Quantitative DNA measurements in an instrument combining scanning electron microscopy and light microscopy

Area of Science:

• Biophysics
• Microscopy
• Cell Biology

Background:

• Conventional microscopy techniques often require separate instruments for high-resolution imaging and quantitative analysis.
• Integrating multiple microscopy modalities can enhance cellular studies.

Purpose of the Study:

• To describe a novel instrument combining light microscopy (LM) and scanning electron microscopy (SEM) with a photometer for quantitative DNA measurements.
• To validate the accuracy of DNA measurements performed using this integrated LM/SEM system.

Main Methods:

• Development of a specialized stage within the SEM vacuum chamber to incorporate LM optics.
• Quantitative DNA staining of cell preparations (chicken erythrocytes, human lymphocytes, mouse liver cells).
• Use of a photometer unit attached to the LM/SEM for simultaneous DNA quantification during imaging.

Main Results:

• The combined LM/SEM instrument successfully performed simultaneous imaging and quantitative DNA measurements.
• DNA measurements obtained with the LM/SEM were comparable to those from conventional fluorescence microscopy.
• A gold coating on specimens, necessary for SEM, slightly reduced fluorescence but did not impede DNA measurement accuracy.

Conclusions:

• The developed LM/SEM instrument is a viable tool for correlative microscopy and quantitative cellular analysis.
• This integrated system offers a powerful approach for studying cellular DNA content alongside detailed morphological information.
• The findings support the utility of combined microscopy techniques in advancing cell biology research.