In the Transgenic and Knockout Core, transgenic mice are generated by pronuclear microinjection of foreign DNA fragments into one-cell-stage mouse embryos. On average, it takes about three to four months to generate a transgenic mouse strain.
The Transgenic and Knockout Core can assist investigators with the design of transgenic DNA constructs. Once a transgenic construct has been assembled, the investigator files a request for microinjection services.
Core personnel then excise the transgene from the plasmid backbone and prepare it for microinjection. They also set up superovulation and matings to obtain one-cell-stage embryos for microinjection and prepare pseudopregnant surrogate mothers for embryo-transfer procedures.
The DNA construct is typically injected into fertilized eggs over a period of two days. Microinjected embryos are transferred into surrogate mothers, which develop these embryos to term.
Once pups are born from these eggs, tail biopsies are collected for preparation of genomic DNA. This DNA is screened by polymerase chain reaction analysis for the presence of transgenic DNA. Transgenic animals are then bred to establish a cohort of mice, which can be used to study the phenotypic consequences of transgene expression.