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PubMed2000

Influence of nutrient supply on shade-sun acclimation of Picea abies seedlings: effects on foliar morphology, photosynthetic performance and growth.

Norway spruce seedlings (Picea abies Karst.) were grown in low light for one year, under conditions of adequate and limiting nutrition, then transferred to high light. Three months after transfer we measured photosynthesis, leaf nitrogen concentration, leaf chlorophyll concentration and leaf mass per area (LMA) of current-year and 1-year-old shoots; silhouette area ratio (SAR, the ratio of shoot silhouette area to projected needle area) was also measured in current-year shoots. At the foliage level, the effects of light and nutrient treatments differed markedly. Light availability during foliage expansion primarily affected LMA and SAR (morphological acclimation at the needle and shoot level, respectively). By contrast, nutrient supply in high light affected photosynthetic capacity per unit of leaf tissue (physiological acclimation at the cellular level) but did not affect LMA and SAR. The capacity for shade-sun acclimation in foliage formed before transfer to high light differed greatly from that of foliage formed following the transfer. The morphological inflexibility of mature needles (measured by LMA) limited their shade-sun acclimation potential. In contrast, at high nutrient supply, shoots that developed just after the change in photosynthetic photon flux density largely acclimated, both morphologically and physiologically, to the new light environment. The acclimation response of both current- and 1-year-old shoots was prevented by nutrient limitation. Analysis of growth at the whole-plant level largely confirmed the conclusions drawn at the shoot level. We conclude that nutrient shortage subsequent to the opening of a canopy gap may strongly limit the acclimation response of Norway spruce seedlings. Successful acclimation was largely related to the plant's ability to produce sun foliage and adjust whole-plant biomass allocation rapidly.

Journal Article↗

PubMed1983

Effect of cold acclimation on intracellular ice formation in isolated protoplasts.

When cooled at rapid rates to temperatures between -10 and -30 degrees C, the incidence of intracellular ice formation was less in protoplasts enzymically isolated from cold acclimated leaves of rye (Secale cereale L. cv Puma) than that observed in protoplasts isolated from nonacclimated leaves. The extent of supercooling of the intracellular solution at any given temperature increased in both nonacclimated and acclimated protoplasts as the rate of cooling increased. There was no unique relationship between the extent of supercooling and the incidence of intracellular ice formation in either nonacclimated or acclimated protoplasts. In both nonacclimated and acclimated protoplasts, the extent of intracellular supercooling was similar under conditions that resulted in the greatest difference in the incidence of intracellular ice formation-cooling to -15 or -20 degrees C at rates of 10 or 16 degrees C/minute. Further, the hydraulic conductivity determined during freeze-induced dehydration at -5 degrees C was similar for both nonacclimated and acclimated protoplasts. A major distinction between nonacclimated and acclimated protoplasts was the temperature at which nucleation occurred. In nonacclimated protoplasts, nucleation occurred over a relatively narrow temperature range with a median nucleation temperature of -15 degrees C, whereas in acclimated protoplasts, nucleation occurred over a broader temperature range with a median nucleation temperature of -42 degrees C. We conclude that the decreased incidence of intracellular ice formation in acclimated protoplasts is attributable to an increase in the stability of the plasma membrane which precludes nucleation of the supercooled intracellular solution and is not attributable to an increase in hydraulic conductivity of the plasma membrane which purportedly precludes supercooling of the intracellular solution.

Journal Article↗

PubMed1987

Evaluation of Polyamine and Proline Levels during Low Temperature Acclimation of Citrus.

The polyamines (PA) putrescine (Put), spermidine (Spd), and spermine (Spm) were measured during 3 weeks exposure to cold hardening (15.6 degrees C day and 4.4 degrees C night) and nonhardening (32.2 degrees C day and 21.1 degrees C night) temperature regimes in three citrus cultivars: sour orange (SO) (Citrus aurantium L.), ;valencia' (VAL) (Citrus sinensis L. Osbeck), and rough lemon (RL) (Citrus jambhiri Lush). The changes in PA were compared to the amount of free proline, percent wood kill and percent leaf kill. A 2- to 3-fold increase in Spd concentrations were observed in hardened RL, SO, and VAL leaves compared to nonhardened leaves. Spermidine reached its highest level of approximately 200 nanomoles per gram fresh weight after 1 week of acclimation in both SO and VAL leaves, while RL spermidine content continued to increase up to the third week of acclimation. Spm levels in acclimated VAL and RL leaves increased 1- to 4-fold. However, SO leaves Spm content decreased with acclimation. Putrescine levels in SO and VAL increased 20 to 60% during the first 2 weeks of acclimation then declined after 3 weeks. RL putrescine content was not affected by cold acclimation. The data presented here provided direct relationship between increased Spd concentration and citrus cold hardiness. Free proline was 3- to 6-fold higher in acclimated than in nonacclimated trees. Results also demonstrate that in acclimated versus nonacclimated citrus trees the absolute amount rather than the ratio of increase in free proline is more important in predicting their ability to survive freezing stress.

