title: A new resource for characterizing X-linked genes in Drosophila melanogaster: systematic coverage and subdivision of the X chromosome with nested, Y-linked duplications.
abstract: Interchromosomal duplications are especially important for the study of X-linked genes. Males inheriting a mutation in a vital X-linked gene cannot survive unless there is a wild-type copy of the gene duplicated elsewhere in the genome. Rescuing the lethality of an X-linked mutation with a duplication allows the mutation to be used experimentally in complementation tests and other genetic crosses and it maps the mutated gene to a defined chromosomal region. Duplications can also be used to screen for dosage-dependent enhancers and suppressors of mutant phenotypes as a way to identify genes involved in the same biological process. We describe an ongoing project in Drosophila melanogaster to generate comprehensive coverage and extensive breakpoint subdivision of the X chromosome with megabase-scale X segments borne on Y chromosomes. The in vivo method involves the creation of X inversions on attached-XY chromosomes by FLP-FRT site-specific recombination technology followed by irradiation to induce large internal X deletions. The resulting chromosomes consist of the X tip, a medial X segment placed near the tip by an inversion, and a full Y. A nested set of medial duplicated segments is derived from each inversion precursor. We have constructed a set of inversions on attached-XY chromosomes that enable us to isolate nested duplicated segments from all X regions. To date, our screens have provided a minimum of 78% X coverage with duplication breakpoints spaced a median of nine genes apart. These duplication chromosomes will be valuable resources for rescuing and mapping X-linked mutations and identifying dosage-dependent modifiers of mutant phenotypes.
authors.affiliation: Bloomington Drosophila Stock Center, Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
authors.forename: R Kimberley
authors.initials: RK
authors.lastname: Cook
authors.forename: Megan E
authors.initials: ME
authors.lastname: Deal
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Deal
authors.forename: Russell D
authors.initials: RD
authors.lastname: Garton
authors.forename: C Adam
authors.initials: CA
authors.lastname: Brown
authors.forename: Megan E
authors.initials: ME
authors.lastname: Ward
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Andrade
authors.forename: Eric P
authors.initials: EP
authors.lastname: Spana
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Kaufman
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Cook
mesh_terms: D000818:Animals; D020811:Biomedical Technology / Q000379:methods*; D004331:Drosophila melanogaster / Q000235:genetics*; D020440:Gene Duplication; D050172:Genes, X-Linked / Q000235:genetics*; D008297:Male; D008722:Methods; D009154:Mutation; D011995:Recombination, Genetic / Q000235:genetics; D014960:X Chromosome / Q000235:genetics*; D014998:Y Chromosome / Q000235:genetics*