Colony Monitoring and History

Colony Monitoring

NIA mice and rats are monitored on a regular basis to detect genetic changes that could result from contamination. Colony animals also are monitored regularly for pathology and evidence of pathogens. The results will be sent with every animal shipment. The health report may be sent on request before the animals are shipped. Some of the barriers housing NIA colonies are positive for Helicobacter. If the facility requires Helicobacter-free animals, this must be requested upon order submission.

History

Inbred and hybrid mice in this NIA colony were derived from NIH-pedigreed breeding stock in 1974. For several years, these animals were maintained as closed inbred colonies. As mutations occured in both the NIA colony and the NIH breeding colonies, the NIA and NIH genotypes drifted apart. Periodically rederiving NIA substrains from a common pedigreed breeding stock provided a solution. One disadvantage to this procedure is that if rederivation occurs during an ongoing research project, some differences in genotype of animals used early and late in the project may be unavoidable. Whether these differences pose a research problem is largely a matter of chance, depending on whether significant mutations have occurred and which genetic loci are involved.

Rederivation

Because the problems of substrain differentiation are more significant to NIA programs as a whole, NIA initiated a rederivation policy from pedigreed stock at the beginning of each new 9-year contract. This rederivation interval maintains substrain differentiation at a minimum and minimizes potential disruption of ongoing research. The first rederivation of the NIA mouse colonies occurred in 1983, and the second rederivation occurred in 1990. The rederivation in 1990 used Jackson Laboratory as the source of breeder animals. A third rederivation was conducted in 1998, also from Jackson Laboratory stock. The BALB/c mice are the BY substrain (BALB/cByJ).

The Fischer (F) 344 rat colony was rederived in 1990–1991 using Harlan Sprague Dawley commercial pedigreed stock that had been rederived from NIH stock in 1988, and again in 1998 using NIH stock. In September 1985, a contract was awarded for establishing a NIA colony of Brown Norway (BN) rats and the F1 hybrids of the BN x F344 and F344 x BN crosses. These hybrids were selected as an alternative model to the Fischer 344, based on an NIA study of several F1 hybrids resulting from various crosses that showed the BN-F 344 crosses to produce progeny with fewer detrimental pathologies and later age of onset than other crosses studied. Rederivation of this colony occurred in 1992 and again in 1999, using BN/BiRij stock originating from TNO, The Netherlands, and F344 stock from NIH.

The caloric-restricted colony currently includes three rat genotypes (F344NNia, BN/BiRijNia, and F344 x BNF1Nia). These animals are maintained under conditions similar to NIA's other colonies, but they are individually caged. Ad libitum-fed controls maintained under the same conditions as restricted animals also are available. The original colony was derived from NIH stock, and the colony was rederived in 1998 again using NIH stock for the rat strains.

Barrier Environmental Information