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1. Heat Stress of Algal Partner Hinders Colonization Success and Alters the Algal Cell Surface Glycome in a Cnidarian-Algal Symbiosis

   https://doi.org/10.1128/spectrum.01567-22  

   Maruyama, Shumpei ; Mandelare-Ruiz, Paige E. ; McCauley, Mark ; Peng, Wenjing ; Cho, Byeong Gwan ; Wang, Junyao ; Mechref, Yehia ; Loesgen, Sandra ; Weis, Virginia M. ( May 2022 , Microbiology Spectrum)

   Kormas, Konstantinos Aristomenis (Ed.)

   ABSTRACT Corals owe their ecological success to their symbiotic relationship with dinoflagellate algae (family Symbiodiniaceae). While the negative effects of heat stress on this symbiosis are well studied, how heat stress affects the onset of symbiosis and symbiont specificity is less explored. In this work, we used the model sea anemone, Exaiptasia diaphana (commonly referred to as Aiptasia), and its native symbiont, Breviolum minutum , to study the effects of heat stress on the colonization of Aiptasia by algae and the algal cell-surface glycome. Heat stress caused a decrease in the colonization of Aiptasia by algae that were not due to confounding variables such as algal motility or oxidative stress. With mass spectrometric analysis and lectin staining, a thermally induced enrichment of glycans previously found to be associated with free-living strains of algae (high-mannoside glycans) and a concomitant reduction in glycans putatively associated with symbiotic strains of algae (galactosylated glycans) were identified. Differential enrichment of specific sialic acid glycans was also identified, although their role in this symbiosis remains unclear. We also discuss the methods used to analyze the cell-surface glycome of algae, evaluate current limitations, and provide suggestions for future work in algal-coral glycobiology. Overall, this study provided insight into how stress may affect the symbiosis between cnidarians and their algal symbionts by altering the glycome of the symbiodinian partner. IMPORTANCE Coral reefs are under threat from global climate change. Their decline is mainly caused by the fragility of their symbiotic relationship with dinoflagellate algae which they rely upon for their ecological success. To better understand coral biology, researchers used the sea anemone, Aiptasia, a model system for the study of coral-algal symbiosis, and characterized how heat stress can alter the algae's ability to communicate to the coral host. This study found that heat stress caused a decline in algal colonization success and impacted the cell surface molecules of the algae such that it became more like that of nonsymbiotic species of algae. This work adds to our understanding of the molecular signals involved in coral-algal symbiosis and how it breaks down during heat stress. 

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2. Bioavailability of Mineral-Bound Iron to a Snow Algal-Bacterial Coculture and Implications for Albedo-Altering Snow Algal Blooms

   https://doi.org/10.1128/AEM.02322-17  

   Harrold, Z. R. ; Hausrath, E. M. ; Garcia, A. H. ; Murray, A. E. ; Tschauner, O. ; Raymond, J. A. ; Huang, S. ; Löffler, Frank E. ( April 2018 , Applied and Environmental Microbiology)

   ABSTRACT Snow algae can form large-scale blooms across the snowpack surface and near-surface environments. These pigmented blooms can decrease snow albedo and increase local melt rates, and they may impact the global heat budget and water cycle. Yet, the underlying causes for the geospatial occurrence of these blooms remain unconstrained. One possible factor contributing to snow algal blooms is the presence of mineral dust as a micronutrient source. We investigated the bioavailability of iron (Fe)-bearing minerals, including forsterite (Fo 90 , Mg 1.8 Fe 0.2 SiO 4 ), goethite, smectite, and pyrite as Fe sources for a Chloromonas brevispina -bacterial coculture through laboratory-based experimentation. Fo 90 was capable of stimulating snow algal growth and increased the algal growth rate in otherwise Fe-depleted cocultures. Fo 90 -bearing systems also exhibited a decrease in the ratio of bacteria to algae compared to those of Fe-depleted conditions, suggesting a shift in microbial community structure. The C. brevispina coculture also increased the rate of Fo 90 dissolution relative to that of an abiotic control. Analysis of 16S rRNA genes in the coculture identified Gammaproteobacteria , Betaproteobacteria , and Sphingobacteria , all of which are commonly found in snow and ice environments. Archaea were not detected. Collimonas and Pseudomonas , which are known to enhance mineral weathering rates, comprised two of the top eight (>1%) operational taxonomic units (OTUs). These data provide unequivocal evidence that mineral dust can support elevated snow algal growth under otherwise Fe-depleted growth conditions and that snow algal microbial communities can enhance mineral dissolution under these conditions. IMPORTANCE Fe, a key micronutrient for photosynthetic growth, is necessary to support the formation of high-density snow algal blooms. The laboratory experiments described herein allow for a systematic investigation of the interactions of snow algae, bacteria, and minerals and their ability to mobilize and uptake mineral-bound Fe. Results provide unequivocal and comprehensive evidence that mineral-bound Fe in Fe-bearing Fo 90 was bioavailable to Chloromonas brevispina snow algae within an algal-bacterial coculture. This evidence includes (i) an observed increase in snow algal density and growth rate, (ii) decreased ratios of bacteria to algae in Fo 90 -containing cultures relative to those of cultures grown under similarly Fe-depleted conditions with no mineral-bound Fe present, and (iii) increased Fo 90 dissolution rates in the presence of algal-bacterial cocultures relative to those of abiotic mineral controls. These results have important implications for the role of mineral dust in supplying micronutrients to the snow microbiome, which may help support dense snow algal blooms capable of lowering snow albedo and increasing snow melt rates on regional, and possibly global, scales. 

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3. An unprecedented coastwide toxic algal bloom linked to anomalous ocean conditions: THE 2015 U.S. WEST COAST TOXIC ALGAL BLOOM

   https://doi.org/10.1002/2016GL070023  

   McCabe, Ryan M. ; Hickey, Barbara M. ; Kudela, Raphael M. ; Lefebvre, Kathi A. ; Adams, Nicolaus G. ; Bill, Brian D. ; Gulland, Frances M. ; Thomson, Richard E. ; Cochlan, William P. ; Trainer, Vera L. ( October 2016 , Geophysical Research Letters)
4. Ice algal communities in the Chukchi and Beaufort Seas in spring and early summer: Composition, distribution, and coupling with phytoplankton assemblages: Ice algal-phytoplankton coupling in Chukchi Sea

   https://doi.org/10.1002/lno.10757  

   Selz, Virginia ; Laney, Samuel ; Arnsten, Alexandra E. ; Lewis, Kate M. ; Lowry, Kate E. ; Joy-Warren, Hannah L. ; Mills, Matthew M. ; van Dijken, Gert L. ; Arrigo, Kevin R. ( May 2018 , Limnology and Oceanography)
5. Organellar phylogenomics inform systematics in the green algal family Hydrodictyaceae (Chlorophyceae) and provide clues to the complex evolutionary history of plastid genomes in the green algal tree of life

   https://doi.org/10.1002/ajb2.1066  

   McManus, Hilary A. ; Fučíková, Karolina ; Lewis, Paul O. ; Lewis, Louise A. ; Karol, Kenneth G. ( March 2018 , American Journal of Botany)