Open Close
Gong, W.J., McKim, K.S., Hawley, R.S. (2005). All paired up with no place to go: pairing, synapsis, and DSB formation in a balancer heterozygote.  PLoS Genet. 1(5): e67.
FlyBase ID
Publication Type
Research paper

The multiply inverted X chromosome balancer FM7 strongly suppresses, or eliminates, the occurrence of crossing over when heterozygous with a normal sequence homolog. We have utilized the LacI-GFP: lacO system to visualize the effects of FM7 on meiotic pairing, synapsis, and double-strand break formation in Drosophila oocytes. Surprisingly, the analysis of meiotic pairing and synapsis for three lacO reporter couplets in FM7/X heterozygotes revealed they are paired and synapsed during zygotene/pachytene in 70%-80% of oocytes. Moreover, the regions defined by these lacO couplets undergo double-strand break formation at normal frequency. Thus, even complex aberration heterozygotes usually allow high frequencies of meiotic pairing, synapsis, and double-strand break formation in Drosophila oocytes. However, the frequencies of failed pairing and synapsis were still 1.5- to 2-fold higher than were observed for corresponding regions in oocytes with two normal sequence X chromosomes, and this effect was greatest near a breakpoint. We propose that heterozygosity for breakpoints creates a local alteration in synaptonemal complex structure that is propagated across long regions of the bivalent in a fashion analogous to chiasma interference, which also acts to suppress crossing over.

PubMed ID
PubMed Central ID
PMC1285065 (PMC) (EuropePMC)
Associated Information
Associated Files
Other Information
Secondary IDs
    Language of Publication
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    PLoS Genet.
    PLoS Genetics
    Publication Year
    1553-7404 1553-7390
    Data From Reference
    Aberrations (3)
    Alleles (2)
    Genes (4)
    Transgenic Constructs (2)