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Southern blot
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<p>Southern blot is a method used for detection and quantification of a specific <a href="/facts/DNA_sequence/hsPsNCQW">DNA sequence</a> in DNA samples. This method is used in <a href="/facts/Molecular_biology/YgqU35ub">molecular biology</a>. Briefly, purified DNA from a biological sample (such as blood or tissue) is digested with <a href="/facts/Restriction_enzyme/Mg0VgkCX">restriction enzymes</a>, and the resulting DNA fragments are <a href="/facts/Electrophoresis/B0aLKHTt">separated by electrophoresis using an electric current</a> 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 <a href="/facts/DNA_probe/j3pu1L7E">DNA probe</a> 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. </p><p>The Southern blotting combines the transfer of <a href="/facts/Agarose_gel_electrophoresis/JxY5UUXv">electrophoresis</a>-separated DNA fragments to a filter membrane in a process called <a href="/facts/Blot_(biology)/jg2BK0aP">blotting</a>, and the subsequent fragment detection by <a href="/facts/Probe_hybridization/j3pu1L7E">probe hybridization</a>. </p><p>The method is named after the British biologist <a href="/facts/Edwin_Southern/U6Nj8GXr">Edwin Southern</a>, who first published it in 1975. Other <a href="/facts/Blot_(biology)/jg2BK0aP">blotting</a> methods (i.e., <a href="/facts/Western_blot/YEr6huPC">western blot</a>, <a href="/facts/Northern_blot/pRUrdy2n">northern blot</a>, <a href="/facts/Eastern_blotting/KdbTMGq4">eastern blot</a>, <a href="/facts/Southwestern_blot/DJbaqL8x">southwestern blot</a>) that employ similar principles, but using RNA or protein, have later been named for <a href="/facts/Compass/86MaeFXu">compass</a> directions as a sort of pun from Southern's name. As the label is <a href="/facts/Eponym/2q9tXlTQ">eponymous</a>, Southern is capitalized, as is conventional of <a href="/facts/Proper_noun/bMbxQSn7">proper nouns</a>. The names for other blotting methods may follow this convention, by analogy. </p>