Temperature induced variation in the distribution of different types of muscle fibre in the goldfish (Carassius auratus)

Summary Goldfish (Carassius auratus L.) were acclimated to environmental temperatures of 3 °C, 18 °C and 31 °C for a period of three months. Cytochemical techniques were used to study the metabolism and myofibrillar ATPase activities of individual muscle fibres. Fish muscle is composed of three basic fibre types each with distinct contractile and metabolic characteristics. Cold acclimation resulted in a shift to a more aerobic type of metabolism, particularly in the red and pink fibres. In addition, environmental temperature was found to affect the size and relative distribution of the different fibre types in the myotome. The total number of pink and red fibres increased significantly with cold acclimation. Mechanisms of environmentally-induced adaptation of muscle fibre phenotype are discussed.In addition to changes in the metabolism and distribution of muscle-fibre types, biochemical studies have provided evidence for different kinetic forms of Mg²⁺Ca²⁺ myofibrillar ATPase at different environmental temperatures. Activities of myofibrillar ATPase assayed at 31 °C were 2–3 times higher in fish acclimated to the higher environmental temperature. Activation enthalpy (H ) of the ATPase was also signficantly reduced in the cold adapted enzyme. Reduction of H in the cold acclimated ATPase is thought to reduce the temperature sensitivity of the activation process thus partly compensating for the reduced cell temperature.     

Capillarisation,oxygen diffusion distances and mitochondrial content of carp muscles following acclimation to summer and winter temperatures

Summary Many species of fish show a partial or complete thermal compensation of metabolic rate on acclimation from summer to winter temperatures. In the present study Crucian carp (Carassius carassius L.) were acclimated for two months to either 2° C or 28° C and the effects of temperature acclimation on mitochondrial content and capillary supply to myotomal muscles determined.Mitochondria occupy 31.4% and 14.7% of slow fibre volume in 2°C- and 28° C-acclimated fish, respectively. Fast muscles of coldbut not warm-acclimated fish show a marked heterogeneity in mitochondrial volume. For example, only 5 % of fast fibres in 28° C-acclimated fish contain 5 % mitochondria compared to 34 % in 2° C-acclimated fish. The mean mitochondrial volume in fast fibres is 6.1 % and 1.6 % for coldand warm-acclimated fish, respectively.Increases in the mitochondrial compartment with cold acclimation were accompanied by an increase in the capillary supply to both fast (1.4 to 2.9 capillaries/fibre) and slow (2.2 to 4.8 capillaries/fibre) muscles. The percentage of slow fibre surface vascularised is 13.6 in 28° C-acclimated fish and 32.1 in 2° C-acclimated fish. Corresponding values for fast muscle are 2.3 and 6.6 % for warm and cold-acclimated fish, respectively. Maximum hypothetical diffusion distances are reduced by approximately 23–30 % in the muscles of 2° C-compared to 28° C-acclimated fish. However, the capillary surface supplying 1 ³ of mitochondria is similar at both temperatures.Factors regulating thermal compensation of aerobic metabolism and the plasticity of fish muscle to environmental change are briefly discussed.     

Temperature acclimation in brook trout muscle: Adenine nucleotide concentrations, phosphorylation state and adenylate energy charge

Summary Cold acclimation in fish is associated with an elevation in metabolic rate. The present study investigates the role of adenine nucleotides and related compounds in metabolic regulation following temperature acclimation. Brook trout (Salvelinus fontinalis) were acclimated for 10 weeks to either +4°C or +24°C. Both groups of fish were exercised at 2.5 body lengths s^–1 for 2 weeks prior to sacrifice in order to control for differences in spontaneous activity.Concentrations of ATP, ADP, AMP, P _i and PC were approximately 2-fold higher in white than red muscles. Temperature acclimation had little effect on total adenine nucleotide concentration in either muscle type. In white fibres acclimation to 4°C results in a 39% increase in [ADP] and [AMP], a 35% decrease in [PC] (phosphorylcreatine), and no significant change in [P _i ]. In contrast temperature has little effect on concentrations of these compounds in red muscle.Parameters of metabolic control — adenylate energy charge ([ATP]+0.5 [ADP]/[ATP]+[ADP]+[AMP]), phosphorylation state ([ATP]/[ADP]·[P _i ]), and the ratios [ATP][ADP] and [ATP][AMP] — were significantly lower in cold- than warm-acclimated white muscle. The observed changes in phosphorylation state and [ATP][AMP] are consistent with an increase in mitochondrial respiration and glycolysis, respectively.In conclusion, changes in metabolites may be an important factor in producing an enhanced metabolic rate in cold-acclimated fish.     

