DNA by the Day

Credit: L.A. Cicero

It wasn't until the late 1950's that Watson and Crick's conclusions regarding the structure of DNA were confirmed in the laboratory. This allowed scientists back then to investigate DNA further and come up with solutions to some of life's mysteries. Around 60 years after, technology is so advanced that scientists can now look at the individual strands by the nanometer.

Led by W. E. Moerner, the founder of single-molecule spectroscopy, the team of researchers developed a technique that allows them to figure out the orientation of the molecules attached to the DNA. It uses a type of fluorescent dye that slips in the area between the bases.

The Technique

The team employed the well-studied technique that utilizes a single-molecule microscope with an additional optical element known as the electro-optic modulator. This changes the polarization of the laser light used to illuminate the dyes for each frame of the camera.

A dye molecule oriented as aligned as possible to the laser's polarization will appear the brightest. Measuring the brightness of each molecule in each frame allowed them to identify its orientation. The measurements they obtained have an accuracy of around 5 degrees. They also measured the rotational dynamics of the molecules.

According to Adam S. Backer, the first author of the paper, "If someone has a single-molecule microscope, they can perform our technique pretty easily by adding the electro-optic modulator. We've used fairly standard tools in a slightly different way and analyzed the data in a new way to gain additional biological and physical insight."

This development could help scientists look closely at damaged DNA or how cellular processes affect gene expression. The method is also faster as compared to existing methods.

Access the paper here.

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