The physiological effects ofheat stress and the role of heat shock proteins in rainbow trout (Oncorhynchus f) red blood cells |
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| Authors: | SG Lund BL Tufts |
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| Institution: | (1) Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada |
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| Abstract: | The effects of in vitro thermal stress and the potential role ofheat shock proteins in thermoprotection were examined in the nucleated red blood cells (rbcs) of rainbow trout (Oncorhynchusmykiss). Oxygen consumption, a general indicator of cellular metabolism, was maintained in trout rbcs until 30 °C, but was markedly reduce by 35 °C. Subsequent experiments were then conducted which involved exposing rbcs to 30 °C to determine which physiological variables might be compromised by an extendedheat stress. Although this temperature challenge caused an induction of Hsp 70 mRNA, and a significant reduction in the amount of oxygen bound to hemoglobin, carbonic anhydrase (CA) activity was unaffected by an 8 h, 30 °C exposure.heat stress also caused a rise in methemoglobin formation, but the increase in rbc methemoglobin concentration did not appear to be a stimulus for Hsp 70 induction. Rbc oxygen consumption, CA activity and hemoglobin/oxygen binding ability were unaltered when hsp synthesis was inhibited by the translational inhibitor, cycloheximide. These results indicate that hsps do not have a role in protecting rbc metabolism or the function of important rbc proteins, such as hemoglobin and CA. Extended 30 °Cheat stress did cause a significant leakage of potassium from the rbcs, which appeared to be intensified in the presence of cycloheximide. These latter results suggest that hsps may play a limited role in preserving rbc membrane integrity and/or ionoregulatory processes. |
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| Keywords: | carbonic anhydrase erythrocyte fish heat shock hemoglobin Hsp 70 metabolism oxygen consumption potassium thermotolerance |
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