Generation and Preservation of Novel Mouse Models

The Generation and Preservation of Novel Mouse Models Core provides cryopreservation and reconstitution of frozen sperm and embryos for the cost-effective storage, safekeeping and distribution of genetically modified mice, of which YRDRCC investigators have a unique collection. Our purpose is to provide these services and the usefulness of our mouse repository both within and outside of Yale via a database of all stored strains that is publicly available on the web (see below), and to enable the distribution of frozen sperm/embryos by shipping to outside investigators. We also make accessible to all RDRCC investigator labs the ability to create novel strains of genetically engineered mice, including conditional and/or tissue specific gene Kos, knockin mutants, and engineered bacterial artificial chromosome (BAC) transgenic (Tg) mice.

Both goals of the Core, to cryopreserve existing strains and to help investigators develop new ones, are vigorously pursued and have been quite successful. We have initiated sperm freezing at Yale, along with in vitro fertilization, proving that we can recover the sperm that was frozen. Our success rate is excellent for all strains, including autoimmune-prone strains such as MRL and NOD. We have subsequently demonstrated that observation of cell division by fertilized embryos in vitro is a reliable surrogate marker of sperm viability and hence the ability to recover a strain. This is economical and less time consuming, allowing us to devote more resources to freezing rather than testing. All frozen sperm have been tested, and if recovery is <25% of eggs that divide, sperm are refrozen; this has occurred very rarely. For safekeeping, we have stored frozen sperm in two separate locations in widely separated buildings (TAC and the 300 George Street Building), insuring that a strain will survive a catastrophe in one. We also have collected data about the nature of each frozen strain to increase reliability and usefulness of the data; please click here to see the data and for further questions, please contact Jon Alderman at jonathan.alderman@yale.edu. We also require that the donating investigator PCR retype the tails of the male mice used for sperm donation and provide us with an image of a gel confirming the typing; thus, we know that all of the sperm frozen, to the best of our ability, has the correct genotype. Finally, we report to investigators the status of freezing and testing, so that they know the recoverability of their strain prior to letting the live mice go down or exporting sperm. We have now performed over 400 freezings (of over 380 distinct strains) from 16 investigators. This P30-funded collection may be one of the largest of immunologic relevance in the US, and possibly the world (outside of JAX).

The strain construction element of the Core is a different enterprise, as it is customized to each project and user. Our goal is to help in design and implementation of constructs needed for genome modification, although investigators bear the actual costs of mouse construction. The Core has indeed helped labs that had little or no access or track record with these technologies, as well as helped extend the technology in labs with some experience. In addition, in keeping with our overall goal of outreach, we have helped investigators at other institutions develop strains, in part made here at Yale.

For questions concerning freezing strains, contact Patricia Ranney. For questions on obtaining a frozen strain, or for help with designing and producing a new strain, contact the Core Director, Dr. Mark Shlomchik.