Cardiac frequency compensation responses of adult blue crabs (Callinectes sapidus Rathbun) exposed to moderate temperature increases

• 1.1. Cardiac frequency patterns of Callincctes sapidus Rathbun were used to evaluate potential thermal stress after exposure to 5°C increases over a range of acclimation temperatures from 5° to 30°C.
• 2.2. An acclimated rate-temperature curve (R-T curve), acute R-T curves of the stabilized rates at the increased temperatures and Q₁₀ temperature coefficients were used to assess the significance of the changes in rate frequency.
• 3.3. The acclimated R-T curve showed that blue crabs go through a series of seasonal adaptation types characterized by a plateau of perfect adaptation for both cold and warm adapted organisms. Paradoxical adaptation occurred between the transition from cold to warm acclimation temperatures.
• 4.4. The acute R-T curves showed that cardiac frequency was highly responsive to a 5°C increase when the organisms were acclimated to low temperatures.
• 5.5. The Q₁₀'s of the acute R-T curves at the warm acclimation temperatures approximated those values derived for the acclimated R-T curve.
• 6.6. This suggests that the temperature increase had a negligible effect on the warm adapted crabs, that is, little or no thermal stress occurred.

     

Adaptative features of amazon fishes: Hemoglobins,hematology, intraerythrocytic phosphates and whole blood Bohr effect of Pterygoplichthys multiradiatus (Siluriformes)

• 1.1. Hemoglobin, hematological parameters, intraerythrocytic phosphates and whole blood Bohr effect of Pterygoplichthys multiradiatus, from the Amazon river, were studied in three different conditions: in their natural environment, acclimated to normoxia and acclimated hypoxia conditions.
• 2.2. Nine anodal hemoglobin fractions were detected on starch gel electrophoresis. No qualitative differences in the Hb electrophoretic patterns were detected in the three studied groups.
• 3.3. Hematocrit, hemoglobin concentration, MCV, MCHC and MCH were different among studied conditions.
• 4.4. GTP was almost absent in the blood of animals in natural conditions and acclimated to hypoxia, but was present at a concentration similar to ATP in normoxic acclimated animals.
• 5.5. There is a tendency for higher Hb-O₂ affinity for hypoxic acclimated/acclimatized animals.

     

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.

     

Lactate dehydrogenase of goldfish red and white muscle in relation to thermal accumulation

• 1.1. Activities of the red and white muscle LDH from 8°C-acclimated goldfish were about three times higher than those acclimated to 28°C.
• 2.2. Isozyme composition and some kinetic properties of the red muscle LDH differed from those of the white muscle enzyme.
• 3.3. The amount of red muscle as well as LDH activity tended to increase during cold acclimation.

     

Comparative study of hemoglobins from different Artemia populations. The influence of temperature on the oxygen equilibria

• 1.1. The P50 values of extracellular hemoglobin (Hb) of five Artemia populations from different geographical origin are affected by temperature.
• 2.2. The free oxygen binding energy is high for all the populations (ΔH between −34.7 and −56.2kj/mol).
• 3.3. A possible correlation between thermal sensitivity of Hb and the ambient temperature of the habitat must be considered very carefully.
• 4.4. The occurence of different quantities of Hb1 (αα chains) Hb2 (αβ chains) and Hb3 (ββ chains) in the different populations possibly influences thermal sensitivity.

     

Effects of acclimation temperature,season, and time of day on the critical thermal maxima and minima of the crayfish Orconectes rusticus

• 1.1. The critical thermal minima (CTMin) and maxima (CTMax) were determined for field-acclimatized and laboratory-acclimated crayfish (Orconectes rusticus) throughout 1984.
• 2.2. The CTMin and CTMax of field-acclimatized crayfish were seasonally adjusted by 9.7 C and 14.7 C respectively.
• 3.3. Seasonal variation in both tolerance regimes persisted in crayfish acclimated in the laboratory at 5 and 25°C for one week; however, no diel variation existed in either the CTMin or CTMax of laboratory-acclimated crayfish.
• 4.4. Integration of thermal acclimation of the CTMin and CTMax with seasonal conditioning may influence the functional capacities of this species when considered in relation to the seasonal ranges in stream temperature.

