Energy metabolism and body temperature in 13 sunbird species (Nectariniidae)

• 1.1. Diurnal cycles of body temperature, T_b, and energy metabolism, M, at different ambient temperatures (T_a: +5 −+ 32°C) were tested in 13 sunbird species from various habitats and of different body masses (5.2–14.2 g) including one of the smallest passerines, Aethopyga christinae.
• 2.2. Resting M-level (night) reaches T_a-dependent mean values of 54% (+5°C) and 49% (+25°C) of activity M-levels (day). Expected level is ca 75%.
• 3.3. Resting metabolic rate of sunbirds lies within the range of theoretically expected values for birds.
• 4.4. Mean linear metabolism-weight regression of the night values follows: M = 0.102 × W^0.712 (M = energy metabolism in kJ/hr and W = body mass in g).
• 5.5. Thermal conductances, T_c, are lower (−24%) than the predicted values. This is caused by a decrease of T_b at low T_a. Mean nocturnal T_c is 3.2 J/g × hr × °C, mean day-time value is 4.3 J/g × hr × °C.
• 6.6. The zone of thermoneutrality is, in most species, within a T_a-range of 24–28°C.
• 7.7. Normal day and night levels of T_b are in the same range as reported for other birds of the same weight class. T_b decreases slightly with falling T_a (partial heterothermia). Lowest recorded T_b was 34.2°C.
• 8.8. No species tested showed any sign of torpor at night, independent of T_a, body mass or habitat origin.

     

Thermoregulation in the cicada Platypedia putnami variety lutea (Homoptera: Tibicinidae) with a test of a crepitation hypothesis

• 1.Measurements of body temperature (T_b) in the field demonstrate that Platypedia putnami var. lutea Davis regulates T_b through behavioral mechanisms.
• 2.Thermal responses (minimum flight temperature 17.3°C, maximum voluntary tolerance-temperature 32.5°C, and heat torpor temperature 44.4°C) of P. putnami var. lutea are related to the altitude of their habitat.
• 3.Water loss rates increase with ambient temperature (T_a). Water loss rates are not significantly different at the extremes of the active T_b range but increase significantly when exposed to elevated T_a.
• 4.Acoustic activity was restricted at 6.7°C T_b range. This is similar to the lower end of the T_b range for singing measured in cicada species that produce sound with a timbal mechanism.
• 5.The use of the wing musculature to produce acoustic signals in P. putnami var. lutea does not increase the T_b range over which the species can call compared to timbal calls produced by other cicada species.

     

Determination of temperature preference and the role of the enlarged cheliped in thermoregulation in male sand fiddler crabs,Uca pugilator

• 1.Male Uca pugilator whose major cheliped was immersed in 3 °C water bath experienced a significant drop in T_b. Thus, the enlarged claw of male Uca pugilator may have an unexplored function: thermoregulation.
• 2.Crabs prefer warmer substrates (19–24 and 28–30 °C) over cooler (15–17 °C).
• 3.Mean selected temperature (MST) may not be an accurate reflection of T_b. Crabs in a thermal chamber preferred temperatures between 25 and 30 °C but their average T_b was 23.2 °C.

     

Cardiac responses to stress and activity in the armoured legless lizard Ophisaurus apodus: Comparison with snake and tortoise

• 1.1. Heart rate (HR) was measured during and after stress and activity in the armoured legless lizard Ophisaurus apodus, the snake Natrix natrix and the tortoise Testudo hermanni, at different body temperatures T_b. These are discussed in relation to field T_b, defensive behaviour and published V́O₂.
• 2.2. Ophisaurus apodus used passive defence, including hemipenis or cloacal sac eversion and prolonged immobility after release. This was correlated with a low degree of tachycardia, bradycardia at low T_b, low metabolism and armour.
• 3.3. Defence behaviour was T_b-dependent in wild T. hermanni, with passive withdrawal into the shell at low T_b, and active struggling at high T_b. The degree of tachycardia was lower at low T_b.
• 4.4. Standard and active oxygen pulse OP were insensitive to T_b in O. apodus and N. natrix, and their SOP was lower than tetrapod lizards. Factorial scope of HR was reduced at 35°C, just above the activity T_b range of these species.
• 5.5. Recovery of HR after activity in T. hermanni was much more rapid than in the squamates, and of similar duration to recovery after stress. It is suggested that tortoises do not utilize anaerobic metabolism during activity.