Temperature acclimation and the expression of contractile protein isoforms in the skeletal muscles of the common carp (Cyprinus carpio L.)

Summary Common carp (Cyprinus carpio L.) were acclimated to either 2, 5, 8, 11, 15, 20, or 23°C for 12 weeks (12 h light: 12 h dark). Fish did not feed after 6 weeks at temperatures below 8°C. Skinned fibres were prepared from fast myotomal muscle by freeze-drying. Measured at 0°C unloaded contraction velocity (Vmax) and maximum isometric tension generation (Po) were 2–3 times higher in the 11°C-than 23°C-acclimated groups, and had intermediate values in 15 °C-acclimated fish. Po and Vmax at 0°C were not significantly different for carp maintained at 2, 5, 8, or 11°C. Measured at the acclimation temperature of each group Vmax and Po were 51% and 71% lower for fibres from 2°C- than 23°C-acclimated fish. The results indicate a partial capacity adaptation of muscle power output in fish acclimated between 11°C and 23°C. At 8°C the ATPase activity of myofibrils was 2 times higher in fish acclimated to 8°C than to 20°C. The effects of temperature acclimation on the protein composition of myofibrils was investigated using one- and two-dimensional electrophoresis. Peptide maps of purified myosin heavy chains and actin prepared by proteolytic digestion with either Staphylococcus aureus V8 protease or chymotrypsin were similar for both acclimation groups. The molecular weights and isoelectric points of the major isoforms of tropomyosin, troponin C, troponin I, troponin T, and myosin light chains (MLC1, MLC2 and MLC3) were also similar in 8°C- and 20°C-acclimated carp. A 20 kDa molecular weight protein with a pI intermediate between that for MLC2 and MLC3 was found in myofibrils and single fibres from carp acclimated to 8°C but was not present in carp acclimated to 20°C. It is suggested that this band corresponds to a myosin light chain isoform unique to cold-acclimated fish. Evidence was also obtained that myofibrils from warm-acclimated fish contained a second minor isoform of troponin I.     

Effect of extracellular calcium on the contractility of warm-and cold-acclimated crucian carp heart

Crucian carp (Carassius carassius L.) were acclimated for at least 4 weeks to 2°C or 22°C, and the consequences of thermal acclimation on force development, time-course of contraction and action potential duration of the ventricular myocardium were studied. In cold-acclimated fish contraction was activated at much lower external [Ca] than in warm-acclimated fish: [Ca] for half-maximal force was 0.9±0.15 and 3.1±0.92 mmol·l^-1 (P<0.05) for cold- and warm-acclimated fish, respectively. Durations of contraction and relaxation were significantly longer in fish acclimated to 2°C than in fish acclimated to 22°C, especially at [Ca] below 2 mmol·l^-1. In low-Ca solution ventricular action potential was prolonged both in cold- and warm-acclimated fish. In 0.5 mmol·l^-1 Ca action potential duration at zero voltage level was longer in cold- than warm-acclimated fish. Although lengthening of action potential was evident in both acclimation groups, a marked prolongation of contraction duration by low-Ca solutions occurred only in cold-acclimated fish. This suggests that a plateau component of contraction is present in cold-acclimated fish but less well developed in warm-acclimated fish hearts. Contractions were strongly inhibited by sarcolemmal Ca-channel blocker, cadmium (100 and 300 mol·l^-1), in both warm- and cold-acclimated crucian carp hearts. However, the sarcoplasmic reticulum Ca release channel blocker, ryanodine (10 mol·l^-1), had no effect on the force of contraction in either acclimation group. These results suggest that the contraction of crucian carp heart is controlled by sarcolemmal mechanisms without contribution by sarcoplasmic reticulum Ca release. Since the Ca sensitivity of myofilaments was not altered by thermal acclimation, the results indicate that thermal acclimation alters Ca activation of contraction of the crucian carp heart at the level of sarcolemma.Abbreviations AP action potential - EGTA ethyleneglycol-bis-(-aminoethylether)-N,N,N,N-tetra-acetic acid - F _max maximum force - F _max maximum rate of contraction - F _min maximum rate of relaxation - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid - pCa log [Ca] - Pl action potential plateau - SL sarcolemma - SR sarcoplasmic reticulum - TPF time to peak force - T1/2R time to half relaxation from the peak force     

