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DNA microarrays have become a popular technique to
detect changes in gene expression in response to a wide variety of
conditions including cancer, aging and development.
The basic principle underlying
microarray analysis is that the measured intensities for each arrayed gene
represent its relative expression level. The basic concept behind the use
of GeneChip arrays for gene expression is simple: The samples (the
‘targets’) for arrays are labeled representations of mRNA derived from
tissue preparations or in vitro cell culture hybridized to an individual
array. After removing unbound target molecules, GeneChips are scanned for
fluorescence emission. By monitoring the amount of fluorescence associated
with each DNA location, it is possible to estimate the abundance of each
mRNA species represented.
(http://www.affymetrix.com/technology/ge_analysis/index.affx)
Affymetrix GeneChip microarrays are fabricated
using light-activated chemistry and photolithography methods (http://www.affymetrix.com/technology/manufacturing/index.affx).
Affymetrix probes sets represent a series of 11
25-mer probes from the 3' end of each transcript or predicted transcript in
the genome; each of the 11 probes is then paired with a similar mismatch
probe that is designed to contain a mutation in the middle position of the
oligo serving as a form of control for hybridisation specificity. (http://www.affymetrix.com/technology/design/index.affx).
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