The MMRRC is now maintaining two exciting new lines with broad applicability and interest to scientists working in many different areas. These mouse lines are called “Mouse for Actively Recording Cells 1” or MARC1. Donated by Dr. George M. Church, Ph.D., and Dr. Reza Kalhor, Ph.D., of Harvard Medical School, they are used for barcoding and lineage tracing applications in the mouse (PMID:30093604). Although these lines do not express any disease-related phenotypes, when a MARC1 mouse is crossed to mice expressing cas9 (universally or in a lineage-specific manner), combinatorial and cumulative barcoding starts in the progeny during their development, leading to developmentally barcoded animals that can be used for a multitude of applications, including lineage tracing.

The available lines are:

• STOCK MARC1-PB7/Mmucd, RRID: MMRRC_065424-UCD, was founded by a chimeric male mouse that carried 60 homing guide RNA (hgRNA) loci scattered throughout its genome in a heterozygous state. The founder (#7) was crossed to wild-type C57BL/6J and CD1 mice initially, and the donor then used random intra-strain mating for approximately 10 generations. The genetic background of this line is deemed STOCK due to contributions from more than two inbred lines, and is a mixed background of C57BL/6J, 129S4, and CD1.


• STOCK MARC1-PB3/Mmucd, RRID: MMRRC_065812-UCD, was founded by chimera #3 that carried 50 heterozygote germline-transmissible integrations of hgRNAs, including one on chromosome X. The selected founder was crossed with CD1 females to create the F1 generation. The donor used random intra-strain mating for approximately 12 generations prior to depositing to the MMRRC. The genetic background of this line is deemed STOCK due to contributions from more than two inbred lines and is a mixed background of CD1, C57BL/6J, and 129S4.

Please contact our customer service center at service@mmrrc.org if you have any questions about these new lines.