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PubMed1985

Temperature acclimation and oxygen binding properties of blood of the European eel, Anguilla anguilla.

Temperature acclimation of the European eel, Anguilla anguilla, resulted in red cell GTP/Hb molar ratios of 1.20, 1.77 and 0.80 at 2, 17 and 29 degrees C, respectively. A small increase in blood oxygen capacity was present in 29 degrees C acclimated eels. The CO2 Bohr effect and the shape of the oxygen binding curve (n-Hill) were invariant with both temperature and GTP/Hb. The significant differences in the GTP/Hb ratio corresponded with a strong enhancement of the temperature effect on blood oxygen affinity between 2 and 17 degrees C and a similarly strong compensation between 17 and 29 degrees C. Predicted in vivo P50 values were 3.0, 13.8 and 17.6 mmHg at 2 degrees C, 17 and 29 degrees C, respectively. The adaptational value of these findings are discussed in relation to standard metabolic rates at the various temperatures. A tentative hypothesis is proposed that the present study confirms and expands earlier work and supports the contention that adjustments in blood oxygen affinity of thermally acclimated teleosts serve to provide them with an unloading O2 tension for diffusion closely matching the standard oxygen requirements at the various temperatures.

Acclimatization↗

PubMed1987

Cold acclimation in food-restricted rats.

Food intake, body weight and brown adipose tissue (BAT) mass and composition of rats exposed at 6 degrees C either with food ad libitum or food-restricted were compared with those of rats in the thermoneutral zone, with food ad libitum. Cold acclimation with food ad libitum increases food intake and prevents body weight gains. IBAT (interscapular BAT) increases its mass and changes its composition after 3 weeks of cold exposure. Cold acclimation with food restriction produces a progressive decrease in body weight. IBAT mass increases after 3 weeks but changes in composition occur sooner. It is concluded that the overfeeding that accompanies cold acclimation is not necessary for non-shivering thermogenesis in BAT.

Acclimatization↗

PubMed1987

The effects of cold acclimation on electrocardiogram parameters in five species of turtles.

The effects of thermal acclimation at 25 or 5 degrees C on electrical activity in the heart were investigated in Pseudemys scripta, Terrapene carolina, Chrysemys picta marginata, Chrysemys picta dorsalis, Chelydra serpentina, and Sternotherus odoratus. The durations of the QRS complex and P-R, R-T and R-R intervals were found to increase with decreasing body temperature in all animals tested. The amplitudes of the P and T waves and QRS complex were dependent upon both acclimation temperature and test temperature. Differences between acclimation groups in the change in QRS amplitudes between 20 and 0 degrees C were statistically significant for all species.

Acclimatization↗

PubMed1992

Effects of salt acclimation on water and urea permeabilities across the frog bladder: relationship with intramembrane particle aggregates.

1. In salt-acclimated frogs, water and urea bladder permeabilities are markedly higher than in tap water-acclimated animals. 2. Intra-membrane particle aggregates (IMPA) cover an unusually large surface area of the salt-acclimated frog bladder apical plasma membrane. 3. In saline-adapted animals, proteins extracted from the apical plasma membrane contain additional species of 19, 26, 31 and 53-61 kDa. These proteins might be related to the water channels contained by IMPA.

Adaptation, Physiological↗

PubMed1992

Thermal sensitivity and effect of temperature acclimation on ocular serotonin N-acetyltransferase activity in Rana perezi.

The thermal sensitivity and the response to thermal acclimation of the serotonin N-acetyltransferase (NAT) activity in frog ocular tissue were studied. The ocular NAT shows a positive thermal modulation for both cosubstrates (tryptamine and acetyl-CoA). The higher NAT activity in the cold-acclimated group (4 degrees C) with respect to the warm-acclimated one (24 degrees C) implies a partial thermal compensation of the enzyme. The present results suggest that frog ocular NAT response to temperature entails a modulation of thermal sensitivity of the enzyme rather than changes in enzyme concentration.

Acclimatization↗

PubMed1978

Amylase activity, glycoprotein and electrolyte concentration in rat's submaxillary salivary gland during heat acclimation.

1. Amylase activity, glycoproteins, Na and K concentrations were measured in submaxillary salivary gland of the rat during heat acclimation (34 degrees C). 2. Acclimation resulted in a decrease in glycoprotein concentration and amylase activity, whereas Na and K concentrations and the Na/K ratio increased. 3. It is suggested that heat acclimation results in an increase in glandular activity leading to increased water secretion and depletion of the glycoprotein store. The decrease in amylase activity is probably due to liver atrophy which occurs during prolonged heat exposure.

