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Cross-tolerance in an inter-tidal sculpin
Comparative Biochemistry and Physiology, Part A 150 (2008) S155–S161
Contents lists available at ScienceDirect
Comparative Biochemistry and Physiology, Part A j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / c b p a
Society for Experimental Biology Annual Main Meeting 6th – 10th July 2008, Marseille, France
C3 — CROSS-TOLERANCE TOWARDS ENVIRONMENTAL STRESS: MOLECULAR MECHANISMS AND ECOLOGICAL CASE STUDIES C3.1 Strategies for cold and drought tolerance in soil invertebrates: Different stressors but same mechanisms M. Holmstrup (University of Aarhus) Soil invertebrates have developed a number of physiological adaptations that may provide protection against dehydration at both high and low temperature. Among the most familiar are the use of compatible osmolytes reducing water loss and protecting membranes and proteins in a dehydrated state. Stress proteins such as Hsp 70 and other chaperones seem to play a role in the survival of dehydration. Lastly, dehydration has been shown to initiate the same membrane composition modifications as normally observed during cold acclimation. There seems therefore to be a close link between cold and desiccation tolerance in soil invertebrates — a phenomenon that is further corroborated by the observation that pre-acclimation to drought conditions at summer temperatures confers increased cold tolerance. doi:10.1016/j.cbpa.2008.04.399
C3.2 Preconditioning of neural function by environmental stressors: Adaptive mechanisms in model systems M. Robertson (Queen's University) Neuronal circuits critical for organismal survival fail when exposed to extreme conditions such as hypoxia and hyperthermia but their operating ranges can be extended by prior exposure to similar, sublethal stress. Our research uses model circuits in locusts and fruit flies to investigate the mechanisms underlying failure and preconditioning of motor pattern generators. Different stressors converge on multiple, overlapping mechanisms though induced cross-tolerance can be unidirectional. Mechanisms that adaptively tune the operation of
neuronal circuits are both slow and relatively long-lasting (e.g. upregulation of heat shock proteins) and rapid (e.g. modulation of the cGMP/PKG signaling pathway). Current research investigates the existence of similar mechanisms in different organisms including vertebrates and mammals. doi:10.1016/j.cbpa.2008.04.400
C3.3 Cross-tolerance in an inter-tidal sculpin G. Iwama (Carleton University); A. Todgham (University of California) The tidepool sculpin (Oligocottus maculosus) and the fluffy sculpin (O. snyderi), live on the west coast of North America from Alaska to central California. They home to their tidepools and are highly tolerant of the changes in water quality that are different and unpredictable from one low tide to the next. The tidepool sculpin is found in all tidepools as well as all around Vancouver Island, whereas the fluffy sculpin is found only in the lower tidepools where the magnitude of change in water quality is relatively lower, and only on the west coast of Vancouver Island where the average temperatures are about 2 °C lower than in the Straight of Georgia between the Island and the Mainland. We have determined that both species show the classical neuroendocrine response to a wide range of stressors and that heat shock transcripts and proteins increase in several tissues to these stressors. These responses appear to be important to adaptation and survival of these fishes in the face of imposed stressors and furthermore that the natural cycling of water quality with the tides is vital to both these stress responses and survival. Removing such natural cycling in the laboratory mutes or abolishes the cellular HSP70 response and dramatically increases mortality in the face of a stressor like heat shock. We have observed that hormesis or crosstolerance occurs in these fishes, a mild stressor increases the resistance of the fish to a subsequent more severe stressor. The absolute magnitude of these imposed stressors, particularly the initial mild stressor, is crucial in that the two stressors can have an additive and negative effect. We
S156
Abstracts / Comparative Biochemistry and Physiology, Part A 150 (2008) S155–S161
will present and discuss these findings in light of the question that remains, how will these features of living in the intertidal zone affect their response to climate change scenarios? doi:10.1016/j.cbpa.2008.04.401
C3.4 Thermal and osmotic tolerances affect biogeographic patterning of congeners of Blue Mussels (genus Mytilus)
metal exposure on aerobic metabolic machinery on one hand, and elevated costs of basal maintenance on the other, result in a mismatch between energy demand and supply and in progressive hypoxemia. As a result, energy-dependent protective mechanisms (e.g., antioxidants, metallothioneins and heat shock proteins) fail leading to elevated mortality and whole-organism physiological stress. Such interactive effects of temperature and pollution stress can have important implications for survival of ectotherms in the face of the global climate change and anthropogenic pollution and must be taken into account in environmental risk assessment. doi:10.1016/j.cbpa.2008.04.403
G. Somero (Stanford University) Two species of blue mussel occur on the Pacific Coast of North America. A native species, Mytilus trossulus, is dominant northwards from the approximate latitude of San Francisco Bay. To the south, M. galloprovincialis, a native of the Mediterranean Sea introduced into California waters in the mid-20th century, has replaced the native congener. We are characterizing the physiologies of these two species to determine if interspecific differences in thermal and osmotic optima and tolerance limits may help to explain these differences in biogeographic patterning, and to generate a basis for predicting the further northward spread of the invasive Mediterranean species. M. trossulus appears to be the more cold adapted species, based on enzymatic traits (enzyme kinetic properties and specific activities of metabolic enzymes), thermal limits and rates of cardiac function, and temperatures at which stress proteins are induced. The native congener also is more tolerant of reduced salinities. The relative abundances of the native and invasive blue mussels at several locations in the San Francisco and Monterey Bays that differ in temperature and salinity suggest that osmotic tolerance may play a stronger role than thermal tolerance in establishing biogeographic patterning. The further spread of the invasive species may be restricted in areas where winter rains lead to low salinities in near-shore waters that are prohibitive to colonization by M. galloprovincialis.
