These transgenic mice carry the Brainbow 1.0 cassette, incorporating dTomato, mCerulean, and EYFP, driven by the broadly-expressed CAG (CMV-chicken beta actin) promoter. These fluorescent markers are useful in tracing cell lineage.
This strain, line 2, carries at least 5 copies of the transgene. dTomato red fluorescent protein is expressed strongly in a variety of tissues and developmental stages. Exposure of the transgene to Cre recombinase stochastically alters individual copies of the transgenes such that either EYFP (enhanced yellow fluorescent protein) or mCerulean (blue fluorescent protein) become expressed, resulting in labeling of cells with distinct colors. As many as 21 distinct color combinations have been observed in this line. Expression is reportedly seen in E3.5, 4.5, 6.5, and 7.5 embryos as well as neonates. In adult mice, expression has been observed in skeletal and cardiac muscle, kidneys, lungs, brain, spinal cord, and a portion of the eye, stomach, pancreas, and intestine. By FACS, expression has been observed in thymocytes and splenocytes, as well as CD4, CD8, CD19, CD11b and CD11c positive cells. No expression has been observed in adult liver. These alterations are genetic and heritable by the progeny of the cells.
Homozygous mice show an elevated tendency for seizures and early death not seen in the hemizygotes, likely due to high expression of dTomato.
