| blot | 1. To spot, stain, or bespatter, as with ink. "The brief was writ and blotted all with gore." (Gascoigne) 2. To impair; to damage; to mar; to soil. "It blots thy beauty, as frosts do bite the meads." (Shak) 3. To stain with infamy; to disgrace. "Blot not thy innocence with guiltless blood." (Rowe) 4. To obliterate, as writing with ink; to cancel; to efface; generally with out; as, to blot out a word or a sentence. Often figuratively; as, to blot out offenses. "One act like this blots out a thousand crimes." (Dryden) 5. To obscure; to eclipse; to shadow. "He sung how earth blots the moon's gilded wane." (Cowley) 6. To dry, as writing, with blotting paper. Synonym: To obliterate, expunge, erase, efface, cancel, tarnish, disgrace, blur, sully, smear, smutch. Origin: Cf. Dan. Plette. See Blot. Source: Websters Dictionary (01 Mar 1998) |
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| blot, northern | A technique in molecular biology, used mainly to separate and identify pieces of RNA. Called a Northern blot only because it is similar to a Southern blot (which is named after its inventor, the British biologist M.E. Southern). (12 Dec 1998) |
| blot, southern | A common test for checking for a match between DNA molecules. DNA fragments are separated by agarose gel electrophoresis, transferred (blotted) onto membrane filters, and hybridised with complementary radiolabelled probes. The aim is to detect specific base sequenceswith the probes. Lest all of this sound esoteric, note that in the television series The X Files a Southern blot was done (in this case, to learn if some alien virus genome had been integrated into a person's genome). The Southern blot is named after its inventor, the British biologist M.E. Southern. There is also a Northern blot and a Western blot. (12 Dec 1998) |
| blot, western | A technique in molecular biology, used to separate and identify proteins. Called a Western blot merely because it has some similarity to a Southern blot (which is named after its inventor, the British biologist M.E. Southern). (12 Dec 1998) |
| blotch | 1. A blot or spot, as of colour or of ink; especially a large or irregular spot. Also Fig.; as, a moral blotch. "Spots and blotches . . . Some red, others yellow." (Harvey) 2. <medicine> A large pustule, or a coarse eruption. "Foul scurf and blotches him defile." (Thomson) Origin: Cf. OE. Blacche in blacchepot blacking pot, akin to black, as bleach is akin to bleak. See Black, or cf. Blot a spot. Source: Websters Dictionary (01 Mar 1998) |
| blote | To cure, as herrings, by salting and smoking them; to bloat. Origin: Cf. Sw. Blot-fisk soaked fish, fr. Blota to soak. See 1st Bloat. Source: Websters Dictionary (01 Mar 1998) |
| blots | Refers to a number of similar techniques that facilitate the analysis of biological molecules. Initially, mixtures of proteins or DNA or RNA fragments are separated by electrophoresis through a polymeric gel (most commonly agarose or polyacrylamide). The separated components are then transferred to a membrane where they are immobilised and can be analysed and visualised by a variety of techniques, including antibody binding and DNA hyrbridisation. Some of the various types of blots are briefly described below. Southern blot - The gel is a DNA electrophoresis system and the molecules transferred are DNA molecules. Northern blot - Similar to the Southern blot, but used to analyse RNA. Western blot - The molecules analysed in a Western blot are proteins, separated by gel electrophoresis, then identified by reacting them with an antibody. Southwestern blot - This is a variant of the Southern blot used to find protein molecules that stick to DNA molecules. Dot blot. DNA, RNA, or protein are dotted directly onto the membrane support, so that they form discrete spots. (14 Nov 1997) |
| blotting | <molecular biology, procedure> General term for the transfer of protein, RNA or DNA molecules from a relatively thick acrylamide or agarose gel or to a paper like membrane (usually nylon or nitrocellulose) by capilliarity or an electric field, preserving the spatial arrangment. Once on the membrane, the molecules are immobilised, typically by baking or by ultra violet irradiation and can then be detected at high sensitivity by hybridisation (in the case of DNA & RNA) or antibody labelling (in the case of protein). RNA blots are called Northern blots, DNA blots, Southern, protein blots, Western. (18 Nov 1997) |
| blotting, northern | Detection of RNA that has been electrophoretically separated and immobilised by blotting on nitrocellulose or other type of paper or nylon membrane. (12 Dec 1998) |
| blotting, southern | A method (first developed by e.m. Southern) for detection of DNA that has been electrophoretically separated and immobilised by blotting on nitrocellulose or other type of paper or nylon membrane. (12 Dec 1998) |
| blotting, western | Identification of proteins or peptides that have been electrophoretically separated by blotting and transferred to strips of nitrocellulose paper. The blots are then detected by radiolabelled antibody probes. (12 Dec 1998) |
| western blot | <technique> A technique similar to Southern blotting, though it is used for proteins. (09 Oct 1997) |
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| Western blot analysis | A procedure in which proteins separated by electrophoresis in polyacrylamide gels are transferred (blotted) onto nitrocellulose or nylon membranes and identified by specific complexing with antibodies that are either pre-or post-tagged with a labelled secondary protein. See: immunoblot. Synonym: Western blot, Western blotting. Origin: coined to distinguish it from eponymic Southern blot a. (05 Mar 2000) |
| southern blot | A technique used for searching for a specific DNA fragment. The process is as follows: 1. separate DNA fragments by gel electrophoresis 2. Change pH of gel to basic, thus allowing disruption of H-bonds 3. blot gel with nitrocellulose paper 4. Heat paper so as to fix DNA fragments 5. probe with labelled messenger RNA or cDNA 6. wash Complementary mRNA/cDNA fragments will have hybridised. (09 Oct 1997) |
| Southern blot analysis | A procedure to separate and identify DNA sequences; DNA fragments are separated by electrophoresis on an agarose gel, transferred (blotted) onto a nitrocellulose or nylon membrane, and hybridised with complementary (labelled) nucleic acid probes. (05 Mar 2000) |
| Northern blot | <molecular biology, procedure> An electroblotting method in which RNA is transferred to a filter and detected by hybridisation to (32)P labelled RNA or DNA. (18 Nov 1997) |
| Northern blot analysis | A procedure similar to the Southern blot analysis, used mostly to separate and identify RNA fragments; typically via transferring RNA fragments from an agarose gel to a nitrocellulose filter followed by detection with a suitable probe. Origin: coined to distinguish it from eponymic Southern blot a. (05 Mar 2000) |
| dot blot | <molecular biology, procedure> Method for detecting a specific protein or message. A spot of solution is dotted onto nitrocellulose paper, a specific antibody or probe is allowed to bind and the presence of bound antibody/probe then shown by using a peroxidase coupled second antibody, as in Western blotting or by other visualisation methods. (18 Nov 1997) |
| ink blot tests | Projective tests utilizing ink blots to which a subject responds. They are used in personality diagnosis. (12 Dec 1998) |
| zoo blot analysis | A procedure using Southern blot analysis to test the ability of a nucleic acid probe from one species to hybridise with the DNA fragment of another species. (05 Mar 2000) |