Gram staining uses two dyes : Crystal violet and Fuchsin or Safranin ( the counterstain ) to differentiate between Gram-positive bacteria ( large Peptidoglycan layer on outer surface of cell ) and Gram-negative bacteria.
32.
"Like MG [ malachite green ], CV [ crystal violet ] is readily absorbed into fish tissue from water exposure and is reduced metabolically by fish to the leuco moiety, leucocrystal violet ( LCV ).
33.
My problem is thus : the current protocol requires the removal of the medium ( DMEM, 10 % FBS, 1 % P / S antibiotics ) before addition of the crystal violet / ethanol solution.
34.
Gram-negative bacteria cannot retain the violet stain after the decolorization step; alcohol used in this stage degrades the outer membrane of gram-negative cells making the cell wall more porous and incapable of retaining the crystal violet stain.
35.
The decolorization step is critical and must be timed correctly; the crystal violet stain is removed from both gram-positive and negative cells if the decolorizing agent is left on too long ( a matter of seconds ).
36.
In an 1898 experiment using crystal violet as a specific stain, Benda first became aware of the existence of hundreds of these tiny bodies in the cytoplasm of eukaryotic cells and assumed that they reinforced the cell structure.
37.
The leuco dyes used in direct thermal paper are usually triaryl methane phthalide dyes, such as Yamamoto Blue 4450, or fluoran dyes, such as Pergascript Black 2C . A third widely used leuco dye is Crystal Violet lactone.
38.
Gram-positive bacteria retain the crystal violet dye, and thus are stained violet, while the Gram-negative bacteria do not; after washing, a counterstain is added ( commonly safranin or fuchsine ) that will stain these Gram-negative bacteria a pink color.
39.
It is one of the four components of basic fuchsine . ( The others are rosaniline, new fuchsine and magenta II . ) It is structurally related to other triarylmethane dyes called methyl violets including crystal violet, which feature methyl groups on nitrogen.
40.
The thermochromic droplets are actually a mixture of several chemicals crystal violet lactone ( the color-changing dye itself ), benzotriazole ( a weak acid ), and a quaternary ammonium salt of a fatty acid ( myristylammonium oleate ) dissolved in 1-dodecanol as solvent.
