Chemical fixation creates nanoscale clusters on the cell surface by aggregating membrane proteins

Area of Science:

• Cell Biology
• Biophysics
• Microscopy Techniques

Background:

• Chemical fixations are standard for preserving cellular structures but may introduce nanoscale artifacts.
• Protein aggregation by fixatives can alter cell surface morphology, particularly for mobile membrane proteins.
• Lack of high-resolution nanoscale imaging methods has limited research into fixation-induced artifacts.

Purpose of the Study:

• To develop a novel method for high-resolution nanoscale observation of cell surfaces.
• To investigate the potential for chemical fixatives to induce nanoscale artifacts on cell surfaces.
• To characterize the impact of common fixatives on membrane protein distribution and cell surface structures.

Main Methods:

• Development of a high-resolution atomic force microscopy (AFM) technique.
• Utilized a microporous silicon nitride membrane for stable cell surface imaging.
• Applied three common chemical fixatives to cell samples prior to AFM analysis.

Main Results:

• Demonstrated a method for stable, high-resolution nanoscale imaging of cell surfaces.
• Observed significant increases in the size of cell surface protrusions after fixation.
• Confirmed that these protrusions result from the aggregation of membrane proteins induced by fixatives.

Conclusions:

• Chemical fixatives can induce nanoscale artifacts by aggregating membrane proteins on cell surfaces.
• The developed AFM method allows for the detection and characterization of these fixation artifacts.
• Results highlight the importance of considering fixation artifacts when interpreting nanoscale cell surface images.