MA/MyJ is descended from the ancestral strain MA, which was first developed by Marsh in the early 1900s. Marsh took mice from the Lathrop-Loeb colony and bred the offspring for 32 generations of cousin-mating. MA/MyJ was separated from MA after 37 generations by Murray and Warner. Finally, Warner passed MA/MyJ to the Jackson Laboratory in 1948.
Behavioral Characteristics & Handling
According to the Jackson Laboratory Handbook, these mice are easy to work with. Researchers requiring a docile strain should thus feel confident in choosing MA/MyJ. The handbook does caution however that they are poor breeders with small litters, and also that they are sometimes found with chewed tails.
A 2010 study looking at anxiety and despair in a range of mouse strains found that MA/MyJ showed relatively low immobility in the open field test (lower than BALB/J, C57BL/6J and CBA/J amongst others) as well as high overall distance travelled. This suggests that MA/MyJ is an active and non-anxious strain.
MA/MyJ is most prominently noted for its abnormal liver formation. Specifically, a mutation of the gene hf (hepatic fusion) results in different lobes of the liver becoming fused. It is not clear what the consequences of this are for liver function in this strain.
While MA/MyJ shows a low incidence of mammary tumors, like the ancestral MA strain, it is very susceptible to infection by mouse mammary tumor virus (MMTV). These mice are also resistant to X-ray radiation and can survive for an extended period in an atmosphere with 90% oxygen, suggesting they perhaps have superior DNA repair mechanisms.
Polyuria and polydipsia are seen in breeding females over six months of age, although this strain is resistant to diabetes. Cysts are found in the pituitary gland of over half of these mice, and their blood pressure is unusually high. Finally, like many inbred mice, they possess the ahl mutant allele of cadherin 23 resulting in progressive hearing loss from a young age.
Major Experimental Uses
MA/MyJ’s liver abnormalities make it of interest to scientists researching metabolism. These mice can also be used in the study of sensory and neurological disorders.
- 000677 – MA/MyJ. 2019. 000677 – MA/MyJ. [ONLINE] Available at: https://www.jax.org/strain/000677. [Accessed 17 September 2019].
- MGI – Inbred Strains: MA. 2019. MGI – Inbred Strains: MA. [ONLINE] Available at: http://www.informatics.jax.org/inbred_strains/mouse/docs/MA.shtml. [Accessed 17 September 2019].
- The Jackson Laboratory Handbook on Genetically Standardized Mice. 6th ed. 2009. [ONLINE]. Available at: http://jackson.jax.org/rs/444-BUH-304/images/JAX%20Handbook%20Genetically%20Standardized%20Mice.pdf.
- Miller BH, Schultz LE, Gulati A, Su AI, Pletcher MT. 2010. Phenotypic Characterization of a Genetically Diverse Panel of Mice for Behavioral Despair and Anxiety. PLoS ONE. 5(12): e14458.