Effects of temperature acclimation on lactate dehydrogenase of cod(<i>Gadus morhua</i>): genetic, kinetic and thermodynamic aspects

Journal of Experimental Biology

2010

1,161

984

SummaryThe concept of oxygen-and capacity-dependent thermal tolerance in aquatic ectotherms has successfully explained climateinduced effects of rising temperatures on species abundance in the field. Oxygen supply to tissues and the resulting aerobic performance characters thus form a primary link between organismal fitness and its role and functioning at the ecosystem level. The thermal window of performance in water breathers matches their window of aerobic scope. Loss of performance reflects the earliest level of thermal stress, caused by hypoxaemia and the progressive mismatch of oxygen supply and demand at the borders of the thermal envelope. Oxygen deficiency elicits the transition to passive tolerance and associated systemic and cellular stress signals like hormonal responses or oxidative stress as well as the use of protection mechanisms like heat shock proteins at thermal extremes. Thermal acclimatization between seasons or adaptation to a climate regime involves shifting thermal windows and adjusting window widths. The need to specialize on a limited temperature range results from temperaturedependent trade-offs at several hierarchical levels, from molecular structure to whole-organism functioning, and may also support maximized energy efficiency. Various environmental factors like CO 2 (ocean acidification) and hypoxia interact with these principal relationships. Existing knowledge suggests that these factors elicit metabolic depression supporting passive tolerance to thermal extremes. However, they also exacerbate hypoxaemia, causing a narrowing of thermal performance windows and prematurely leading the organism to the limits of its thermal acclimation capacity. The conceptual analysis suggests that the relationships between energy turnover, the capacities of activity and other functions and the width of thermal windows may lead to an integrative understanding of specialization on climate and, as a thermal matrix, of sensitivity to climate change and the factors involved. Such functional relationships might also relate to climate-induced changes in species interactions and, thus, community responses at the ecosystem level.

Section: Acclimatizationmentioning

confidence: 99%

Oxygen- and capacity-limitation of thermal tolerance: a matrix for integrating climate-related stressor effects in marine ecosystems

Journal of Experimental Biology

2010

1,161

984

“…3). Accordingly, less cellular space is required for mitochondria, more can be allocated to contractile proteins, and higher cellular protein concentrations result (Zakhartsev et al 2004b;Fig. 2).…”

Section: Cellular Design Optimization For High Energy Turnover In Eurmentioning

confidence: 99%

Climate Variability and the Energetic Pathways of Evolution: The Origin of Endothermy in Mammals and Birds

Physiological and Biochemical Zoology

2004

Large-scale climate oscillations in earth's history have influenced the directions of evolution, last but not least, through mass extinction events. This analysis tries to identify some unifying forces behind the course of evolution that favored an increase in organismic complexity and performance, paralleled by an increase in energy turnover, and finally led to endothermy. The analysis builds on the recent concept of oxygen-limited thermal tolerance and on the hypothesis that unifying principles exist in the temperature-dependent biochemical design of the eukaryotic cell in animals. The comparison of extant waterbreathing and air-breathing animal species from various climates provides a cause-and-effect understanding of the tradeoffs and constraints in thermal adaptation and their energetic consequences. It is hypothesized that the high costs of functional adaptation to fluctuating temperatures, especially in the cold (cold eurythermy), cause an increase in energy turnover and, at the same time, mobility and agility. These costs are associated with elevated mitochondrial capacities at minimized levels of activation enthalpies for proton leakage. Cold eurythermy is seen as a precondition for the survival of evolutionary crises elicited by repeated cooling events during extreme climate fluctuations. The costs of cold eurythermy appear as the single most important reason why metazoan evolution led to life forms with high energy turnover. They also explain why dinosaurs were able to live in subpolar climates. Finally, they give insight into the pathways, benefits, and trade-offs involved in the evolution of constant, elevated body temperature maintained by endothermy. Eurythermy, which encompasses cold tolerance, is thus hypothesized to be the "missing link" between ectothermy and endothermy. Body temperatures between 32Њ and 42ЊC in mammals and birds then result from trade-offs *

“…For each individual fish the temperature dependence of enzyme kinetics was read at a statistically satisfying level (at 10 pyruvate concentrations under seven temperatures in triplicate). This approach of temperature control in the microplate allowed Zhakartsev et al [35] to study the temperature dependence of LDH kinetic and thermodynamic parameters for an even larger number of fish (n ¼ 36) acclimated to different temperatures with the same high-throughput system.…”

Section: T-microplatementioning

confidence: 99%

“…It appears that the enzyme is well suited to tolerate rapid fluctuations of habitat temperatures on top of the general seasonal trend. This excludes the necessity to express different isozymes depending on the season [35].…”

Section: Kineticsmentioning

confidence: 99%

“…The technique of temperature control in microplates developed in this study has been applied for the parallel study of acclimation effects of Atlantic cod to seasonal temperature variation [35] and it has demonstrated its efficiency. Despite earlier studies reporting kinetic differences between LDH allozymes [9] our parallel study [35] of crude tissue homogenates of cod G. morhua could not reveal kinetic differences (in V 0 max , K 0PYR m , K PYR si , protein concentration, and E A ) among Ldh-B phenotypes (overall LDH suites).…”

Section: Kineticsmentioning

confidence: 99%

See 1 more Smart Citation

Environmentally low-temperature kinetic and thermodynamic study of lactate dehydrogenase from Atlantic cod (G. morhua) using a 96-well microplate technique

Zakhartsev

Analytical Biochemistry

Blust

2004

Self Cite

Analyses of temperature-dependent kinetic parameters in enzymes extracted from tissues of ectothermic animals are usually carried out within the range of physiological temperatures (0-40 degrees C). However, multisample spectrophotometers (so-called microplate readers) with efficient wide-range temperature control (including cooling) have previously been unavailable. This limits the statistical quality of the measurements. A temperature-controlled microplate was designed for a 96-well microplate reader to overcome this limitation. This so-called T-microplate is able to control assay temperature between the freezing point of a liquid sample and 60 degrees C with high stability and accuracy in any data acquisition mode. At 4 degrees C the accuracy of the temperature control was +/-0.1 degrees C and temperature homogeneity across the microplate was +/-0.3 degrees C. As examples, analyses of the temperature dependence of Michaelis-Menten (K'(PYR)(m) and substrate inhibition (K'(PYR)(si) constants for pyruvate, of the maximal rate of reaction (V'(max), of the apparent Arrhenius activation energy (E(A), and of the Gibbs free-energy change (deltaG) of lactate dehydrogenases from muscle of Atlantic cod Gadus morhua acclimated to 4 degrees C are described. The large dataset obtained allowed evaluation of a new mechanism of metabolic compensation in response to seasonal temperature change.