DNA, Recombinant

Recombinant DNA, also written as rDNA, is the combining of genes from two or more organisms. The procedure is to construct a DNA molecule in vitro and then insert it into a host cell or organism. The product of the procedure usually is defined as being genetically engineered, although the two terms genetically modified or transgenic are also used. Recombinant DNA is one of three types of cloning and often is mistakenly identified with one of the other two types: reproductive cloning and therapeutic cloning, although there is overlap.

Reproductive cloning (cloning is from the Greek word for twig) has been used for plants since ancient times, as a twig from a plant would be put in the ground and grow. But the first cloned animal, a tad-pole, did not occur until 1952. Much popular attention has been given to reproductive cloning, largely since the cloning of a sheep, “Dolly,” in 1997, by the Roslin Institute in Scotland. Since then, a number of other animals have been cloned (e.g.,mice, cows, pigs); attempts to clone some other animals (e.g., monkeys, cats, dogs) have been unsuccessful; and the possible cloning of humans has become a major topic of concern, with much opposition. Mice are the main source of animal-cloning experiments, but cloning of pigs is a goal because their tissues and organs are similar to those of humans. Reproductive cloning is very expensive, and most experiments are not a success.

[Page 761]The most popularly known example of therapeutic cloning is stem cell research, which first became a controversial political issue in the United States during the 2004 presidential election, when President George W. Bush opposed the furtherance of the small amount of stem cell research the United States has sponsored and his Democratic challenger, John Kerry, supported an increase in stem cell research. Because an embryo is destroyed in the process, some people object to stem cell research on religious grounds, as being similar to abortion. Possibilities are cures for cancer, heart disease, Alzheimer's, and other serious medical conditions. In the same 2004 election,California voted to provide $3 billion over 10 years for stem cell research, 12 times as much annually as the nation's 2004 funding. The hope is that in the future, entire organs can be produced from single cells and be used to replace defective organs.

Recombinant DNA has not received the controversial emotional and political coverage received by animal cloning and stem cell research. However, it does exert an important role in the success of biotechnology and has led to many successful advances. Crucial vaccines are in the pipeline. Foods, for example, have been produced that can resist insecticides, pesticides, or viruses, provide more nutritional value, grow faster and larger, or resist bad weather conditions.

The 1953 discovery, by James Watson and Francis Crick, of the structure of DNA started the continuing explosion of genetic research, including recombinant DNA technology. In 1962, Watson, Crick, and Maurice Wilkins received the Nobel Prize for Physiology and Medicine. Rosalind Franklin, the fourth discoverer, had died in 1958 at age 37. Among other examples of the explosion, the genetic code was cracked in 1966. In 1972, Paul Berg pasted two DNA strands together, forming the first recombinant DNA molecule; and the following year, Stanley Cohen, Annie Chang, and Herbert Boyer produced the first recombinant DNA organism by splicing a recombinant DNA molecule into bacteria DNA. In 1975, at Asilomar,California, an international conference of scientists asked the government to regulate recombinant DNA experiments, and in 1976, many types of experiments were restricted. The recombinant DNA Advisory Committee was established by the U.S. National Institutes of Health. The same year, two famous scientists founded Genentech, Inc., a biotechnology company whose goal was to develop and market recombinant-DNA-based products.

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