Effects of fuchsin variants in aldehyde fuchsin staining.

Abstract

Aldehyde fuchsin stains pancreatic B cell granules, hypophyseal basophils, goblet cell mucins, gastric chief cells, hyaline cartilage, and elastica. Neither the chemical structure of aldehyde fuchsin nor its staining mechanism is known. This study was undertaken to clarify the role of the fuchsin component of aldehyde fuchsin in its staining reaction. The major findings of this investigation include: 1) single N-methylation of the fuchsin molecule abolishes staining of unoxidized pancreatic B cells, although it does Paraldehyde, a cyclic trimer of acetaldehyde, depolymerizes to acetaldehyde in the presence of HCI. Bangle (1954) suggested that the acetaldehyde then could react with the amino groups of basic fuchsin to form a Schiff base (azomethine). Sumner (1965) confirmed that the amino groups offuchsin are the sites ofaldehyde attachment by using amine blocking reagents to prevent the formation of aldehyde fuchsin. Buehner et al. (1979) systematically varied the aldehyde moiety ofaldehyde fuchsin to determine its role in the staining reaction. They showed that acetaldehyde, whether reacted with pararosaniline-HCI directly or as paraldehyde, produced the most intense stain for almost all aldehyde fuchsin-positive tissues tested. They also showed that only acetaldehyde and paraldehyde fuchsins stained unoxidized B cells of the pancreas. Because their experimental aldehyde fuchsin analogs stained known tissue anions, but not unoxidized B cells, they concluded that the reaction of aidehyde fuchsin with unoxidized pancreatic B cells is more specific than electrostatic attraction ofa basic dye to an acidic tissue. by these aldehyde fuchsin variants. Materials and Methods Dyes. The following dyes, in as pure form as possible, were used as fuchsin variants in this investigation: A. Triaminotriphenylmethanes I. Pararosaniline-HCI (CI. #42500) 2. N-Methylated pararosaniline-HCI (No CI. Number) 3. Methyl violet 2B (Cl. #42535) 4. Crystal violet (Cl. #42555) B. Thiazins 1. Thionin-HCI (Cl. #52000) 2. Azure C (CI. #52002) 3. Azure A (CI. #52005) The hydrochloride ofpararosaniline was prepared by recrystallization of the carbinol (Chroma-Gesellschaft, Schmid and Co. , West Germany) from acid alcohol (l9 v/v concentrated HCI in 70% ethanol). The dye content of this lot was 92%. The Chroma pararosaniline was analyzed by mass spectrometry, courtesy of the

A histochemical investigation of the mechanism of Aldehyde Fuchsin staining of pancreatic B-cell granules

“…The observations reported here corroborate those of Buehner et aI. (1979) and Lichtenstein & Nettleton (1980) who investigated the chemical nature of Aldehyde Fuchsin and its effect on staining. The present study was undertaken to examine the nature of the reactive groups of the B-cell granules.…”

“…Together the studies by Buehner et al (1979) and Lichtenstein & Nettleton (1980) demonstrated that selective staining of unoxidized pancreatic B-cell granules depends more on the chemical structure of the dye than its charge. The work of these authors supports the hypothesis that a non-ionic reaction mechanism is responsible for the selective staining of pancreatic B-cell granules by Aldehyde Fuchsin.…”

“…In a parallel study, Lichtenstein & Nettleton (1980) examined the effects of fuchsin variants used in the preparation of Aldehyde Fuchsin. N-methylated fuchsins and other amine-bearing basic dyes were substituted for the pararosaniline normally used for preparing Aldehyde Fuchsin.…”

Multicolor counterstaining for immunohistochemistry – a modified Movat's pentachrome

“…It was perhaps the alkaline environment of the prior step that produced ionization of carboxylic and phenolic groups of elastic fi ber protein components that were more favorable to binding the cationic aldehyde fuchsin (Horobin 1982, Lichtenstein and Nettleton 1980, Puchtler 1961. A subsequent washing/differentiation step using 70% ethanol as suggested by Spicer and Meyer (1960) was avoided, because we were concerned that this could weaken the staining of elastic fi bers.…”

Enlightening the Path to Protein Engineering: Chemoselective Turn-On Probes for High-Throughput Screening of Enzymatic Activity

“…Methylation has a large effect on the absorption spectra after conjugation to formaldehyde. 317 Robins et al used NMR spectroscopy to study the colored species and the kinetics of its formation. 318 They found that "careful calibration is required" to obtain accurate results when quantifying aldehydes, with a complicated dependency on the concentrations of the dye, the sulfurous acid (or SO 2 ) used as the nucleophile, and the aldehyde.…”