Spring Conference 2011 - Society for General Microbiology

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Please note: Abstracts are published as received from the authors and are not subject to editing. 49 Spring Meeting 11–14 April 2011 Harrogate – www.sgmharrogate2011.org.uk SESSION AbSTrACTS ↑Contents HA10 Cont. Coevolution between microbes and insect behaviour – defensive symbionts in beewolf antennae Martin Kaltenpoth Max Planck Institute for Chemical Ecology, Research Group Insect Symbiosis, Hans-Knoell-Str. 8, 07745 Jena, Germany Microbial symbionts represent a major source for evolutionary innovation in insects. Although nutritional symbioses are the most common types of interactions, mutualistic microbes can fulfil a variety of other functions, notably the protection against pathogenic micro-organisms. Beewolves of the genera Philanthus, Trachypus, and Philanthinus (Hymenoptera, Crabronidae) cultivate defensive Streptomyces bacteria in specialized antennal glands. The bacteria are transmitted vertically by an unusual route that involves specialized adaptations in the beewolf’s behaviour: After secretion from the mother’s antennae into the brood cell, the larva detects and acquires the bacteria from the brood cell environment and applies them to the cocoon silk, from where they are later taken up by the adult beewolf into the antennae shortly before emergence. On the cocoon, the symbionts provide protection against a wide range of potentially detrimental fungi and bacteria by producing a cocktail of at least nine different antibiotic substances. in addition to this protective function, the antennal secretion containing the symbionts confers directional information to the larva that is crucial for successful cocoon-spinning and adult emergence. Thus, beewolves constitute a fascinating model system in which the dual function of the microbial symbionts is tightly intertwined with the host’s ecology and behaviour. Fungal partners in the diversification of gall midges Patrick Abbot Dept of Biological Sciences, Vanderbilt University, 7280A MRB III, 465 21st Ave South, USA Symbiosis with prokaryotic and eukaryotic micro-organisms is a common feature of life for insects, and recent studies have emphasized the degree to which microbial symbionts can act as sources of adaptive phenotypic complexity for their hosts. However, despite the ubiquity of symbiosis, only a handful of organisms have been studied in depth, meaning that our understanding of how co-evolutionary interactions between host and symbiont contribute to phenotypic complexity remains incomplete. i describe co-evolutionary patterns between the ectosymbiotic fungal symbiont and the goldenrod galling midge, Asteromyia carbonifera. Phylogenetic reconstruction placed the fungal symbiont within the same clade as Botryosphaeria dothidea, a typically free-living, generalist plant pathogen and endophyte. Symbiont isolates from four divergent midge lineages and several geographic locations demonstrated a striking phylogenetic discord between the two, despite evidence indicating that the interaction is an obligate one for the midge. However, new genomic data is revealing the extraordinary degree to which a history of interaction with fungi has shaped the midge genome, ultimately acting as a source of evolutionary innovation and ecological opportunity. Offered paper Leafcutter ant symbionts and their antifungal compounds rYAN SEiPKE1 , Jörg Barke1 , Sabine Grüschow1 , rebecca Goss1 , Douglas Yu1,2 , Matthew Hutchings1 1 2 University of East Anglia, Norwich; Kunming Institute of Zoology, Kunming, China leafcutter ants live in a tripartite symbiosis with the fungus Leucoagaricus gongylophorus, which they farm for food, and antifungal-producing actinobacteria in genus Pseudonocardia that have been proposed to be the sole, co-evolved, mutualists of leafcutter ants. Next generation sequencing phylogenetic studies revealed that many other genera of actinobacteria are present on the ant cuticle, raising the possibility that Pseudonocardia may not be the only antifungal-producing mutualist. in order to address this possibility we isolated actinomycetes from the leafcutter ant species Acromyrmex octospinosus and obtained two Pseudonocardia spp. (P1-P2) and nine Streptomyces spp. (S1-S9). Antifungal bioassays revealed that isolates P1, S3, S4, S5 and S9 inhibited the growth of the garden parasite, Escovopsis weberi. We further characterized P1 and S4 using a genomics-guided chemistry approach. This approach demonstrated that P1 produces a novel polyene antifungal related to nystatin, and that S4 produces the antifungal candicidin and also identified a novel antifungal biosynthetic cluster whose product remains unknown. These data support an environmental acquisition model in which A. octospinosus recruits useful actinomycetes from the soil to protect the fungal garden, and furthermore suggest that the environmental acquisition and co-evolution models are not necessarily mutually exclusive and may be occurring simultaneously. Offered paper Modelling metabolite flux between the pea aphid and its endosymbiont Buchnera aphidicola APS SANDY MACDONALD1 , Gavin Thomas1 , Angela Douglas1,2 1 2 Dept of Biology, University of York, York, North Yorkshire; Dept of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA The pea aphid and its bacterial endosymbiont Buchnera aphidicola APS form an obligate symbiosis, with the bacterium synthesizing essential amino acids (EAAs) lacking in the phloem sap diet of the aphid. A recent genome scale metabolic model of Buchnera reinforced the role s o c i e t y f o r g e n e r a l Microbiology
