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Although much is known about interactions between bacterial endosymbionts and their hosts, little is known concerning the host factors that influence endosymbiont titer. Wolbachia endosymbionts are globally dispersed throughout most insect species and are the causative agent in filarial nematode-mediated disease. Our investigation indicates that gurken (grk), a host gene encoding a crucial axis determinant, has a cumulative, dosage-sensitive impact on Wolbachia growth and proliferation during Drosophila oogenesis. This effect appears to be mediated by grk mRNA and its protein-binding partners Squid and Hrp48/Hrb27C, implicating the grk mRNA–protein (mRNP) complex as a rate-limiting host factor controlling Wolbachia titer. Furthermore, highly infected flies exhibit defects that match those occurring with disruption of grk mRNPs, such as nurse cell chromatin disruptions and malformation of chorionic appendages. These findings suggest a feedback loop in which Wolbachia interaction with the grk mRNP affects both Wolbachia titer and grk mRNP function.


  • Funding

    This work was supported by a National Institutes of Health Ruth L. Kirschstein National Service Award [grant number F32 GM080192]; the National Institutes of Health Initiative to Maximize Student Diversity [grant number R25 GM058903]; the National Science Foundation Frontiers in Integrative Biological Research [grant number EF-0328363]; the California Alliance for Minority Participation [grant number HRD-0603239]; the Sinsheimer Laboratories Insurance fund [grant number 433317-09577]; and the Program of the Presidium of RAS ‘Biodiversity’ [grant number 26.30]. Deposited in PMC for release after 12 months.

  • Supplementary material available online at

  • Accepted August 31, 2011.
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