Acclimatization↗

PubMed1979

Significance of the variation in isozymes of liver lactate dehydrogenase with thermal acclimation in goldfish--II. Effect of pH.

1. Effect of pH on liver lactate dehydrogenase (LDH) and its isozymes was examined in the goldfish acclimated to different temperatures and some purification of the LDH was attempted. 2. The optimal pH and the Km value at 30 degrees C of the enzyme were independent of acclimation temperature. 3. the optimal pH of isozyme was more basic in the order of LDH-1, LDH-2, LDH-3, LDH-4 and LDH-5. Km values of isozymes at 30 degrees C were higher in the order of LDH-1, LDH-3 and LDH-5. 4. There was no change in the enzyme activity during thermal acclimation.

Acclimatization↗

PubMed1984

Fatty acid synthesis in brown adipose tissue of the Mongolian gerbil (Meriones unguiculatus): influence of acclimation temperature on synthesis in brown adipose tissue and the liver in relation to whole-body synthesis.

Fatty acid synthesis was measured in vivo with 3H2O in Mongolian gerbils acclimated at different temperatures. At 31 degrees C the highest rate of synthesis was in the liver, and the liver accounted for approximately one half of whole-body synthesis. At 20 and 40 degrees C, the highest synthesis rate (per g tissue) occurred in brown adipose tissue, and this tissue was estimated to account for some 15% of whole-body synthesis at both these temperatures. In contrast to other rodent species whole-body fatty acid synthesis in the Mongolian gerbil was lower in cold-acclimated than warm-acclimated animals, despite the cold-induced increase in energy intake.

Acclimatization↗

PubMed1985

Effects of cold acclimation on the activity of lipoprotein lipase in adipose tissues of genetically obese Zucker rats.

The activity of lipoprotein lipase (LPL) was studied in interscapilar brown adipose tissue (BAT), epididymal white adipose tissue (WAT) and in the heart of lean and obese adult Zucker rats maintained at 22 degrees C or adapted to cold (10 degrees C). In WAT the specific activity per gram of tissue was lower in obese than in lean rats but the total activity within the tissue was three-fold higher. Cold acclimation did not modify total activity in either lean or obese rats. In BAT, but not in the heart, both specific and total activities were lower in obese than in lean animals. They were enhanced in both tissues following cold acclimation. Six-hour fasting led to a decrease in specific activity in WAT of lean rats but had no effect in obese animals; an increase was observed in BAT and heart of both genotypes. Insulin administration has no effect on activities in WAT in either 22 or 10 degrees C adapted obese rats. Norepinephrine administration stimulates LPL activity in BAT and heart of all groups. It is concluded that the lack of development of obesity previously observed in obese rats following cold acclimation is not due to a decreased capacity of lipid uptake by WAT. It might in part be due to an increased lipid oxidation in BAT.

Acclimatization↗

PubMed1986

The effects of in vivo acclimation temperature on the fatty acid composition of channel catfish (Ictalurus punctatus) peripheral blood cells.

Channel catfish were acclimated in vivo to 12, 17, 22 or 27 degrees C and their peripheral blood erythrocytes, thrombocytes, T lymphocytes and B lymphocytes assayed for cellular fatty acid composition. Excepting cells from 12 degrees C acclimated fish, all cells responded to acclimation to lower temperatures by exhibiting increased levels of phospholipid unsaturated fatty acids. Although temperature independent differences were observed between erythrocytes, thrombocytes and lymphocytes, no differences between T lymphocytes and B lymphocytes were seen.

Acclimatization↗

PubMed1987

Increased oxidative capacity in skeletal muscles from cold-acclimated ducklings: a comparison with rats.

1. The effects of prolonged cold exposure on cytochrome oxidase activity were investigated in skeletal muscles, liver and adipose tissues from cold-acclimated (CA) and control (TN) ducklings and rats. 2. Cold acclimation increased the oxidative capacity of skeletal muscles (+33% in gastrocnemius and +195% in pectoral) and liver (+47%) from CA ducklings, but decreased the oxidative capacity of gastrocnemius muscle (-22%) from CA rats. On the other hand, in these CA rats it increased the oxidative capacity of liver by 88% and, above all, brown adipose tissue by 544%. 3. The significance of these changes due to acclimation to cold in ducklings and rats is discussed. Such an increase in oxidative capacity of CA duckling muscles may explain the non-shivering thermogenesis observed in these birds.

