title: Specificity and efficiency of Cre-mediated recombination in Emx1-Cre knock-in mice.
abstract: Emx1 is a mouse homologue of the Drosophila homeobox gene empty spiracles and its expression is restricted to the neurons in the developing and adult cerebral cortex and hippocampus. We reported previously the creation of a line of transgenic mice in which the cre gene was placed directly downstream of the putative Emx1 promoter using ES cell technology. We showed that Cre protein was present in the cerebral cortex of the transgenic mice and was able to mediate loxP-specific recombination in vitro. In the present study, the specificity and efficiency of the cre-mediated recombination were determined using three independent lines of reporter mice and a combination of histochemical staining, neuronal culture, and Southern detection of the genomic DNA. Our results showed that the recombination was highly efficient in all three lines of reporter mice tested and confirmed that the deletion was restricted to the neurons in the cerebral cortex and hippocampus. Furthermore, we have determined that the recombination efficiency in the cerebral cortex was 91%. Our results suggest that Emx1 is not expressed in every neuron in the developing and adult cerebral cortex. This line of cre mice should contribute to the studies of cortical development and plasticity.
authors.affiliation: Department of Molecular and Integrative Physiology, Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801, USA.
authors.forename: H
authors.initials: H
authors.lastname: Guo
authors.forename: S
authors.initials: S
authors.lastname: Hong
authors.forename: X L
authors.initials: XL
authors.lastname: Jin
authors.forename: R S
authors.initials: RS
authors.lastname: Chen
authors.forename: P P
authors.initials: PP
authors.lastname: Avasthi
authors.forename: Y T
authors.initials: YT
authors.lastname: Tu
authors.forename: T L
authors.initials: TL
authors.lastname: Ivanco
authors.forename: Y
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D005260:Female; D005801:Genes, Homeobox; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics*; D019426:Integrases / Q000235:genetics* / Q000378:metabolism*; D007763:Lac Operon; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D011995:Recombination, Genetic; D014157:Transcription Factors; D014764:Viral Proteins; D000099260:Empty Spiracles Homeobox Proteins
chemical_list: D018398:Homeodomain Proteins; D019426:Integrases; D014157:Transcription Factors; D014764:Viral Proteins; D000099260:Empty Spiracles Homeobox Proteins; C045073:Cre recombinase