^★Track: Inferred counting and tracking of replicating DNA loci

Area of Science:

• Cellular and Molecular Biology
• Genetics and Genomics
• Biophysics

Background:

• Fluorescent microscopy is key for studying DNA organization.
• Live-cell imaging faces challenges like low signal-to-noise and variability, hindering quantitative analysis.
• Accurate tracking of fluorescent particles (e.g., DNA loci) is crucial for mechanistic insights.

Purpose of the Study:

• To introduce ★Track, an inference method for precise temporal tracking of intracellular DNA loci.
• To enable accurate prediction of particle copy numbers and replication timing.
• To overcome challenges in live-cell imaging for quantitative DNA organization studies.

Main Methods:

• Developed ★Track, an inference method for temporal tracking of replicating intracellular particles.
• Algorithm accounts for missing, merged, and spurious detections in live-cell imaging data.
• Applied ★Track to analyze plasmid copy number control and bacterial chromosome replication.

Main Results:

• ★Track enables accurate prediction of particle copy numbers and replication event timing.
• Demonstrated new insights into plasmid copy number regulation.
• Revealed the volume dependence of bacterial chromosome replication initiation.

Conclusions:

• ★Track significantly enhances quantitative measurements in live-cell DNA organization studies.
• The method facilitates uncovering mechanistic principles of chromosome organization and dynamics.
• ★Track is applicable across a diverse range of biological systems for DNA dynamics research.