title: Intensity of Mutualism Breakdown Is Determined by Temperature Not Amplification of Wolbachia Genes.
abstract: Wolbachia are maternally transmitted intracellular bacterial symbionts that infect approximately 40% of all insect species. Though several strains of Wolbachia naturally infect Drosophila melanogaster and provide resistance against viral pathogens, or provision metabolites during periods of nutritional stress, one virulent strain, wMelPop, reduces fly lifespan by half, possibly as a consequence of over-replication. While the mechanisms that allow wMelPop to over-replicate are still of debate, a unique tandem repeat locus in the wMelPop genome that contains eight genes, referred to as the "Octomom" locus has been identified and is thought to play an important regulatory role. Estimates of Octomom locus copy number correlated increasing copy number to both Wolbachia bacterial density and increased pathology. Here we demonstrate that infected fly pathology is not dependent on an increased Octomom copy number, but does strongly correlate with increasing temperature. When measured across developmental time, we also show Octomom copy number to be highly variable across developmental time within a single generation. Using a second pathogenic strain of Wolbachia, we further demonstrate reduced insect lifespan can occur independently of a high Octomom locus copy number. Taken together, this data demonstrates that the mechanism/s of wMelPop virulence is more complex than has been previously described.
authors.affiliation: School of Natural Sciences, Griffith University, Nathan, Australia.|Eskitis Institute for Cell and Molecular Therapies, Griffith University, Nathan, Australia.
authors.forename: Chelsie E
authors.identifier: http://orcid.org/0000-0003-1668-514X
authors.initials: CE
authors.lastname: Rohrscheib
authors.affiliation: Institute of Health and Biomedical Innovation and School of Biomedical Sciences, Queensland University of Technology, Kelvin Grove, Australia.
authors.forename: Francesca D
authors.initials: FD
authors.lastname: Frentiu
authors.affiliation: School of Natural Sciences, Griffith University, Nathan, Australia.
authors.forename: Emilie
authors.initials: E
authors.lastname: Horn
authors.affiliation: School of Natural Sciences, Griffith University, Nathan, Australia.
authors.forename: Fiona K
authors.initials: FK
authors.lastname: Ritchie
authors.affiliation: Queensland Brain Institute, The University of Queensland, St. Lucia, Australia.
authors.forename: Bruno
authors.initials: B
authors.lastname: van Swinderen
authors.affiliation: School of Natural Sciences, Griffith University, Nathan, Australia.|Eskitis Institute for Cell and Molecular Therapies, Griffith University, Nathan, Australia.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Weible
authors.affiliation: School of Biological Sciences, Monash University, Clayton, Australia.
authors.forename: Scott L
authors.initials: SL
authors.lastname: O'Neill
authors.affiliation: School of Natural Sciences, Griffith University, Nathan, Australia.|Environmental Futures Research Institute, Griffith University, Nathan, Australia.
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Brownlie