the naked RNA with nitrous acid, which is known to affect the RNA's code-carrying bases. After the nitrous acid had. acted, the RNA was enabled to clothe itself...
...Tsugita and Fraenkel-Conrat went farther: when they had grown in tobacco plants a good supply of mutated virus, they analyzed its protein and found that it was not quite the same as the protein of normal virus. And in the specialized world of biochemistry this was exciting news. Other chemically induced mutations have shown themselves as changes of behavior, which cannot be described chemically. Now the effect of the change in the virus's RNA can be seen as a definite chemical change in its protein...
Changing the Code. The report from Tsugita and Fraenkel-Conrat went little farther than that. But Nobel Prizewinning Wendell M. Stanley, head of Berkeley's Virus Laboratory, believes that the original action of the nitrous acid was to change one kind of RNA base into another...
...Stanley thinks that the techniques used by Tsugita and Fraenkel-Conrat may be developed to the point of proving "a Rosetta Stone for the language of life.'' If applied to many mutant viruses, they may break entire genetic codes, telling which groups of bases are responsible for what characteristics. The next step, perhaps years away, will be to do the same with the more complicated molecules of DNA that govern the heredity of higher animals. At some point during this effort...