Protective systems against active oxygen species in spinach: response to cold acclimation in excess light

Spinach (Spinacia oleracea L.) plants were acclimated to 1° C or maintained at 18° C under the same light regime (260–300 mol photons·m^–2·s^–1). The cold acclimation led to several metabolic and biochemical changes that apparently include improved protection of the photosynthetic apparatus against active oxygen species. In particular, cold-acclimated leaves exhibited a considerably higher ascorbate content and significantly increased activities of superoxide dismutase, ascorbate peroxidase, and monodehydroascorbate reductase in the chloroplasts. The level of dehydroascorbate reductase did not alter. Catalase activity decreased. The photosynthetic pigment composition of cold-acclimated spinach was characterized by increased levels of the xanthophylls lutein + zeaxanthin and violaxanthin. The observed changes are discussed in terms of their possible relevance for plant resistance to photoinhibition at chilling temperatures.Abbreviations DHA dehydroascorbate - GSH reduced glutathione - MDA monodehydroascorbate - SOD superoxide dismutase The authors thank the Deutsche Forschungsgemeinschaft for financial support of this study.     

Heat Resistance and Thermal Acclimation Rate in Tropical Tetra <Emphasis Type="Italic">Astyanax bimaculatus</Emphasis> of Venezuela

Venezuelan river tetra, Astyanax bimaculatus juveniles of 34.1–36.7mm standard length and 0.83–1.0g wet weight were acclimated for four weeks to 24–33°C, which are approximate average minimum and maximum river temperatures throughout the year. The fish acclimated to 24, 27, 30, and 33°C were exposed for 10000 minutes at 35, 36, 37, 38, and 39°C to determine individual heat resistance times. To determine acclimation rates, the juveniles acclimated to 24 and 30°C were tested for individual heat resistance times at 39°C by changing acclimation temperatures. The individual heat resistance times were increased in accordance with an increase in acclimation temperature and a decrease in test temperature, indicating that acclimation level has a great influence on thermal resistance of the fish tested. As the fish were transferred from 24 to 30°C (upward acclimation), they completed their acclimation level in a few days, while those transferred from 30 to 24°C (downward acclimation) required about 14 days. It has reaffirmed the following general behavior: the rate of gain in thermal resistance is fast and the loss in heat tolerance is very slow. This physiological phenomenon is very important for tropical fish, which acclimates rapidly in rising temperature during the hot day and does not lose this level in decreasing temperature during the cool night. Consequently, a tropical fish can maintain its maximum resistance level, adapt well in thermally fluctuating tropical waters, and survive in lethally high temperatures caused by a sudden increase in temperature during hot day.     

Incorporation of 1-14C-acetate into fatty acids and sterols by isolated hepatocytes of thermally acclimated rainbow trout (Salmo gairdneri)

