Important Note
Important Note regarding transgene insertion and linkage to H-2b MHC haplotype: In Liu et al. 2020 J Immunol. 204:1982 [PMID:32122998], it was discovered that the UBC-GFP transgene integrated into chromosome 17 at nucleotide position 29,435,589 (reference sequence NC_000083.6; GRCm38.p6) - this is a noncoding region centromeric from the H-2 locus (~4.6 Mbp away from H2-K1). The number of transgene copies was not determined. Furthermore, this determined that BALB/cBy-congenic UBC-GFP transgenic mice (N11+ from Stock No. 007076) retained the H-2b MHC haplotype from the genetic background upon which it was created (C57BL/6), rather than the H-2d MHC haplotype of BALB/cBy.
Although close to the H-2 locus, segregation is possible. For experiments where MHC haplotype is a factor, researchers should determine if the UBC-GFP transgenic mice are H-2b or H-2d.
Detailed Description
In 2020, the UBC-GFP transgene was determined to have integrated at Chr17:29,435,589 - a noncoding region centromeric from the H-2 locus (~4.6 Mbp away from H2-K1) - and is closely linked to H-2b MHC haplotype. See Important Note for additional details.
Rag1-deficient ubiquitin-GFP mice on the C57BL/6 genetic background (B6.Rag1-/-;UBC-GFP) combine lymphocyte-deficiency with widespread green fluorescent protein expression.
Mice homozygous for both the Rag1 null allele and the UBC-GFP transgene (Rag1-/-;UBC-GFP+/+) are viable and fertile. Double homozygous mice produce no mature T cells or B cells, and have widespread GFP expression that is uniform within cell lineage. GFP expression varies between different cell types; hematopoietic cells have high expression levels compared with other cells. Red blood cells from UBC-GFP homozygotes should fluoresce at approximately twice the level compared to UBC-GFP hemizygotes.
Similar to other immunodeficient strains, maintaining Rag1-deficient mice in high health status (specific pathogen-free) vivaria promotes overall colony health. If Rag1-deficient animals are maintained in low health barrier rooms, the use of medicated water (sulfatrim/trimethoprim-sulfa) is suggested to increase overall colony health.
C57BL/6J-congenic mice harboring this Rag1 null allele are described and available from The Jackson Laboratory Repository as Stock No. 002216.
UBC-GFP transgenic mice from founder line 30 on a C57BL/6 genetic background are described and available from The Jackson Laboratory Repository as Stock No. 004353. The transgene insertion on chromosome 17 results in linkage to H-2b MHC haplotype (see Important Note).
