hat constitutes a genetically modified organism (GMO) is not always clear and can vary widely. At its broadest it can include anything that has had its genes altered, including by nature. Taking a less broad view it can encompass every organism that has had its genes altered by humans, which would include all crops and livestock. In 1993 the Encyclopedia Britannica defined genetic engineering as “any of a wide range of techniques …
among them artificial insemination, in vitro fertilization (e.g., “test-tube” babies), sperm banks, cloning, and gene manipulation.”[3] The European Union (EU) included a similarly broad definition in early reviews, specifically mentioning GMOs being produced by “selective breeding and other means of artificial selection.” They later excluded traditional breeding, in vitro fertilization, induction of polyploidy, mutagenesis and cell fusion techniques that do not use recombinant nucleic acids or a genetically modified organism in the process.
A narrower definition provided by the Food and Agriculture Organization, the World Health Organization and the European Commission says that the organisms must be altered in a way that does “not occur naturally by mating and/or natural recombination”. There are examples of crops that fit this definition, but are not normally considered GMOs. For example, the grain crop triticale was fully developed in a laboratory in 1930 using various techniques to alter its genome. The Cartagena Protocol on Biosafety in 2000 used the synonym living modified organism (LMO) and defined it as “any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology.” Modern biotechnology is further defined as “In vitro nucleic acid techniques, including recombinant deoxyribonucleic acid (DNA) and direct injection of nucleic acid into cells or organelles, or fusion of cells beyond the taxonomic family.” Genetically engineered organism (GEO) can be considered a more precise term compared to GMO when describing organisms’ genomes that have been directly manipulated with biotechnology. The term GMO originally was not typically used by scientists to describe genetically engineered organisms until after usage of GMO became common in popular media.[14] The United States Department of Agriculture (USDA) considers GMOs to be plants or animals with heritable changes introduced by genetic engineering or traditional methods, while GEO specifically refers to organisms with genes introduced, eliminated, or rearranged using molecular biology, particularly recombinant DNA techniques, such as transgenesis. The definitions focus on the process more than the product, which means there could be GMOS and non-GMOs with very similar genotypes and phenotypes. This has led scientists to label it as a scientifically meaningless category, saying that it is impossible to group all the different types of GMOs under one common definition. It has also caused issues for organic institutions and groups looking to ban GMOs. It also poses problems as new processes are developed. The current definitions came in before genome editing became popular and there is some confusion as to whether they are GMOs.The EU has adjudged that they are changing their GMO definition to include “organisms obtained by mutagenesis”.In contrast the USDA has ruled that gene edited organisms are not considered
GMOs.
Creating a genetically modified organism (GMO) is a multi-step process. Genetic engineers must isolate the gene they wish to insert into the host organism. This gene can be taken from a cell or artificially synthesized.If the chosen gene or the donor organism’s genome has been well studied it may already be accessible from a genetic library. The gene is then combined with other genetic elements, including a promoter and terminator region and a selectable marker. A number of techniques are available for inserting the isolated gene into the host genome. Bacteria can be induced to take up foreign DNA, usually by exposed heat shock or electroporation. DNA is generally inserted into animal cells using microinjection, where it can be injected through the cell’s nuclear envelope directly into the nucleus, or through the use of viral vectors. In plants the DNA is often inserted using Agrobacterium-mediated recombination,biolistics or electroporation.
As only a single cell is transformed with genetic material, the organism must be
regenerated from that single cell. In plants this is accomplished through tissue
culture. In animals it is necessary to ensure that the inserted DNA is present in
the embryonic stem cells. Further testing using PCR, Southern hybridization,
and DNA sequencing is conducted to confirm that an organism contains the
new gene. Traditionally the new genetic material was inserted randomly within the host genome. Gene targeting techniques, which creates double-stranded breaks and takes advantage on the cells natural homologous recombination repair systems, have been developed to target insertion to exact locations. Genome editing uses artificially engineered nucleases that create breaks at specific points. There are four families of engineered nucleases:
meganucleases, zinc finger nucleases, transcription activator-like
effector nucleases (TALENs), and the Cas9-guideRNA system (adapted from CRISPR). TALEN and CRISPR are the two most commonly used and each has its own advantages.TALENs have greater target specificity, while CRISPR is
easier to design and more efficient.
