"We could eventually do direct detection of a DNA sequence from native DNA" without manipulation now performed in the laboratory," says Dr. Michael L. Metzker, assistant professor in the BCM Human Genome Sequencing Center. "We could make sequencing portable and do it faster."

In the study paper, Metzker, Rice University Professor Robert Curl and colleagues describe a new way of doing DNA sequencing that could be more accurate than current methods.

Most DNA sequencing today is done with one laser and optics to separate the DNA fragment dyes of the four bases into the colours, blue, green, yellow, and red. A common problem with the technique is that the colour of light emitted by the dyes is similar. Even with complex computer programs to assist in deciphering the signals, this cross-talk between the dyes results in subtle variations that can cause nucleotides to be miscalled.

The new method developed at BCM and Rice, called pulsed multiline excitation, uses four lasers, each matched to a particular dye. PME enables the researchers to take advantage of the entire visible spectrum, eliminating the problem of cross-talk between dyes, says Metzker.

Because there are four lasers, scientists can manipulate the system so that each dye gives the same intensity of fluorescent signal, eliminating the need for further software processing to yield readable sequence information.

"We have built a highly sensitive instrument for the measuring of fluorescence, because PME gives brighter signals and collects more of that signal by eliminating the need for a prism to separate the light into colours," Metzker explains.

MEDICA.de; Source: Rice University