Summary Rates of 1-¹⁴C-acetate incorporation into specific fatty acids and sterol fractions were determined at assay temperatures of 5°C and 20°C in hepatocytes isolated from warm (20°C)- and cold (5°C)- acclimated rainbow trout (Salmo gairdneri). Rates of sterol lipogenesis were 2.5- to 3-fold higher in hepatocytes from cold-acclimated trout. Rates of acetate oxidation and of total fatty acid lipogenesis did not differ significantly between acclimation groups. Fatty acid compositions did not change significantly during the experiment (9–12 h), but hepatocytes from cold-acclimated trout possessed significantly higher levels of polyunsaturates and unsaturates of the linolenic acid (n-3) family, and significantly lower levels of monounsaturates than did hepatocytes from warm-acclimated animals. Hepatocytes from cold-acclimated trout channeled a larger percentage of their total acetate incorporation into unsaturated fatty acids at 5°C than at 20°C due primarily to increased recovery of acetate in polyunsaturates and monoenes at 5°C. In contrast, hepatocytes from warm-acclimated trout channeled a slightly smaller percentage of their total acetate incorporation into unsaturates at 5°C than at 20°C. Hepatocytes from warm-acclimated trout incorporated significantly more 1-¹⁴C-acetate into the unsaturated fatty acid fraction (due primarily to incorporation into the diene fraction and less importantly all other classes of unsaturates) and significantly less into the saturated fatty acid fraction than hepatocytes from cold-acclimated trout when assayed at 20°C; similar but less dramatic differences were observed at 5°C. Consequently, unsaturated/saturated ratios for acetate incorporation ranked: warm-acclimated at 20°Cwarm-acclimated at 5°Ccold-acclimated at 5°C>cold-acclimated at 20°C. These results suggest that regulation of the relative rates of unsaturated and saturated fatty acid synthesis is involved in lipid restructuringduring adaptation from one temperature regime to another, but that other mechanisms must be invoked to explain the maintenance of observed steady state differences between the fatty acid compositions of warm- and cold-acclimated trout.This work was supported by grant PCM-76-04313-AO1 from the National Science Foundation     

Neurochemical Changes in Cerebellum of Goldfish Exposed to Various Temperatures

Acclimation of goldfish at 35°C increased the cerebellar content of aspartate, glutamate, and taurine and [³H]glutamate uptake. Acclimation at 4°C increased the levels of glutamine, serine, and alanine and glutamine synthetase (GS) activity. Adenosine content increased in cerebellum of fish acclimated to warm temperature. K⁺-evoked release of endogenous and exogenous glutamate from cerebellar slices increased in fish acclimated at 35°C compared to 4°C. The basal level of cyclic adenosine 3:5-monophosphate (cAMP) in perfused cerebellar slices in fish acclimated at 35°C was much higher than in fish acclimated at 5° and 22°C. It is concluded that variations of environmental temperature produces large neurochemical changes in goldfish cerebellum.     

Acyl and alkenyl group composition of brain subcellular fractions of goldfish (Carassius auratus L.) acclimated to different environmental temperatures

Goldfish were acclimated to 5, 15, and 30°C, and the acyl group composition of choline phosphoglycerides (CPG) and ethanolamine phosphoglycerides (EPG) from whole brain and brain subcellular particles was examined. With the exception of synaptosomal CPG, the acyl group composition of CPG from whole brain and subcellular particles, including myelin, from cold-acclimated fish showed little response to the change in environmental temperature. Those changes that did occur were consistent with the expected trend toward a higher degree of unsaturation of the CPG acyl groups in fish acclimated to 5°C. The acyl group composition of CPG from synaptosomes of the cold-acclimated fish did, however, differ markedly in having a reduced unsaturation index (U.I.) and unsaturated: saturated fatty acid ratio (UFA:SFA) which was caused mainly by the decrease in 226n-3 content. In contrast, changes in the acyl group composition of EPG on cold acclimation were greater than those observed in any CPG fraction. The generally expected trend toward greater unsaturation was observed only in mitochondrial and myelin EPG. Moreover, in all fractions the amount of 226n-3 in EPG was lower at decreased environmental temperatures. In the synaptosomal and microsomal EPG, the reduction in 226n-3 was such that a markedly reduced U.I. was obtained. It is suggested that two compensatory mechanisms maintain the necessary degree of membrane permeability and fluidity in order to prevent transition to a crystalline state at lower temperatures.     

