Fluorescence in-situ hybridization | FISH 

Fluorescence in-situ hybridization, commonly designated as FISH is a technique that is widely used for the detection of DNA sequences or genes on the chromosome. In this method, the cells are fixed and treated with mild detergent to cause cell lysis. The presence of alkali, converts double stranded DNA into single stranded DNA. Next a fluorescence labeled probe is prepared by amplifying the known DNA sequence using PCR. This probe is then allowed to hybridize with the sample and the sample is studied under fluorescence microscope.