Transcriptional responses in a Drosophila defensive symbiosis. Issue 6 (28th December 2013)

• Record Type: Journal Article
• Authors: Hamilton, Phineas T.; Leong, Jong S.; Koop, Ben F.; Perlman, Steve J.
• Is Part Of: Molecular ecology. Volume 23:Issue 6(2014)
• Page Start: 1558
• Page End: 1570
• Publication Date: 2013-12-28
• Subjects: Molecular ecology -- Periodicals; Molecular population biology -- Periodicals; 576
• DOI: 10.1111/mec.12603
• Languages: English
• ISSNs: 0962-1083

Abstract

<abstract abstract-type="main" id="mec12603-abs-0001"> <title>Abstract</title> <p>Inherited symbionts are ubiquitous in insects and can have important consequences for the fitness of their hosts. Many inherited symbionts defend their hosts against parasites or other natural enemies; however, the means by which most symbionts confer protection is virtually unknown. We examine the mechanisms of defence in a recently discovered case of symbiont‐mediated protection, where the bacterial symbiont <italic>Spiroplasma</italic> defends the fly <italic>Drosophila neotestacea</italic> from a virulent nematode parasite, <italic>Howardula aoronymphium</italic>. Using quantitative PCR of <italic>Spiroplasma</italic> infection intensities and whole transcriptome sequencing, we attempt to distinguish between the following modes of defence: symbiont–parasite competition, host immune priming and the production of toxic factors by <italic>Spiroplasma</italic>. Our findings do not support a model of exploitative competition between <italic>Howardula</italic> and <italic>Spiroplasma</italic> to mediate defence, nor do we find strong support for host immune priming during <italic>Spiroplasma</italic> infection. Interestingly, we recovered sequence for putative toxins encoded by <italic>Spiroplasma</italic>, including a novel putative ribosome‐inactivating protein, transcripts of which are up‐regulated in response to nematode exposure. Protection via the production of toxins may be a widely used and important mechanism in heritable defensive symbioses in insects.</p> </abstract>