Thermal acclimation of aerobic metabolism and O2-Hb binding in the snake,Vipera berus

Summary Snakes,Vipera berus, were acclimated to 5 and 25 °C for 3 months preceding measurements of O₂ uptake and blood respiratory properties. O₂ uptake measured at the lower acclimation temperature (5 °C) shows lower values for the cold-acclimated snakes. Measured at 25 °C cold-acclimation results in O₂ uptakes slightly higher than in warm-acclimated snakes. The temperature sensitivity (Q₁₀) of aerobic metabolism in thus higher for the cold-acclimated snakes being 3.17 compared to 2.11 for the warmacclimated.O₂-Hb dissociation curves of whole blood from the two acclimation groups show a marked increase in O₂ affinity associated with cold-acclimation independent of blood pH. The shift in O₂ affinity correlates with a marked decrease in red cell organic phosphate concentration (ATP) in cold-acclimated snakes. The temperature sensitivity of the O₂-Hb binding expressed by the H values was rather uniform at about –11 kcal·mol^–1 (O₂) for both acclimation groups. The CO₂ Bohr factor in cold-acclimated blood at –0.55 was about double that in warm-acclimated. Then value for both acclimation groups increased with higher temperatures. Hematocrit and blood O₂ capacity were higher in the cold-acclimated snakes.The acclimation effects on O₂ uptake, O₂-Hb affinity and the Bohr effect, are opposite to those obtained earlier on reptiles at lower latitudes. It is discussed how a downward translation of the O₂ uptake-temperature curve and a high thermal sensitivity (Q₁₀) may be adaptive for species at latitudinal extremes where the active season is short and diurnal temperatures fluctuate widely. It is further discussed how a change in O₂ affinity by its influence on the capillary to cellular O₂ gradients may affect the aerobic metabolism.     

Evolutionary temperature adaptation of fish sarcoplasmic reticulum

Summary Sarcoplasmic reticulum has been isolated from the white muscle of 15 species of teleost fish adapted to diverse thermal environments. Evidence has been obtained that the Ca²⁺-dependent ATPase of fish sarcoplasmic reticulum has undergone evolutionary modification for function at different temperatures. Compared with tropical fish, cold adapted species have higher rates of Ca²⁺ transport and Ca²⁺-ATPase activities at low temperatures. Most species have linear Arrhenius plots over the temperature range 0–30°C. Activation enthalpies (H ) of the ATPase ranged from 53–190 kJ mol^–1 and were positively correlated with environment temperature. Activation entropy (S ) varied from negative values in cold adapted species to positive values in tropical fish.In contrast to the Ca²⁺-ATPase, the basal ATPase of fish sarcoplasmic reticulum showed no relationship between either ATPase activity or thermodynamic activation parameters and environmental temperature.Only the Ca²⁺-dependent ATPase is coupled to Ca²⁺ transport. The percentage of total ATPase activity which is Ca²⁺ activated is higher at low temperatures in cold than in warm adapted species. For example, ratios of Ca²⁺-dependent/total ATPase at 2°C varied from 80–98% in Arctic, Antarctic and North Sea species to only 2–50% in various tropical fish. Above 20°C, similar ratios in the range 80–98% were obtained for all species. The nature of the basal ATPase and mechanisms of temperature adaptation of fish sarcoplasmic reticulum are discussed.Abbreviations ET environmental temperature - EGTA ethylene glycol-bis (-aminolethyl ether)-N, N-tetraacetic acid - HEPES N-2-hydroxylpiperazine-N-2-ethanesulfonic acid - SR sarcoplasmic reticulum     

Resistance adaptation of the freshwater crayfish and thermal inactivation of membrane-bound enzymes

Summary Heat death and resistance adaptation of freshwater crayfish are thought to be properties of its muscle membranes. The inactivation at high temperatures of a membrane-bound enzyme, the Ca⁺⁺-stimulated ATPase of crayfish abdominal muscle sarcoplasmic reticulum, and the effect of thermal acclimation of crayfish upon the inactivation kinetics have been investigated. In the absence of KCl, the Ca⁺⁺-stimulated ATPase is irreversibly inactivated with pseudo-first order kinetics at temperatures that cause heat death in the whole animal. 0.1–10.0 mM KCl resulted in slower inactivation, while 100 mM KCl activated the enzyme to 120–180% of its original activity. Enzyme activation by KCl and heat involved a shift in the enzyme concentration/activity curve. Thermal acclimation of crayfish had no significant effect upon the kinetics or Arrhenius activation energy for enzyme inactivation (100.6±10.5 and 92.3±14.6 kcal/mole for preparations from 4°C and 25°C acclimated crayfish).Ca⁺⁺-stimulated ATPase isolated from heat dead crayfish exhibited normal in vitro activity due presumably to the high intracellular K⁺ concentration. Nevertheless, the close correspondence between heat death temperatures and inactivation temperatures for several membrane-bound enzymes of muscle is thought to reflect some perturbation of muscle structure that occurs during heat death.Abbreviations ATP Ademosine 5-Triphosphate - EGTA Ethyleneglycol-bis [-amino-ethyl ether] - N N-tetraacetic acid - Hepes N-2-Hydroxyethylpiperazine-N-2-ethanesulphonic acid - FSR Fragmented sarcoplasmic reticulum - Tris Tris (hydroxymethyl)aminomethane     

