QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online August 22, 2008
Journal of Experimental Biology 211, 2889-2898 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.016782

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Anestis, A. Articles by Michaelidis, B. Search for Related Content PubMed Articles by Anestis, A. Articles by Michaelidis, B. Social Bookmarking                         What's this?

Metabolic and molecular stress responses of sublittoral bearded horse mussel Modiolus barbatus to warming sea water: implications for vertical zonation

Andreas Anestis¹, Hans O. Pörtner², Antigone Lazou¹ and Basile Michaelidis^1,*

¹ Laboratory of Animal Physiology, Department of Zoology, School of Biology, Faculty of Science, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
² Alfred-Wegener-Institut für Polar-und Meeresforschung, Ökophysiologie mariner Tiere, Postfach 120161, D-27515 Bremerhaven, Germany

^* Author for correspondence (e-mail: michaeli{at}bio.auth.gr)

Accepted 10 June 2008

The present study set out to investigate the thermal limits of the Mediterranean bivalve Modiolus barbatus, acclimated to various temperatures, and includes a comparison of laboratory determined limits with its temperature-dependent restriction to deeper water layers in its natural habitat. Thermal responses and limits were determined by integrating information from various levels of biological organization, including the expression of Hsp70 and Hsp90, the phosphorylation of stress-activated protein kinases, p38 mitogen-activated protein kinase (p38 MAPK) and cJun-N-terminal kinases (JNKs) as well as metabolic adjustments. The latter were assessed by examining temperature effects on the activity of the key glycolytic enzyme pyruvate kinase (PK). The expression of Hsp70 and Hsp90 was activated when mussels were acclimated to temperatures above 20°C. Increased phosphorylation of p38 MAPK and JNKs at about the same temperatures indicate activation of MAPK signaling cascades and their potential involvement in the induction of Hsp genes. As indicated by the activity of PK, Modiolus barbatus maintains some aerobic capacity when acclimated to temperatures up to 24°C, while further warming probably caused metabolic depression and a shift from aerobic to anaerobic metabolism. An increase in mortality occurred in parallel, during acclimation to temperatures above 24°C. Our results indicate that both the biochemical stress indicators and metabolic status respond in parallel once hypoxemia becomes extreme. Comparison with our previous study of thermal limits and vertical distribution in M. galloprovincialis dwelling in shallow waters emphasizes the relevance of maintained aerobic scope over that of passive tolerance for permanent vertical zonation at higher temperatures in the field. These findings and conclusions are in line with the concept of oxygen and capacity limited thermal tolerance and the associated systemic to molecular hierarchy of thermal limitation.

Key words: bivalves, temperature, mortality, heat shock proteins, mitogen-activated protein kinases, pyruvate kinase, aerobic scope

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?