Metabolic and molecular stress responses of the gilthead seabream Sparus aurata during long-term exposure to increasing
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ORIGINAL PAPER
Metabolic and molecular stress responses of the gilthead seabream Sparus aurata during long-term exposure to increasing temperatures Konstantinos Feidantsis · Hans O. Pörtner · Antigoni Lazou · Basile Kostoglou · Basile Michaelidis
Received: 21 March 2008 / Accepted: 11 January 2009 / Published online: 30 January 2009 © Springer-Verlag 2009
Abstract Tolerance to a changing climate regime and persistence in the natural environment depends on the limited capacity to acclimate to changing temperatures. The present study aimed to identify and characterize thermal limits of the Mediterranean Wsh Sparus aurata as well as the processes providing heat protection during exposure to high temperatures. Processes studied included heat shock protein expression, protein kinase activity and metabolic adjustments. Molecular responses were addressed through the expression of Hsp70 and Hsp90 and the phosphorylation of stress-activated protein kinases, p38 mitogen-activated protein kinase (p38 MAPK) and cJun-N-terminal kinases (JNKs). Thermal impacts on metabolic capacities were assessed by studying the maximum activities of citrate synthase (CS), malate dehydrogenase (MDH) and 3hydroxyacyl CoA dehydrogenase (HOAD) as well as pyruvate kinase (PK) and lactate dehydrogenase (L-LDH). The
Communicated by M. I. Taylor. K. Feidantsis · A. Lazou · B. Kostoglou · B. Michaelidis Laboratory of Animal Physiology, Department of Zoology, Faculty of Sciences, School of Biology, University of Thessaloniki, 54124 Thessaloniki, Greece H. O. Pörtner Alfred-Wegener-Institut für Polar-und Meeresforschung, Physiologie mariner Tiere, Postfach 120161, 27515 Bremerhaven, Germany B. Michaelidis (&) Laboratory of Animal Physiology, Department of Zoology, Faculty of Science, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece e-mail: [email protected]
expression of Hsp70 and hsp90 was activated when the Wsh were exposed to temperatures beyond 20°C. Increased phosphorylation of p38 MAPK and JNKs indicated the parallel activation of MAPK signaling cascades and the potential involvement of MAPKs in the induction of Hsp genes. Exposure to extreme temperatures beyond 24°C caused an increase in the enzymatic activity of PK and LDH indicating an enhanced glycolytic potential.
Introduction The rapid increase in atmospheric CO2 levels as well as associated trends of global warming caused by rising concentrations of greenhouse gases during the last 50 years (Trenbberth 1997; Quay 2002) have stimulated considerable scientiWc interest (IPCC 2001). Simultaneously, the world’s oceans have experienced net warming (Levitus et al. 2000; Sheppard 2001; Fukasawa et al. 2004). An increase by a few degrees in atmospheric temperature is associated with shifts in the geographical distribution of Wsh, invertebrate and plant species as well as with changes in the composition of marine and estuarine communities (McGinn 2002). The identiWcation of the mechanisms of thermal limitation and adaptation is considered important for a cause
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