Interactive effects of season and temperature on enzyme activities,tissue and whole animal respiration in roach,Rutilus rutilus

Synopsis This paper reviews investigations on the ecophysiology of a population of roach, Rutilus rutilus, from a subalpine oligotrophic lake in the Austrian Tirol. Metabolic responses to season and temperature were studied in whole animals, tissues and selected enzymes. The exponent of the relationship between body mass and three levels of the metabolic rate of acclimated fish was 0.82 ± 0.02, 0.60 ± 0.15, and 0.75 ± 0.01 at 4, 12, and 20° C respectively. Various combinations of long-term acclimation to constant or seasonally fluctuating temperatures and long-term (up to 14 days) monitoring of O₂ at the acclimation temperature led to the conclusion that the aerobic power of fish swimming in the routine mode does not show any sign of being temperature compensated. On the other hand, there are several indications that the energy expenditure of spontaneously swimming fish is adjusted to the seasonal pattern of environmental change and that these responses of metabolism and behaviour are controlled by both endogenous and exogenous factors. The rate of oxygen consumption of gill and muscle tissue brei from fish caught during a seasonal cycle and measured at 15° C appears to follow closely the reproductive and gonadal cycle of the living fish. The same holds for the activities of phosphofructokinase, acetoacetyl-CoA thiolase, and cytochrome oxidase. On the other hand, the Na⁺, K⁺-ATPase of the kidney shows near perfect temperature compensation when fish acclimated to 5 and 25° C are compared, whereas an equally pronounced case of inverse temperature acclimation has been reported for the activity of digestive enzymes in the gut. Summarizing these data it is pointed out that the temperature relationship of a poikilothermic organism is the sum of often very diverse temperature relationships of specific metabolic and behavioural functions. In the case of the roach, strong effects of acclimation temperature on the molecular level, sometimes in the opposite direction, combine with seasonal effects on enzyme activities and tissue respiration. However, on the whole animal level the fish behave as strictly non-compensating poikilotherms, the reproductive cycle being the only detectable influence capable of modulating the basic temperature relationship of energy expenditure.     

Turnover of the fatty acyl and glycerol moieties of microsomal membrane lipids from liver, gill and muscle tissue of thermally acclimated rainbow trout,Salmo gairdneri

