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Harmful algal blooms: mechanisms, monitoring, and prevention in a rapidly changing world
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Molecular mechanisms of temperature acclimation and adaptation in marine diatoms
Wednesday 9th @ 1350-1410, Multifunction Hall
Yue Liang* , Department of Mathematics and Computer Science, Mount Allison University, Sackville, New Brunswick, Canada
Julie A. Koester, Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, USA
Justin D. Liefer, Environmental Science Program, Mount Allison University, Sackville, New Brunswick, Canada
Andrew J. Irwin, Department of Mathematics and Computer Science, Mount Allison University, Sackville, New Brunswick, Canada
Zoe V. Finkel, Environmental Science Program, Mount Allison University, Sackville, New Brunswick, Canada
Presenter Email: yliang@mta.ca |
| Ocean temperatures are projected to increase over the coming century, with dramatic consequences for the marine biosphere. However, we lack the information necessary to predict how primary producers, such as the diatoms, are likely to acclimate and adapt to changes in temperature anticipated over the next centuries. Diatoms are important contributors to marine primary production and the ocean carbon cycle. Here we grew two strains of Chaetoceros sp. that had been isolated from different regions of the oceans with different average temperature to three experimental temperatures: their optimum temperature for growth and a cooler and warmer temperature that corresponded to approximately half their maximum growth rate. We extracted RNA once the strains had been acclimated to temperature for a minimum of 10 generations and analyzed the transcriptome-wide response to temperature using RNAseq. Low translational efficiency, slow protein turnover, decreased membrane fluidity, and excessive ATP, NADPH and acetyl-CoA are the main physiological challenges at colder temperatures, while high translation efficiency versus relatively slower protein processing in the ER, heat-induced protein misfolding and aggregation, and insufficient energy and metabolites for high growth rate are the main challenges for success at warmer temperature. Our results indicate that diatoms have adapted to different optimal growth temperatures through transcriptional frontloading (elevated baseline expression level) or divestment (lowered baseline expression level) of genes and pathways that maintain metabolic, redox and energetic homeostasis in the face of temperature-induced shifts in the ratio of photosynthesis and biosynthetic demand under their respective optimal growth temperatures. As a result of evolutionary change in gene expression, the colder- and warmer-adapted species have largely different transcriptional responses to growth under sub- and supra-optimal temperature. In aggregate these results suggest that short-term acclimation to temperature will species-specific, shaped by evolutionary history. Projecting phytoplankton responses to century-scale climate change should take the species-specific evolutionary history into account. |
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