Journal Article↗

PubMed1994

Effect of acclimation temperature on the concentration of uncoupling protein and GDP binding in rat brown fat mitochondria.

The effect of the acclimation temperature on the concentration of the uncoupling protein (UCP) and specific GDP binding in rat brown adipose tissue mitochondria was investigated. UCP was measured by competition ELISA using purified UCP as a standard and antiserum developed against the C-terminus of the protein. UCP was purified by means of specific polyclonal antibodies immobilized on protein-A--agarose. It represented 2.4% of the total protein in brown fat mitochondria from rats acclimated to 4 degrees C and 1.1% in mitochondria from rats acclimated to 29 degrees C. No UCP was found in liver mitochondria. The molar ratio of bound GDP and UCP was 0.5 in mitochondria from warm-acclimated rats and 1.0 in cold-acclimated rats. The GDP/UCP ratio was increased from 0.5 to 1.0 after a 90-min exposure to 4 degrees of warm-acclimated rats; it was decreased from 1.0 to 0.5, when cold-acclimated rats were transferred to 29 degrees C for 2 4h. Treatment of mitochondrial membranes from warm-acclimated rats with 3 M urea at pH 10.0 increased the GDP/UCP ratio from 0.5 to 1.0. Specific GDP binding was a direct measure of the UCP concentration during maximally activated or inactivated thermogenesis in brown adipose tissue. We suggest that variable GDP binding reflects the functional activity of UCP based on different protein conformations.

Acclimatization↗

PubMed1984

Anaerobic biodegradation of chlorophenols in fresh and acclimated sludge.

We investigated the anaerobic biodegradation of mono- and dichlorophenol isomers by fresh (unacclimated) sludge and by sludge acclimated to either 2-chlorophenol, 3-chlorophenol, or 4-chlorophenol. Biodegradation was evaluated by monitoring substrate disappearance and, in selected cases, production of 14CH4 from labeled substrates. In unacclimated sludge, each of the monochlorophenol isomers was degraded. The relative rates of disappearance were in this order: ortho greater than meta greater than para. For the dichlorophenols in unacclimated sludge, reductive dechlorination of the Cl group ortho to phenolic OH was observed, and the monochlorophenol compounds released were subsequently degraded. 3,4-Dichlorophenol and 3,5-dichlorophenol were persistent. Sludge acclimated to 2-chlorophenol cross-acclimated to 4-chlorophenol but did not utilize 3-chlorophenol. This sludge also degraded 2,4-dichlorophenol. Sludge acclimated to 3-chlorophenol cross-acclimated to 4-chlorophenol but not to 2-chlorophenol. This sludge degraded 3,4- and 3,5-dichlorophenol but not 2,3- or 2,5-dichlorophenol. The specific cross-acclimation patterns observed for monochlorophenol degradation demonstrated the existence of two unique microbial activities that were in turn different from fresh sludge. The sludge acclimated to 4-chlorophenol could degrade all three monochlorophenol isomers and 2,4- and 3,4-dichlorophenol. The active microbial population in this sludge appeared to be a mixture of populations present in the 2-chlorphenol- and 3-chlorophenol-acclimated sludges, both of which could utilize 4-chlorophenol. Experiments with 14C-radiolabeled p-chlorophenol, o-chlorophenol, and 2,4-dichlorophenol demonstrated that these compounds were converted to 14CH4 and 14CO2.

Anaerobiosis↗

PubMed1986

Exercise suppression of thermoregulatory thermogenesis in warm- and cold-acclimated rats.

