A Normalization Protocol Reduces Edge Effect in High-Throughput Analyses of Hydroxyurea Hypersensitivity in Fission...

Area of Science:

• Microbiology
• Genomics
• Biotechnology

Background:

• Edge effect, enhanced microbial growth at agar plate edges, is a confounding factor in high-throughput screening.
• This phenomenon is often attributed to increased nutrient availability and reduced competition at the periphery.
• It can lead to misinterpretation of cell fitness, particularly in genome-wide studies using mutant libraries.

Purpose of the Study:

• To visualize and address the confounding impact of edge effect in high-density microbial pinning arrays.
• To develop and validate a normalization approach to accurately quantify drug-hypersensitivity in microbial strains.
• To provide a practical solution for improving the reliability of high-throughput screening experiments.

Main Methods:

• High-throughput, high-density pinning arrays were used to visualize edge effect.
• A normalization approach based on colony growth rate was developed and applied.
• Drug-hypersensitivity to hydroxyurea was quantified in fission yeast strains using the normalization method.

Main Results:

• Edge effect was successfully visualized in high-density pinning arrays.
• The normalization procedure compensated for growth rate discrepancies across the plate.
• The method significantly reduced false-positive and false-negative frequencies in fitness measurements.
• Accuracy of drug-hypersensitivity quantification was improved.

Conclusions:

• The developed normalization approach offers a simple, coding-free solution to mitigate edge effect in high-throughput screening.
• This method enhances the accuracy of cell fitness measurements, crucial for genetic studies.
• The findings have significant implications for robotics-based high-throughput screening experiments in microbiology and drug discovery.