Hybridization in situ
Last reviewed: 23.04.2024
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The hybridization procedure can be carried out not only on the gel, on filters or in solution, but also on histological or chromosomal preparations. This method is called in situ hybridization. A variant of the method in which DNA or RNA preparations labeled with fluorochromes are used as probes is called FISH (fluorescein in situ hybradization). The labeled DNA probe is applied to preparations of differentially colored and prepared for hybridization (denatured) metaphase chromosomes. Pre-treatment of chromosomes is used to facilitate access of the probe to genomic DNA. After washing out unbound DNA molecules and applying a photosensitive emulsion (using a radioactive label) or performing appropriate treatment (using biotin or fluorescein-labeled DNA probes), the locations of DNA sequences that are complementary to the used DNA probe can be directly detected by microscopy in the form of characteristic points over the corresponding parts of certain chromosomes.
This method of investigation makes it possible to determine not only the chromosomal affiliation, but also the intrachromosomal localization of the gene under investigation.