     

Anuran amphibia which are not acclimable to high salt,tolerate high plasma urea

• 1.1. The capacity of five anuran Amphibians (Bufo viridis B. regularis, Rana ridibunda, Hyla arborea and Pelobates syriacus) to acclimate to NaCl and urea solutions was investigated.
• 2.2. All species could be acclimated to relatively high concentrations of urea solutions, while only Bufo viridis and Hyla arborea could be acclimated to 500 mOsm/kg or higher NaCl solutions.
• 3.3. The plasma urea concentration in B. viridis and H. arborea was elevated to levels over 140 mmol/1.
• 4.4. The sum of plasma sodium and chloride concentrations did not increase over 400 mmol/l in any species.
• 5.5. Urine osmolality, which was normally low, increased, but never exceeded the plasma osmolality.
• 6.6. In the urea acclimation conditions, urine electrolytes diminished, similarly in all species in this study.
• 7.7. It is concluded that anuran Amphibians can tolerate high plasma urea concentrations, but only those species which can elevate it, either through retention or net synthesis, can be acclimated to high salt solutions.

     

Cold tolerance of steinernematid and heterorhabditid nematodes

• 1.1. Nematodes survive subzero temperatures using either a freeze-avoiding or freezing-tolerant strategy. Steinernema anomali, S. feltiae, and Heterorhabditis bacteriophora were all found to be freezing tolerant.
• 2.2. The lower lethal temperatures were −22, −19 and −14°C for S. feltiae, H. bacteriophora and S. anomali, respectively.
• 3.3. Survival after prolonged freezing at −4°C was 6, 5 and 3 days for S. feltiae, H. bacteriophora and S. anomali, respectively.
• 4.4. Acclimation to lower temperatures increased freezing tolerance. The freezing tolerance of Heterorhabditis bacteriophora increased under a stepwise acclimation regime; S. feltiae acclimated better under a direct acclimation regime.

     

Pulmonary hypertension and the smooth muscle of the pulmonary arterioles in chickens at high altitude

• 1.1. One-day-old male (m) and female (f) chickens from a population living at 3300m for several generations were raised at 3300 m (HA) and at sea level (SL).
• 2.2. The histology of the pulmonary arterioles was studied in the HA and SL chickens when they were 4 weeks old and the thickness of their muscular coat (MT) determined.
• 3.3. Pulmonary arterial pressure (Ppa), hematocrit (Hct) and the wet and dry weights of the total ventricle, left ventricle, septum and right ventricle (RV) were obtained when the HA and SL birds were 8 weeks old.
• 4.4. Results indicated that chickens have a thick muscular coat in their pulmonary arterioles. MT expressed as a fraction of arteriolar diameter (MT/AD) was 0.113 at SL. Exposure to HA increased this value in the m (0.137, P < 0.01) but not in the f (0.123, P > 0.05).
• 5.5. Ppa, RV and Hct were significantly higher at HA in both sexes. The degree of pulmonary hypertension and right ventricular hypertrophy observed was smaller than that found in earlier generations of these chickens studied several years ago. This probably indicates some degree of adaptation after generations of life at HA.

     

Cyclic AMP stimulation and prostaglandin inhibition of Na transport in freshwater mussels

• 1.1. Pondwater acclimated Carunculina texasensis and Ligumia subrostrata experienced a 230% increase in Na influx when injected with dibutyryl cyclic AMP (0.4mM/l blood).
• 2.2. Theophylline, a phosphodiesterase inhibitor, or indomethacin, an inhibitor of prostaglandin (PG) synthetase, caused a dose dependent stimulation of Na transport.
• 3.3. Prostaglandin E₂ injected into mussels caused an inhibition of Na influx. Arachidonic acid, the precursor of PGE₂, inhibited Na influx or stimulated Na efflux depending on the animal's acclimation conditions.
• 4.4. Chloride transport was unaffected by the drugs used in this study.

     

Sea-water tolerance in freshwater-resident arctic charr (Salvelinus alpinus)

• 1.1. Freshwater-resident Arctic charr acclimated for 2 months at 8°C, 15% were divided into four experimental groups in July and exposed to 1 and 8°C in 15 and 34% salinity.
• 2.2. Only slight changes in gill Na-K-ATPase activity, blood plasma osmolality and blood plasma concentrations of Cl⁻ and Mg²⁺ were found for the fish exposed to 1 or 8°C in brackish water.
• 3.3. When exposed to sea-water at 8°C, an increase in osmolality and in concentrations of Cl⁻ and Mg²⁺ took place during the first 2–3 days, after which it levelled off.
• 4.4. If exposed to sea-water at 1°C, however, marked increases were found for all parameters measured and all the fish were dead within 5 days of exposure.
• 5.5. These results show that freshwater-resident Arctic charr—if acclimated to brackish water—can survive in sea-water during summer if the environmental temperature is not too low.

