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Rapid manipulation in irradiance induces oxidative free-radical release in a fast-ice algal community (McMurdo Sound, Antarctica)


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Kennedy, F ORCID: 0000-0003-1796-0764, Martin, A ORCID: 0000-0001-8260-5529, Castrisios, K, Cimoli, E ORCID: 0000-0001-7964-2716, McMinn, A ORCID: 0000-0002-2133-3854 and Ryan, KG 2020 , 'Rapid manipulation in irradiance induces oxidative free-radical release in a fast-ice algal community (McMurdo Sound, Antarctica)' , Frontiers in Plant Science, vol. 11 , pp. 1-12 , doi: 10.3389/fpls.2020.588005.

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Sea ice supports a unique assemblage of microorganisms that underpin Antarctic coastal food-webs, but reduced ice thickness coupled with increased snow cover will modify energy flow and could lead to photodamage in ice-associated microalgae. In this study, microsensors were used to examine the influence of rapid shifts in irradiance on extracellular oxidative free radicals produced by sea-ice algae. Bottom-ice algal communities were exposed to one of three levels of incident light for 10 days: low (0.5 μmol photons m−2 s−1, 30 cm snow cover), mid-range (5 μmol photons m−2 s−1, 10 cm snow), or high light (13 μmol photons m−2 s−1, no snow). After 10 days, the snow cover was reversed (either removed or added), resulting in a rapid change in irradiance at the ice-water interface. In treatments acclimated to low light, the subsequent exposure to high irradiance resulted in a ~400× increase in the production of hydrogen peroxide (H2O2) and a 10× increase in nitric oxide (NO) concentration after 24 h. The observed increase in oxidative free radicals also resulted in significant changes in photosynthetic electron flow, RNA-oxidative damage, and community structural dynamics. In contrast, there was no significant response in sea-ice algae acclimated to high light and then exposed to a significantly lower irradiance at either 24 or 72 h. Our results demonstrate that microsensors can be used to track real-time in-situ stress in sea-ice microbial communities. Extrapolating to ecologically relevant spatiotemporal scales remains a significant challenge, but this approach offers a fundamentally enhanced level of resolution for quantifying the microbial response to global change.

Item Type: Article
Authors/Creators:Kennedy, F and Martin, A and Castrisios, K and Cimoli, E and McMinn, A and Ryan, KG
Keywords: oxidative stress, Antarctica, sea-ice algae, hydrogen peroxide (H2O2), nitric oxide (NO), microelectrodes, snow, photophysiology
Journal or Publication Title: Frontiers in Plant Science
Publisher: Frontiers Research Foundation
ISSN: 1664-462X
DOI / ID Number: 10.3389/fpls.2020.588005
Copyright Information:

Copyright © 2020 Kennedy, Martin, Castrisios, Cimoli, McMinn and Ryan. Thisis an open-access article distributed under the terms of the Creative CommonsAttribution License (CC BY) The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms

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