Mice homozygous for the transgenic insert are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. These "BAT-GAL" transgenic mice are a reporter strain that express beta-galactosidase in the presence of activated beta-catenin. The transgene expresses the lacZ gene under the control of a regulatory sequence consisting of seven consensus LEF/TCF-binding motifs upstream of the Xenopus siamois gene minimal promoter. Transgenic mice display beta-galactosidase activity beginning at embryonic day 6.0 in the posterior side of the proximal epiblast. Beta-galactosidase expression is detectable in the posterior primitive streak and node at gastrulation, and progresses to the paraxial mesoderm and notochord. Beta-galactosidase activity in developing and adult nervous tissue mimics the pattern of Wnt signaling. When bred to other mutant strains, this reporter strain may be useful for identifying mutations that affect the Wnt-signalling pathway, and in the identification of Wnt-responsive cell populations in development and disease.
In 2012, the laboratory of Dr. Glen L Radice (Thomas Jefferson University, Philadelphia) reported that when breeding BAT-GAL transgenic mice with junction plakoglobin mutant mice (Jup; see Stock No. 017575), the BAT-GAL transgene did not segregate randomly with respect to the Jup locus. They concluded that the BAT-GAL transgene is located within several centimorgans (11/201, 5.47% recombination frequency) of the Jup gene (Chr11:100230272-100259077 bp; - strand [NCBI Build 37]). For similar Wnt-signalling beta-galactosidase reporter function with mutant alleles on chromosome 11, they suggest considering TOP-GAL transgenic mice (Stock No. 004623).
