Kimberly Halsey

Phytoplankton Physiological Ecology

Cleo receives an award

Congratulations to post doc Cleo Davie-Marin who received an award to study the volatile organic carbon  metabolome. This award will help her to develop a new incubation technique to investigate VOC “fingerprints” produced by the abundant cyanobacterium, Synechococcus sp. This work builds on the momentum developed through her mentorship of undergraduate researcher, Duncan Ocel. Duncan and Cleo are an adventurous team, both scaling rocks and seeking other adventures whenever not in the lab, where they are also exploring new territory.

Moore et al. 2017 published in PLoS One

Our newest lab paper was published today. This manuscript describes two important discoveries in diatom lifecycles.

PLoS ONE 12(7): e0181098. https://doi.org/10.1371/journal.pone.0181098

1.) Thalassiosira pseudonana IS a sexual diatom species

2.) Ammonium induces sex in T. pseudonana and at least two other centric diatoms.

To prove these discoveries, Eric Moore with help from Briana Bullington carried out a number of carefully controlled culturing experiments, imaged all of the cell morphologies in the lifecycle, and identified >1,200 genes that were differentially expressed under conditions of ammonium induced cell differentiation. Some of these genes are involved in meiosis, flagellar synthesis, and sex differentiation.

Thanks to all of our co-authors, Alex Weisberg, Jeff Chang, and Yuan Jiang for their help with gene expression analysis and statistical testing.

Diatom sex

Nobody had ever seen the model centric diatom, Thalassiosira pseudonana, undergo sexual reproduction. Grad student, Eric Moore, documented the sexual stages and showed upregulation of genes involved in meiosis and flagellar synthesis. Moreover, he figured out what triggers these diatoms and other centric diatoms to shift into the sexual cycle resulting in cell enlargement. Read about it here on BioRxiv.

doi: https://doi.org/10.1101/144667

Plankton actively cycle volatile organic carbon

Our most recent paper on VOC cycling in the surface ocean was just published in Limnology and Oceanography. Phytoplankton produce different profiles of VOCs depending on species and some bacterioplankton, including the ubiquitous and abundant SAR11 bacteria consume these compounds. We designed new incubation chambers and attached these chambers to a PTR-MS to make real time measurements of VOC production and consumption . This work was a collaborative effort with atmospheric physicists at NOAA. Halsey et al. 2017 doi: 10.1002/lno.10596

Kelsey…left her mark and now moving on

Congratulations to Kelsey!! She defended her MS on December 7, and a few weeks later packed her bags for sunny UCSB. Kelsey will be a culturing technician in Alyson Santoro’s lab. Kelsey was energetic, creative, and dedicated…qualities that are essential for graduate school. We will sure miss her humor…and look forward to hearing about her new adventures down south.

Duncan receives a scholarship

Duncan Ocel received the OSU Honors College DeLoach Work Scholarship to pursue investigations of VOCs produced by marine cyanobacteria. This scholarship will allow him to spend more hours in the lab – and we are happy with that outcome!

Scheffers et al. 2016 The footprint of climate change

New review in Science today highlighting the environmental impacts of climate change. Is everyone listening?

From the abstract:

“Understanding shifts in ecological processes can guide human adaptation strategies. In addition to reducing greenhouse gases, climate action and policy must therefore focus equally on strategies that safeguard biodiversity and ecosystems.”

Climate change impacts on ecological processes in marine, freshwater, and terrestrial ecosystems

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Impacts can be measured on multiple processes at different levels of biological organization within ecosystems. In total, 82% of 94 ecological processes show evidence of being affected by climate change. Within levels of organization, the percentage of processes impacted varies from 60% for genetics to 100% for species distribution.

Briana landed a job!

Way to go, Briana! Briana helped generate some very exciting data for an upcoming paper during her undergraduate and post-baccalaureate research in our lab. She will be working at OSU’s Veterinary Diagnostics Lab as a medical technician.

Congratulations, Eric!

Eric Moore was awarded the Middlekauf Graduate Achievement Award in Microbiology! He has made some exciting progress and discoveries that I hope we can announce soon…stay tuned!

New paper on light limitation

Our newest paper on photosynthetic energy use was accepted yesterday in Photosynthesis Research. Former graduate student Nerissa Fisher (MS 2015) discovered that under very low light availability, diatoms shift their metabolism in favor of very short ATP generating pathways that circumvent carbon intermediates. These results suggest that this type of pathway gating facilitates the remarkably high efficiencies with which diatoms convert light energy into biomass, especially in low light (Fisher and Halsey, 2016). The paper can be found here:

Mechanisms that increase the growth efficiency of diatoms in low light

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