Acclimatization↗

PubMed1993

Effect of cold acclimation on oxidative capacity and respiratory properties of liver and muscle mitochondria in ducklings, Cairina moschata.

1. The effect of cold acclimation on the oxidative capacity of the skeletal muscle (gastrocnemius and pectoralis) and the liver of ducklings was investigated. 2. In cold-acclimated (CA) ducklings, the oxidative capacity of the liver was higher (+40%) than in ducklings reared at thermoneutraility (TN). In these animals an increase in state 4 respiration and a decrease in the respiratory control index (RCI) was also found. 3. The oxidative capacity of both pectoralis and gastrocnemius muscles also increased in CA animals. 4. In these muscles the oxidatibe capacity of the subsarcolemmal mitochrondrial fraction of CA ducklings was higher (+96% in the gastrocnemius and +58% in the pectoralis) than the intermyofibrillar one (+51% in the gastrocnemius and +33% in the pectoralis). No variations were observed in either the RCI or the ADP/O ratios. 5. These findings indicate that the energy expenditure needed for non-shivering thermogenesis (NST) in cold-acclimated ducklings can be met by the increase in the oxidative capacity of the skeletal muscle and the liver, each by different mechanisms; the gastrocnemius muscle would seem to play a prominent role.

Acclimatization↗

PubMed1990

The effect of thermal acclimation on the activity of arylhydrocarbon hydroxylase in rainbow trout (Oncorhynchus mykiss).

1. The possibility that temperature acclimation (to 10 or 18 degrees C for 28 days) would alter the cytochromes P-450 of rainbow trout was addressed. 2. The specific content of LM4b (P-450 IA1), the trout isozyme responsible for activation of polynuclear aromatic hydrocarbons, was lower in 18 degrees C fish than it was in 10 degrees C fish. 3. Kinetic analysis of aryl hydrocarbon hydroxylase indicated that, while thermal acclimation caused no change in Vmax, it lowered the apparent Km of this enzyme for benzo[a]pyrene when assayed at acutely shifted temperatures. 4. Thermal acclimation of fish may have significance when feral populations are subjected to acute temperature shifts.

Acclimatization↗

PubMed2004

Influence of the origin of the inoculum and the acclimation strategy on the degradation of 4-chlorophenol.

The influence of the inoculum source and the acclimation strategy on the 4-chlorophenol (4CP) degradation in a sequencing batch reactor (SBR) was studied. Three different sources of inocula were obtained from the aeration tank of domestic, municipal and industrial wastewater treatment plants. The acclimation was performed using two strategies, the first one fixing the reaction time, independent of the removal efficiency (fixed time) and the second one fixing a removal efficiency of 90% as 4CP (variable time). The degradative activity was followed for each condition. Bacterial identification was carried out at the beginning and at the end of the experiments. Variable time strategy produced a microbial community with higher specific activity compared with those obtained for the fixed time strategy. The microbial activity was dependent of the origin of the inoculum. Each inoculum presented different specific activity to 4CP degradation. It was observed that the use of the fixed time strategy for the acclimation reduced the bacterial community diversity.

Acclimatization↗

PubMed2006

Turning up the heat: the effects of thermal acclimation on the kinetics of hsp70 gene expression in the eurythermal goby, Gillichthys mirabilis.

Most organisms respond to temperature fluctuations by altering the expression of an evolutionarily conserved family of proteins known as heat shock proteins (Hsps). Studies have shown Hsp expression and the activation of HSF1, one of the primary regulators of Hsp transcription, are highly malleable, varying with the recent thermal history of the organism; however, the mechanisms that confer plasticity to the regulation of this ubiquitous response are not well-understood. This study furthers our knowledge in this area by characterizing the activation kinetics of HSF1 and the corresponding transcription of hsp70 in the liver of the eurythermal goby, Gillichthys mirabilis, following a month-long acclimation at 13, 21 or 28 degrees C. Our data revealed HSF1 DNA-binding kinetics varied as a function of acclimation temperature and magnitude/duration of exposure, with gobies acclimated at 21 degrees C exhibiting the most robust response. Hsp70 mRNA followed a similar pattern with induction first occurring in the 13 and 21 degrees C fish, and then most robustly in the 28 degrees C group at 36 degrees C. The hsp70 mRNA induction pattern was corroborated by levels of HSF1 DNA-binding activity in each group and may have been lowest in the 28 degrees C group due to the 2-fold greater levels of hsp70 protein prior to thermal exposure. This study illustrates the integral role of HSF1 as a key regulator of Hsp induction and helps explain the plasticity of this response in ectothermic organisms.

