Two-Replication Round, Telomere Strand-Specific, Chromosome Orientation Fluorescent In Situ Hybridization

Telomere strand-specific, two-replication-round, chromosome orientation fluorescence in situ hybridization (2R telomeric-CO-FISH) is a molecular cytogenetic protocol that allows simultaneous detection of genomic and telomeric sister chromatid exchanges along with telomeric intrachromosomal conservative break-induced replication. The combination of differential sister-chromatid and strand-specific telomeric labeling, provides information about intrachromosomal DNA recombinational events occurring in the last two consequent replication rounds of living cells grown in the presence of nucleic acid analogs. Despite a plethora of research applications, this methodology can be used to validate the extent of exposure to genotoxic agents and efficiency of recombinational DNA repair.