RESUMEN
The Australian sheep blowfly Lucilia cuprina is a major pest for the Australian and New Zealand sheep industries. With the long-term aim of making a strain of L. cuprina suitable for a genetic control program, we previously developed a tetracycline-repressible female lethal genetic system in Drosophila. A key part of this system is a female-specific promoter from a yolk protein (yp) gene controlling expression of the tetracycline-dependent transactivator (tTA). Here we report the sequence of a 14.2 kb genomic clone from L. cuprina that contains a cluster of three complete yp genes and one partial yp gene. The Lcyp genes are specifically expressed in females that have received a protein meal. A bioinformatic analysis of the promoter of one of the yp genes (LcypA) identified several putative binding sites for DSX, a known regulator of yp gene expression in other Diptera. A transgenic strain of L. cuprina was made that contained the LcypA promoter driving the expression of the Escherichia coli lacZ reporter gene. Transgenic females express high levels of ß-galactosidase after a protein meal. Thus the LcypA promoter could be used to obtain female-specific expression of tTA in transgenic L. cuprina.
Asunto(s)
Animales Modificados Genéticamente/genética , Dípteros/genética , Proteínas del Huevo/genética , Genes de Insecto , Familia de Multigenes , Ovinos/parasitología , Secuencia de Aminoácidos , Animales , Australia , Femenino , Regulación de la Expresión Génica , Vectores Genéticos , Células Germinativas , Masculino , Datos de Secuencia Molecular , Nueva Zelanda , Transformación Genética , TransgenesRESUMEN
BACKGROUND: Germ-line transformation of insects is now a widely used method for analyzing gene function and for the development of genetically modified strains suitable for pest control programs. The most widely used transposable element for the germ-line transformation of insects is piggyBac. The site of integration of the transgene can influence gene expression due to the effects of nearby transcription enhancers or silent heterochromatic regions. Position effects can be minimized by flanking a transgene with insulator elements. The scs/scs' and gypsy insulators from Drosophila melanogaster as well as the chicken beta-globin HS4 insulator function in both Drosophila and mammalian cells. RESULTS: To minimize position effects we have created a set of piggyBac transformation vectors that contain either the scs/scs', gypsy or chicken beta-globin HS4 insulators. The vectors contain either fluorescent protein or eye color marker genes and have been successfully used for germ-line transformation of Drosophila melanogaster. A set of the scs/scs' vectors contains the coral reef fluorescent protein marker genes AmCyan, ZsGreen and DsRed that have not been optimized for translation in human cells. These marker genes are controlled by a combined GMR-3xP3 enhancer/promoter that gives particularly strong expression in the eyes. This is also the first report of the use of the ZsGreen and AmCyan reef fluorescent proteins as transformation markers in insects. CONCLUSION: The insulated piggyBac vectors should protect transgenes against position effects and thus facilitate fine control of gene expression in a wide spectrum of insect species. These vectors may also be used for transgenesis in other invertebrate species.