NIA mice and rats are monitored on a regular basis to detect genetic changes that could result from contamination. Colony animals are also monitored quarterly for pathology and evidence of pathogens. The results of the health monitoring for animals in the same room as your shipment will be sent with every animal shipment. Health summaries are available for download. If your institution has specific health status requirements, health reports should be reviewed before placing the order, and acceptable barriers specified in the special instructions section of the order form.
Inbred and hybrid mice in this NIA colony were derived from NIH pedigreed breeding stock in 1974 and for many years were maintained as closed inbred colonies. As mutations occur in both the NIA colony and the NIH breeding colonies, the NIA and NIH genotypes would undoubtedly drift apart. The solution to this problem is to periodically rederive NIA substrains from a common pedigreed breeding stock. One disadvantage to this procedure is that if the rederivation occurs in the middle of 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 or not is largely a matter of chance, depending upon whether significant mutations have occurred and which genetic loci are involved.
Since the problems of substrain differentiation are more significant to NIA programs as a whole, NIA initiated a policy of rederivation from pedigreed stock every 6-7 years. This rederivation interval should keep substrain differentiation at a minimum and still minimize potential disruption of ongoing research. The first rederivation of the NIA mouse colonies occurred in 1983, with subsequent rederivations in 1990, 1998, 2005, and 2010. The 1990, 1998, 2005 and 2010 rederivations used Jackson Laboratory stock.
The Fischer 344 rat colony was rederived in 1990 using Harlan Sprague Dawley Inc.'s commercial pedigreed stock that had been rederived from NIH stock in 1988, and again in 1998 and 2005 using NIH stock.
In September 1985, a colony of Brown Norway (BN) rats and the F1 hybrids of the F344 X BN cross was established to provide an alternative model to the Fischer 344, based on studies that showed the F344 x BN cross produced progeny with fewer detrimental pathologies than inbred strains. Rederivation of this colony occurred in 1992 and again in 1999, using BN/BiRij stock originating from TNO, The Netherlands, and F344 stock from the NIH. The last rederivation was in 2005, using stock from the NIH for both strains.
The Caloric Restricted colony currently includes two mouse genotypes maintained under conditions similar to our other colonies except that they are individually caged. Ad libitum-fed controls maintained under the same conditions as restricted animals are also available. The mice in the caloric restricted colony were rederived in 1998 and in 2005 and 2011 using stock from The Jackson Laboratory.