Document 0953
 DOCN  M9540953
 TI    Chromosome damage and early developmental arrest caused by the Rex
       element of Drosophila melanogaster.
 DT    9504
 AU    Robbins LG; Pimpinelli S; Genetics Program, Michigan State University,
       East Lansing; 48824-1312.
 SO    Genetics. 1994 Oct;138(2):401-11. Unique Identifier : AIDSLINE
       MED/95129804
 AB    Rex (Ribosomal exchange) is a genetically identified repeated element
       within the ribosomal DNA (rDNA) of Drosophila melanogaster. Rex has a
       semidominant maternal effect that promotes exchange between and within
       rDNA arrays in the first few embryonic mitoses. Several of Rex's genetic
       properties suggest that its primary effect is rDNA-specific chromosome
       breakage that is resolved by recombination. We report here that rDNA
       crossovers are only a small, surviving minority of Rex-induced events.
       Cytology of embryos produced by Rex-homozygous females reveals obvious
       chromosome damage in at least a quarter of the embryos within the first
       three mitotic divisions. More than half of the embryos produced by Rex
       females die, and the developmental arrest is among the earliest reported
       for any maternal-effect lethal. The striking lethal phenotype suggests
       that embryos with early chromosome damage could be particularly fruitful
       subjects for analysis of the cell biology of early embryos.
 DE    Animal  Cell Division  Crosses, Genetic  Crossing Over (Genetics)
       Drosophila melanogaster/EMBRYOLOGY/*GENETICS  DNA Damage  DNA,
       Ribosomal/*GENETICS  Embryo, Non-Mammalian/CYTOLOGY/*PHYSIOLOGY  Female
       Gene Products, rex/*GENETICS  Genes, Insect  Genes, Lethal  Male
       Mitosis  Support, Non-U.S. Gov't  Support, U.S. Gov't, Non-P.H.S.
       Support, U.S. Gov't, P.H.S.  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).