*This web page was produced as an assignment for an undergraduate course at Davidson College.*


How does FISH work?


The above diagram illustrates the process of Fluorescence In-Situ Hybridization (FISH).  The figure was obtained from the National Health Museum website.  Permission to use this diagram is pending.


FISH Broken Down Into Five Steps:

1)  Identify Probe - Researchers must prepare short sequences of DNA which are complementary to the DNA sequences that they want to examine.  Click for the theory behind probes.

2)  Label Probe - Once researchers have identified the probe that they are going to use, they must label the probe with fluorescent dye.  Fluorescein is an example of a fluorescent marker that can be used to label the probe.

3)  Denature Chromosome and Probe - First, denature the chromosomes by way of heat or pH.  Then denature the probe via heat or pH. 

4)  Hybridization - Add the denatured chromosomes and the denatured probe to a microscope slide.  Allow the probe to hybridize to its complementary site. 

5)  Analysis - Finally wash away the excess probe and use a fluorescence microscope to observe where the probe hybridized. 

                                                                       FISH Sample.  Permission pending for use of this image.

*FISH is unlike many other techniques because it does not require cells to divide.  FISH's ability to perform on nondividing cells makes it a highly versatile procedure. (click to see examples of FISH)


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