title: Quantitative analysis of tetracycline-inducible expression of the green fluorescent protein gene in transgenic chickens.
abstract: The use of transgenic farm animals as "bioreactors" to address the growing demand for biopharmaceuticals, both in terms of increased quantity and greater number, represents a key development in the advancement of medical science. However, the potential for detrimental side-effects as a result of uncontrolled constitutive expression of foreign genes in transgenic animals is a well-recognized limitation of such systems. Previously, using a tetracycline-inducible expression system, we demonstrated the induction of expression of a transgene encoding green fluorescent protein (GFP) in transgenic chickens by feeding with doxycycline, a tetracycline derivative; expression of GFP reverted to pre-induction levels when the inducer was removed from the diet. As a proof of principle study, however, quantitative assessment of expression was not possible, as only one G0 and one G1 transgenic chicken was obtained. In the current study, a sufficient number of G2 and G3 transgenic chickens were obtained, and quantification analysis demonstrated up to a 20-fold induction of expression by doxycycline. In addition, stable transmission of the transgene without any apparent genetic modifications was observed through several generations. The use of an inducible expression system that can be regulated by dietary supplementation could help mitigate the physiological disruption that can occur in transgenic animals as a result of uncontrolled constitutive expression of a transgene. Importantly, these results also support the use of the retroviral system for generating transgenic animals with minimal risk in terms of biosafety.
authors.affiliation: Department of Physiology, Catholic University of Daegu School of Medicine, Daegu 705-034, Korea.
authors.forename: Bon Chul
authors.initials: BC
authors.lastname: Koo
authors.forename: Mo Sun
authors.initials: MS
authors.lastname: Kwon
authors.forename: Ji Yeol
authors.initials: JY
authors.lastname: Roh
authors.forename: Minjee
authors.initials: M
authors.lastname: Kim
authors.forename: Jin-Hoi
authors.initials: JH
authors.lastname: Kim
authors.forename: Teoan
authors.initials: T
authors.lastname: Kim
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D002645:Chickens / Q000235:genetics*; D004318:Doxycycline; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D013752:Tetracycline; D019076:Transgenes
chemical_list: D049452:Green Fluorescent Proteins; D013752:Tetracycline; D004318:Doxycycline