Another Case of Unequal Crossing-Over in Drosophila Melanogaster

  • E. B. Lewis


Females homozygous for the sex-linked dominant, Bar, occasionally give rise to wildtype reversions and to forms with more extreme eye reduction than Bar. This behavior was shown by Sturtevant1 to result from unequal crossing-over. The Bar-reverted type was considered to be a deficiency for the Bar gene; while the extreme form, called Ultra-Bar or Double-Bar, was interpreted as a duplication for that gene. Later, Wright2 suggested that Bar itself had something additional present which when lost by unequal crossing-over would give back a normal chromosome (Bar-reverted).


Normal Chromosome Star Locus Land Chromosome Extra Vein 
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Copyright information

© Springer Science+Business Media New York 2004

Authors and Affiliations

  • E. B. Lewis
    • 1
  1. 1.Wm. G. Kerckhoff Laboratories of the Biological SciencesCalifornia Institute of TechnologyUSA

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