Microarrays and Applications
A “classic” microarray is composed of a collection of unique DNA probes
that are arranged in a regular lattice on a solid substrate (e.g., glass).
Each probe is composed of a DNA sequence that is complementary to the
sequence of interest. Nucleic acid “targets” are applied to these probes in
a hybridization fluid. Targets will anneal to complementary probes and
unhybridized target is washed away. The probe:target duplex is then detected
using some type of direct or indirect reporter system combined with a laser
or white-light based scanner system. The resulting image usually resembles a
lattice of spots with varying intensities or colors depending on the
application. Differential color or signal intensity correlates with target
abundance. For readers familiar with basic techniques in molecular biology,
you may recognize a microarray as being a high-density, miniaturized,
reverse-dot-blot.
The type of probe that is used will depend on the particular application,
substrate, reporter molecule and image detection system. Generally,
synthetic DNA (oligonucleotides) between 9 and 100 bases long are used or
longer PCR products (300-3,000 bases) are used as probes. The
oligonucleotides can be mechanically deposited onto the substrate or
generated in situ using lithographic or “virtual-well” technologies. PCR
products are usually deposited mechanically onto silanized glass or nylon
membranes.
Microarrays have been coupled with PCR to detect single nucleotide
polymorphisms (SNPs) or to detect and genotype pathogenic organisms. Arrays
are commonly used to assess gene expression for a large number of genes
(10-1000’s) and have been used to some success for sequencing DNA. Arrays
have also been used to directly detect RNA or DNA from environmental samples
or to characterize single bacterial isolates such as with genomic arrays.
Our lab focuses on low and high density arrays printed on Teflon masked
and unmasked, glass slides. We take advantage of epoxy-silane attachment
procedures and use direct fluorescent labels, biotin-streptavidin labeling
systems, and enzymatic amplification systems to detect probe:target
duplexes.
Additional information and a general description of microarrays can be
found at the following
<link>
Last Edited: Dec 26, 2007 4:52 PM