     

Temperature acclimation in respiratory and cytochrome c oxidase activity in common carp (Cyprinus carpio)

• 1.1. Common carp (Cyprinus carpio) exposed to experimental temperatures of 12, 18, 24, 30 or 36°C for a 4-week period were used to investigate the effect of temperature acclimation on the frequency of opercular movement (FOM), growth and cytochrome c oxidase (CCO) activity in heart, liver and muscle.
• 2.2. An exponential relationship between FOM and temperature after the first week (10₁₀ =1.76) disappeared after the second week.
• 3.3. The initially high FOM at temperatures of 30 or 36°C and the low FOM at 18 or 12°C changed over 4 weeks to approach the FOM of fish at 24°C.
• 4.4. This change in the relationship of FOM to temperature from highly dependent to independent appeared to be thermal compensation.
• 5.5. Heart and liver CCO activities were significantly affected by temperature, with the lowest activity at the approximate optimum temperature for growth, 24°C.
• 6.6. Highest CCO activities for heart and liver occurred at both the highest and lowest temperatures.
• 7.7. Among the three tissues, heart CCO activity was generally the highest and most affected by acclimation temperature.
• 8.8. Muscle tissue had the lowest CCO activity and was unaffected by temperature.
• 9.9. The high CCO activity at a cold acclimation of temperature 12°C was probably due to thermal compensation and the high activity at 36°C may have been a result of thermal stress.

     

Behavioural thermoregulation and critical thermal limits of Macrobrachium acanthurus (Wiegman)

• (1)The preferred temperatures of Macrobrachium acanthurus were determined for prawns acclimated to 20°C, 23°C, 26°C, 29°C and 32°C, and the final preferendum estimate was (29.5°C).
• (2)The critical thermal minima (CTMin) and maxima (CTMax) were 11.0°C, 12.1°C, 13.0°C and 14.8°C, and 34.2°C, 35.0°C, 36.1°C and 39.8°C, respectively.
• (3)The zone of thermal tolerance assessed using the CTMin and CTMax boundaries was 644°C².
• (4)The acclimation response ratio was between 0.33 and 0.62.
• (5)To cultivate this species in the southeastern region of México it should be done in not <15°C (CTMin) during the winter and below 38°C in summer (CTMax).

     

Seasonal adaptations in oxygen transport in brown trout Salmo trutta fario

• 1.1. Blood parameters determining oxygen capacity and oxygen affinity were measured in brown trout at different times of the year.
• 2.2. Haematological data indicate a slight decrease in blood oxygen capacity during the warm seasons. 3. Oxygen affinity increases significantly during summer and decreases in winter.
• 3.4. The changes in P₅₀ exhibited a positive correlation with the amount of anodic haemoglobin components, and a negative correlation with the amount of cathodic haemoglobin components.
• 4.5. The changes observed in the [ATP]/[Hb] molar ratio were not correlated with oxygen affinity and gave values near one.
• 5.6. We conclude that the oxygen affinity increase could be a physiological adaptation to oxygen transport during the wanner period. A possible mechanism is discussed.

     

Effect of warm acclimation on the cationic concentrations in the extracellular and intracellular body fluid of hibernating Rhagium inquisitor beetles

• 1.1. The effect of warm acclimation on the cationic concentrations of hibernating Rhagium inquisitor beetles was studied.
• 2.2. Following warm acclimation, the extracellular concentration of Mg²⁺ dropped from about 80 to about 50 mM. For Na⁺ and K⁺ the extracellular concentration remained constant at about 40 mM. The estimated intracellular concentration of Mg²⁺ was not affected by the warm acclimation, being about 80 mM in both groups of beetles. The corresponding concentration of Na⁺ increased from about 20 to about 30 mM, whereas for K⁺ there was no change, the concentration being about 140mM in both groups of beetles.
• 3.3. The marked drop in the extracellular concentration of Mg²⁺ might indicate that Mg²⁺ is involved in the regulation of the concentration of glycerol, which was reduced to zero during the warm acclimation.
• 4.4. The estimated equilibrium potentials of the respective ions might indicate that K⁺ is in electrochemical equilibrium across the cell membranes, whereas Na⁺ and to a lesser extent Mg²⁺ are actively transported out of the cells.
• 5.5. For Na⁺ there was a high positive equilibrium potential even in the cold acclimated beetles, indicating that Na⁺ has a high electrochemical potential difference across the cell membranes even at low temperatures. This is in agreement with the observation that hibernating insects are able to perform coorclinated walking immediately after heating to temperatures near zero.

     

The influences of individual variations in metabolic rate and tidal conditions on the response to hypoxia in Carcinus maenas (L.)

