A collaborative project between American and Chinese researchers developed a way to study the function of genes in mice and man by using a moveable genetic element found in cabbage looper moths, called the piggyBac transposon.
Transposons are genetic elements that migrate around DNA, allowing material to be either inserted or relocated. One of the ways this is evident is the manner in which bacteria swap antibiotic resistance genes. Although scientists have been able to adapt this natural procedure to learn the function of individual genes in fruit flies and other simple organisms, they have been unable to do so with vertebrates and mammals.
These genetics were limited as they travelled at low frequencies to limited locations, and had little capacity to carry DNA fragments. The piggyBac transposon however was able to overcome this problem due to its stability and versatility in the mouse and human lines.
The genes piggyBac associates with were made easier to see by adding a red fluorescent protein and an enzyme that changes the coat colour of a white mouse to grey or black. The genes carried by the transposons have been stably inherited and expressed through five generations. "The transposon acts as a genetic beacon, so researchers can easily track its location without having to sequence the entire genome," said senior author Tian Xu, Professor and Vice Chair of Genetics at Yale University School of Medicine. PiggyBac incorporated into many chromosomes in human and mouse cells can be removed from a mouse lineage by breeding with another mouse that has the enzyme to excise the transposon. This technique is a powerful new tool for generating transgenic animals for vertebrates and mammals, and a potential new vehicle for human gene therapy. Although piggyBac inserts itself randomly into the DNA, it most often locates in genes, making it useful for mutating genes and thus, revealing gene functions.
In three months, the two graduate students who worked on the project generated mice mutating 75 different genes. Xu expects the technique to be particularly useful for identifying genes and drug targets for diseases such as cancers and diabetes.
By: Gillian Lawrence, student number 41938955
Tutor:Brenda MacDonald, Prac session: 9 (Thursday 1pm)
References:
http://www.sciencedaily.com : ScienceDaily (Aug. 15, 2005) — New Haven, Conn
Picture-http://www.sciencedaily.com/images/2005/08/050814163056.jpg
