Webinars

Microorganisms drive the marine carbon cycle by controlling the rates of carbon fixation and remineralization in ocean environments. Embedded within the bulk rates of this cycle are metabolic reactions catalyzed by enzymes expressed by microbes in response to changing nutrient concentrations, light levels and temperature. Metabolite dynamics, thus, integrate a microbe’s response to external parameters and metabolite concentrations and/or fluxes can be used to infer relative importance of different biogeochemical processes within the carbon cycle. While particulate metabolites provide a snapshot of biochemical reactions within microbial cells, dissolved metabolites are the external footprint of microbial physiology and are the currencies for microbe-microbe interactions in ocean environments. The Kujawinski lab develops metabolomics methods to answer key questions within microbial oceanography, with an emphasis on extracting and quantifying labile dissolved metabolites. In our M2C2 seminar, we will provide an overview of the lab’s activities and emerging methods, and three group presentations on (i) a four-year time-series of dissolved metabolites in the north Atlantic Ocean, (ii) physiological shifts in eukaryotic phytoplankton under nutrient stress and (iii) metabolite assimilation capabilities of the heterotroph, Alteromonas macleodii.

The Signals in the Sea research group work on chemically mediated interactions in the marine pelagic. We are particularly interested of the role of copepods in the marine food web. Copepods exude a unique bouquet of polar lipids, copepodamides, that induce defensive traits in a wide variety of prey organisms. This includes phycotoxin production, bioluminescence increase, altered swimming behavior and diel feeding rhythms. Copepodamides provide a useful tool to gain mechanistic understanding for chemical communication in plankton. We will present some recent results where we use copepodamides to evaluate defensive traits and tradeoffs, molecular mechanisms, and ecological effects of grazer cues. Finally, we develop new tools based on holographic microscopy and deep learning algorithms to explore the whereabouts of the most important but least known grazers in the sea, the microzooplankton.

The Pohnert group elucidates new chemical defence- and communication strategies of marine algae using the tools of modern bioorganic chemistry. We seek to understand the chemical language spoken between organisms. In the aquatic environment we focus on the language of algae that release molecules into the water in order to communicate with each other, to interact with microorganisms or to defend themselves. Our work aims to understand the role of chemical compounds as mediators of ecological interactions of entire communities. Isolation, spectroscopy and organic synthesis of natural products are important aspects of our work, but we believe that the full picture of the role of the compounds can only be obtained if biochemistry and ecology are brought in as well. We also develop new methods based on metabolomics techniques (i.e. the monitoring of all metabolites released by a given organisms) to understand chemically mediated processes in communities. Our interdisciplinary work gives new insights into the chemically mediated species interactions and the function of natural products.