Acclimatization↗

PubMed2006

Arginine vasotocin, isotocin and melatonin responses following acclimation of gilthead sea bream (Sparus aurata) to different environmental salinities.

Gilthead sea bream (Sparus aurata) is a euryhaline species with a capacity to cope with demands in a wide range of salinities and thus is a perfect model-fish to study osmoregulatory responses to salinity-adaptive processes and their hormonal control. Immature sea bream acclimated to different salinities, i.e. SW (38 per thousand), LSW (5 per thousand) and HSW (55 per thousand), were kept at 18 degrees C under natural photoperiod. Arginine vasotocin (AVT) and isotocin (IT) in plasma and pituitary were determined by HPLC. Plasma melatonin (Mel) was assayed by RIA. Plasma osmolality, ion concentrations (Na(+), K(+), Ca(2+), Cl(-)) and Na(+),K(+)-ATPase activity in gill were measured. A steady increase in plasma AVT, along with increasing water salinity was observed. Pituitary IT concentration in HSW-acclimated fish was significantly higher than that in LSW group. AVT/IT secretory system of sea bream does appear to be involved in the mechanism of long-term acclimation to different salinities. The distinct roles and control mechanisms of both nonapeptides are suggested. Plasma Mel was significantly higher in LSW compared with both HSW and SW groups. Data indicate that the changes in Mel level are linked to osmoregulation. Further studies are required to elucidate a complex role of AVT, IT and Mel in sea bream osmoregulation.

Acclimatization↗

PubMed2004

Changes in some nitrogenous compounds in the blood and tissues of freshwater pikeperch (Sander lucioperca) during salinity acclimation.

The effect of ambient salinity changes (0.9, 6 and 12 psu) on the levels of dissolved ammonia (DA), ninhydrin positive substances (NPS), trimethylamine (TMA) and trimethylamine oxide (TMAO) in the blood and tissue of medium-acclimated Sander lucioperca L. (also Stizostedion lucioperca) were investigated. In freshwater, blood and tissue total free amino acid levels (measured as NPS) were 3.62 mM and 60.61 mM, respectively. The NPS content increased significantly (P<0.05) in the tissue and blood on acclimation to 6 and 12 psu salinities. The mass-specific tissue TMAO concentration of pikeperch acclimated to normal freshwater was 0.413+/-0.084 micromol TMAO g(-1). Results reveal that TMAO levels are positively influenced by the external salinity medium where significant differences in mean levels occurred between the groups (P<0.05). The calculated p[NH(3)] and [NH(4)(+)] gradients reveal that the [NH(3)] gradient was consistently low (cf. the [NH(4)(+)] gradient). The gradient of p[NH(3)] decreased with the medium increased salinities. The results suggest that freshwater pikeperch may be able to resist salinity changes by manipulation of nitrogen metabolism. Free amino acids and TMAO are involved in mediating response to salinity exposure in freshwater pikeperch.

Adaptation, Physiological↗

PubMed2004

Temperature acclimation modulates the oxygen binding properties of the Atlantic cod (Gadus morhua L.) genotypes-HbI1/1, HbI1/2, and HbI*2/2-by changing the concentrations of their major hemoglobin components (results from growth studies at different temperatures).

The influence of long-term acclimation temperatures in Atlantic cod (Gadus morhua) was studied by growth experiments carried out over a total of 272 individuals. The attention focused on the structural and functional modulation of the five electrophoretically distinguishable genotypes of cod hemoglobin (HbI*1/1, HbI*1/2, HbI*2/2, HbI*1/2b, and HbI*2/2b) and on the correlation with body length/weight. The main results can be summarized as follows. (1) Acclimation to lower (4 and 8 degrees C) and higher (12 and 15 degrees C) temperatures favors the expression of, respectively, more anodic and more cathodic hemoglobin components. (2) The optimal O(2) transporting features are observed at 12 degrees C, as well as a saturation-dependent temperature dependence of O(2) binding, which furthermore is strongly dependent upon the acclimation background. (3) The optimal growth condition for the three main genotypes (HbI*1/1, HbI*1/2, and HbI*2/2) is associated with T=12 degrees C. The overall results are consistent with the idea that environmental temperatures constitute a primary factor in the aggregation of individuals physiologically more than genetically homogeneous. This is fully confirmed by careful statistical analysis carried out over a subset of individuals for which the full set of structural (isoelectric focusing), functional (O(2) binding), and growth data was available.

Acclimatization↗