Single-cell absolute contact probability detection reveals chromosomes are organized by multiple low-frequency yet...

Area of Science:

• Genomics
• Molecular Biology
• Epigenetics

Background:

• Eukaryotic genomes are organized into topologically associated domains (TADs) and nuclear compartments at the kilobase to megabase scale.
• Understanding the variability and underlying mechanisms of this genome organization is crucial.

Purpose of the Study:

• To investigate the multiscale organization of the Drosophila genome.
• To reveal the variability in genome structure at the single-cell level.
• To identify factors influencing the association frequencies within and between TADs.

Main Methods:

• Utilized high-content super-resolution microscopy.
• Employed advanced DNA-labeling techniques.
• Analyzed genome organization in Drosophila.

Main Results:

• Found association frequencies within TADs and between TAD borders to be below ~10%, irrespective of TAD size, epigenetic state, or cell type.
• Visualized nanometer-sized epigenetic domains at the single-cell level despite significant heterogeneity.
• Demonstrated that genomic distance, higher-order chromosome architecture, and epigenetic identity largely define absolute contact frequencies.

Conclusions:

• Topologically associated domains (TADs) and nuclear compartments are organized by numerous, low-frequency, specific interactions.
• Epigenetics and transcriptional state play key roles in regulating these interactions and overall genome organization.