Molecular Methods for the Detection of Waterborne Pathogens - Waterborne Pathogens: Detection Methods and Applications - page 238

locations. The supports themselves are usually glass microscope slides, but
can also be silicon chips or nylon membranes. The DNA is printed, spot-
ted, or actually synthesized directly onto the support. A microarray works
by exploiting the ability of a given mRNA molecule obtained from the
target sample in question to bind specifically to, or hybridize to, the DNA
template on the solid support that is complimentary to it. A researcher
uses the location of each spot in the array to identify a particular gene
sequence. With the aid of a computer, the amount of mRNA bound to
the spots on the microarray is precisely measured, generating a profile
of gene expression in the cell ( Fig. 8.10 ). Microarrays are a significant
advancement in the rapid detection of multiple genes or organisms in
samples because they screen for a very large number of sequences and
because of their small compact size.
Many microarrays have been developed that have targeted multiple
waterborne pathogens to those specifically aimed at detecting strains of a
specific species. Like PCR, the targets chosen have ranged from universal
Figure 8.9 Schematic illustration of the experimental procedure for detection of aqua-
culture pathogens in the microfluidic loop-mediated isothermal amplification (LAMP)
system. (a) Thermal lysis and hybridization between the magnetic beads and pathogen
DNA. (b) Pathogen DNA isolation occurs when an external magnetic field is applied.
(c) LAMP reaction of the extracted DNA. (d) Optical detection of the LAMP products.
Source: Adapted from Ref. 84 . (For color version of this figure, the reader is referred to the
online version of this topic.)