Unequal crossing-over within the B duplication of Drosophila melanogaster: a molecular analysis.
The B mutation is associated with a tandem duplication of 16A1-16A7. It is unstable, mutating to wild type and to a more extreme form at a frequency of one in 1000 to 3000. The reversion to wild type is associated with the loss of one copy of the duplication, whereas the mutation to extreme B is associated with a triplication of the region. The instability of B has been attributed to unequal crossing-over between the two copies of the duplication. Recent molecular data show that there is a transposable element, B104, between the two copies of the duplication and support the hypothesis that this element generated the duplication via a recombination event. These data suggest that unequal crossing-over within the duplication may not be the cause of the instability of B. Instead, the instability may be caused by a recombination event involving the B104 element. This issue was addressed using probes for the DNA on either side of the B104 element at the B breakpoint. All of the data indicate that the B104 element is not involved in the instability of B and support the original unequal crossing-over model.
Tsubota
S I
SI
Department of Biology, University of Michigan, Ann Arbor 49109.
D000818:Animals; D015139:Blotting, Southern; D003434:Crossing Over, Genetic; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000235:genetics*; D009154:Mutation; D015183:Restriction Mapping
D004251:DNA Transposable Elements