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1953 - 1976: Expanding the Boundaries of DNA Research

The discovery of the structure of DNA resulted in an explosion of research in molecular biology and genetics, paving the way for the biotechnology revolution.


1953

Nature magazine published James Watson's and Francis Crick's manuscript describing the double helix structure of DNA.


1953

Gey developed the HeLa human cell line.


1955

Seymour Benzer at Purdue University devised an experimental setup to map mutations within a short genetic region of a particular bacterial virus. Over a five-year period, Benzer mapped recombinations of genetic material that distinguished mutational changes that had taken place at adjacent base pairs.


1956

Heinz Fraenkel-Conrat took apart and reassembled the tobacco mosaic virus, demonstrating "self assembly."


1957

Francis Crick and George Gamov worked out the "central dogma," explaining how DNA functions to make protein. Their "sequence hypothesis" posited that the DNA sequence specifies the amino acid sequence in a protein. They also suggested that genetic information flows only in one direction, from DNA to messenger RNA to protein, the central concept of the central dogma.


1957

Mexico became self-sufficient in wheat production for the first time as a result of plant breeding efforts that began in 1943.


1957

Matthew Meselson and Frank Stahl demonstrated the replication mechanism of DNA.


1958

Coenberg discovered and isolated DNA polymerase, which became the first enzyme used to make DNA in a test tube.


1958

The National Seed Storage Laboratory (NSSI) was opened in Fort Collins, Colorado, becoming the first long-term seed storage facility in the world.


1959

Reinart regenerated plants from carrot callus culture.


1959

Francois Jacob and Jacques Monod established the existence of genetic regulation - mappable control functions located on the chromosome in the DNA sequence - which they named the repressor and operon. They also demonstrated the existence of proteins that have dual specificities.


1959

Nikita Krushchev introduced hybrid corn to the Soviet Union after visiting an Iowa corn farm belonging to Roswell Garst.


1959

The steps in protein biosynthesis were delineated.


1959

Systemic fungicides were developed.


1960

The Rockefeller and Ford Foundation jointly established the first international agricultural research center in cooperation with the Philippine government and the International Rice Research Institute (IRRI).


1961

Marshall Nirenberg built a strand of mRNA comprised only of the base uracil. This strand is called "poly-u," and by examining it Nirenberg discovered that UUU is the codon for phenylalanine. This was the first step in cracking the genetic code, which Nirenberg and colleagues succeeded in doing within five years.


1961

UPOV, the International Union for the Protection of New Varieties of Plants, is negotiated in Paris. The goal of the "Convention of Paris" was to make uniform the enactment and enforcement of Plant Breeders' Rights legislation around the world.


1962

Watson and Crick shared the 1962 Nobel Prize for Physiology and Medicine with Maurice Wilkins. Unfortunately, Rosalind Franklin, whose work greatly contributed to the discovery of the double helical structure of DNA, died before this date, and the Nobel Prize rules do not allow a prize to be awarded posthumously.


1962

The planting of high-yield wheat varieties (later known as Green Revolution grains) began in Mexico. The seeds were released by the Mexican Agricultural Program to other countries.


1964

The FAO, backed by the U.N. Special Fund, established the Crop Research and Introduction Center at Izanir, Turkey, for the study of germplasm in that region.


1965

Scientists noticed that genes conveying antibiotic resistance in bacteria are often carried on small, supernumerary chromosomes called plasmids. This observation led to the classification of the plasmids.


1965

Harris and Watkins successfully fused mouse and human cells.


1966

The genetic code was "cracked". Marshall Nirenberg, Heinrich Mathaei, and Severo Ochoa demonstrated that a sequence of three nucleotide bases (a codon) determines each of 20 amino acids.


1967

Arthur Kornberg conducted a study using one strand of natural viral DNA to assemble 5,300 nucleotide building blocks. Kornberg's Stanford group then synthesized infectious viral DNA.


1967

Mary Weiss and Howard Green took a crucial step in human gene mapping with the publication of a technique for using human cells and mouse cells grown together in one culture. This was called somatic-cell hybridization.


1969

Leonard Herzenberg, a geneticist at Stanford, developed the fluorescence-activated cell sorter, which can identify up to 5,000 closely related animal cells.


1970

Peter Duesberg and Peter Vogt, virologists at UCSF, discovered the first oncogene in a virus. This SRC gene has since been implicated in many human cancers.


1970

Howard Temin and David Baltimore, working independently, first isolated "reverse transcriptase" a restriction enzyme that cuts DNA molecules at specific sites. Their work described how viral RNA that infects a host bacteria uses this enzyme to integrate its message into the host's DNA. This discovery allowed scientists to create clones and observe their function.


1970

Torbjorn Caspersson, L. Zech, and other colleagues in Sweden, published the first method for staining human or other mammalian chromosomes in such a way that banding patterns appear, like those Painter found in the giant chromosomes of fruit flies nearly 40 years earlier.


1972

Immunologist Hugh McDevitt, in an article in Science, reported observing genes that control immune responses to foreign substances. His observations suggested predictable, inherited susceptibility to some diseases.


1972

Paul Berg isolated and employed a restriction enzyme to cut DNA. Berg used ligase to paste two DNA strands together to form a hybrid circular molecule. This was the first recombinant DNA molecule.


1972

The first successful DNA cloning experiments were performed in California.


1972

In a letter to Science, Stanford biochemist Paul Berg and others called for the National Institutes of Health to enact guidelines for DNA splicing. Their letter recommended that scientists stop doing certain types of recombinant DNA experiments until questions of safety could be addressed. This letter was provoked by experiments planned by Berg, which had drawn vocal concern from the scientific community. Their concerns eventually led to the 1975 Asilomar Conference.


1973

Scientists for the first time successfully transferred deoxyribonucleic acid (DNA) from one life form into another. Stanley Cohen and Annie Chang of Stanford University and Herbert Boyer of UCSF "spliced" sections of viral DNA and bacterial DNA with the same restriction enzyme, creating a plasmid with dual antibiotic resistance. They then spliced this recombinant DNA molecule into the DNA of a bacteria, thereby producing the first recombinant DNA organism.


1973

Bruce Ames, a biochemist at UC Berkeley, developed a test to identify chemicals that damage DNA. The Ames Test becomes a widely used method to identify carcinogenic substances.


1973

The first human-gene mapping conference took place. The conference was inspired primarily by the rapid development in mapping by somatic-cell hybridization.


1974

The Proceedings of the National Academy of Sciences published a paper by Stanford geneticist Stanley Cohen and UCSF biochemist Herbert Boyer in which they demonstrated the expression of a foreign gene implanted in bacteria by recombinant DNA methods. Cohen and Boyer showed that DNA can be cut with restriction enzymes and reproduced by inserting the recombinant DNA into Escherichia coli.


1975

A moratorium on recombinant DNA experiments was called for at an international meeting at Asilomar, California, where scientists urged the government to adopt guidelines regulating recombinant DNA experimentation. The scientists insisted on the development of "safe" bacteria and plasmids that could not escape from the laboratory.


1975

Kohler and Milstein fused cells together to produce monoclonal antibodies.


1976

Herbert Boyer and Robert Swanson founded Genentech, Inc., a biotechnology company dedicated to developing and marketing products based on recombinant DNA technology.


1976

J. Michael Bishop and Harold Varmus, virologists at UCSF, showed that oncogenes appear on animal chromosomes, and alterations in their structure or expression can result in cancerous growth.


1976

The NIH released the first guidelines for recombinant DNA experimentation. The guidelines restricted many categories of experiments.


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