Reference number : GC-2017-Q1-02227, amendment number : , agreement type : G, recipient legal name : Case, Rebecca (University of Alberta), recipient country : CA, recipient province : nan, recipient city : Alberta, recipient postal code : nan, program name english : Discovery Grants Program - Individual, program name french : Programme de subventions à la découverte - individuelles, program purpose english : Microbes dominate marine habitats and these microscopic life forms are responsible for driving the biogeochemical cycles that sustain life on our planet. Perhaps most important are phytoplankton, as these microalgae perform half of the photosynthesis on earth, removing carbon dioxide from the atmosphere and generating oxygen. One ubiquitous and abundant member of this group is Emiliania huxleyi , which can form blooms in the oceans as large as countries. Besides fixing carbon through photosynthesis, it can also mineralize it into calcite disks that cover its surface. These fall to the bottom of the ocean when the microalgae dies, where they can stay for over 50,000 years. E. huxleyi is also unique in that it uses biologically produced molecules to interact with higher (fish and birds) and lower (protist grazers and viruses) tropic levels within the marine food web. We have recently identified that E. huxleyi also closely interacts with bacteria, which can be pathogenic towards their host and thereby accelerate release of calcite. One such bacterium, Phaeobacter inhibens , produces a novel algaecicidal antibiotic, roseobacticide, to kill E. huxleyi . By sequencing all the RNA transcripts of genes activated in E. huxleyi (transcriptomics) when it is exposed to roseobacticides, we aim to discover the target and mode of action of this antibiotic. Also, by investigating mutants of P. inhibens unable to produce this compound, we will try to identify the genes responsible for its biosynthesis. We have also found that two different types of E. huxleyi cells, those covered in calcite disks and others that are bald, signal each other using auxin, a type of plant hormone. Also using transcriptomics, we will look for the pathway for the synthesis of these auxins as well as its receptor. This research proposal will elucidate how this novel antibiotic targets E. huxleyi and will allow us to be the first to eavesdrop on the conversation E. huxleyi cells are having between themselves., program purpose french : Microbes dominate marine habitats and these microscopic life forms are responsible for driving the biogeochemical cycles that sustain life on our planet. Perhaps most important are phytoplankton, as these microalgae perform half of the photosynthesis on earth, removing carbon dioxide from the atmosphere and generating oxygen. One ubiquitous and abundant member of this group is Emiliania huxleyi , which can form blooms in the oceans as large as countries. Besides fixing carbon through photosynthesis, it can also mineralize it into calcite disks that cover its surface. These fall to the bottom of the ocean when the microalgae dies, where they can stay for over 50,000 years. E. huxleyi is also unique in that it uses biologically produced molecules to interact with higher (fish and birds) and lower (protist grazers and viruses) tropic levels within the marine food web. We have recently identified that E. huxleyi also closely interacts with bacteria, which can be pathogenic towards their host and thereby accelerate release of calcite. One such bacterium, Phaeobacter inhibens , produces a novel algaecicidal antibiotic, roseobacticide, to kill E. huxleyi . By sequencing all the RNA transcripts of genes activated in E. huxleyi (transcriptomics) when it is exposed to roseobacticides, we aim to discover the target and mode of action of this antibiotic. Also, by investigating mutants of P. inhibens unable to produce this compound, we will try to identify the genes responsible for its biosynthesis. We have also found that two different types of E. huxleyi cells, those covered in calcite disks and others that are bald, signal each other using auxin, a type of plant hormone. Also using transcriptomics, we will look for the pathway for the synthesis of these auxins as well as its receptor. This research proposal will elucidate how this novel antibiotic targets E. huxleyi and will allow us to be the first to eavesdrop on the conversation E. huxleyi cells are having between themselves., agreement title english : Small molecules mediate interactions between Emiliania huxleyi and roseobacters, agreement title french : Small molecules mediate interactions between Emiliania huxleyi and roseobacters, agreement number : RGPIN, agreement value : 26000.0, agreement start date : 2017-05-10, agreement end date : nan, description english : nan, description french : nan, expected results english : nan, expected results french : nan, additional information english : Grant or Award spanning more than one fiscal year. (2017-2018 to 2018-2019), additional information french : Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2018-2019), owner organization : nserc-crsng, owner organization title : Natural Sciences and Engineering Research Council of Canada | Conseil de recherches en sciences naturelles et en génie du Canada