The Transgenic Core works with investigators to generate animal models that will increase our[unreadable] fundamental understanding of gene function in rheumatic diseases. This Core was established in 1989 and[unreadable] produces transgenic mice and rats, and gene-targeted mice (knockouts) for Rheumatic Disease Core Center[unreadable] members. Other services include rederivation of pathogen free mice, mouse strain cryopreservation and[unreadable] recovery, and transgenic technology training. The Transgenic Core maintains specialized equipment for[unreadable] microinjection, cryopreservation, and mouse embryonic stem (ES) cell culture. The Core maintains and[unreadable] distributes plasmids for transgene or gene targeting vector construction. To maximize gene targeting[unreadable] success, the Core performs quality assurance tests on ES cell lines, feeder cells, and serum for ES cell[unreadable] culture. This is a collaborative Core that combines the expertise of investigators in the molecular biology of[unreadable] the genes they study and the Core's expertise in producing genetically engineered mice.[unreadable] Unique capabilities that set this Core apart are 1) guaranteed production of transgenic mice and rats, 2)[unreadable] routine production of BAG transgenic mice, 3) production of transgenic mice in unique genetic backgrounds,[unreadable] 4) gene targeting in C57BL/6 ES cell lines in addition to 129/Sv ES cells, 5) open access to reagents and[unreadable] equipment, and training in ES cell culture and microinjection methods. Access to the Transgenic Core[unreadable] obviates the need for investigators to devote resources to equipment purchases and personnel time to[unreadable] training in micromanipulation, ES cell culture, and mouse embryo manipulation. Consultation on all aspects[unreadable] of transgenic and ES cell research is provided, from the design of transgenes and conditional targeting[unreadable] vectors to mouse breeding and phenotype analysis.[unreadable] We deliver an average of ten transgenic founder mice and guarantee that at least three founders will be[unreadable] produced for each DMA construct submitted to the Core. The Core electroporates totipotent ES cells with[unreadable] targeting vectors, selects 480 ES cell clones, and provides investigators with ES cell clone DNA to screen for[unreadable] homologous recombination with targeting vectors. We guarantee that ES cell clones with desired genetic[unreadable] changes will be microinjected into at least 50 mouse blastocysts to produce ES cell-mouse chimeras. The[unreadable] efficiency of these procedures meets or exceeds published values in the literature.[unreadable] Based on past use, the projected annual usage by Center members is 30 transgenic mouse orders, 6 ES[unreadable] cell electroporation orders, and 15 ES cell-mouse chimera orders. This is 34% of the Core's total universitywide[unreadable] capacity and is consistent with past usage by Center Members.