C3.6 Synergistic interactions of environmental stressors: Dilemma or benefit? H. Pörtner (Alfred Wegener Institute, Bremerhaven); L. Eckerle, M. Lucassen (AWI)
C3.5 Surviving global change in polluted environments: Physiological and molecular mechanisms of cadmium and temperature interactions in a marine ectotherm Crassostrea virginica
The recent concept of oxygen and capacity dependent thermal tolerance in aquatic ectotherms has been used successfully to explain climate induced effects of rising temperatures on species abundance and survival in the field (Pörtner and Knust, 2007). According to these findings and from a general point of view physiological performance characters form the primary link between the well-being of the organism and its role and functioning in the ecosystem. The thermal window of performance in water breathers matches the window of aerobic scope. Thermal acclimation between seasons involves a shift of the thermal window and thus, reflects the need to specialize on a limited temperature range. Loss of performance would have to be considered the first sign of environmental stress, in this case associated with the onset of hypoxemia at the borders of the thermal envelope, caused by a progressive mismatch between oxygen supply and demand. This lack of respiratory capacity likely involves an accumulation of CO2 and the evolution of systemic stress signals like oxidative stress or hormonal responses. The question arises to what extent they contribute when the organism undergoes thermal acclimation. It will be discussed how other environmental factors would interact with these principle relationships, like ambient hypoxia or hypercapnia, e.g. by synergistically strengthening the regulatory cascade, supporting passive tolerance but leading the organism earlier to the limits of its acclimation capacity.
I. Sokolova (University of North Carolina at Charlotte); G. Lannig (Alfred-Wegener-Institute for Polar and Marine Research)
doi:10.1016/j.cbpa.2008.04.404
doi:10.1016/j.cbpa.2008.04.402
The thermal environment plays a key role in the distribution and survival of marine ectotherms through the direct effects on their physiology and indirectly affecting their susceptibility to other stressors. Our studies show that exposure to a trace metal, cadmium (Cd) sensitizes a model marine ectotherm Crassostrea virginica (eastern oyster) to temperature stress, and vice versa. Exposure to Cd results in a significant increase in standard metabolic rate of oysters, mostly due to the elevated costs of protein synthesis and expression of stress proteins. Combined Cd and temperature stresses negatively affect aerobic capacity due to the limitation of oxygen delivery systems, higher Cd sensitivity of mitochondrial function and a decrease in mitochondrial abundance in Cd-exposed oysters at elevated temperatures. At moderate temperatures cell protection capacities are sufficient to minimize the negative effect of Cd exposure on oxygen supply systems, and the oxygen supply is sufficient to cover elevated maintenance costs. With rising temperature, the synergistic effects of elevated temperature and
C3.7 The proteome response to temperature and salinity stress in Blue Mussel (genus Mytilus) congeners L. Tomanek (California Polytechnic State University); P. Fields (Franklin and Marshall College)
The two North Pacific Blue Mussel congeners Mytilus galloprovincialis and M. trossulus differ in thermal and salinity tolerance and show distinct distribution patterns along the coast of North America. In general, M. galloprovincialis is the more heat-tolerant and stenohaline congener of the two species and is more common along the southern to central Californian coast whereas M. trossulus becomes
Contents lists available at ScienceDirect
Comparative Biochemistry and Physiology, Part A j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / c b p a
Society for Experimental Biology Annual Main Meeting 6th – 10th July 2008, Marseille, France
C3 — CROSS-TOLERANCE TOWARDS ENVIRONMENTAL STRESS: MOLECULAR MECHANISMS AND ECOLOGICAL CASE STUDIES C3.1 Strategies for cold and drought tolerance in soil invertebrates: Different stressors but same mechanisms M. Holmstrup (University of Aarhus) Soil invertebrates have developed a number of physiological adaptations that may provide protection against dehydration at both high and low temperature. Among the most familiar are the use of compatible osmolytes reducing water loss and protecting membranes and proteins in a dehydrated state. Stress proteins such as Hsp 70 and other chaperones seem to play a role in the survival of dehydration. Lastly, dehydration has been shown to initiate the same membrane composition modifications as normally observed during cold acclimation. There seems therefore to be a close link between cold and desiccation tolerance in soil invertebrates — a phenomenon that is further corroborated by the observation that pre-acclimation to drought conditions at summer temperatures confers increased cold tolerance. doi:10.1016/j.cbpa.2008.04.399
