Bleed-through correction for rendering and correlation analysis in multi-colour localization microscopy

Abstract

Multi-colour localization microscopy has enabled sub-diffraction studies of colocalization between multiple biological species and quantification of their correlation at length scales previously inaccessible with conventional fluorescence microscopy. However, bleed-through, or misidentification of probe species, creates false colocalization and artificially increases certain types of correlation between two imaged species, affecting the reliability of information provided by colocalization and quantified correlation. Despite the potential risk of these artefacts of bleed-through, neither the effect of bleed-through on correlation nor methods of its correction in correlation analyses has been systematically studied at typical rates of bleed-through reported to affect multi-colour imaging. Here, we present a reliable method of bleed-through correction applicable to image rendering and correlation analysis of multi-colour localization microscopy. Application of our bleed-through correction shows our method accurately corrects the artificial increase in both types of correlations studied (Pearson coefficient and pair correlation), at all rates of bleed-through tested, in all types of correlations examined. In particular, anti-correlation could not be quantified without our bleed-through correction, even at rates of bleed-through as low as 2%. Demonstrated with dichroic-based multi-colour FPALM here, our presented method of bleed-through correction can be applied to all types of localization microscopy (PALM, STORM, dSTORM, GSDIM, etc.), including both simultaneous and sequential multi-colour modalities, provided the rate of bleed-through can be reliably determined.

Super-Resolution Imaging of Molecular Emission Spectra and Single Molecule Spectral Fluctuations

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The Continuing Mystery of Lipid Rafts

“…This experimental pitfall can be overcome by imaging two distinguishable sets of molecules to measure their co-distribution 145, 147-149 . This too is not without experimental complexities: fluorescent impurities and spectral overlap can give rise to misidentification and artifactual co-localization 150, 151 . Although the currently available number and types of fluorophores limit these approaches, probe development is an active area of research.…”

Challenges facing quantitative large-scale optical super-resolution, and some simple solutions

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