125:. More recently, Karlheinz Toepfer published in 1970 spectral shifts with increasing concentration of the thiazine dyes that matched the spectra of dye:heparin mixtures, showing clearly that metachromasia, corresponding to the colour of stained cartilage, could be reproduced by high concentration of the dye alone in solution. Hence, proximity of the dye molecules was the key parameter in defining metachromasia. Another example of metachromatic dye (fluorochrome) is acridine orange. Under certain conditions it stains single-stranded nucleic acids fluorescing red (red luminescence) while when interacts with double stranded nucleic acids gives green fluorescence.
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monomeric dye molecules. Cell and tissue structures that have high concentrations of ionized sulfate and phosphate groups—such as the ground substance of cartilage, heparin-containing granules of mast cells, and rough endoplasmic reticulum of plasma cells—exhibit metachromasia. This depends on the charge density of the negative sulfate and carboxylate anions in the glycosaminoglycan (GAG). The GAG polyanion stabilizes the stacked, positively-charged dye molecules, resulting in a spectral shift as the conjugated double bond π-orbitals of adjacent dye molecules overlap. The greater the degree of stacking, the greater the metachromatic shift. Thus,
90:, lacking sulphate groups and with only moderate charge density, causes slight metachromasia; chondroitin sulfate, with an additional sulfate residue per GAG saccharide dimer, is an effective metachromatic substrate, whilst heparin, with further N-sulfation, is strongly metachromatic. Therefore, toluidine blue will appear purple to red when it stains these components.
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The metachromatic properties of dimethylmethylene blue, a thiazine dye closely related to toluidine blue, have been exploited to assay glycosaminoglycans extracted from cartilage and other connective tissues. The absorption peak shifts from about 630 nm (red absorption, therefore blue colour)
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within the tissue. When these tissues are stained with a concentrated basic dye solution, such as toluidine blue, the bound dye molecules are close enough to form dimeric and polymeric aggregates. The light absorption spectra of these stacked dye aggregates differ from those of the individual
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Darzynkiewicz Z, Kapuscinski J. (1990)“Acridine Orange, a
Versatile Probe of Nucleic Acids and Other Cell Constituents.” Chapter in: Flow Cytometry and Sorting. Melamed MR, Mendelsohn M & Lindmo T (eds), Alan R. Liss, Inc., New York. pp. 291-314. ISNBM
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that also contain thiazine dyes: the white cell nucleus stains purple, basophil granules intense magenta, whilst the cytoplasms (of mononuclear cells) stains blue, which is called the
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to about 530 nm in the presence of GAG. Humbel and
Etringer's original assay was developed by others to create a stable and widely used dimethylmethylene blue reagent.
109:(1854-1915) who gave its name and studied it more extensively. The modern understanding of metachromasia was advanced by Belgian histologist
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Humbel R, Etringer S. (1974) Colorimetric Method for the Assay of
Sulfated Glycosaminoglycans. "Rev. Roumaine de Biochemie." 11: 21–24.
113:, who studied it between 1933 and 1936 and ascertained its value in the quantitative determination of sulfate
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Improved quantitation and discrimination of sulphated glycosaminoglycans by use of dimethylmethylene blue.
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when they bind to particular substances present in these tissues, called
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The underlying mechanism for metachromasia requires the presence of
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becomes dark blue (with a colour range from blue-red dependent on
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Although metachromasia was observed and described since 1875, by
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66:. Other widely used metachromatic stains is the family of
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185:Farndale R, Buttle DJ, Barrett AJ. (1986)
179:"Prog. Histochem. Cytochem." 1(5): 1–76.
105:and others, it was the German scientist
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121:. He also studied the metachromasia of
34:) is a characteristical change in the
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189:Biochim. Biophys. Acta 883: 173-177
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153:Bergeron JA, Singer M. (1958)
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166:Metachromasy of nucleic acids
164:Lison L, Mutsaars W. (1950)
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170:Quart. J. Microscop. Sci.
177:Die Thiazinefarbstoffe.
62:content) when bound to
46:, exhibited by certain
175:Toepfer K. (1970)
44:biological tissues
72:Romanowsky effect
68:Romanowsky stains
60:glycosaminoglycan
16:(Redirected from
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119:molecular weight
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28:Metachromasia
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111:Lucien Lison
107:Paul Ehrlich
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52:chromotropes
32:metachromasy
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159:J Cell Biol
161:4:433-457.
129:References
83:polyanions
203:Histology
64:cartilage
197:Category
117:of high
40:staining
103:Ranvier
115:esters
99:Cornil
30:(var.
36:color
48:dyes
38:of
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