title: Sensitivity of Allelic Divergence to Genomic Position: Lessons from the Drosophila tan Gene.
abstract: To identify genetic variants underlying changes in phenotypes within and between species, researchers often utilize transgenic animals to compare the function of alleles in different genetic backgrounds. In Drosophila, targeted integration mediated by the ΦC31 integrase allows activity of alternative alleles to be compared at the same genomic location. By using the same insertion site for each transgene, position effects are generally assumed to be controlled for because both alleles are surrounded by the same genomic context. Here, we test this assumption by comparing the activity of tan alleles from two Drosophila species, D. americana and D. novamexicana, at five different genomic locations in D. melanogaster We found that the relative effects of these alleles varied among insertion sites, with no difference in activity observed between them at two sites. One of these sites simply silenced both transgenes, but the other allowed expression of both alleles that was sufficient to rescue a mutant phenotype yet failed to reveal the functional differences between the two alleles. These results suggest that more than one insertion site should be used when comparing the activity of transgenes because failing to do so could cause functional differences between alleles to go undetected.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: Alisha V
authors.initials: AV
authors.lastname: John
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Sramkoski
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Walker
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: Arielle M
authors.initials: AM
authors.lastname: Cooley
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109 wittkopp@umich.edu.
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Wittkopp
mesh_terms: D000483:Alleles; D000818:Animals; D030801:Animals, Genetically Modified; D002868:Chromosomal Proteins, Non-Histone / Q000096:biosynthesis / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000235:genetics*; D049750:Genome, Insect; D023281:Genomics; D019426:Integrases / Q000235:genetics; D010641:Phenotype; D013045:Species Specificity; D019076:Transgenes / Q000235:genetics*
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C431070:t protein, Drosophila; D019426:Integrases
keywords: allele-specific; pigmentation; position effect; tan; transgenic analysis