Please note: Abstracts are published as received from the authors and are not subject to editing. 50 Spring Meeting 11–14 April 2011 Harrogate – www.sgmharrogate2011.org.uk SESSION AbSTrACTS ↑Contents HA10 Cont. & HA11 of Buchnera in synthesizing EAAs for the aphid, and suggested the possibility that the profile of EAAs synthesised by the Buchnera could be altered by differing supply of carbon and nitrogen sources to the Buchnera from the aphid. Here, we used this metabolic model, in tandem with 454 pyrosequencing, to investigate the basis for observed variation in the dietary requirement for EAAs among four pea aphid clones. First, we sequenced the Buchnera from the four pea aphid clones, and showed that the differing dietary EAA phenotypes of the aphids could not be attributed to sequence variation in the Buchnera. Second, using flux balance analysis of the Buchnera metabolic model, we showed that the four profiles of EAAs could be reproduced by supplying distinctly different profiles of carbon and nitrogen sources to the Buchnera, suggesting that the differing nutritional phenotypes seen are governed by aphid metabolism and not Buchnera genotype. The microbiota of Drosophila as a model system for insect interactions with symbiotic micro-organisms Nichole A. Broderick Global Health institute, Ecole Polytechnique Federale de lausanne (EPFl), Switzerland Eukaryotes and microbes have co-existed and co-evolved for billons of years. The importance of this association is particularly evident when considering the contributions of gut microbes to animal health and physiology. While the importance of gut microbes in vertebrate health is widely appreciated, the complex diversity of these communities complicates their decipherment. in contrast, the relative simplicity of invertebrate gut microbial communities, especially in insects, provides a simpler model. Here i will describe how the genetically tractable model Drosophila melanogaster provides a useful system to elucidate mechanisms underlying the complex relationships between a host and its microbiota. The gut of Drosophila parallels that of other animals and the microbiota of lab stocks is simple in composition and diversity. However, this simple consortium has important contributions to the host, as flies lacking their microbiota are altered in their basal immune status and pathways controlling gut homeostasis. This basal response is in turn an important regulator of the abundance, diversity, and spatial localization of microbiota. Furthermore, gut microbiota of Drosophila can influence susceptibility to infection through interactions with host immune and stress responses. Thus, Drosophila provides a useful model to decipher mechanisms by which gut microbiota impact gut physiology and homeostasis. benefit and dependence in insect–microbial symbioses Fabrice Vavre Laboratory of Biometry & Evolutionary Biology, University Lyon I, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France (Email: Fabrice.vavre@univ-lyon1.fr) Numerous insects interact with vertically transmitted symbionts that exhibit very diverse effects. Many of these symbionts are mutualists and bring important advantages to their hosts, notably through the complementation of their diet. Others manipulate the reproduction of their host to their own advantage. Such manipulations include feminization of genetic males, male-killing, induction of parthenogenesis or cytoplasmic incompatibility. These two types of symbiosis have classically been studied separately, but recent advances show that this dichotomy is not as pertinent as previously thought. First, it is becoming clear that reproductive manipulators can also provide advantages to their hosts. Second, some examples show that the dependence of the host upon its symbiont may rapidly evolve even when the symbiont does not bring benefit to its host. These recent developments in the field of insect symbiosis provide interesting new scenarios for the evolution of obligatory host-symbiont relationships. HA11 Working with the media ↑Contents Science in the media Julia Wilson Sense About Science Sense About Science is a small charity that equips people to make sense of science and evidence. This session will discuss science related controversies in media reporting and what scientists can do to respond to misconceptions in public discussions. Do you think it is important for good science and evidence to be communicated to a wider audience? What happens when research announcements go wrong; statistics are manipulated; risk factors are distorted; or discussions become polarised? Not yet the leaders in the field what can early career researchers do to encourage good science and evidence in the public domain? using examples of myth-busting and evidence hunting projects of the Voice of Young Science network of early career researchers, Julia will discuss the impact and importance of standing up for science. s o c i e t y f o r g e n e r a l Microbiology
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