Automated
Sequencing
Automated DNA sequencing utilizes a fluorescent dye to label the
nucleotides
instead of a radioactive isotope. The fluorescent dye is not an
environmentally
hazardous chemical and has no special handling or disposal
requirements. Instead
of using X-ray film to read the sequence, a laser is used to stimulate
the
fluorescent dye. The fluorescent emissions are collected on a charge
coupled
device that is able to determine he wavelength. The Perkin-Elmer
Applied
Biosystems (ABI) DNA sequencers are designed to discriminate all four
fluorescent dye wavelengths simultaneously, which allows for complete
DNA
sequencing in one lane on the gel.
Varying degrees of automation are also available. For full automation,
all that
is required is to load a sample tray with template DNA; the equipment
performs
the labeling and analysis. The other option is to perform the labeling
reactions with fluorescent dyes, load the samples onto a gel, and place
the gel
into the DNA sequencer. The equipment performs the separation and
analysis. The
system automatically identifies the nucleotide sequence and saves the
information on the computer. Thus, only a review of the data is
necessary to
ensure no anomalies were misidentified by the computer.
The greatest obstacle to researchers when converting from manual to
automatic
DNA sequencing is being required to learn the use of computer software
necessary to interpret the results.
Automated DNA sequencing equipment can eliminate the need for
radioactive isotopes to label DNA, thereby reducing the volume of
low-level
radioactive waste generated on campus. As a general approximation, one
template
of manual DNA sequencing will produce 83 mL of liquid waste and 0.167
gallon of
solid waste. As a result, every 45 templates processed by automated DNA
sequencing reduces the amount of manual DNA sequencing. The time saved
is due
to not having to perform autoradiography or associated tasks required
for
working with radioactive materials such as radiation surveys,
inventory/disposal documentation, etc. Finally, automated DNA
sequencing
provides more reliable research results than manual DNA sequencing,
thus
maintaining the integrity of the research.
<>http://www.dnalc.org/ddnalc/resources/shockwave/cycseq.html