Quick validation of genetic quality for conditional alleles in mice

Genetic quality: a complex issue for experimental study reproducibility

Laboratory animal research involving mice, requires consideration of many factors to be controlled. Genetic quality is one factor that is often overlooked but is essential for the generation of reproducible experimental results. Whether experimental research involves inbred mice, spontaneous mutant, or genetically modified strains, exercising genetic quality through careful breeding, good recordkeeping, and prudent quality control steps such as validation of the presence of mutations and verification of the genetic background, will help ensure that experimental results are accurate and that reference controls are representative for the particular experiment. In this review paper, we will discuss various techniques used for the generation of genetically altered mice, and the different aspects to be considered regarding genetic quality, including inbred strains and substrains used, quality check controls during and after genetic manipulation and breeding. We also provide examples for when to use the different techniques and considerations on genetic quality checks. Further, we emphasize on the importance of establishing an in-house genetic quality program.

Mouse resources at the RIKEN BioResource Research Center and the National BioResource Project core facility in Japan

The RIKEN BioResource Research Center (BRC) was established in 2001 as a comprehensive biological resource center in Japan. The Experimental Animal Division, one of the BRC infrastructure divisions, has been designated as the core facility for mouse resources within the National BioResource Project (NBRP) by the Japanese government since FY2002. Our activities regarding the collection, preservation, quality control, and distribution of mouse resources have been supported by the research community, including evaluations and guidance on advancing social and research needs, as well as the operations and future direction of the BRC. Expenditure for collection, preservation, and quality-control operations of the BRC, as a national core facility, has been funded by the government, while distribution has been separately funded by users' reimbursement fees. We have collected over 9000 strains created mainly by Japanese scientists including Nobel laureates and researchers in cutting-edge fields and distributed mice to 7000 scientists with 1500 organizations in Japan and globally. Our users have published 1000 outstanding papers and a few dozen patents. The collected mouse resources are accessible via the RIKEN BRC website, with a revised version of the searchable online catalog. In addition, to enhance the visibility of useful strains, we have launched web corners designated as the "Mouse of the Month" and "Today's Tool and Model." Only high-demand strains are maintained in live colonies, while other strains are cryopreserved as embryos or sperm to achieve cost-effective management. Since 2007, the RIKEN BRC has built up a back-up facility in the RIKEN Harima branch to protect the deposited strains from disasters. Our mice have been distributed with high quality through the application of strict microbial and genetic quality control programs that cover a globally accepted pathogens list and mutated alleles generated by various methods. Added value features, such as information about users' publications, standardized phenotyping data, and genome sequences of the collected strains, are important to facilitate the use of our resources. We have added and disseminated such information in collaboration with the NBRP Information Center and the NBRP Genome Information Upgrading Program. The RIKEN BRC has participated in international mouse resource networks such as the International Mouse Strain Resource, International Mouse Phenotyping Consortium, and Asian Mouse Mutagenesis and Resource Association to facilitate the worldwide use of high-quality mouse resources, and as a consequence it contributes to reproducible life science studies and innovation around the globe.

Quick validation of genetic quality for conditional alleles in mice

Site-specific conditional inactivation technologies using Cre-loxP or Flp-FRT systems are becoming increasingly important for the elucidation of gene function and disease mechanism in vivo. A large number of gene knockout mouse models carrying complex conditional alleles have been generated by global community efforts and made available for biomedical researchers. The structures of conditional alleles in these mice are becoming increasingly complex and sophisticated, and so the validation of the genetic quality of these alleles is likewise becoming a laborious task for individual researchers. To ensure the reproducibility of conditional experiments, the researcher should confirm that loxP or FRT is integrated at the correct positions in the genome prior to start of the experiments. We report the successful design of universal PCR primers specific to loxP and FRT for the quick validation of conditional floxed and Flrted alleles. The primer set consists of forward and reverse primers complimentary to the loxP or FRT sequences with partial modifications at the 5' end containing 6-base restriction endonuclease recognition sites. The universal primer set was tested to detect genomic intervals between a pair of cis-integrated loxP or FRT and was useful for quickly validating various floxed or Flrted alleles in conditional mice.