title: Sensitive multicolor fluorescence in situ hybridization using catalyzed reporter deposition (CARD) amplification.
abstract: We describe the simultaneous localization of DNA sequences in cell and chromosome preparations by means of differently fluorochrome-labeled (AMCA, FITC, TRITC) tyramides using the catalyzed reporter deposition (CARD) procedure. For this purpose, repeated as well as single-copy DNA probes were labeled with biotin, digoxigenin, and FITC, hybridized, and visualized with three different cytochemical detection systems based on horseradish peroxidase conjugates. These were sequentially applied to interphase nuclei and metaphase chromosomes at low concentrations to prevent crossreaction and nonspecific background. In situ localized peroxidase activity was visualized by the deposition of fluorochrome-labeled tyramide molecules. To allow specific deposition of a second and a third tyramide conjugate for multiple-target fluorescence in situ hybridization (FISH), remaining peroxidase activity was always completely inactivated by a mild acid treatment before application of the next peroxidase conjugate. The CARD reactions were optimized for maximal signal-to-noise ratio and discrete localization by tuning reaction time, H2O2, and tyramide concentrations. For both repeated and single-copy DNA targets, high FISH signal intensities were obtained, providing improvement of sensitivity over conventional indirect detection systems. In addition, the fluorescence CARD detection system proved to be highly efficient and easy to implement in multiple-labeling studies, such as reported here for FISH.
authors.affiliation: Department of Molecular Cell Biology & Genetics, University of Maastricht, The Netherlands.
authors.forename: E J
authors.initials: EJ
authors.lastname: Speel
authors.forename: F C
authors.initials: FC
authors.lastname: Ramaekers
authors.forename: A H
authors.initials: AH
authors.lastname: Hopman
mesh_terms: D002295:Carcinoma, Transitional Cell / Q000737:chemistry / Q000235:genetics; D002503:Centromere / Q000737:chemistry*; D004247:DNA / Q000032:analysis*; D015342:DNA Probes; D005456:Fluorescent Dyes / Q000737:chemistry*; D015870:Gene Expression; D006735:Horseradish Peroxidase; D006801:Humans; D007124:Immunoenzyme Techniques; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D008677:Metaphase; D014407:Tumor Cells, Cultured; D014439:Tyramine / Q000737:chemistry*
chemical_list: D015342:DNA Probes; D005456:Fluorescent Dyes; D004247:DNA; D006735:Horseradish Peroxidase; D014439:Tyramine