In situ hybridization

In situ hybridization (ISH) is a type of hybridization that uses a labeled complementary DNA, RNA or modified nucleic acids strand (i.e., probe) to localize a specific DNA or RNA sequence in a portion or section of tissue (in situ), or, if the tissue is small enough (e.g., plant seeds, Drosophila embryos), in the entire tissue (whole mount ISH), in cells, and in circulating tumor cells (CTCs). This is distinct from immunohistochemistry, which usually localizes proteins in tissue sections.

Procedure

The procedure of in situ hybridization comprises the following steps:

1. Fixation of tissue section or cells onto a glass slide
2. Pre-hybridization treatment to increase accessibility of target DNA or RNA
3. Hybridization of the probe to the DNA or RNA target
4. Stringent washes to remove excess probe
5. Detection of the hybridized probe
6. Visualization of the target molecule

Applications

In situ hybridization is used in many areas of research and diagnosis including:

1. Developmental biology
2. Cancer and other disease diagnosis
3. Genetics
4. Evolutionary biology

Types of In Situ Hybridization

There are two types of in situ hybridization:

1. Fluorescent in situ hybridization (FISH)
2. Chromogenic in situ hybridization (CISH)

Fluorescent In Situ Hybridization (FISH)

Fluorescent in situ hybridization (FISH) is a molecular cytogenetic technique that uses fluorescent probes that bind to only those parts of the chromosome with a high degree of sequence complementarity.

Chromogenic In Situ Hybridization (CISH)

Chromogenic in situ hybridization (CISH) is a molecular technique that allows the visualization of specific genes or gene fragments in tissues.

See Also

• Molecular biology
• Genetics
• Cytogenetics

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