Strain Rederivation

• Introduction

TAF offers investigators the ability to rederive a particular strain of mice or rats.   Whether an investigator needs to recover a strain which previously had been cryopreserved and is no longer being maintained as live animals, needs to rederive a strain from embryos shipped from a source outside the university, or a strain within the university that carries unwanted pathogens, we will work with the investigator to generate and/or collect embryos for transfer into pathogen-free pseudopregnant recipients.  

The basic steps in a rederivation project are:

1. generation of embryos by mating superovulated females to males
2. collection of embryos from females
3. transfer of embryos into pseudopregnant females

• Getting Started

Prior to rederivation, the investigator will need to meet with TAF staff.   This consultation will enable us to determine the specific needs of the investigator, develop a strategy and schedule for rederivation, and discuss fees. Please contact Anne Griep (aegriep@wisc.edu) or (608) 262-8988 to schedule an initial meeting.

• Embryo Generation, Collection and Transfers

Checklist:

1. review procedure for embryo production
2. complete a billing request form
3. provide an IACUC approved animal protocol number

If a previously cryopreserved strain is being recovered from liquid nitrogen, straws are thawed and embryos transferred into pseudopregnant ICR (for mice) and SD (for rats) recipients.

For projects involving the transfer of a strain from another university, the investigator will generate embryos and ship these embryos to TAF via overnight delivery.  The TAF staff will work with the investigator to provide the necessary guidance so that the investigator can superovulate, mate, collect embryos and prepare the embryos for delivery to the TAF laboratory.

For projects involving the rederivation of pathogen-carrying strains from within the university, we will provide investigators with protocols, hormones and training (if necessary) so that they can superovulate and dissect reproductive tracts from the animals, thereby allowing us to avoid contact with donor animals.  We will collect the embryos from the reproductive tracts and transfer them into pseudopregant ICR (for mice) and SD (for rats) recipients.  The number of transfers completed depends on the number of good quality embryos collected.

In all situations, pups will be born about three weeks later and weaned three weeks after that. Recipient moms will be screened for pathogen status by serological testing. The pups will be transferred to the investigator as soon as serology results indicate the recipient mom is pathogen-free and the animal transfer form has been completed by the investigator and an LAR veterinarian from the relevant school.

When rederiving strains, investigators are charged based on the number of embryo transfers performed.