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  • 1
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    Spatial heterogeneity in particle-associated, light-independent superoxide production within productive coastal waters (2021)
    American Geophysical Union
    Details
    Publication Date: 2022-10-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Sutherland, K. M., Grabb, K. C., Karolewski, J. S., Plummer, S., Farfan, G. A., Wankel, S. D., Diaz, J. M., Lamborg, C. H., & Hansel, C. M. Spatial heterogeneity in particle-associated, light-independent superoxide production within productive coastal waters. Journal of Geophysical Research: Oceans, 125(10), (2020): e2020JC016747, https://doi.org/10.1029/2020JC016747.
    Description: In the marine environment, the reactive oxygen species (ROS) superoxide is produced through a diverse array of light‐dependent and light‐independent reactions, the latter of which is thought to be primarily controlled by microorganisms. Marine superoxide production influences organic matter remineralization, metal redox cycling, and dissolved oxygen concentrations, yet the relative contributions of different sources to total superoxide production remain poorly constrained. Here we investigate the production, steady‐state concentration, and particle‐associated nature of light‐independent superoxide in productive waters off the northeast coast of North America. We find exceptionally high levels of light‐independent superoxide in the marine water column, with concentrations ranging from 10 pM to in excess of 2,000 pM. The highest superoxide concentrations were particle associated in surface seawater and in aphotic seawater collected meters off the seafloor. Filtration of seawater overlying the continental shelf lowered the light‐independent, steady‐state superoxide concentration by an average of 84%. We identify eukaryotic phytoplankton as the dominant particle‐associated source of superoxide to these coastal waters. We contrast these measurements with those collected at an off‐shelf station, where superoxide concentrations did not exceed 100 pM, and particles account for an average of 40% of the steady‐state superoxide concentration. This study demonstrates the primary role of particles in the production of superoxide in seawater overlying the continental shelf and highlights the importance of light‐independent, dissolved‐phase reactions in marine ROS production.
    Description: This work was funded by grants from the Chemical Oceanography program of the National Science Foundation (OCE‐1355720 to C. M. H. and C. H. L.), NASA Earth and Space Science Fellowship (Grant NNX15AR62H to K. M. S.), Agouron Institute Postdoctoral Fellowship (K. M. S.), NSF GRFPs (2016230268 to K. C. G. and 2017250547 to S. P.), and a Sloan Research Fellowship (J. M. D.). The Guava flow cytometer was purchased through an NSF equipment improvement grant (1624593).
    Keywords: reactive oxygen species ; Extracellular superoxide ; Light‐independent ROS
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
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    Development of a deep-sea submersible chemiluminescent analyzer for sensing short-lived reactive chemicals (2022)
    MDPI
    Details
    Publication Date: 2022-10-20
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Taenzer, L., Grabb, K., Kapit, J., Pardis, W., Wankel, S. D., & Hansel, C. M. Development of a deep-sea submersible chemiluminescent analyzer for sensing short-lived reactive chemicals. Sensors, 22(5), (2022): 1709, https://doi.org/10.3390/s22051709.
    Description: Based on knowledge of their production pathways, and limited discrete observations, a variety of short-lived chemical species are inferred to play active roles in chemical cycling in the sea. In some cases, these species may exert a disproportionate impact on marine biogeochemical cycles, affecting the redox state of metal and carbon, and influencing the interaction between organisms and their environment. One such short-lived chemical is superoxide, a reactive oxygen species (ROS), which undergoes a wide range of environmentally important reactions. Yet, due to its fleeting existence which precludes traditional shipboard analyses, superoxide concentrations have never been characterized in the deep sea. To this end, we have developed a submersible oceanic chemiluminescent analyzer of reactive intermediate species (SOLARIS) to enable continuous measurements of superoxide at depth. Fluidic pumps on SOLARIS combine seawater for analysis with reagents in a spiral mixing cell, initiating a chemiluminescent reaction that is monitored by a photomultiplier tube. The superoxide in seawater is then related to the quantity of light produced. Initial field deployments of SOLARIS have revealed high-resolution trends in superoxide throughout the water column. SOLARIS presents the opportunity to constrain the distributions of superoxide, and any number of chemiluminescent species in previously unexplored environments.
    Description: This research was funded by the NSF Oceanographic Technology and Interdisciplinary Coordination (OTIC) program grant number 1736332 and NSF Chemical Oceanography program grant number 1924236. Partial support was provided by the Link Foundation Ocean Engineering and Instrumentation Fellowship (L.T.).
    Keywords: Superoxide ; Chemiluminescence ; Deep-sea
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
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    Exploring the role of reactive oxygen species (ROS) in marine ecosystem health and function (2022)
    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Details
    Publication Date: 2023-01-18
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2022.
