The DD strain represents a specific line of laboratory mice that has become a valuable tool in biological research. These mice are carefully bred to possess uniform genetic characteristics, allowing scientists to conduct controlled experiments and obtain reliable results. The use of such standardized animal models is foundational for understanding complex biological processes and developing new treatments for human diseases.
Understanding DD Strains
The DD strain, often referred to as DDD, is an inbred line of albino laboratory mice originating from Germany. These mice were initially brought to Japan in 1928 from the Hoechst Company in Frankfurt, where they were termed “deutsche Maus” by researchers at the Kitasato Institute.
In 1952, the “deutsche Maus” at Denken (Institute for Infectious Diseases) were formally named dd mice. Inbreeding began in 1957, leading to the establishment of the DDD inbred strain by 1962. The “DD” in the strain name refers to their origin as “deutsche Maus at Denken.” This rigorous inbreeding process, involving more than 20 generations of brother-sister mating, ensures that mice within the strain are nearly genetically identical, which is crucial for experimental reproducibility.
Unique Biological Traits
DD strains exhibit several distinct biological characteristics useful for research. One notable trait is their susceptibility to mammary tumors. Studies show that around 84% of DD mice develop mammary tumors by approximately 7.7 months of age. This high incidence is linked to an endogenous mammary tumor virus (MMTV) within the strain.
Another characteristic is a high incidence of heritable hydronephrosis, a condition involving kidney swelling due to urine backup. This appears to stem from abnormally high internal pressure in the renal pelvis. DD mice also display low natural killer (NK) cell activity, a component of their immune system. They also carry the Fv-2s gene, which confers susceptibility to the Friend leukemia virus.
Research Applications
The specific biological traits of DD strains make them highly valuable in various fields of scientific inquiry. Their susceptibility to mammary tumors, for instance, makes them a relevant model for cancer research, particularly in understanding breast cancer development and testing potential therapies. Researchers utilize these mice to study tumor progression and evaluate the efficacy of new anti-cancer drugs and immunotherapies.
The DD strain’s immune system characteristics, such as low NK cell activity and susceptibility to certain viruses like Friend leukemia virus, also render them useful for immunology studies. Scientists can investigate how specific genetic factors influence immune responses and how different pathogens interact with the host immune system. This helps in deciphering complex immune pathways and developing strategies for managing infectious diseases.
DD mice also contribute to vaccine development due to their predictable responses to certain viral challenges. The consistent experimental outcomes achieved with these mice are important for evaluating vaccine candidates and understanding protective immunity. Studying these specific disease susceptibilities and immunological features in a controlled genetic background supports advancements in biological and medical research.