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A selectable marker is a gene introduced into cells, especially bacteria or cells in culture, which confers one or more traits suitable for artificial selection.They are a type of reporter gene used in laboratory microbiology, molecular biology, and genetic engineering to indicate the success of a transfection or transformation or other procedure meant to introduce foreign DNA into a cell.
In biology, a marker gene may have several meanings. In nuclear biology and molecular biology, a marker gene is a gene used to determine if a nucleic acid sequence has been successfully inserted into an organism's DNA. In particular, there are two sub-types of these marker genes: a selectable marker and a marker for screening.
Trapping is performed with gene trap vectors whose principal element is a gene trapping cassette consisting of a promoterless reporter gene and/or selectable genetic marker, flanked by an upstream 3' splice site (splice acceptor; SA) and a downstream transcriptional termination sequence (polyadenylation sequence; polyA).
Such genes are called reporters because the characteristics they confer on organisms expressing them are easily identified and measured, or because they are selectable markers. Reporter genes are often used as an indication of whether a certain gene has been taken up by or expressed in the cell or organism population.
However, marker expression can have polar effects on the expression of upstream and downstream genes. Removal of selectable markers from the genome by Cre-lox recombination is an elegant and efficient way to circumvent this problem and is therefore widely used in plants, mouse cell lines, yeast, etc. [ 1 ]
It is one of the most important genetic markers in yeast genetic modification. While URA3 is a powerful selectable marker, it has a high background. This background is because cells that pick up mutations in URA3 may also grow on 5-FOA. Colonies should be verified by a second assay such as PCR to confirm the desired strain has been created.
A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. It can be described as a variation (which may arise due to mutation or alteration in the genomic loci) that can be observed.
Marker assisted selection or marker aided selection (MAS) is an indirect selection process where a trait of interest is selected based on a marker (morphological, biochemical or DNA/RNA variation) linked to a trait of interest (e.g. productivity, disease resistance, abiotic stress tolerance, and quality), rather than on the trait itself.