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. 13 Spring Meeting 11–14 April 2011 Harrogate – www.sgmharrogate2011.org.uk SESSION AbSTrACTS ↑Contents HA02 Cont. & HA03 Improving engagement and achievement in science numeracy A. JANET HOrrOCKS, louise Milne University of Abertay, Bell Street, Dundee DD1 1HG Students starting our programmes typically have very little confidence with handling numerical problems and calculations (such as calculating molar concentrations). This lack of confidence even extends to confusion about the correct use of scientific notation and significant figures. We began to included basic numeracy within a first year module focused on laboratory skills however students were able to pass the module without engaging with the numeracy component and assessment so typically students who were intimidated by calculations avoided the numeracy part of the module. The numeracy section of the module was initially delivered via tutorials. For the session 2006/7 the assessment was put online and supported with online tutorials and quizzes in addition to timetabled classes. The quizzes were designed so that students had to pass each section before progressing to the following section however engagement with online material was poor and student performance appeared to deteriorate. The following year students were required to pass a preliminary formative test to gain access to the summative test. The use of a preliminary test improved students performance however further gains in performance were made in later years by setting students clear short term goals and targets (supported by regular emails) and providing focused tutorial support sessions. HA03 Social evolution in micro-organisms ↑Contents Spatio-genetic structure and prudent cooperation in microbes Kevin Foster University of Oxford Since Darwin, evolutionary biologists have been troubled by cooperative behaviours. in microbes, these behaviours are seen in the use of secretions and slow growth, which can both help neighbouring cells to divide and survive. What prevents cooperative cells being exploited by cheaters, which receive cooperative benefits without themselves contributing? i will discuss two solutions to the problem of cooperation in microbes. First, i will describe individual-based simulations and experiments that show genetic segregation in growing biofilms and colonies. This segregation is sufficient to ensure that bacteria are surrounded by their own genotype, which can favour the evolution of cooperation for the same reason that cells in your body cooperate with one another. Second, i will discuss a hypothesis that comes out of experiments with rhamnolipid secretion in the bacterium Pseudomonas aeruginosa. We find that cells only secrete rhamnolipids when it is cheap to do so, something we call metabolic prudence. This makes secretion effectively cost free and removes any advantage to cheater genotypes. in summary, spatio-genetic structure and prudent use of resources can both stabilise cooperation in microbial groups. A simple mechanism for complex social behaviour in Dictyostelium discoideum Chris Thompson Faculty of Life Sciences, Michael Smith Building, Oxford Road, Manchester M13 9PT Despite the appearance of co-operation in nature, selection should often favour exploitative individuals that perform less of a costly cooperative act. This conflict of interests can lead to the evolution of complex, partner specific, social strategies. The social amoeba Dictyostelium discoideum provides a compelling model for studying conflict and cooperation. upon starvation, free-living amoebae aggregate and form a fruiting body composed of dead stalk cells and hardy spores. Different genotypes will aggregate to produce chimeric fruiting bodies, resulting in potential social conflict over who will contribute to the sporehead and who will ‘sacrifice’ themselves to produce the stalk. The outcomes of competitive interactions in chimera appear complex, with social success being strongly partner specific. Here we propose a simple mechanism, based on the production of and response to social signals governing developmental differentiation, to explain social strategies in D. discoideum. indeed, measurements of signal production and response can predict social behaviour of different strains, thus demonstrating a novel and elegantly simple underlying mechanistic basis for natural variation in complex facultative social strategies. This suggests that simple social rules can be sufficient to generate a diverse array of outcomes that appear complex and unpredictable when those rules are unknown. 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. 14 Spring Meeting 11–14 April 2011 Harrogate – www.sgmharrogate2011.org.uk SESSION AbSTrACTS A small rNA controls Myxococcus development and mediates a major social adaptation Yuen-Tsu Nicco Yu, xi Yuan, GrEGOrY J. VEliCEr Dept of Biology, Indiana University, Bloomington, IN 47405 USA See Additional Abstracts (pp. 172–173) ↑Contents HA03 Cont. Cooperation and cheating in Pseudomonas quorum sensing Martin Schuster Dept of Microbiology, Oregon State University, USA Many bacteria demonstrate the hallmarks of a complex social life typically associated with higher organisms. Pseudomonas aeruginosa cells communicate with each other in a process termed quorum sensing (QS) to coordinate the transcription of hundreds of genes. We have shown by ChiP-chip (chromatin immunoprecipitation and microarray analysis) that secreted common goods and secretion machinery are the most overrepresented functions directly controlled by QS. In vitro evolution and co-culturing experiments under conditions that favor QS revealed that common goods production can be exploited by signal-blind regulator mutants, cheaters that gain the benefit of cooperation without contributing themselves. Mutants lacking either lasr, rhlr, or Pqsr, three key regulators in the P. aeruginosa QS network, varied greatly in their ability to invade wild type populations. These behaviors may explain the prevalence of certain QS mutants in natural environments. Social evolution in parasites Sarah reece Institutes of Evolution, Immunology & Infection Research, University of Edinburgh, School of Biological Sciences, Ashworth Laboratories, Edinburgh EH9 3JT Malaria (Plasmodium) and related parasites cause some of the most serious infectious diseases of humans, livestock, companion animals, and wildlife. research in my group uses an evolutionary framework to explain the social strategies that parasites have evolved to maximise in-host survival and between-host transmission. Malaria parasites replicate asexually in their vertebrate hosts, but must reproduce sexually to infect mosquito vectors and be transmitted to new hosts. As different stages are required for these functions, parasites must divide their resources between in-host replication and between-host transmission, and between the production of male and female sexual stages. Our experiments show that social interactions within the host shape the solutions to these resource allocation trade-offs. Moreover, parasites fine-tune their strategies in response to variation in relatedness and density within infections. Explaining within-infection processes is traditionally the domain of reductionist approaches, whereas evolutionary biology tends to focus on between-host processes, so our results represent a rare demonstration of how an evolutionary ecology framework can bridge these scales. More broadly, understanding how natural selection has solved the complex problems faced by parasites is central to biomedicine, yet the success of ‘evolutionary medicine’ hinges on a significantly better understanding of the evolutionary biology of parasites. Theory of social adaptation Andy Gardner1,2 1 2 Dept of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS; Balliol College, University of Oxford, Broad Street, Oxford OX1 3BJ (Email: andy.gardner@zoo.ox.ac.uk) Natural selection explains the appearance of design in the living world, but at what level is this design expected to manifest – gene, individual, society – and what is its function? Social evolution provides a window on this problem, by pitting the interests of genes, individuals and societies against each other. i review the foundations of Darwinian adaptation through the action of direct and indirect (kin selected) fitness effects, and how this leads organisms to appear designed as if to maximize their inclusive fitness. i also consider the possibilities for adaptation at the gene and group levels. The evolution of microbial cooperation and virulence Sam Brown Dept of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS Microbes engage in a remarkable array of social behaviors, secreting shared molecules that are essential for foraging, shelter, microbial warfare, and virulence. These proteins are costly, rendering populations of cooperators vulnerable to exploitation by nonproducing cheaters arising by gene loss or migration. in such conditions, how can cooperation persist? s o c i e t y f o r g e n e r a l Microbiology
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Spring Conference 2011 - Society for General Microbiology

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