AbstractCombined binary ratio labeling (COBRA) is designed to increase the multiplicity of fluorescence in situ hybridization (FISH)鈥攊.e., the number of targets that can be distinguished simultaneously. In principle, chemical (ULS), enzymatic (nick translation or random priming) or PCR-based labeling procedures of probes can be used. The method was originally designed to label chromosome-painting probes, but has also been used for probe sets specific for subtelomeric regions. COBRA imaging requires a digital fluorescence microscope equipped for sequential excitation and recording of color images. Staining of all 24 human chromosomes is accomplished with only four fluorochromes, compared with five for methods based on combinatorial labeling. The COBRA procedure takes 鈭?/span>6 h laboratory work, 2鈥? d incubation and a few hours imaging. 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Rights and permissionsReprints and PermissionsAbout this articleCite this articleSzuhai, K., Tanke, H. COBRA: combined binary ratio labeling of nucleic-acid probes for multi-color fluorescence in situ hybridization karyotyping. Nat Protoc 1, 264鈥?75 (2006). https://doi.org/10.1038/nprot.2006.41Download citationPublished: 27 June 2006Issue Date: June 2006DOI: https://doi.org/10.1038/nprot.2006.41 Birgit Lohberger, Susanne Scheipl, Ellen Heitzer, Franz Quehenberger, Danielle de Jong, Karoly Szuhai, Bernadette Liegl-Atzwanger Beate Rinner Scientific Reports (2021) Ellen Heitzer, Arwin Groenewoud, Katharina Meditz, Birgit Lohberger, Bernadette Liegl-Atzwanger, Andreas Prokesch, Karl Kashofer, Diana Behrens, Johannes Haybaeck, Dagmar Kolb-Lenz, Harald Koefeler, Sabrina Riedl, Helmut Schaider, Carina Fischer, B. Ewa Snaar-Jagalska, Danielle de鈥橨ong, Karoly Szuhai, Dagmar Zweytick Beate Rinner Scientific Reports (2019) Matthias S. Roost, Roderick C. 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