An evaluation was made of the effects of an acute exercise bout on nonshivering thermogenesis (NST) in cold-acclimated rats (4 degrees C for 6 weeks) and shivering thermogenesis in 24 degrees C-acclimated rats (24 degrees C for 6 weeks). Assessment techniques included indirect calorimetry during treadmill running and brown adipose tissue (BAT) mitochondrial guanosine diphosphate (GDP) binding immediately following a treadmill run. Calorimetric results for 24 degrees C-acclimated rats running at 4 degrees C indicated total substitution of shivering thermogenesis by exercise-derived heat. No difference in GDP-binding, an index of BAT nonshivering thermogenic activity, was observed between exercised and nonexercised 24 degrees C-acclimated rats. Calorimetric results for cold-acclimated rats running at 4 degrees C indicated a total suppression in the energy cost associated with NST, exercise-derived heat replacing or substituting for NST. Examining BAT properties in the exercised cold-acclimated rats revealed a significant 40% decrease in BAT mitochondrial GDP-binding. These results suggest that during running, metabolic heat due to the exercise totally replaces shivering in 24 degrees C-acclimated rats and totally replaces BAT nonshivering thermogenesis in cold-acclimated rats.

Acclimatization↗

PubMed1980

Temperature acclimation: effects on membrane physiology of an identified snail neuron.

The neuronal basis for thermal acclimation was examined by comparing the short- and long-term effects of temperature change on the physiological properties of an identified neuron in the isolated ganglion of Hexis aspersa. Using intracellular electrophysiological techniques, we found that the frequency of spontaneous action potentials and excitability of neurons from warm-acclimated animals was depressed by abruptly cooling from 20 to 5 degrees C. After a 2-wk period of acclimation to 5 degrees C, the levels of spontaneous activity and excitability were comparable to those of warm-acclimated neurons at 20 degrees C. Conversely, abrupt warming of neurons from cold-acclimated animals greatly increased the frequency of spontaneous activity, but after acclimation to 20 degrees C the frequency decreased. Although the duration of the action potential and the cell's electrogenic Na-K pump were temperature sensitive, thermal acclimation had no obvious effects on these parameters. Membrane permeability to Na and PNa/PK decreased with cooling, whereas PRb/PK and PCs/PK increased. Warming had the opposite effect on the relative alkali cation permeability (PX/PK). With acclimation PX/PK underwent compensatory changes.

Action Potentials↗

PubMed2002

Changes of carp FoF1-ATPase in association with temperature acclimation.

Previously we have shown, using two-dimensional electrophoresis, that mitochondrial ATP synthase (F(o)F(1)-ATPase) beta-subunit is the 55-kDa protein increased in cold-acclimated carp Cyprinus carpio (Kikuchi K, Itoi S, and Watabe S. Fisheries Sci 65: 629-636, 1999). To clarify the coordinate expression in various subunits of carp F(o)F(1)-ATPase with temperature acclimation, we examined the differences in mRNA levels of mitochondrial proteins encoded by both nuclear and mitochondrial genes in fast muscle of carp acclimated to 10 and 30 degrees C. The mRNA levels of nuclear genes per unit weight of total RNA were nearly twofold higher in the 10 degrees C- than 30 degrees C-acclimated carp. However, the transcripts of mitochondrial genes for the 10 degrees C-acclimated carp in terms of the same comparing unit were six to seven times as much as those for the 30 degrees C-acclimated carp. The F(o)F(1)-ATPase activities measured at 10, 25, and 30 degrees C were nearly twofold higher for the cold-acclimated fish than their warm-acclimated counterparts. Such quantitative and qualitative changes in carp F(o)F(1)-ATPase may contribute to extra ATP production required to compensate for energy balance at suboptimal temperatures.

Acclimatization↗

PubMed2006

Role of glucocorticoid receptor in acclimation of killifish (Fundulus heteroclitus) to seawater and effects of arsenic.

