Analysis of Compounds Related to Nucleic Acids

SPM Observations of Plasmid DNA

The deoxyribonucleic acid (DNA) that carries the genetic information for a living organism can be observed using a scanning probe microscope (SPM).
Circular plasmid DNA molecules* (pGEM-3Zf(+), manufactured by Promega Corporation) are used as vectors* for gene recombination. The SPM image below is a 3D image of these circular plasmid DNA molecules on a natural mica substrate taken using dynamic-mode AFM in air.

A scanning probe microscope achieves high spatial resolution equivalent to an electron microscope but permits observations under a diverse range of conditions in air, in solution, or in a physiological environment.

* A molecule with special functions to introduce a specific gene or base sequence into another cell for gene recombination is known as a "vector." Circular plasmid DNA is a covalently closed circular DNA that is the most commonly used vector for gene recombination.

SPM-9600 Scanning Probe Microscope

This instrument traces the contours of the sample surface with a needle-like sharp tip to capture the surface topography in three dimensions and acquire information on the surface physical properties.
It can produce images of bacteria such as E.coli and lactobacillus with almost no pretreatment. Bacteria are sampled from a colony or culture fluid and dripped onto glass or quartz for direct observations in the atmosphere. SPM offers excellent resolution, capable of observing down the flagella.