- In situ hybridization
In situ hybridization (ISH) is a type of hybridization that uses a labeled
complementary DNA orRNA 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). This is distinct fromimmunohistochemistry , which localizes proteins in tissue sections. DNA ISH can be used to determine the structure of chromosomes. Fluorescent DNA ISH (FISH) can, for example, be used in medical diagnostics to assess chromosomal integrity. RNA ISH (hybridization histochemistry) is used to measure and localize mRNAs and other transcripts within tissue sections or whole mounts.Process
For hybridization histochemistry, sample cells and tissues are usually treated to fix the target transcripts in place and to increase access of the probe. As noted above, the probe is either a labeled
complementary DNA or, now most commonly, a complementaryRNA (riboprobe). The probe hybridizes to the target sequence at elevated temperature, and then the excess probe is washed away (after prior hydrolysis using RNase in the case of unhybridized, excess RNA probe). Solution parameters such as temperature, salt and/or detergent concentration can be manipulated to remove any non-identical interactions (i.e. only exact sequence matches will remain bound). Then, the probe that was labeled with either radio-, fluorescent- or antigen-labeled bases (e.g.,digoxigenin ) is localized and quantitated in the tissue using eitherautoradiography ,fluorescence microscopy orimmunohistochemistry , respectively. ISH can also use two or more probes, labeled with radioactivity or the other non-radioactive labels, to simultaneously detect two or more transcripts.References
#Jin L, Lloyd RV. In situ hybridization: methods and applications. J Clin Lab Anal. 11(1):2-9, 1997. PMID 9021518
# [http://intramural.nimh.nih.gov/lcmr/snge/Protocols/ISHH/ISHH.html Comprehensive and annotated in situ hybridization histochemistry]External links
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* [http://www.cshprotocols.org/cgi/content/full/2008/3/pdb.prot4944 Whole-Mount In Situ Hybridization of RNA Probes to Plant Tissues]
* [http://www.cshprotocols.org/cgi/content/full/2007/10/pdb.prot4730 Preparation of Complex DNA Probe Sets for 3D FISH with up to Six Different Fluorochromes]
* [http://www.cshprotocols.org/cgi/content/full/2006/21/pdb.prot4519 Transcript In Situ Hybridization of Whole-Mount Embryos for Phenotype Analysis of RNAi-Treated Drosophila]
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