Killifish are euryhaline teleosts that adapt to rapid changes in the salinity of the seawater. It is generally accepted that acclimation to seawater is mediated by cortisol activation of the glucocorticoid receptor (GR), which stimulates CFTR mRNA expression and CFTR-mediated Cl- secretion by the gill. Because there is no direct evidence in killifish that the GR stimulates CFTR gene expression, quantitative PCR studies were conducted to test the hypothesis that cortisol activation of GR upregulates CFTR mRNA expression and that this response is required for acclimation to seawater. Inhibition of the GR by RU-486 prevented killifish from acclimating to increased salinity and blocked the increase in CFTR mRNA. In contrast, inhibition of the mineralocorticoid receptor by spironolactone had no effect on acclimation to seawater. Thus acclimation to increased salinity in killifish requires signaling via the GR and includes an increase in CFTR gene expression. Because arsenic, a toxic metalloid that naturally occurs in the aquatic environment, has been shown to disrupt GR transcriptional regulation in avian and mammalian systems, studies were also conducted to determine whether arsenic disrupts cortisol-mediated activation of CFTR gene expression in this in vivo fish model and thereby blocks the ability of killifish to acclimate to increased salinity. Arsenic prevented acclimation to seawater and decreased CFTR protein abundance. However, arsenic did not disrupt the GR-induced increase in CFTR mRNA. Thus arsenic blocks acclimation to seawater in killifish by a mechanism that does not disrupt GR-mediated induction of CFTR gene expression.

Acclimatization↗

PubMed1984

Influence of thermal acclimation on glucose production and ketogenesis in isolated eel hepatocytes.

Hepatocytes were isolated by collagenase perfusion of the liver from adult eels (Anguilla anguilla L.) acclimated to different temperatures. Whereas the relative weight of the liver increased in cold-acclimated fish, hepatocytes from 10- and 20 degrees C-acclimated animals did not differ in cellular weight, dry weight, or protein content. Endogenous rates of oxygen consumption and respiratory control ratios were independent of acclimation temperature. There was no effect of temperature on triacylglycerol content, but glycogen concentration was significantly higher in hepatocytes of cold-acclimated fish. Liver cells from cold-acclimated eels exhibited higher rates of glucose release and ketogenesis than those from warm-acclimated animals. It is concluded that the increase in acetoacetate production induced by cold acclimation results primarily from a higher rate of lipolysis. Cellular interactions between ketogenesis and gluconeogenesis are demonstrated and discussed.

Acetoacetates↗

PubMed1977

Role of ketone bodies in nonshivering thermogenesis in cold-acclimated rats.

The role of ketone bodies (KB) in nonshivering thermogenesis was investigated in warm- and cold-acclimated rats with and without norepinephrine (NE) loads. NE-induced calorigenesis, as evidenced by changes in rectal temperature, was highly developed in cold-acclimated rats, but the levels of blood KB and free fatty acids (FFA) remained almost unaltered. In contrast, FFA turnover rate in cold-acclimated rats under NE load was much greater than in warm-acclimated rats. Similarly, turnover rate of beta-hydroxybutyrate estimated from decay curves of the endogenous substrate in functionally eviscerated rats was significantly higher in cold- than warm-acclimated rats. Perfused livers from cold-acclimated rats produced more KB than warm-acclimated ones. No significant effect of NE load was observed in either group. Quantitative analysis shows that the turnover rate of KB in vivo essentially equals the production rate in the perfused liver when no exogenous NE is added. In contrast, under constant NE infusion the turnover rate in vivo was almost double that of the perfused liver. These results indicate that KB are an energy source as important as FFA in nonshivering thermogenesis. It may be further surmised that increased KB production in vivo, particularly in the cold-acclimated state, is affected by factor(s) other than NE.

Acclimatization↗

PubMed1981

Physiological and hematologic responses to summer and winter dry-heat acclimation.

Differences between acclimation to heat at the end of winter (W) and at the end of summer (S) were studied on the same eight male volunteers. Subjects were exposed to 40 degrees C, 30% rh for 10 consecutive days on two separate occasions approximately 5 mo apart (S and W). Daily exposures lasted 120 min: 10 min rest, 50 min walking 1.34 m . s-1 on the level, 10 min rest, 50 min walking. During W acclimation, rectal temperature (Tre) and heart rate (HR) decreased, sweat rate (msw) remained unchanged, and plasma and red cell volume of the blood expanded. During S acclimation, HR decreased while Tre and msw remained unchanged, and plasma volume increased. The Tre of the acclimated subjects remained higher in W, and the msw lower, than in S. It was concluded that acclimation does not totally eliminate the seasonal differences in thermoregulatory set point and sweating sensitivity. Further, acclimation to a more severe heat did not lower the thermoregulatory set point that was achieved by natural acclimatization to a milder heat but affected the cardiovascular adjustment and caused greater plasma volume expansion. W acclimation caused both plasma and blood cell volume expansion, whereas S acclimation affected only plasma volume.

Acclimatization↗

PubMed1985

Skeletal muscle metabolism during exercise is influenced by heat acclimation.

