Accuracy and reliability of flow cytometric DNA analysis using a simple, one-step ethidium bromide staining protocol

Area of Science:

• Biotechnology
• Cell Biology
• Analytical Chemistry

Background:

• Flow cytometry is a powerful tool for DNA content analysis.
• Understanding sources of variation is critical for accurate results.
• Ethidium bromide staining is a common method for DNA quantification.

Purpose of the Study:

• To investigate sources of variation and error in flow cytometric DNA content analysis.
• To assess the linearity and reliability of different flow cytometers.
• To evaluate suitable biological standards for DNA content analysis.

Main Methods:

• Detergent-isolated nuclei stained with ethidium bromide.
• Analysis of mouse liver nuclei ploidy classes across three instruments.
• Assessment of human peripheral lymphocytes and trout erythrocytes as DNA standards.
• Optimization of staining time and tissue concentration.

Main Results:

• Maximum deviations from linearity were generally around 1% or lower across instruments.
• Trout erythrocytes proved effective as an internal standard for tumor ploidy analysis.
• Extended staining time (24 h) improved homogeneity and separated male/female lymphocytes.
• Variations due to experimental manipulations were typically around 1%.

Conclusions:

• The described flow cytometry technique for DNA content analysis is robust and reliable.
• Optimized staining protocols and the use of appropriate internal standards enhance accuracy.
• This method is suitable for accurate ploidy analysis in various biological samples.