Automating the DNA sequence process is made possible by the use of fluorescent tags. With fluorescent dyes, the entire experiment
can be performed in a single solution instead of four different ones. Using Sanger-based methods, the DNA fragments migrate
through the gel, and the color associated with each successive peak is detected using a laser. The DNA sequence is read by
determining the sequence of colors in the peaks as they pass the detector, and then feeding the data directly to a computer
for instant results.
Capillary electrophoresis (CE)-based DNA sequencing systems consist of a number of different measurements, all of which use
an open fused-silica capillary tube filled with an electrolyte. The ends are immersed in reservoirs, held at high opposing
potentials (+/-). Ions in the solution migrate to the oppositely charged ends. Silanol (-Si-OH) groups on the surface of the
silica capillary give up hydrogen ions in alkaline media and produce a highly negatively charged surface, which in turn causes
the carrier solution in the capillary to move toward the negative electrode. Thus, there is a constant flow of solution, produced
by this electroosmotic phenomenon, in the negative direction. The effect of all this is to produce a separation in which,
as a result of both the electrophoretic effect and the electroosmotic flow, all anions move toward the cathode, but at different
rates. An in-line detector can read all DNA fragments as they go by.
2011 sequencer demand by industry.
Next-generation sequencers have been the latest breakthrough in the automated DNA sequencing market. With only a handful of
vendors involved in next-generation sequencing, sequence-by-synthesis and sequence-by-ligation have emerged as the leading
technologies. Roche's Genome Sequencer FLX system uses a combination emulsion PCR (emPCR) and sequence by synthesis via pyrosequencing.
Similar to Roche, Illumina's Genome Analyzer sequencer uses a sequencing-by-synthesis strategy. However, instead of emulsion
PCR, the Genome Analyzer II uses a cluster amplification process. Applied Biosystems/Life Technologies' SOLiD system uses
emulsion PCR and microbeads that are transferred onto an open glass slide. The system uses a sequence by ligation strategy,
using a two-base encoding chemistry.
SDi estimates that the top five industries account for about 93% of the market share. Academia accounts for over half, followed
by government with 21%. CROs, biotechnology, and pharmaceuticals combine for another 21%.
The foregoing data were extracted and adapted from SDi's Global Assessment Report, Edition 12. For more information, visit