Blots Definition

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Bolt Regional slang for isobutyl nitrite, an alkyl nitrate inhaled as a recreational abuse substance. Medical Definition of blot.: a nitrocellulose sheet that contains spots of immobilized macromolecules (as of DNA, RNA, or protein) or their fragments and that is used to identify specific components of the spots by applying a suitable molecular probe (as a complementary nucleic acid or a radiolabeled antibody) — see northern blot, southern blot, western blot.

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North·ern blot a·nal·y·sis

blot

(blŏt)n.

blot

noun A nitrocellulose or nylon membrane bearing a biomolecule of interest—e.g., DNA, RNA or protein—transferred to the membrane from an electrophoretic gel by either osmosis or vacuum; after transferring the molecule of interest, the membrane is bathed in a solution containing a “mirror-image” of the molecule already on the membrane, producing a hybridisation.
verb To perform any of a number of similar techniques used to analyse biologic molecules. Mixtures of biomolecule—DNA, RNA or protein—fragments are separated by electrophoresis through a polymeric (agarose or polyacrylamide) gel; the separated components are then transferred to a membrane where they are immobilised, analysed and visualised by various techniques including antibody binding and DNA hybridisation.
Southern blot
A technique for identifying the presence or absence of a segment of DNA in a sample; the procedure begins by partial enzymatic digestion of nucleic acids, cutting the DNA at specific sites by any of a number of restriction endonucleases, each of which recognises and cuts at a 5- or 6-nucleotide sequence. For instance, HindIII, from H influenzae, cuts DNA at all sites bearing the nucleotide sequence A/AGCTT at the mirror image sites on the 2 DNA chains between the 2 adenines A/A, resulting in a mixture of DNA fragments of varying lengths measuring up to 30 kD, which is then electrophoresed in an agarose gel and transferred to a membrane. Because the DNA on the membrane is single stranded, it has a high affinity for its complementary strand. The final step in the blot is to radioactively “tag” the complementary DNA (Southern blot, after Dr E. Southern), RNA (Northern blot), protein (Western blot), DNA-protein hybridisation (Southwestern blot), and RNA-protein hybridisation (Northwestern blot).
Dot blot
DNA, RNA, or protein are dotted directly onto a membrane support, and form discrete spots.

North·ern blot a·nal·y·sis

(nōr'dhĕrn blot ă-nal'i-sis)

South·ern blot a·nal·y·sis

(sŭdh'ĕrn blot ă-nal'i-sis)

West·ern blot a·nal·y·sis

(wes'tĕrn blot ă-nal'i-sis)

Eastern Blot Definition

zoo blot a·nal·y·sis

(zū blot ă-nal'i-sis)
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A blot, in molecular biology and genetics, is a method of transferring proteins, DNA or RNA onto a carrier (for example, a nitrocellulose, polyvinylidene fluoride or nylon membrane). In many instances, this is done after a gel electrophoresis, transferring the molecules from the gel onto the blotting membrane, and other times adding the samples directly onto the membrane. After the blotting, the transferred proteins, DNA or RNA are then visualized by colorant staining (for example, silver staining of proteins), autoradiographic visualization of radiolabelled molecules (performed before the blot), or specific labelling of some proteins or nucleic acids. The latter is done with antibodies or hybridization probes that bind only to some molecules of the blot and have an enzyme joined to them. After proper washing, this enzymatic activity (and so, the molecules we search in the blot) is visualized by incubation with proper reactive, rendering either a colored deposit on the blot or a chemiluminescent reaction which is registered by photographic film.

Southern blot[edit]

Torque To Yield Bolts Definition

A Southern blot is a method routinely used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization.^[1]

Western blot[edit]

A western blot is used for the detection of specific proteins in complex samples. Proteins are first separated by size using electrophoresis before being transferred to an appropriate blotting matrix (usually polyvinylidene fluoride or nitrocellulose) and subsequent detection with antibodies.

Far-western blot[edit]

Similar to a western blot, the far-western blot uses protein–protein interactions to detect the presence of a specific protein immobilized on a blotting matrix. Antibodies are then used to detect the presence of the protein–protein complex, making the Far-Western blot a specific case of the Western blot.

Southwestern blot[edit]

A southwestern blot is based on Southern blot and is used to identify and characterize DNA-binding proteins by their ability to bind to specific oligonucleotide probes.^[2] The proteins are separated by gel electrophoresis and are subsequently transferred to nitrocellulose membranes similar to other types of blotting.

Eastern blot[edit]

Ink Blots Definition

The eastern blot is used for the detection of specific posttranslational modifications of proteins. Proteins are separated by gel electrophoresis before being transferred to a blotting matrix whereupon posttranslational modifications are detected by specific substrates (cholera toxin, concanavalin, phosphomolybdate, etc.) or antibodies.^[3]

Far-eastern blot[edit]

The far-eastern blot is for the detection of lipid-linked oligosaccharides. High-performance thin-layer chromatography is first used to separate the lipids by physical and chemical characteristics, then transferred to a blotting matrix before the oligosaccharides are detected by a specific binding protein (i.e. antibodies or lectins).

Northern blot[edit]

The northern blot is for the detection of specific RNA sequences in complex samples. Northern blotting first separates samples by size via gel electrophoresis before they are transferred to a blotting matrix and detected with labeled RNA probes.

Reverse northern blot[edit]

The reverse northern blot differs from both northern and Southern blot in that DNA is first immobilized on a blotting matrix and specific sequences are detected with labeled RNA probes.

Bolts Definition Tool

Dot blot[edit]

A dot blot is a special case of any of the above blots where the analyte is added directly to the blotting matrix (and appears as a 'dot') as opposed to separating the sample by electrophoresis prior to blotting.

List of blots[edit]

• Southern blot for DNA
• northern blot for RNA
• reverse northern blot for RNA
• western blot for proteins
• far-western blot for protein–protein interactions
• eastern blot for post-translational modification
• far-eastern blot for glycolipids

See also[edit]

References[edit]

Blots Definition And Examples

1. ^Towbin, Staehelin T, Gordon J, et al. (1979). 'Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications'. PNAS. 76 (9): 4350–4. Bibcode:1979PNAS...76.4350T. doi:10.1073/pnas.76.9.4350. PMC411572. PMID388439.
2. ^Bowen B, Steinberg J, Laemmli UK, Weintraub H (January 1980). 'The detection of DNA-binding proteins by protein blotting'. Nucleic Acids Res. 8 (1): 1–20. doi:10.1093/nar/8.1.1. PMC327239. PMID6243775.
3. ^Thomas, Thirumalapura N, Crossley EC, Ismail N, Walker DH, et al. (2009). 'Antigenic protein modifications in Ehrlichia'. Parasite Immunology. 31 (6): 296–303. doi:10.1111/j.1365-3024.2009.01099.x. PMC2731653. PMID19493209.

Definition Blots Out