title: Immunological method for mapping genes on Drosophila polytene chromosomes.
abstract: A method is described for localizing DNA sequences hybridized in situ to Drosophila polytene chromosomes. This procedure utilizes a biotin-labeled analog of TTP that can be incorporated enzymatically into DNA probes by nick-translation. After hybridization in situ, the biotin molecules in the probe serve as antigens which bind affinity-purified rabbit antibiotin antibodies. The site of hybridization is then detected either fluorimetrically, by using fluorescein-labeled goat anti-rabbit IgG, or cytochemically, by using an anti-rabbit IgG antibody conjugated to horseradish peroxidase. When combined with Giemsa staining, the immunoperoxidase detection method provides a permanent record that is suitable for detailed cytogenetic analysis. This immunological approach offers four advantages over conventional autoradiographic procedures for detecting in situ hybrids: (i) the time required to determine the site of hybridization is decreased markedly, (ii) biotin-labeled probes are chemically stable and give reproducible results for many months; (iii) biotin-labeled probes appear to produce less background noise than do radiolabeled probes; and (iv) the resolving power is equal to and often greater than that achieved autoradiographically.
mesh_terms: D000818:Animals; D001710:Biotin / Q000276:immunology; D002874:Chromosome Mapping; D002875:Chromosomes / Q000648:ultrastructure*; D004331:Drosophila melanogaster / Q000235:genetics*; D007124:Immunoenzyme Techniques; D008722:Methods; D009693:Nucleic Acid Hybridization
chemical_list: D001710:Biotin