PD Dr. Albert Ricken

photo by: Albert Ricken © Hairs shafts displaying a non-specific
reaction in the S-GAL/ NBT β-Galactosidase assay

The Escherichia coli LacZ reportergene is widely used for the detection of promotor gene activity in transgenic mice. The encoded bacterial β-galactosidase (Bact β-Gal) is classically located using 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside/ferri-/ferrocyanide (X-Gal/FeCN) histochemistry. Uncertainty about the origin of the ß-Gal signal arises in tissues containing high natural levels of mammalian ß-Gal. However reliable results can nevertheless be obtained in these tissues by performing the X-Gal reaction under slightly basic conditions (pH 8-9). This applies, in particular, if tissue sections are examined instead of whole-mounts and if the natural bacterial flora is removed from digestive and genital tract specimens in advance. An alternative chromogenic substrate for β-Gal detection is salmon-gal (S-Gal) in combination with nitro blue tetrazolium chloride (NBT). The reaction is strictly limited to neutral to basic conditions. However, it has its pitfalls since it non-specifically stains keratinized epithelial appendages.

Selected Publications

Merkwitz C, Blaschuk O, Schulz A, Ricken AM (2016) Comments on methods to suppress endogenous β-galactosidase activity in mouse tissues expressing the LacZ reporter gene. J Histochem Cytochem. 64(10):579-86.

Merkwitz C, Blaschuk O, Winkler J, Schulz A, Prömel S, Ricken AM (2017) Advantages and limitations of Salmon-Gal/tetrazolium salt histochemistry for the detection of LacZ reporter gene activity in murine epithelial tissue. J Histochem Cytochem 65(4):197–206.