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<p class="MsoNormal"><span style="font-size:10.5pt;color:#3C4043">Woods Hole Oceanographic Institution<br>
Biology Department Seminar<br>
Thursday, July 20, 2023 – 12:00 Noon <br>
<br>
<b>Miguel J. Frada</b><br>
Senior Lecturer, Department of Ecology, Evolution and Behavior, Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Israel<br>
<br>
<b><i>Emiliania Huxleyi </i>Virus Arrests Cell Growth, Triggers Shifts in Organic Stoichiometry and Influence to Life Cycle of the Phytoplankton-Host Cell</b><br>
Blooms of the dominant coccolithophore <i>Emiliania huxleyi</i> are routinely infected by a specific lytic virus (EhV), which rapidly kills host cells and trigger bloom termination and the export of organic and inorganic materials. We tested the impact of EhV
on the dynamic of resource acquisition and cellular stoichiometry remains unknown. Algal and viral cultures were used to determine the dynamics of alkalinity, modulated by calcification, nitrate and phosphate consumption and organic matter stoichiometry during
infections. Calcification and nutrient uptake are rapidly arrested. In parallel, the stoichiometric ratio of carbon to nitrogen increased and the nitrogen to phosphorus ratio declined, which likely result from shift in macromolecular pool in infected cells.
In addition, after the decline of the host population, a progressive enrichment in phosphorus was detected in cell lysates. We estimate that this stoichiometric shift is driven by heterotrophic bacteria consuming organic materials. We conclude that viral-mediated
cell remodeling and consequent shifts in biomass stoichiometry likely impacts the patterns of nutrient cycling and biological carbon pump efficiency during large-scale blooms in the oceans. In parallel, during infection host
<i>E. huxleyi</i> cell can produce cell variants with radically different phenotypes that are resistant to infection. This may provide an escape strategy fueling population recovery post-infection. Evidence from advanced microscopy and transcriptome analyses
provide novel insight on regulatory mechanism for cell differentiation, which possibly involve epigenetic control and genome reorganization, illustrating the complexity of coccolithophore life cycles.<o:p></o:p></span></p>
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HYBRID! <b> In person</b>: Redfield Auditorium <b> Zoom</b>: <a href="https://whoi-edu.zoom.us/j/95699683374"><span style="color:blue">https://whoi-edu.zoom.us/j/95699683374</span></a> Meeting ID: 956 9968 3374 <b>By phone</b>: Find your local number: <a href="https://whoi-edu.zoom.us/u/aeDHWhbKaH"><span style="color:blue">https://whoi-edu.zoom.us/u/aeDHWhbKaH</span></a><o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Century Gothic",sans-serif;color:#4472C4">Ana María Vélez</span></b><span style="font-size:10.0pt;font-family:"Century Gothic",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:black">Administrative Associate<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:black">O: 508.289.2334<o:p></o:p></span></p>
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