The influence of heat acclimation on skeletal muscle metabolism during submaximal exercise was studied in 13 healthy men. The subjects performed 30 min of cycle exercise (70% of individual maximal O2 uptake) in a cool [21 degrees C, 30% relative humidity (rh)] and a hot (49 degrees C, 20% rh) environment before and again after they were heat acclimated. Aerobic metabolic rate was lower (0.1 l X min-1; P less than 0.01) during exercise in the heat compared with the cool both before and after heat acclimation. Muscle and plasma lactate accumulation with exercise was greater (P less than 0.01) in the hot relative to the cool environment both before and after acclimation. Acclimation lowered (P less than 0.01) aerobic metabolic rate as well as muscle and plasma lactate accumulation in both environments. The amount of muscle glycogen utilized during exercise in the hot environment did not differ from that in the cool either before or after acclimation. These findings indicate that accumulation of muscle lactate is increased and aerobic metabolic rate is decreased during exercise in the heat before and after heat acclimation; increased muscle glycogen utilization does not account for the increased muscle lactate accumulation during exercise under extreme heat stress; and heat acclimation lowers the aerobic metabolic rate and muscle and blood lactate accumulation during exercise in a cool as well as a hot environment.

Adaptation, Biological↗

PubMed2004

Stress-related genomic responses during the course of heat acclimation and its association with ischemic-reperfusion cross-tolerance.

Acclimation to heat is a biphasic process involving a transient perturbed phase followed by a long lasting period during which acclimatory homeostasis is developed. In this investigation, we used cDNA stress microarray (Clontech Laboratory) to characterize the stress-related genomic response during the course of heat acclimation and to test the hypotheses that 1) heat acclimation influences the threshold of activation of protective molecular signaling, and 2) heat-acclimation-mediated ischemic-reperfusion (I/R) protection is coupled with reprogrammed gene expression leading to altered capacity or responsiveness of protective-signaling pathways shared by heat and I/R cytoprotective systems. Rats were acclimated at 34 degrees C for 0, 2, and 30 days. 32P-labeled RNA samples prepared from the left ventricles of rats before and after subjection to heat stress (HS; 2 h, 41 degrees C) or after I/R insult (ischemia: 75%, 45 min; reperfusion: 30 min) were hybridized onto the array membranes. Confirmatory RT-PCR of selected genes conducted on samples taken at 0, 30, and 60 min after HS or total ischemia was used to assess the promptness of the transcriptional response. Cluster analysis of the expressed genes indicated that acclimation involves a "two-tier" defense strategy: an immediate transient response peaking at the initial acclimating phase to maintain DNA and cellular integrity, and a sustained response, correlated with slowly developed adaptive, long-lasting cytoprotective signaling networks involving genes encoding proteins that are essential for the heat-shock response, antiapoptosis, and antioxidation. Gene activation was stress specific. Faster activation and suppression of signaling pathways shared by HS and I/R stressors probably contribute to heat-acclimation I/R cross-tolerance.

Acclimatization↗

PubMed1986

Effect of thermal acclimation on locomotor energetics and locomotor performance in a lungless salamander, Desmognathus ochrophaeus.

To determine the effects of thermal acclimation upon locomotor performance and the rate of oxygen consumption (MO2) during activity, small (less than 3 g), lungless salamanders, Desmognathus ochrophaeus Cope, were acclimated to three temperatures (5, 13 and 21 degrees C) and exercised at various controlled speeds within an exercise wheel while their MO2 was measured. MO2 increased with speed at low speeds (less than 14 cm min-1). Although animals could sustain greater speeds, MO2 did not increase further. These small, exclusively skin-breathing salamanders could increase their MO2 9-11 times during exercise and could sustain nearly half of the oxygen flux expected across a similar surface area of the mammalian lung. However, their maximum aerobic speed was remarkably slow (14 cm min-1) and their net cost of transport remarkably large (15-17 ml O2 g-1 km-1). Thermal acclimation affected MO2 during activity, the maximum sustainable speed and locomotor stamina in different ways. During exercise at 13 degrees C, cold-acclimated animals had a significantly greater MO2 than warm-acclimated animals, but did not differ in stamina or the maximum sustainable speed. During exercise at 21 degrees C, cold acclimation did not affect the MO2 significantly, but it decreased the stamina and increased the rate of lactate accumulation. Thus, these results suggest that thermal acclimation of the MO2 is not tightly coupled to thermal acclimation of locomotor performance in salamanders.