C3.2 Preconditioning of neural function by environmental stressors: Adaptive mechanisms in model systems M. Robertson (Queen's University) Neuronal circuits critical for organismal survival fail when exposed to extreme conditions such as hypoxia and hyperthermia but their operating ranges can be extended by prior exposure to similar, sublethal stress. Our research uses model circuits in locusts and fruit flies to investigate the mechanisms underlying failure and preconditioning of motor pattern generators. Different stressors converge on multiple, overlapping mechanisms though induced cross-tolerance can be unidirectional. Mechanisms that adaptively tune the operation of
neuronal circuits are both slow and relatively long-lasting (e.g. upregulation of heat shock proteins) and rapid (e.g. modulation of the cGMP/PKG signaling pathway). Current research investigates the existence of similar mechanisms in different organisms including vertebrates and mammals. doi:10.1016/j.cbpa.2008.04.400
C3.3 Cross-tolerance in an inter-tidal sculpin G. Iwama (Carleton University); A. Todgham (University of California) The tidepool sculpin (Oligocottus maculosus) and the fluffy sculpin (O. snyderi), live on the west coast of North America from Alaska to central California. They home to their tidepools and are highly tolerant of the changes in water quality that are different and unpredictable from one low tide to the next. The tidepool sculpin is found in all tidepools as well as all around Vancouver Island, whereas the fluffy sculpin is found only in the lower tidepools where the magnitude of change in water quality is relatively lower, and only on the west coast of Vancouver Island where the average temperatures are about 2 °C lower than in the Straight of Georgia between the Island and the Mainland. We have determined that both species show the classical neuroendocrine response to a wide range of stressors and that heat shock transcripts and proteins increase in several tissues to these stressors. These responses appear to be important to adaptation and survival of these fishes in the face of imposed stressors and furthermore that the natural cycling of water quality with the tides is vital to both these stress responses and survival. Removing such natural cycling in the laboratory mutes or abolishes the cellular HSP70 response and dramatically increases mortality in the face of a stressor like heat shock. We have observed that hormesis or crosstolerance occurs in these fishes, a mild stressor increases the resistance of the fish to a subsequent more severe stressor. The absolute magnitude of these imposed stressors, particularly the initial mild stressor, is crucial in that the two stressors can have an additive and negative effect. We
S156
Abstracts / Comparative Biochemistry and Physiology, Part A 150 (2008) S155–S161
will present and discuss these findings in light of the question that remains, how will these features of living in the intertidal zone affect their response to climate change scenarios? doi:10.1016/j.cbpa.2008.04.401
C3.4 Thermal and osmotic tolerances affect biogeographic patterning of congeners of Blue Mussels (genus Mytilus)
metal exposure on aerobic metabolic machinery on one hand, and elevated costs of basal maintenance on the other, result in a mismatch between energy demand and supply and in progressive hypoxemia. As a result, energy-dependent protective mechanisms (e.g., antioxidants, metallothioneins and heat shock proteins) fail leading to elevated mortality and whole-organism physiological stress. Such interactive effects of temperature and pollution stress can have important implications for survival of ectotherms in the face of the global climate change and anthropogenic pollution and must be taken into account in environmental risk assessment. doi:10.1016/j.cbpa.2008.04.403
G. Somero (Stanford University) Two species of blue mussel occur on the Pacific Coast of North America. A native species, Mytilus trossulus, is dominant northwards from the approximate latitude of San Francisco Bay. To the south, M. galloprovincialis, a native of the Mediterranean Sea introduced into California waters in the mid-20th century, has replaced the native congener. We are characterizing the physiologies of these two species to determine if interspecific differences in thermal and osmotic optima and tolerance limits may help to explain these differences in biogeographic patterning, and to generate a basis for predicting the further northward spread of the invasive Mediterranean species. M. trossulus appears to be the more cold adapted species, based on enzymatic traits (enzyme kinetic properties and specific activities of metabolic enzymes), thermal limits and rates of cardiac function, and temperatures at which stress proteins are induced. The native congener also is more tolerant of reduced salinities. The relative abundances of the native and invasive blue mussels at several locations in the San Francisco and Monterey Bays that differ in temperature and salinity suggest that osmotic tolerance may play a stronger role than thermal tolerance in establishing biogeographic patterning. The further spread of the invasive species may be restricted in areas where winter rains lead to low salinities in near-shore waters that are prohibitive to colonization by M. galloprovincialis.
