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How does oxidative stress relate to thermal tolerance in the Antarctic bivalve Yoldia eightsi?

Published online by Cambridge University Press:  27 April 2004

Doris Abele
Affiliation:
Alfred Wegener-Institut für Polar- und Meeresforschung, Marine Ecophysiology, Columbusstrasse, D-27568 Bremerhaven, Germany
Claudia Tesch
Affiliation:
University of Konstanz, Limnological Institute, Box M659, D-78457 Konstanz, Germany
Petra Wencke
Affiliation:
University of Bremen, Marine Zoology, D-28359 Bremen, Germany
Hans Otto Pörtner
Affiliation:
Alfred Wegener-Institut für Polar- und Meeresforschung, Marine Ecophysiology, Columbusstrasse, D-27568 Bremerhaven, Germany

Abstract

Short and long-term exposure to elevated temperatures were studied in the Antarctic stenothermal protobranch bivalve Yoldia eightsi (Courthouy) from Potter Cove, King George Island (South Shetland Islands, Antarctica). Above a breakpoint temperature of 2°C – the upper habitat temperature for the Potter Cove Y. eightsi stock – both routine (RMR) and standard metabolic rate (SMR) increased steeply. The fraction of metabolism allocated to SMR, as well as the number of intervals of elevated activity per hour increased significantly with temperature. During acute exposure, ATP concentrations in the foot muscle peaked at 2°C and fell at 5°C, whereas superoxide dismutase (SOD) activity decreased upon warming. Slow stepwise warming to a final temperature of 11°C resulted in a significant decrease of SOD activity. Malondialdehyde concentration increased compared with controls at 0°C. In contrast to the effect of short-term exposure, tissue adenylate concentrations displayed a mild increase at higher temperatures during slow warming, indicating an acclimation response. A switch to anaerobic energy production could not be observed up to 11°C, demonstrating a higher level of thermal tolerance than in other Antarctic ectotherms, or a failure of the relevant pathways in Y. eightsi. The imbalance between pro- and antioxidant processes upon warming indicate oxidative stress to be one feature accompanying early heat stress in Y. eightsi.

Type
Papers—Life Sciences and Oceanography
Copyright
© Antarctic Science Ltd 2001

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