Summary Rainbow trout (Salmo gairdneri) acclimated to 5°C or 20°C were administered 2-³H-glycerol and 1-¹⁴C-acetate (63 Ci of each isotope/100 g body weight) via intraperitoneal injection, and subsequently maintained at their respective acclimation temperatures. Total lipid extracts (>80% phospholipid) were prepared from isolated microsomes of liver, gill and muscle tissue at various times over a three week period. Half-lives were determined independently for the fatty acyl and glycerol moieties from slopes of regression lines relating dpm/nmole phospholipidP _i vs time. In liver tissue, rates of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) turnover were also determined. Membrane turnover was most rapid in liver followed by gill and muscle. In liver, membrane fatty acids turned over more rapidly in warm-(t _1/2=3.4 days) than in cold-(t _1/2=6.8 days) acclimated fish, whereas in gill, rates of fatty acid turnover, did not differ significantly between acclimation groups. In contrast, rates of glycerol turnover were independent of acclimation temperature in liver, but faster (t _1/2=6.7 days) in warm- than cold- (t _1/2=15.1 days) acclimated fish in gill. In total lipid extracts, rates of fatty acid and glycerol turnover were equivalent in warm-acclimated fish, however, in cold-acclimated trout, there was a tendency for fatty acids (t _1/2=9.1 days) to turnover more rapidly than glycerol (t _1/2=15.1 days) in gill tissue, but more slowly (t _1/2=6.82 days) than glycerol (t _1/2=4.1 days) in liver. Although rates of glycerol turnover were equivalent in PC and PE of liver microsomes, the fatty acyl component turned over significantly more rapidly in PC at both acclimation temperatures. In cold-acclimated trout, rates of fatty acid and glycerol turnover were equivalent in PE, but the fatty acyl moiety of PC (t _1/2=4.7 days) turned over significantly more rapidly than glycerol (t _1/2=7.5 days). These results were interpreted as indicating that: (1) acclimation temperature independently influenced rates of fatty acid and glycerol turnover in a tissue specific manner, (2) a deacylation-reacylation pathway was activated in both liver and gill as a consequence of cold acclimation, but that liver tissue was more effective than gill in reutilizing the fatty acids released by phospholipase activity, and (3), in liver microsomes, patterns of turnover were phospholipid specific, with PC and PE differing either in the susceptibility of their acyl groups to degradation, or in their ability to reutilize fatty acids cleaved during membrane turnover at cold temperatures.     

Effect of acclimation temperature on the elongation step of protein synthesis in different organs of rainbow trout

Summary Cytosolic extracts of liver, kidney, spleen, gill, red and white muscle from rainbow trout acclimated to 4 and 17°C, respectively, have been investigated in vitro with respect to their enzymic activity in stimulating the growth of nascent peptide chains (labelled polyphenylalanine) at assay temperatures from 5 to 25°C using polyuracil as messenger RNA. The elongation step of protein synthesis is characterized by aQ ₁₀ value of about 2.4 (range 10–25°C) in all organs from both, 4 and 17°C acclimated fish.Except for the red muscle, the organs of cold acclimated trout, however, exhibit significantly higher specific elongation rates (mol phenylalanine polymerized/(g wet weight·h)) at any experimental temperature than those of warm acclimated fish. This increase of the elongation rates varies between the organs and ranges from +29% (liver) to +60% in the gill. The specific acylation rate (mol phenylalanyl-tRNA formed/(g wet weight·h)) surpasses the specific elongation rate by a factor of at least 8.5. Moreover, the specific acylation rate per mg protein is independent of acclimation temperature.It is concluded that the increased specific elongation rates in 4°C acclimated trout are not due to altered pool sizes of the precursor phenylalanyl-tRNA, but reflect an effective enhancement of enzymic elongation factor activities.In accordance with data taken from literature, this finding suggests a compensatory enhancement of in vivo protein synthesis to occur in trout during cold acclimation.Abbreviations E _a apparent activation energy - EF elongation factor - HEPES N-2-hydroxyethylpiperazine-N-2-ethane sulfonic acid - PHE phenylalanine - PHE-tRNA phenylalanyl transfer ribonucleic acid - POLY (U) poly-uracil - Q ₁₀ van't Hoff's temperature coefficient - T _accl acclimation temperature - T _exp experimental temperature - TRITON X-100 octylphenol-polyethylene-glycolether     

Electrolyte changes,cell volume regulation and hormonal influences during acclimation of rainbow trout (Salmo gairdnerii) to salt water

• 1.1. Rainbow trout were acclimated to salt water (1.5, 2.0 or 3.0%, which means 40, 60 or 85% concentrated sea-water) and the electrolyte, glucose and cortisol concentrations of the plasma as well as the extra- and intracellular muscle space, the muscle electrolyte concentrations and the ATPase activity were analysed.
• 2.2. Plasma osmolality, Na⁺, Ca²⁺ and Mg²⁺ concentrations of the plasma had a maximum at 24 hr after the start of acclimation when acclimated to 3.0% salt water. Plasma osmolality, Na⁺ and Mg²⁺ concentrations were significantly higher during the whole acclimation time when exposed to 3.0% salt water.
• 3.3. Variations and regulations of ECS and ICS were clearly demonstrated. The intracellular electrolyte concentrations were also maximal at 24 hr.
• 4.4. The plasma glucose level was just slightly elevated, but the cortisol level clearly indicated a stress response at 24 hr.
• 5.5. The activity of gill Na-K-ATPase increased during the acclimation time.
• 6.6. The regulatory processes in trout during acclimation to salt water are compared with those occurring in tilapia and carp.

