title: Superstructure of the Drosophila ribosomal gene family.
abstract: Determining the spatial organization of middle repetitive DNA has proven difficult for several reasons. Repeated arrays are often so large that molecular methods alone cannot resolve their organization, and the lack of phenotypic markers within arrays limits the value of classical genetic analysis. We have characterized the superstructure of one repeated gene family, the ribosomal gene family of Drosophila melanogaster, by a combination of recombinational and molecular analyses of spacer-length variants. The resulting genetic maps demonstrate that some spacer variants are widely dispersed, while others are limited in their distribution. Moreover, exchange among ribosomal DNA (DNA encoding rRNA) arrays was often unequal, leading to a prediction of little or no relationship between physical location in an array and relatedness of gene family members. Extensions of our procedure may be generally useful for mapping the superstructure of repetitive DNA.
authors.affiliation: Department of Zoology, University of Alberta, Edmonton, Canada.
authors.forename: S M
authors.initials: SM
authors.lastname: Williams
authors.forename: L G
authors.initials: LG
authors.lastname: Robbins
authors.forename: P D
authors.initials: PD
authors.lastname: Cluster
authors.forename: R W
authors.initials: RW
authors.lastname: Allard
authors.forename: C
authors.initials: C
authors.lastname: Strobeck
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D004275:DNA, Ribosomal / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D008297:Male; D005810:Multigene Family; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D014960:X Chromosome; D014998:Y Chromosome
chemical_list: D004275:DNA, Ribosomal