Norton D. Zinder, a researcher who helped lay the basis for the new field of molecular biology in the 1950s and ’60s and who played a crucial role in the politics of decoding the human genome, died on Friday in a nursing home in the Riverdale section of the Bronx. He was 83.

The cause was pneumonia after a long illness, his son Stephen said.

Dr. Zinder was interested in genes before the structure of DNA had been discovered and studied them in the best system then available, the viruses that infect bacteria. As a graduate student he made the important discovery that viruses could ferry genes from one bacterium to another. 

He later worked out some of the basic steps in protein synthesis, a principal operation of living cells, by studying viruses that he found used RNA — not DNA, its better-known chemical cousin — as their genetic material. Neck and neck with a competing team led by James D. Watson, Dr. Zinder discovered the universal start signal, the special unit with which all protein molecules begin.

Norton David Zinder was born in New York on Nov. 7, 1928. In a brilliant early career, he graduated from the Bronx High School of Science at 15 and from Columbia University at 18. He earned his Ph.D. at the University of Wisconsin under Joshua Lederberg, another leader in the golden age of molecular biology. 

In 1952, Dr. Zinder moved to Rockefeller University in Manhattan, where he remained for the rest of the career. Through close associations with two eminent scientists, Dr. Lederberg, who later joined him at Rockefeller, and Dr. Watson, the co-discoverer of the DNA double helix, Dr. Zinder became an influential voice in many significant issues of science policy.

In 1973 he was chairman of a committee that reined in a National Cancer Institute program that sought to find the viruses that were then believed to be the source of most human cancers. The program, he wrote, had become “a gravy train” for a handful of favored researchers, and only half of their research was worth supporting.

In the early 1970s, when researchers with no microbiological training took up the study of animal tumor viruses, Dr. Zinder became concerned about research safety and co-wrote a report warning of the risks.

His next concern was about the invention of a method, called the recombinant DNA technique, for transferring genes from one organism to another. He and others wrote a letter, published in Science magazine, asking scientists to hold off using the technique until its risk could be assessed. 

Though scientists generally dislike any curbs on their research, the letter’s signatories were of such stature that the moratorium was observed until safety rules could be developed.

After the early rivalry with Dr. Watson, Dr. Zinder became a close friend of his and a trustee of the Cold Spring Harbor Laboratory, a leading center of molecular biology directed by Dr. Watson.

“Jim would get excitable, and Norton was the trustee who would calm things down,” said a colleague at Rockefeller University, Jesse H. Ausubel. “They were both prodigies who burst on the scene in the early ’40s as 20-year-olds, clever beyond their years, and for that reason they both had long careers.” 

With Dr. Watson, Dr. Zinder was deeply involved in initiating the human genome project. Many leading biologists opposed the project, fearing that their federal patron, the National Institutes of Health, would take money out of their research funds to finance it. Dr. Zinder and Dr. Watson persuaded them that the project should proceed.

Dr. Watson became director of the institutes’ genome project, setting its strategy and goal of completion in 15 years at a cost of $3 billion. But after Dr. Watson’s resignation in 1992, Dr. Zinder became concerned that the agency was “dawdling” and that its leadership was more interested in ventures that would please Congress, like the genetics of disease, than in the long-term payoff from sequencing the human genome. 

With the side objective of galvanizing the institutes into more serious action, Dr. Zinder became one of the few establishment scientists to support Craig Venter, a pioneer in DNA sequencing who had started his own genome sequencing company, Celera, in competition.

When Dr. Venter developed a better sequencing strategy and seemed likely to humiliate the institutes, Dr. Zinder, a member of Celera’s scientific board, tried to mediate a truce. Though his efforts were not entirely successful, the two sequencing teams agreed long enough to declare a joint victory in June 2000.

Dr. Zinder’s influence rested on his being one of a handful of people who were trusted by both of the genome-sequencing camps. “He had trouble keeping his mouth shut, but in some ways that was disarming for people,” Mr. Ausubel said. 

Dr. Zinder’s wife of 54 years, Marilyn, died before him. In addition to his son Stephen, a microbiologist at Cornell, he is survived by another son, Michael, a lawyer, and five grandsons.