Examples
- The first TEs were discovered in maize (Zea mays), by Barbara McClintock in 1948, for which she was awarded a Nobel Prize in 1983. She noticed insertions, deletions, and translocations, caused by these elements. These changes in the genome could, for example, lead to a change in the color of corn kernels. About 85% of the genome of maize consists in TEs. The Ac/Ds system described by McClintock are class II TEs. Transposition of Ac in tobacco has been demonstrated by B. Baker (Plant Transposable Elements, pp 161–174, 1988, Plenum Publishing Corp., ed. Nelson).
- One family of TEs in the fruit fly Drosophila melanogaster are called P elements. They seem to have first appeared in the species only in the middle of the twentieth century. Within 50 years, they have spread through every population of the species. Gerald M. Rubin and Allan C. Spradling pioneered technology to use artificial P elements to insert genes into Drosophila by injecting the embryo.
- Transposons in bacteria usually carry an additional gene for function other than transposition---often for antibiotic resistance. In bacteria, transposons can jump from chromosomal DNA to plasmid DNA and back, allowing for the transfer and permanent addition of genes such as those encoding antibiotic resistance (multi-antibiotic resistant bacterial strains can be generated in this way). Bacterial transposons of this type belong to the Tn family. When the transposable elements lack additional genes, they are known as insertion sequences.
- The most common form of transposable element in humans is the Alu sequence. It is approximately 300 bases long and can be found between 300,000 and a million times in the human genome.
- Mariner-like elements are another prominent class of transposons found in multiple species including humans. The Mariner transposon was first discovered by Jacobson and Hartl in Drosophila. This Class II transposable element is known for its uncanny ability to be transmitted horizontally in many species. There are an estimated 14 thousand copies of Mariner in the human genome comprising 2.6 million base pairs. The first mariner-element transposons outside of animals were found in Trichomonas vaginalis. . These characteristics of the Mariner transposon have inspired the science fiction novel titled, "The Mariner Project".
- Mu phage transposition is the best known example of replicative transposition. Its transposition mechanism is somewhat similar to a homologous recombination.
- The five distinct yeast (Saccharomyces cerevisiae) retrotransposon families: Ty1, Ty2, Ty3, Ty4 and Ty5
- A helitron is a TE found in eukaryotes that are thought to replicate by a rolling-circle mechanism.
Read more about this topic: Transposable Element
Famous quotes containing the word examples:
“Histories are more full of examples of the fidelity of dogs than of friends.”
—Alexander Pope (1688–1744)
“It is hardly to be believed how spiritual reflections when mixed with a little physics can hold people’s attention and give them a livelier idea of God than do the often ill-applied examples of his wrath.”
—G.C. (Georg Christoph)
“There are many examples of women that have excelled in learning, and even in war, but this is no reason we should bring ‘em all up to Latin and Greek or else military discipline, instead of needle-work and housewifry.”
—Bernard Mandeville (1670–1733)