Detecting and Segmenting Nanodiscs in Immuno-Electron Micrographs

Nanodiscs are soluble nanoscale phospholipid bilayers with applications in drug delivery and the study of membrane proteins, for example. They can be imaged using electron microscopy, along with immunogold markers indicating locations of proteins of interest. We describe and evaluate methods for automatically detecting and segmenting nanodiscs in electron micrographs. The detection method modifies aspects of the Fast Radial Symmetry Transform to detect nanodiscs that exhibit approximate radial symmetry against noisy but predominantly lighter background. Detected nanodiscs are then segmented using radial active contours. Experiments on micrographs both with and without immunogold markers indicate promising detection and segmentation performance, and that information on nanodisc quantities, locations, size distributions, and co-location with proteins of interest could be extracted automatically.