Drawing the letters “Y”, “H” and “O” with artificial nanodomains is no child's play – University of Copenhagen

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07 September 2015

Drawing the letters “Y”, “H” and “O” with artificial nanodomains is no child's play

Cover story

The cover illustration of the September 2015 issue of Cytometry Part A is made with CAB’s super resolution microscope.

Cover story of the September 2015 issue of Cytometry Part A written by CAB researchers Iwona Ziomkiewicz, Thomas Pomorski and Alexander Schulz.

The invention of super resolution microscopy has made it possible to measure the location of a single fluorescent molecule with a hitherto unseen accuracy. For Alexander Schulz and his colleagues this new technology has enabled them to study the organization of proteins and lipids into micro- or nanodomains in cells’ plasma membranes.

Nanodomains with irregular shapes

Many membrane proteins are not evenly distributed over the plasma membrane, but gathered in domains assumed to have a particular lipid composition. Using single molecule localization microscopy (SMLM) the authors of the paper localized the nanodomains in a specialized plant cell type, and compared the suitability of three methods to estimate their size.

As conventional methods full width at half maximum (FWHM) and the full diameter (FWMin) of domains were used. A boundary detection method of the domain area (DA) was performed in order to take irregular shapes into account.

Collaboration with computer scientist

In order to compare the influence of the chosen measurement methods, together with Jon Sporring from the Department of Computer Science, UCPH, they developed a MatLab program that allows for automated analysis of domain sizes from multiple SMLM images. They found that DA value matches regular as well as irregular shapes best, as derived from computer-generated, irregular point clusters.

The cover illustration shows domain area detection of irregular and non-uniform domain shapes as modelled with synthetic point patterns.

These irregular shapes, like the banana shape and the letters “Y”, “H” and “O”, were created to challenge the Matlab analyze.m program in order to achieve an accurate size measurement of plasma membrane nanodomains by single molecule localization microscopy.