Unit: Mouse Genetics Engineering Center (Platform)

Director: Francina Langa Vives

The Centre d'Ingénierie Génétique Murine (CIGM) is a novel technological facility within the Institut Pasteur. This core facility aims to generate genetically-engineered mice either by classical transgenesis techniques or by homologous recombination in embryonic stem (ES) cells. The CIGM is open to the Pasteur community and also to external customers interested in new transgenic, knock-out or knock-in murine models.

The Centre d'Ingénierie Génétique Murine (CIGM), attached to the Département de Biologie du Développement, has officially been created in June 2003. The CIGM is a novel technological core facility within the Institut Pasteur, which aims to generate new models of genetically-engineered mice by classical transgenesis techniques or by homologous recombination in embryonic stem (ES) cells (targeted transgenesis).

The classical transgenesis activity, which consists in the microinjection of the gene of interest into the pronuclei of fertilized eggs, was the main CIGM activity in 2003. In 2004 we have extended this activity to pure mouse genetic backgrounds. We carried out 8 collaborations (with other Units within Institut Pasteur and with outside laboratories) and we have obtained more than 20 "transgenic founder" mice, including 5 pure C57BL/6 transgenic lines. All of these transgenic lines are being studied by our partners.

Targeted transgenesis in the endogenous gene by the technique of homologous recombination in ES cells started in November 2003. The first step of homologous recombination, involving electroporation of a DNA construct in ES cells, picking and selection of clones, resulted in successful ES cell positive recombinant clones in January 2004. After microinjection of these modified ES cells in mouse blastocysts (second step of homologous recombination technique), we obtained our first chimeras in March 2004. The confirmed germ-line transmission achieved in June 2004 enabled us to obtain heterozygous mice for the desired mutation. Subsequently, first homozygous mice created at CIGM were obtained in September 2004.

Since then, we also achieved heterozygous mice as a result of two other collaborations, and two new collaborations are in the process of microinjecting positive recombinant ES cell clones. The last three collaborations started in 2004 are presently under analysis in order to find positive clones. The microinjection of these positive recombinant clones and new others will consist the main CIGM activity for 2005.

In addition, 4 new projects have already been evaluated and are included in the CIGM waiting list for 2005 (the construction of the homologous recombination vectors is ongoing in the respective laboratories).

Our core facility also provides expertise regarding the design of gene constructions suitable for transgenesis and homologous recombination experiments.

Keywords: mouse, transgenesis, homologous recombination, Embryonic Stem (ES) cells, microinjection

Activity Reports 2004 - Institut Pasteur

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