genetic engineering

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Genetic engineering: Gene-splicing techniques

genetic engineering, the use of various methods to manipulate the DNA (genetic material) of cells to change hereditary traits or produce biological products. The techniques include the use of hybridomas (hybrids of rapidly multiplying cancer cells and of cells that make a desired antibody) to make monoclonal antibodies; gene splicing or recombinant DNA, in which the DNA of a desired gene is inserted into the DNA of a bacterium, which then reproduces itself, yielding more of the desired gene; polymerase chain reaction, which makes perfect copies of DNA fragments and is used in DNA fingerprinting; and any of several genome-editing techniques involving nucleases (enzymes that cut the bonds that join nucleotides), especially the CRISPR-Cas9 system, which can more easily edit or engineer genes and also has been used experimentally to activate and deactivate genes.

Genetically engineered products include bacteria designed to break down oil slicks and industrial waste products, drugs (human and bovine growth hormones, human insulin, interferon), plants that are resistant to diseases, insects, and herbicides, that yield fruits or vegetables with desired qualities, or that produce toxins that act as pesticides, salmon that grow twice as fast as unmodified salmon, and swine that do not produce a sugar that can produce allergic reactions. Genetic engineering techniques have also been used in the direct genetic alteration of livestock and laboratory animals (see pharming). In 2014 scientists at the Scripps Research Institute created genetically engineered Escherichia coli bacteria that included a pair of synthetic nucleotides, or DNA bases, in its genetic code. A Chinese scientist claimed in 2018 to have genetically edited human embryos prior to implantation using the CRISPR technique to increase resistance to HIV infection; the claim led to an international outcry denouncing his work as unethical human experimentation, and China later formally banned such work. Genetically engineered products usually require the approval of at least one U.S. government agency, such as the Dept. of Agriculture, the Food and Drug Administration, or the Environmental Protection Agency.

Because genetic engineering involves techniques used to obtain patents on human genes and to create patentable living organisms, it has raised many legal and ethical issues. The safety of releasing into the environment genetically altered organisms that might disrupt ecosystems has also been questioned. The discovery in 2001 of genetically engineered DNA in native Mexican corn varieties made concerns of genetic pollution actual, and led some scientists to worry that the spread of transgenes through cross-pollination could lead to a reduction in genetic diversity in important crops. Transgenic rape (canola) plants also have been found in the wild in several countries. Imports of genetically modified corn, soybeans, and other crops have been curtailed or limited in some countries, and the vast majority of such crops are grown in just a handful of nations. The Cartagena Protocol on Biosafety, which has been signed by more than 100 nations and took effect in Sept., 2003, requires detailed information on whether and how imported seeds, plants, animals, other organisms, and the like are genetically modified and permits a nation to bar those imports, but a 2006 World Trade Organization decision treated the banning of genetically modified crops as a form of protectionism. The United States is not party to the 2003 treaty.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2024, Columbia University Press. All rights reserved.

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