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Differential coral bleaching-Contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress.

Abstract

Mass coral bleaching due to thermal stress represents a major threat to the integrity and functioning of coral reefs. Thermal thresholds vary, however, between corals, partly as a result of the specific type of endosymbiotic dinoflagellate (Symbiodinium sp.) they harbour. The production of reactive oxygen species (ROS) in corals under thermal and light stress has been recognised as one mechanism that can lead to cellular damage and the loss of their symbiont population (Oxidative Theory of Coral Bleaching). Here, we compared the response of symbiont and host enzymatic antioxidants in the coral species Acropora millepora and Montipora digitata at 28°C and 33°C. A. millepora at 33°C showed a decrease in photochemical efficiency of photosystem II (PSII) and increase in maximum midday excitation pressure on PSII, with subsequent bleaching (declining photosynthetic pigment and symbiont density). M. digitata exhibited no bleaching response and photochemical changes in its symbionts were minor. The symbiont antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and catalase peroxidase showed no significant upregulation to elevated temperatures in either coral, while only catalase was significantly elevated in both coral hosts at 33°C. Increased host catalase activity in the susceptible coral after 5days at 33°C was independent of antioxidant responses in the symbiont and preceded significant declines in PSII photochemical efficiencies. This finding suggests a potential decoupling of host redox mechanisms from symbiont photophysiology and raises questions about the importance of symbiont-derived ROS in initiating coral bleaching.

Authors+Show Affiliations

School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand; Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland. Electronic address: thomas.krueger@epfl.ch.School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand; College of Earth, Ocean and Environment, University of Delaware, Lewes, DE 19958, USA. Electronic address: thawkins@udel.edu.School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand. Electronic address: susanne.becker25@gmail.com.School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand. Electronic address: steffipont@gmail.com.School of Biological Sciences & ARC Centre of Excellence for Coral Reef Studies, University of Queensland, Brisbane, QLD 4072, Australia. Electronic address: s.dove@cms.uq.edu.au.Global Change Institute, University of University of Queensland, Brisbane, QLD 4072, Australia. Electronic address: oveh@uq.edu.au.Comparative Genomics Centre, School of Pharmacy and Molecular Sciences & ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia. Electronic address: bill.leggat@jcu.edu.au.School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand; School of Civil Engineering, University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: p.fisher@uq.edu.au.School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand. Electronic address: simon.davy@vuw.ac.nz.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

26310104

Citation

Krueger, Thomas, et al. "Differential Coral bleaching-Contrasting the Activity and Response of Enzymatic Antioxidants in Symbiotic Partners Under Thermal Stress." Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology, vol. 190, 2015, pp. 15-25.
Krueger T, Hawkins TD, Becker S, et al. Differential coral bleaching-Contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress. Comp Biochem Physiol A Mol Integr Physiol. 2015;190:15-25.
Krueger, T., Hawkins, T. D., Becker, S., Pontasch, S., Dove, S., Hoegh-Guldberg, O., Leggat, W., Fisher, P. L., & Davy, S. K. (2015). Differential coral bleaching-Contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress. Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology, 190, 15-25. https://doi.org/10.1016/j.cbpa.2015.08.012
Krueger T, et al. Differential Coral bleaching-Contrasting the Activity and Response of Enzymatic Antioxidants in Symbiotic Partners Under Thermal Stress. Comp Biochem Physiol A Mol Integr Physiol. 2015;190:15-25. PubMed PMID: 26310104.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Differential coral bleaching-Contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress. AU - Krueger,Thomas, AU - Hawkins,Thomas D, AU - Becker,Susanne, AU - Pontasch,Stefanie, AU - Dove,Sophie, AU - Hoegh-Guldberg,Ove, AU - Leggat,William, AU - Fisher,Paul L, AU - Davy,Simon K, Y1 - 2015/08/23/ PY - 2015/04/22/received PY - 2015/08/13/revised PY - 2015/08/19/accepted PY - 2015/8/28/entrez PY - 2015/8/28/pubmed PY - 2016/7/23/medline KW - APX KW - Acropora millepora KW - CAT KW - Global change KW - Montipora digitata KW - Oxidative stress KW - SOD KW - Symbiodinium KW - Symbiosis KW - Thermal biology SP - 15 EP - 25 JF - Comparative biochemistry and physiology. Part A, Molecular & integrative physiology JO - Comp Biochem Physiol A Mol Integr Physiol VL - 190 N2 - Mass coral bleaching due to thermal stress represents a major threat to the integrity and functioning of coral reefs. Thermal thresholds vary, however, between corals, partly as a result of the specific type of endosymbiotic dinoflagellate (Symbiodinium sp.) they harbour. The production of reactive oxygen species (ROS) in corals under thermal and light stress has been recognised as one mechanism that can lead to cellular damage and the loss of their symbiont population (Oxidative Theory of Coral Bleaching). Here, we compared the response of symbiont and host enzymatic antioxidants in the coral species Acropora millepora and Montipora digitata at 28°C and 33°C. A. millepora at 33°C showed a decrease in photochemical efficiency of photosystem II (PSII) and increase in maximum midday excitation pressure on PSII, with subsequent bleaching (declining photosynthetic pigment and symbiont density). M. digitata exhibited no bleaching response and photochemical changes in its symbionts were minor. The symbiont antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and catalase peroxidase showed no significant upregulation to elevated temperatures in either coral, while only catalase was significantly elevated in both coral hosts at 33°C. Increased host catalase activity in the susceptible coral after 5days at 33°C was independent of antioxidant responses in the symbiont and preceded significant declines in PSII photochemical efficiencies. This finding suggests a potential decoupling of host redox mechanisms from symbiont photophysiology and raises questions about the importance of symbiont-derived ROS in initiating coral bleaching. SN - 1531-4332 UR - https://www.unboundmedicine.com/medline/citation/26310104/Differential_coral_bleaching_Contrasting_the_activity_and_response_of_enzymatic_antioxidants_in_symbiotic_partners_under_thermal_stress_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1095-6433(15)00225-1 DB - PRIME DP - Unbound Medicine ER -