Acclimatization↗

PubMed1996

Design of an acclimation system capable of controlling carbon dioxide concentration.

The production system for grafted seedlings mainly consists of three processes; 1) growth of seedlings, 2) grafting of seedlings, and 3) acclimation of grafted seedlings. Of the three processes, the duration of acclimation is highly influenced by the acclimation conditions. The acclimation environment after grafting was controlled to be satisfied the demands of grafted seedlings in the point of the physiological reaction such as photosynthesis, respiration, transpiration, and translocation nutrients. In the present study, a preliminary experiment was conducted to understand the relationship between the factors concerned with the acclimation of grafted seedlings, using a new acclimation apparatus. The factors of interest were air temperature, relative humidity, light, and carbon dioxide concentration. In the presence of light, the air temperature and relative humidity were interfered each other, so that both factors were difficult to keep at a constant value. Furthermore, the concentration of carbon dioxide was remarkably fluctuated by the relative humidity regulated by the humidifier and dehumidification which was controlled by the temperature differences between water and ambient air. A new device of acclimation system which is automatically controlled would be expected to construct in near future. Such a device will make it possible to shorten the duration of acclimation and produce high quality of grafted seedlings.

Acclimatization↗

PubMed2005

Importance of acclimation to environmentally relevant zinc concentrations on the sensitivity of Daphnia magna toward zinc.

Daphnia magna was acclimated for six generations to an acclimation range of 0.02 to 74 microg/L of Zn2+. This range was determined by combining physicochemical water characteristics of European surface waters with total Zn concentrations in these waters in such a way that they resulted in minimal and maximal free (i.e., assumed bioavailable) Zn ion activities. No significant differences were found in acute Zn tolerance between the different acclimation concentrations: Average 48-h median effective concentration (EC50) values ranged from 608+/-94 to 713+/-249 microg/L of Zn2+. Also, no significant shifts in chronic tolerance were observed: Average 21-d EC50 (based on net reproductive rate) ranged from 91+/-20 to 124+/-22 microg/L of Zn2+. However, at test concentrations less than the 21-d EC50, acclimation significantly increased the reproductive capacity of the offspring produced. This indicates that metal acclimation is not necessarily accompanied by an increase in tolerance but also may manifest in other responses (e.g., reproduction rate). Organisms acclimated to a range from 6 to 22 microg/L of Zn2+ produced significantly more offspring than organisms acclimated to lower and higher Zn concentrations in test concentrations up to 50 microg/L of Zn2+. This range corresponds to a previously established optimal concentration range for D. magna. Bioconcentration factors indicated that Zn was actively regulated in the acclimation range tested.

Acclimatization↗

PubMed2006

Combined effects of temperature acclimation and cadmium exposure on mitochondrial function in eastern oysters Crassostrea virginica gmelin (Bivalvia: Ostreidae).

Cadmium and temperature have strong impacts on the metabolic physiology of aquatic organisms. To analyze the combined impact of these two stressors on aerobic capacity, effects of Cd exposure (50 microg/L) on mitochondrial function were studied in oysters (Crassostrea virginica) acclimated to 12 and 20 degrees C in winter and to 20 and 28 degrees C in fall. Cadmium exposure had different effects on mitochondrial bioenergetics of oysters depending on the acclimation temperature. In oysters acclimated to 12 degrees C, Cd exposure resulted in elevated intrinsic rates of mitochondrial oxidation, whereas at 28 degrees C, a rapid and pronounced decrease of mitochondrial oxidative capacity was found in Cd-exposed oysters. At the intermediate acclimation temperature (20 degrees C), effects of Cd exposure on intrinsic rates of mitochondrial oxidation were negligible. Degree of coupling significantly decreased in mitochondria from 28 degrees C-acclimated oysters but not in that from 12 degrees C- or 20 degrees C-acclimated oysters. Acclimation at elevated temperatures also increased sensitivity of oyster mitochondria to extramitochondrial Cd. Variation in mitochondrial membrane potential explained 41% of the observed variation in mitochondrial adenosine triphosphate synthesis and proton leak between different acclimation groups of oysters. Temperature-dependent sensitivity of metabolic physiology to Cd has significant implications for toxicity testing and for extrapolation of laboratory studies to field populations of aquatic poikilotherms, indicating the importance of taking into account the thermal regime of the environment.

Acclimatization↗