Antioxidant enzyme cycling over reproductive lunar cycles in Pocillopora damicornis
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Abstract
The impacts of continued degradation of watersheds on coastal coral reefs world-wide is alarming. Action addressing anthropogenic stressors and subsequent rehabilitation of watersheds and adjacent reefs is an urgent priority. The aim of this study is to develop and improve the use of antioxidant enzymes as biomarkers in coral species. In order to fully develop such tools, it is necessary to perform sampling of coral tissues over reproductive cycles to determine variations from baseline. By developing a greater understanding of biochemical markers of stress in corals, specifically antioxidant defense enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), we have provided molecular tools that identify thresholds of stress on coral reefs. Our results suggest that the coral reproductive state is a significant factor affecting the activity of antioxidant enzymes. Specifically, CAT (65.92 mmol/min/mg protein, p = 0.0177) and GR (12.64 nmol/min/mg protein, p < 0.0001) display maximum activity during peak reproductive state. Whereas significant maximal SOD (154.92 nmol/min/mg protein, p < 0.0454) and Se-independent GPx (5.35 nmol/min/mg protein, p = 0.0001) activity was measured during off-peak reproductive cycles. Such insight into the cyclical variation of the activity of these enzymes should be applied towards differentiating the influence of natural biological activity cycling in diagnostic tests identifying the effects of different physical environmental factors and chemical pollutants on coral health. Through the development and application of these molecular biomarkers of stress, we look to improve our ability to identify problems at the sub-lethal level, when action can be taken to mitigate a/biotic impacts.
Cite this as
2018. Antioxidant enzyme cycling over reproductive lunar cycles in Pocillopora damicornis. PeerJ Preprints 6:e26765v1 https://doi.org/10.7287/peerj.preprints.26765v1note This preprint is not peer-reviewed. You may wish to reference the subsequent peer-reviewed version of this article.
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This is a submission to PeerJ for review.
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Supplemental Information
Raw enzyme activity assay values
Activity values are displayed in mmols/min/mg protein for CAT and nmols/min/mg protein for GR, GPx, and SOD. Assays were rerun if replicates experienced errors, these could be due in part to issues such as bubbling during the metabolism of substrates. If assays could not be rerun due to concerns about sample or reagent integrity, those values were excluded (-).
Untruncated western blotting image of Superoxide dismutase (23 kDa) versus moon phase cycle
Samples are denoted by arrows.
Acute tracking of SOD versus time following peak reproduction (¼ moon phase)
Samples labeled by arrows denoting collection time points following peak reproduction.
Additional Information
Competing Interests
The authors declare that they have no competing interests.
Author Contributions
James WA Murphy conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Abby C Collier analyzed the data, contributed reagents/materials/analysis tools, authored or reviewed drafts of the paper, approved the final draft.
Robert H Richmond contributed reagents/materials/analysis tools, authored or reviewed drafts of the paper, approved the final draft.
Field Study Permissions
The following information was supplied relating to field study approvals (i.e., approving body and any reference numbers):
Department of Land and Natural Resources - Division of Aquatic Resources coral collection permit 2015-06 and 2015-17 (O‘ahu, HI, USA).
Funding
This project was financially supported through National Oceanic and Atmospheric Administration (grant number NA09NOS4780178) and the Charles H. and Margaret B. Edmondson Research Fund (University of Hawai‘i at Mānoa Department of Biology). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.