Editing Southern blot (section)

{{Short description|DNA analysis technique}}
[[File:Recombinant DNA- southern blot (1).jpg|thumb|[[Agarose gel electrophoresis|Agarose gel]]]]
[[File:Aufbau Southern-Blot.jpg|thumb|Tray with a stack consisting top down of a weight, paper towels, [[artificial membrane|membrane]] of [[nitrocellulose]] or [[nylon]], gel, salt solution and a slab of glass.]]
[[File:Southern blot membrane.jpg|thumb|Southern blot membrane after [[Nucleic acid hybridization|hybridization]] and rinsing.]]
[[File:Southern-Blot-Agarosegel.jpg|thumb|Southern blot agarose gel under [[ultraviolet]] illumination.]]
[[File:Southern-Blot-Autoradiogramm.jpg|thumb|Southern blot [[autoradiography|autoradiogram]].]]
'''Southern blot''' is a method used for detection and quantification of a specific [[DNA sequence]] in DNA samples. This method is used in [[molecular biology]]. Briefly, purified DNA from a biological sample (such as blood or tissue) is digested with [[restriction enzyme]]s, and the resulting DNA fragments are [[electrophoresis|separated by electrophoresis using an electric current]] to move them through a sieve-like gel or matrix, which allows smaller fragments to move faster than larger fragments. The DNA fragments are transferred out of the gel or matrix onto a solid membrane, which is then exposed to a [[DNA probe]] labeled with a radioactive, fluorescent, or chemical tag. The tag allows any DNA fragments containing complementary sequences with the DNA probe sequence to be visualized within the Southern blot.<ref>{{cite web |title=Talking Glossary of Genetic Terms {{!}} NHGRI |publisher=National Institutes of Health |url=https://www.genome.gov/genetics-glossary/Enzyme.3 |website=www.genome.gov |access-date=24 January 2023}} {{PD-notice}}</ref>

The  Southern blotting combines the transfer of [[agarose gel electrophoresis|electrophoresis]]-separated DNA fragments to a filter membrane in a process called [[Blot (biology)|blotting]], and the subsequent fragment detection by [[probe hybridization]].<ref>{{Cite web|url=https://www.genome.gov/genetics-glossary/Southern-Blot|title=Southern Blot}}</ref>

The method is named after the British biologist [[Edwin Southern]], who first published it in 1975.<ref>{{cite journal
| last = Southern
| first = Edwin Mellor
| author-link = Edwin Southern
| date = 5 November 1975
| title = Detection of specific sequences among DNA fragments separated by gel electrophoresis
| journal = [[Journal of Molecular Biology]]
| volume = 98
| issue = 3
| pages = 503–517
| issn = 0022-2836
| doi = 10.1016/S0022-2836(75)80083-0
| pmid = 1195397
| s2cid = 20126741
}}</ref>  Other [[Blot (biology)|blot]]ting  methods (i.e., [[western blot]],<ref>{{cite journal | last1 = Towbin | last2 = Staehelin | first2 = T | last3 = Gordon | first3 = J | display-authors = etal   | year = 1979 | title = Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications | journal = PNAS | volume = 76 | issue = 9| pages = 4350–4 | doi = 10.1073/pnas.76.9.4350 | pmid = 388439 | pmc=411572| bibcode = 1979PNAS...76.4350T | doi-access = free }}</ref> [[northern blot]], [[eastern blotting|eastern blot]], [[southwestern blot]]) that employ similar principles, but using RNA or protein, have later been named for [[compass]] directions as a sort of pun from Southern's name. As the label is [[eponym]]ous, Southern is capitalized, as is conventional of [[proper noun]]s. The names for other blotting methods may follow this convention, by analogy.<ref>{{cite journal
| last = Burnette
| first = W. Neal
|date=April 1981
| title = Western Blotting: Electrophoretic Transfer of Proteins from Sodium Dodecyl Sulfate-Polyacrylamide Gels to Unmodified Nitrocellulose and Radiographic Detection with Antibody and Radioiodinated Protein A
| journal = [[Analytical Biochemistry (journal)|Analytical Biochemistry]]
| volume = 112
| issue = 2
| pages = 195–203
| issn = 0003-2697
| doi = 10.1016/0003-2697(81)90281-5
| pmid = 6266278
}}</ref>