    Description: With the rapid decline of coastal ecosystems such as coral reefs and seagrasses, it is crucial to better understand the health of these ecosystem to prevent future loss. Reactive oxygen speices (ROS), such as superoxide and hydrogen peroxide, play an underappreciated role in both organism health and ecosystem biogeochemical cycles. This thesis lays the foundation to measure and identify ROS production by coral in situ and through genomic analysis while also highlighting the important role that ROS can play within biogeochemical cycling within seagrass ecosystems. To measure in situ extracellular superoxide, we develop the first DIver-operated Submersible Chemiluminescent sensOr (DISCO), enabling high resolution, non-invasive measurements in real time. We further refine DISCO by making it more compact, user-friendly, adaptable, and robust, enabling measurements of superoxide across a diversity of environments. Using DISCO, I observe species-specific variation in extracellular superoxide concentrations associated with healthy coral. Despite these variations across species, bioinformatic analysis of coral proteins reveal that nearly all coral species have the extracellular superoxide-producing enzyme NADPH oxidase (NOX), and thus the genetic potential to produce extracellular superoxide. This suggests that coral species likely exhibit differential NOX regulation and expression as a function of physiological responses to external stressors, which may play a role in coral immunity. I then turn to seagrass ecosystems, where I observe rapid hydrogen peroxide production and decay through predominantly reductive pathways. This has implications on the environmental redox state and biogeochemical cycling, impacting the ecosystem services that seagrasses provide to marine environments and coastal communities. Overall, this thesis highlights the potential role that ROS may be playing in organism and ecosystem health and lays the groundwork to further develop ROS as a tool to protect these coastal ecosystems against further degradation.
    Description: Funding for this work was provided by the following grants: NSF GRFP (2016230168), Schmidt Marine Technology Partners (G-1801-57385 andG-2010-59878), WHOI Ocean Ventures Fund (2020 and 2021), and the MIT Wellington and Irene Loh Fund Fellowship (4000111995).
    Keywords: Reactive oxygen species ; Coral ; Seagrass
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 4
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    Design optimization of a submersible chemiluminescent sensor (DISCO) for improved quantification of reactive oxygen species (ROS) in surface waters (2023)
    MDPI
    Details
    Publication Date: 2023-03-08
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Grabb, K., Pardis, W., Kapit, J., Wankel, S., Hayden, E., & Hansel, C. Design optimization of a submersible chemiluminescent sensor (DISCO) for improved quantification of reactive oxygen species (ROS) in surface waters. Sensors, 22(17), (2022): 6683, https://doi.org/10.3390/s22176683.
    Description: Reactive oxygen species (ROS) are key drivers of biogeochemical cycling while also exhibiting both positive and negative effects on marine ecosystem health. However, quantification of the ROS superoxide (O2−) within environmental systems is hindered by its short half-life. Recently, the development of the diver-operated submersible chemiluminescent sensor (DISCO), a submersible, handheld instrument, enabled in situ superoxide measurements in real time within shallow coral reef ecosystems. Here, we present a redesigned and improved instrument, DISCO II. Similar to the previous DISCO, DISCO II is a self-contained, submersible sensor, deployable to 30 m depth and capable of measuring reactive intermediate species in real time. DISCO II is smaller, lighter, lower cost, and more robust than its predecessor. Laboratory validation of DISCO II demonstrated an average limit of detection in natural seawater of 133.1 pM and a percent variance of 0.7%, with stable photo multiplier tube (PMT) counts, internal temperature, and flow rates. DISCO II can also be optimized for diverse environmental conditions by adjustment of the PMT supply voltage and integration time. Field tests showed no drift in the data with a percent variance of 3.0%. Wand tip adaptations allow for in situ calibrations and decay rates of superoxide using a chemical source of superoxide (SOTS-1). Overall, DISCO II is a versatile, user-friendly sensor that enables measurements in diverse environments, thereby improving our understanding of the cycling of reactive intermediates, such as ROS, across various marine ecosystems.
    Description: The development and verification of DISCO was funded by Schmidt Marine Technology Partners (G-2010-59878 to C.M.H., S.D.W. and J.K.). This research was further supported, in part, by grants from NSF GRFP (2016230168 to K.C.G.), WHOI Ocean Ventures Fund (2020 and 2021 to K.C.G.), and the MIT Wellington and Irene Loh Fund Fellowship (4000111995 to K.C.G.).
    Keywords: Reactive oxygen species ; Superoxide ; Chemiluminescent ; In situ analysis ; Ocean sensor ; Corals
    Repository Name: Woods Hole Open Access Server
    Type: Article
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