Enhancer trap
Encyclopedia
An enhancer trap is a transgenic
construction for the identification of enhancers
, produced by the fusing of two proteins, genes for which are inserted into the genome
. The enhancer trap structure contains a mobile element (necessary for random insertion in the genome) usually some sort of P element (a promoter that must be sensitive to the enhancer) and a reporter gene. The reporter gene
is necessary for identification of the spatial regulation by enhancers. The most common and basic enhancer traps are: P[ lacZ ] from the bacterium E. coli
and P[ GAL4
] from yeast
.
The enhancer trap also uses some sort of visible marker that allows the new insertions to be recognized such as the white gene, resulting in a red eye color in Drosophila
or ampicillin resistance for E. coli.
There exists a large number of fly stocks containing GAL4 insertions and an equally large number of fly stocks containing an UAS DNA sequence followed by a gene of interest. The beauty of this arrangement is that the expression of a large number of genes with different GAL4 "drivers" is possible. Rather than generating transgenic flies with the enhancer linked directly to the gene of interest (this takes about a year, if you are starting without the appropriate DNA construct), you simply mate (cross) one transgenic fly with another transgenic fly.
Transgene
A transgene is a gene or genetic material that has been transferred naturally or by any of a number of genetic engineering techniques from one organism to another....
construction for the identification of enhancers
Enhancer (genetics)
In genetics, an enhancer is a short region of DNA that can be bound with proteins to enhance transcription levels of genes in a gene cluster...
, produced by the fusing of two proteins, genes for which are inserted into the genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
. The enhancer trap structure contains a mobile element (necessary for random insertion in the genome) usually some sort of P element (a promoter that must be sensitive to the enhancer) and a reporter gene. The reporter gene
Reporter gene
In molecular biology, a reporter gene is a gene that researchers attach to a regulatory sequence of another gene of interest in cell culture, animals or plants. Certain genes are chosen as reporters because the characteristics they confer on organisms expressing them are easily identified and...
is necessary for identification of the spatial regulation by enhancers. The most common and basic enhancer traps are: P[ lacZ ] from the bacterium E. coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
and P[ GAL4
GAL4/UAS system
The GAL4-UAS system is a biochemical method used to study gene expression and function in organisms such as the fruit fly. It was developed by Andrea Brand and Norbert Perrimon in 1993 and is considered a powerful technique for studying the expression of genes...
] from yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
.
The enhancer trap also uses some sort of visible marker that allows the new insertions to be recognized such as the white gene, resulting in a red eye color in Drosophila
Drosophila
Drosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
or ampicillin resistance for E. coli.
There exists a large number of fly stocks containing GAL4 insertions and an equally large number of fly stocks containing an UAS DNA sequence followed by a gene of interest. The beauty of this arrangement is that the expression of a large number of genes with different GAL4 "drivers" is possible. Rather than generating transgenic flies with the enhancer linked directly to the gene of interest (this takes about a year, if you are starting without the appropriate DNA construct), you simply mate (cross) one transgenic fly with another transgenic fly.