     

Changes in carp myosin ATPase induced by temperature acclimation

Summary Myosins were isolated from dorsal ordinary muscles of carp acclimated to 10°C and 30°C for a minimum of 5 weeks and examined for their ATPase activities. Ca²⁺-ATPase activity was different between myosins from cold-and warm-acclimated carp, especially at KCl concentrations ranging from 0.1 to 0.2 M, when measured at pH 7.0. The highest activity was 0.32 mol P_i·min^-1·mg^-1 at 0.2 M KCl for cold-acclimated carp and 0.47 mol P_i·min^-1·mg^-1 at 0.1 M KCl for warm-acclimated fish. The pH-dependency of Ca²⁺-ATPase activity at 0.5 M KCl for both carp was, however, similar exhibiting two maxima around 0.3 mol P_i·min^-1·mg^-1 at pH 6 and 0.4 mol P_i·min^-1·mg^-1 at pH 9. K⁺(EDTA)-ATPase activity at pH 7.0 neither exhibited differences between both myosins. It increased with increasing KCl concentration showing the highest value of about 0.4 mol P_i·min^-1·mg^-1 at 0.6–0.7 M KCl. Actin-activated myosin Mg²⁺-ATPase activity was markedly different between cold-and warm-acclimated carp. The maximum initial velocity was 0.53 mol P_i·min^-1·mg^-1 myosin at pH 7.0 and 0.05 M KCl for cold-acclimated carp, which was 1.6 times as high as that for warm-acclimated carp. These differences were in good agreement with those obtained with myofibrillar Mg²⁺-ATPase activity between both carp. No differences were, however, observed in myosin affinity to actin. Differences in myosin properties between cold- and warm-acclimated carp were further evidenced by its thermal stability. The inactivation rate constant of myosin Ca²⁺-ATPase was 25·10^-4·s^-1 at 30°C and pH 7.0 for cold-acclimated carp, which was about 4 times as high as that for warm-acclimated carp. Light chain composition did not differ between both carp myosins. The differences in a primary structure of the heavy chain subunit was, however, clearly demonstrated between both myosins by peptide mapping.Abbreviations ATPase adenosine 5-triphosphatase - DTNB 5,5 dithio-bis-2-nitrobenzoic acid - DTT dithiothreitol - EGTA ethyleneglycol bis (-aminoethylether)-N,N,N,N-tetraacetic acid - K _D inactivation rate constant - SDS sodium dodecyl sulfate - SDS-PAGE SDS-polyacrylamide gel electrophoresis     

Effect of Thermal Acclimation on the Expression of Gene Coding for Lactate Dehydrogenase A4 in Loach Skeletal Muscle

Acclimation of Misgurnus fossilis to 5 and 18°C induced considerable changes in LDH-A gene expression in white skeletal muscle. Qualities of total and messenger RNA isolated from weighted portions of muscle are considerably higher after acclimation to 18°C as compared to 5°C. However, a PCR assay of cDNA synthesized from these mRNA and equalized by optical density demonstrated that the level of LDH-A gene expression was indistinguishable for high and low acclimation temperatures, while expression of other genes (glyceraldehyde-3-phosphate dehydrogenase and -actin) considerably increased at 18°C as compared to 5°C. The specific enzymatic activity of LDH from white skeletal muscle of the fish acclimated to low temperature is by 20% higher than that for high-temperature acclimation. Structural analysis of the PCR products synthesized on cDNA-5°C and cDNA-18°C has revealed no differences. However, there are indirect indications of the differences in the C-thermal region of the LDH-A molecule. Northern hybridization reveals the differences at the RNA level: one (1400 bp) or two (about 1600 and 1400 bp) hybridization signals have been found in mRNA-5°C and mRNA-18°C, respectively. The presence of two fractions in the mRNA-18°C indicates alternative splicing.