• 1.1. The oxygen consumption of crabs in normoxic and hypoxic (50% O₂) seawater was measured directly after collection.
• 2.2. The influences of size and lunar cycles were removed by scaling the data.
• 3.3. Strong negative correlations between low individual levels of O₂ consumption and the ability to compensate for hypoxia were apparent in Wicklow (subtidal) crabs.
• 4.4. Compensation for hypoxia was much greater on the flood tide than on the ebb.
• 5.5. Crabs from Roscoff (intertidal) had lower levels of compensation than those from Wicklow.
• 6.6. Size, sex and condition had no apparent effect upon these relationships.
• 7.7. Crabs acclimated to laboratory conditions have not shown this tidal variation in compensation for hypoxia.

     

Compensations for temperature in the activities of digestive enzymes of Periplan eta americana (L.)

• 1.1. Differential thermal acclimatory responses of maximal catalytic rates (V_max) of digestive enzymes have been measured in both sexes of Periplaneta americana adapted to 16 and 32°C.
• 2.2. Salivary amylase of females and gastric protease of males exhibit “translational” acclimation, the former showing a “complete” but the latter only a “partial” compensation. The value of Q₁₀ is not altered in the adaptive response.
• 3.3. An alteration of the thermal coefficient is evidenced by the “translational-cum-rotational” compensation of gastric amylolytic activity, with significant warm acclimation but no cold acclimation in both sexes.
• 4.4. Gastric protease of female cockroaches and gastric lipase of both sexes are characterized by the lack of an adaptive compensation to temperature, while salivary amylase of male appears to manifest an “inverse” acclimation.
• 5.5. Sexual dimorphism in the levels of the activities and in the patterns of thermal acclimation of the digestive enzymes is indicated.

     

Temperature acclimation in amphibians: Changes in lactate dehydrogenase activities and isoenzyme patterns in several tissues from adult Discoglossus pictus pictus (Otth.)

• 1.1. The effect of cold (8 ± 2°C) acclimation on the lactate dehydrogenase activities and isoenzyme patterns from sartorius muscle, liver, heart and brain of adult Discoglossus pictus pictus (Otth.) was studied.
• 2.2. Two groups of animals were studied: one set of animals was trapped in October and another set in December. In both cases some of the animals were sacrificed upon collection and some others subjected to 5 months of acclimation at 8 ± 2°C before being sacrificed for analysis.
• 3.3. A general trend towards a decrease in LDH specific activity was observed during cold acclimation. The magnitude of change, but not the direction, depends on both the tissue examined and the season at which the experiment was initiated.
• 4.4. A complex LDH isoenzyme reorganization was also found in liver, heart and brain. In liver from Experiment 1 and in heart from both experiments, a relative maintenance in M-type LDH activity during cold acclimation was observed. However, in brain there was a relative maintenance of LDH₃ activity in both experiments.
• 5.5. The low behavioral activity (and its metabolic consequences) and the existence of an intrinsic annual rhythm in D. pictus metabolism are suggested as responsible for the observed enzymatic changes.

     

The effect of temperature on oxygen equilibrium curves of trout blood (Salmo gairdnerii)

• 1.1. Oxygen equilibrium curves were measured on trout red blood cell suspensions at pH 7.8 and 8.4 at 15, 20 and 25 C. Normal red cells and red cells that had been depleted of their ATP content were used.
• 2.2. The equilibrium data were fitted to the Adair's model and the enthalpy (ΔH) and entropy (ΔS) changes for the first and fourth steps of oxygenation and for overall oxygenation were calculated from the temperature dependencies of the Adair constants.
• 3.3. For normal red blood cells, the apparent heat for the first oxygenation step, δh₁, is close to zero.
• 4.4. Temperature insensitivity of this step at physiological pH, combined with a large pH dependence, probably denotes a property of Hb4, the Root effect Hb of trout blood.
• 5.5. At pH 7.8, ΔH₄ is about —4kcal/mol, a small value which may be attributed to the large release of Bohr protons that occurs at the last oxygenation step and corresponds to an endothermic process which opposes to the exothermic oxygenation of the haem.
• 6.6. The ΔH₄ value appears to have a large influence on the enthalpy for overall oxygenation.
• 7.7. Results for ATP-free red cells are consistent with a mere increase in the intracellular pH and suggest that ATP has no specific effect at and above pH_i ~ 7.7.
• 8.8. Effects of temperature and pH on trout red blood cell isotherms emphasize the primary importance of the major component of trout blood, namely Hb4, in trout blood functional properties.