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#DNA break

2 public questions tagged with this topic.

Recombination

Spo11 protein introduces which type of DNA break during meiosis?

Meiotic recombination is initiated intentionally to promote homolog pairing and crossovers. Spo11, conserved protein related to archaeal Topoisomerase VI catalytic subunit Top6A, performs controlled cleavage of both strands of single duplex simultaneously, generating double-strand break with covalent phosphotyrosyl links at 5' ends. Unlike single-strand nicks created during replication or base excision repair, these DSBs are highly recombinogenic and activate downstream MRX resection. Absence of Spo11 leads to failure of synapsis and infertility, highlighting essence of programmed DSBs, not spontaneous lesions, for meiosis.

Ref: Watson et al., Molecular Biology of the Gene, 7th ed., Chapter 12: Spo11-Mediated Double-Strand Breaks in Meiosis

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DNA-Protein Interaction analysis

Which protein showed constitutive binding to the break site in ChIP?

Time-resolved ChIP after inducing chromosomal break distinguishes persistent versus dynamic repair factor recruitment. Some proteins peak transiently then dissociate, others spread outward. Constitutive binding indicates stable occupancy at break site across all examined intervals without significant decline. In described experimental dataset, enrichment profiles show Rep3 maintaining high occupancy at break site from initial time point through later points, suggesting role as scaffold or structural maintenance component anchoring repair complex. This contrasts with Rep1 transient recruitment and Rep2 spreading phenotype, establishing Rep3 as constitutive binder at break.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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