Scientific instrumentation has the ability to turn theory into observed fact. This is, of course, a very important part of the advance of scientific knowledge. Without the microscope, we might know nothing of the world beyond our eyesight, or at best, we could only guess about it. This sort of progress (and it is certainly difficult to say this isn’t Progress) goes on all the time; it’s one of the hallmarks of the relationship between science and technology. A recent example is the development of microscopy to observe the workings of living cells at the molecular level.

Biologists know that, for example, the way protein molecules fold (their configuration) is crucial to the chemical pathways of many cell processes. In theory, certain folding is necessary, but no one has seen the folding take place because scientists haven’t had the equipment to observe it. Technically, achieving this kind of instrumentation is difficult. For one thing, the scale is very small, nanoscale (billionths of a meter), and only the most powerful of microscope technology can achieve this scale. For another, most microscope technology powerful enough to make the observations at the molecular level are also destructive of living processes.

One of the newest approaches, developed by Laurent Cogent and colleagues at the University of Bordeaux (France) and published in Biophysical Journal, is called points accumulation for imaging in nanoscale topography (or PAINT) microscopy. In a sense the technique works like a super high-speed camera (driven by software) that acquires images at the rate of 50 milliseconds for about 5,000 consecutive frames at the resolution of roughly 50 nanometers.

The key to the equipment, which can work with a variety of microscopes capable of observation at the molecular level, is the combination of high-speed imaging and the software to sort out the dynamic frame-to-frame activity. It can, for example, work with multicolor imaging where multiple physiological processes are occurring simultaneously, and unravel the relationships between the processes. The approach requires fluorophores, molecules that absorb energy at a particular wavelength and then emit light – fluoresce – at a corresponding color. These ‘colored molecules’ are markers that can be tracked in the imaging as opposed to the more non-descript background of the image.

The types of applications for this technology are described in a blog at the National Association of Science Writers:

The scientists studied COS-7 cells, possessing green fluorescent protein anchored to the cell membrane, which bind to a particular antibody (a different kind of protein). Based on over 24,000 measurements, they clearly observed two distinct protein populations (as well as a small number of irrelevant, nonspecific “binding” events).

One population of proteins clearly moved more slowly than the other. The scientists attribute this to lipid phase separation, a hypothesized contributor to cell membrane organization.

Going back to the fibroblast cells, the scientists also found two distinct populations of proteins, but a larger proportion of them were faster this time. Protein mobility was clearly reduced at the edges of the cell (relative to the rest of the cell), which the scientists attribute to intermolecular interactions and membrane curvature prevalent at cell edges.

[Source: NASW]