Quantification of biological interactions with particle image cross-correlation spectroscopy (PICCS)

Area of Science:

• Cell Biology
• Biophysics
• Developmental Biology

Background:

• Two-color microscopy is crucial for observing complex biological processes involving multiple interacting molecules.
• Quantifying the correlation between signals in different color channels is essential for understanding molecular interactions.
• Existing methods may lack the precision needed for accurate correlation measurements in live biological systems.

Purpose of the Study:

• To introduce a novel analysis method, particle image cross-correlation spectroscopy (PICCS), for robust quantification of signal correlations in two-color microscopy.
• To demonstrate the capability of PICCS in extracting correlation fraction and length scale information.
• To apply PICCS for analyzing molecular interactions in living tissues, specifically quantifying morphogen presence in cellular compartments.

Main Methods:

• Development and application of particle image cross-correlation spectroscopy (PICCS).
• Exploitation of high positional accuracy from single-object and single-molecule microscopy.
• Imaging of the morphogen Decapentaplegic (Dpp) in fruit fly wing imaginal disks using two-color microscopy.

Main Results:

• PICCS enables robust quantification of correlation between signals in different color channels.
• The method successfully extracts correlation fraction and length scale.
• PICCS was applied to living tissues, quantifying the fraction of early endosomes containing Dpp in fruit fly larvae.

Conclusions:

• PICCS is a powerful new tool for analyzing molecular interactions with high precision using two-color microscopy.
• The method is applicable to complex biological systems, such as morphogen distribution in developing tissues.
• This technique advances our ability to study molecular co-localization and dynamics in live biological samples.