C3.6 Synergistic interactions of environmental stressors: Dilemma or benefit? H. Pörtner (Alfred Wegener Institute, Bremerhaven); L. Eckerle, M. Lucassen (AWI)
C3.5 Surviving global change in polluted environments: Physiological and molecular mechanisms of cadmium and temperature interactions in a marine ectotherm Crassostrea virginica
The recent concept of oxygen and capacity dependent thermal tolerance in aquatic ectotherms has been used successfully to explain climate induced effects of rising temperatures on species abundance and survival in the field (Pörtner and Knust, 2007). According to these findings and from a general point of view physiological performance characters form the primary link between the well-being of the organism and its role and functioning in the ecosystem. The thermal window of performance in water breathers matches the window of aerobic scope. Thermal acclimation between seasons involves a shift of the thermal window and thus, reflects the need to specialize on a limited temperature range. Loss of performance would have to be considered the first sign of environmental stress, in this case associated with the onset of hypoxemia at the borders of the thermal envelope, caused by a progressive mismatch between oxygen supply and demand. This lack of respiratory capacity likely involves an accumulation of CO2 and the evolution of systemic stress signals like oxidative stress or hormonal responses. The question arises to what extent they contribute when the organism undergoes thermal acclimation. It will be discussed how other environmental factors would interact with these principle relationships, like ambient hypoxia or hypercapnia, e.g. by synergistically strengthening the regulatory cascade, supporting passive tolerance but leading the organism earlier to the limits of its acclimation capacity.
I. Sokolova (University of North Carolina at Charlotte); G. Lannig (Alfred-Wegener-Institute for Polar and Marine Research)
doi:10.1016/j.cbpa.2008.04.404
doi:10.1016/j.cbpa.2008.04.402
The thermal environment plays a key role in the distribution and survival of marine ectotherms through the direct effects on their physiology and indirectly affecting their susceptibility to other stressors. Our studies show that exposure to a trace metal, cadmium (Cd) sensitizes a model marine ectotherm Crassostrea virginica (eastern oyster) to temperature stress, and vice versa. Exposure to Cd results in a significant increase in standard metabolic rate of oysters, mostly due to the elevated costs of protein synthesis and expression of stress proteins. Combined Cd and temperature stresses negatively affect aerobic capacity due to the limitation of oxygen delivery systems, higher Cd sensitivity of mitochondrial function and a decrease in mitochondrial abundance in Cd-exposed oysters at elevated temperatures. At moderate temperatures cell protection capacities are sufficient to minimize the negative effect of Cd exposure on oxygen supply systems, and the oxygen supply is sufficient to cover elevated maintenance costs. With rising temperature, the synergistic effects of elevated temperature and
C3.7 The proteome response to temperature and salinity stress in Blue Mussel (genus Mytilus) congeners L. Tomanek (California Polytechnic State University); P. Fields (Franklin and Marshall College)
The two North Pacific Blue Mussel congeners Mytilus galloprovincialis and M. trossulus differ in thermal and salinity tolerance and show distinct distribution patterns along the coast of North America. In general, M. galloprovincialis is the more heat-tolerant and stenohaline congener of the two species and is more common along the southern to central Californian coast whereas M. trossulus becomes