On May 18, 2012, we received an email that a user could not detect any positive mice of semaphorin KO gene in recovered litters from frozen embryos. A result of our genotyping PCR with DNA samples provided by the user showed that the recovered litters were derived from a different strain. We are sorry for letting the user waste their invaluable time, effort and resources by sending the wrong frozen strain.
Our genotyping result was also same as reported by the user, which indicated that an unintended mix-up had occurred with embryos of different strains during handling and freezing processes on the same day. We asked the user to destroy the recovered litters by an appropriate method and sent the user authentic semaphorin KO mice.
Immediately after this incidence, we have revised protocols for cryopreservation and used clearer visual markers to distinguish cryotubes and culture dishes for different strains as the preventive measure so that we never mix-up embryos of different strains again. We would like to reaffirm the users of our commitment to providing high quality mouse resources. We appreciate all users for your support and understanding for our activities.
