Mouse Genetic Engineering: Mouse Injection

Baylor College of Medicine Intellectual and Developmental Disabilities Center
Center URL: https://www.bcm.edu/research/centers/iddrc/
Core URL: http://mrrc.bcm.tmc.edu/cores/m-injection.html

Core Personnel
Core Director: Paul Overbeek, Ph.D.

Core Keywords
Mouse Genetic Engineering; Mouse Injection; Microinjected DNA; Recombinant DNA; Transgenic Mice

The objective of the Microinjection Core is to generate transgenic mice by embryo microinjection for MRDDRC investigators to use in their studies of mental retardation and developmental disabilities.

Recombinant DNA can be introduced into the mouse genome by microinjection of the DNA into the pronuclei of one-cell stage mouse embryos. A fraction (usually around 20%) of the subsequent newborn mice has been found to contain the microinjected DNA stably integrated in their genome. The new DNA typically integrates as a tandem head-to-tail multimer at a single site in the genome. In most cases, the DNA integrates shortly after microinjection so that it is present in the germ line and is stably transmitted to subsequent generations. The transgenic DNA is typically transcribed and translated in a tissue-specific and stage-specific pattern which is determined by regulatory sequences included in the recombinant DNA. Consequently, transgenic mice represent an experimental system in which it is possible to add new DNA to the genome of a mammalian organism and then to study the consequences and/or pattern of expression of the new genetic information.

The DNA to be microinjected can be purified after excision from standard cloning vectors, or can be larger pieces of DNA such as intact BAC clones. The BAC clones can be engineered by homologous recombination prior to microinjection. The Microinjection Service will assist MRDDRC investigators with protocols for BAC engineering and BAC DNA purification.

Transgenic mice are being used increasingly for studies of neuronal development and neuron-specific gene expression. Experiments using transgenic mice include: a) studies of cis-acting regulatory sequences that direct gene expression to specific neuronal cell types, b) studies of inappropriate synthesis of cell-surface markers that are essential for normal neuronal morphogenesis, c) studies of neuronal maturation, cell cycle control and apoptosis, and d) studies of nuclear inclusions and RNA binding proteins. Such experiments contribute to a better understanding both of normal neurological function, and of the disorders that can lead to mental retardation.

The primary function of the Microinjection Service will be to generate transgenic mice by microinjection of recombinant DNA into mouse embryos. The recombinant DNA will be constructed and provided by the laboratories of the MRDDRC investigators. The core unit will purify DNA fragments or BAC clones for microinjection, isolate the mouse embryos, microinject the DNA into the mouse embryos, re-implant the mouse embryos into pseudopregnant foster mothers, and supervise the husbandry of the newborn mice. At weaning age the mice will be ear tagged for identification, then transferred to individual investigators for further characterization. The core lab will provide advice on construction of DNAs for microinjection, screening of newborn mice for integration of microinjected DNA, and characterization of gene expression in the transgenic mice.

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Last Edited: 02/15/06 12:00 AM by Celine Coutte