title: Genetically manipulated mice: a powerful tool with unsuspected caveats.
abstract: Although genetic manipulations in mice have provided a powerful tool for investigating gene function in vivo, recent studies have uncovered a number of developmental phenomena that complicate the attribution of phenotype to the specific genetic change. A more realistic approach has been to modulate gene expression and function in a temporal and tissue-specific manner. The most common of these methods, the CreLoxP and tetracycline response systems, are surveyed here and their recently identified shortcomings discussed, along with a less well known system based on the E. coli lac operon and modified for use in mammals. The potential for further complications in interpretation due to hitherto unexpected epigenetic effects involving transfer of RNA or protein in oocytes or sperm is also explored. Given these problems we reiterate the necessity for the use of completely reversible methods that will allow each experimental group of animals to act as their own control. Using these methods with a number of specific modifications to eliminate non-specific effects from random insertion sites and inducer molecules, the full potential of genetic manipulation studies should be realized.
authors.affiliation: Gene Targeting Laboratory, The John Curtin School of Medical Research, GPO Box 334, Canberra City, ACT 0200, Australia. klaus.matthaei@anu.edu.au
authors.forename: Klaus I
authors.initials: KI
authors.lastname: Matthaei
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000502:physiology; D004622:Embryo, Mammalian / Q000502:physiology; D044127:Epigenesis, Genetic; D004926:Escherichia coli / Q000235:genetics; D017353:Gene Deletion; D015870:Gene Expression / Q000187:drug effects; D005818:Genetic Engineering / Q000639:trends; D019426:Integrases; D007763:Lac Operon; D051379:Mice; D008822:Mice, Transgenic / Q000235:genetics* / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D014018:Tissue Distribution; D015534:Trans-Activators / Q000187:drug effects; D019076:Transgenes
chemical_list: D011500:Protein Synthesis Inhibitors; D015534:Trans-Activators; C045073:Cre recombinase; D019426:Integrases; D013752:Tetracycline