Gene targeting in the context of "Genetically modified"

Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms. New DNA is obtained by either isolating and copying the genetic material of interest using recombinant DNA methods or by artificially synthesising the DNA. A construct is usually created and used to insert this DNA into the host organism. The first recombinant DNA molecule was designed by Paul Berg in 1972 by combining DNA from the monkey virus SV40 with the lambda virus. As well as inserting genes, the process can be used to remove, or "knock out", genes. The new DNA can either be inserted randomly or targeted to a specific part of the genome.

An organism that is generated through genetic engineering is considered to be genetically modified (GM), and the resulting entity is a genetically modified organism (GMO). The first GMO was a bacterium generated by Herbert Boyer and Stanley Cohen in 1973. Rudolf Jaenisch created the first GM animal when he inserted foreign DNA into a mouse in 1974. The first company to focus on genetic engineering, Genentech, was founded in 1976 and began the production of human proteins. Genetically engineered human insulin was produced in 1978, and insulin-producing bacteria were commercialised in 1982. Genetically modified food has been sold since 1994, with the release of the Flavr Savr tomato. The Flavr Savr was engineered to have a longer shelf life, but most current GM crops are modified to increase resistance to insects and herbicides. GloFish, the first GMO designed as a pet, was sold in the United States in December 2003. In 2016, salmon modified with a growth hormone were sold.

Gene knockouts (also known as gene deletion or gene inactivation) are a widely used genetic engineering technique that involves the targeted removal or inactivation of a specific gene within an organism's genome. This can be done through a variety of methods, including homologous recombination, CRISPR-Cas9, and TALENs.

One of the main advantages of gene knockouts is that they allow researchers to study the function of a specific gene in vivo, and to understand the role of the gene in normal development and physiology as well as in the pathology of diseases. By studying the phenotype of the organism with the knocked out gene, researchers can gain insights into the biological processes that the gene is involved in.

Sir Martin John Evans FRS FMedSci FLSW (born 1 January 1941) is an English biologist who, with Matthew Kaufman, was the first to culture mice embryonic stem cells and cultivate them in a laboratory in 1981. He is also known, along with Mario Capecchi and Oliver Smithies, for his work in the development of the knockout mouse and the related technology of gene targeting, a method of using embryonic stem cells to create specific gene modifications in mice. In 2007, the three shared the Nobel Prize in Physiology or Medicine in recognition of their discovery and contribution to the efforts to develop new treatments for illnesses in humans.

He won a major scholarship to Christ's College, Cambridge at a time when advances in genetics were occurring there and became interested in biology and biochemistry. He then went to University College London where he learned laboratory skills supervised by Elizabeth Deuchar. In 1978, he moved to the Department of Genetics, at the University of Cambridge, and in 1980 began his collaboration with Matthew Kaufman. They explored the method of using blastocysts for the isolation of embryonic stem cells. After Kaufman left, Evans continued his work, upgrading his laboratory skills to the newest technologies, isolated the embryonic stem cell of the early mouse embryo and established it in a cell culture. He genetically modified and implanted it into adult female mice with the intent of creating genetically modified offspring, work for which he was awarded the Nobel Prize in 2007. In 2015, he was elected a Fellow of the Learned Society of Wales. Today, genetically modified mice are considered vital for medical research.

A knockout moss is a kind of genetically modified moss. One or more of the moss's specific genes are deleted or inactivated ("knocked out"), for example by gene targeting or other methods. After the deletion of a gene, the knockout moss has lost the trait encoded by this gene. Thus, the function of this gene can be inferred. This scientific approach is called reverse genetics because the scientist wants to understand the function of a specific gene. In classical genetics, the scientist starts with a phenotype of interest and searches for the gene that causes this phenotype. Knockout mosses are relevant for basic research in biology as well as in biotechnology.