     

The influence of temperature on the haemocyanin function and oxygen uptake of the freshwater crab Potamonautes warreni calman

• 1.1. At 35°C a maximal VO₂ value of 110 ml O₂/kg/hr was obtained with a significant decrease in the value at 40°C.
• 2.2. The Bohr-effect for P. warreni is — 0.28 and does not change significantly at 15, 25 and 35°C.
• 3.3. The ability of the crab to extract oxygen from the water medium during a single exhalation is on average 41.2% whilst the limitation diffusion (L. diff, Piiper, [1982], A Companion to Animal Physiology, pp. 49–64. Cambridge University Press.) is 0.84.
• 4.4. Compared to land and marine crabs, in P. warreni, the P_aO₂ (29.5 mm Hg) and the P_vO₂ (15.3 mm Hg) is low.

     

Comparative study of the oxyhaemoglobin dissociation curve of four mammals: Man,dog, horse and cattle

• 1.1. The entire oxygen dissociation curve (ODC) and the effects of temperature, pH and 2,3-diphosphoglycerate (DPG) on this curve, have been compared in four mammalians: man, dog, horse and cattle.
• 2.2. If the oxyphoric capacities are similar between these species (around 1.39ml O₂/gHb), their P50, measured in standard conditions, i.e. at pH 7.4;.pCO₂ 40mmHg and T 37°C, varies between 23.8 (± 0.8) mmHg for the horse, 25.0 (± 1.4) mmHg for cattle, 26.6 (± 1.2) for man and 28.8 (± 2.6) mmHg for the dog.
• 3.3. The higher dispersion of the dog's P50 is due to difference between breeds; in seven breeds investigated, the P50 ranges from 25.8 (spaniel) to 35.8 (hound).
• 4.4. We noted no sex difference in the four species.
• 5.5. The DPG level is confirmed to be low in cattle (< 1 μmol/gHb) as compared to man (13.5 ± 2.1 gmmol/gHb), horse (16.9 ± 1.1 gmmol/gHb) and dog (19.4 ± 2.8 μmol/gHb).
• 6.6. The oxygen exchange fraction defined as the difference in vol% between a pO₂ of 80 and 35 mmHg is, respectively, 3.6 (± 0.6) vol% for cattle, 4.0 (0.4) vol% for the horse, 5.5 (± 0.5) vol% for man and 6.6 (± 1.7) vol% for the dog.
• 7.7. The position and shape of the ODC, as well as T, DPG and pH effects, indicate that the haemoglobin of man and dog seem better adapted to O₂ delivery as compared to the horse and cattle.

     

Characterization of two distinct latent proteinases associated with myofibrils of crucian carp (Carassius auratus cuvieri)

:

• 1.1. Enzymatic properties of two distinct proteinases tightly associated with crucian carp myofibrils were characterized.
• 2.2. These proteinases were latent but activated at 50 and 60°C, respectively.
• 3.3. The optimum pH of 50°C-proteinase was neutral-alkaline, while that of 60°C-proteinase was weak acid-neutral pH.
• 4.4. Both proteinases required more than 1% NaCl for the activity, but 50°C-proteinase was partially inhibited at higher concentrations of NaCl.
• 5.5. Both proteinases were regarded as trypsin-like proteinases belonging to a serine proteinase family, but only 60°C-proteinase was sensitive to urea, n-butanol and iso-propanol.

     

Lipoxygenase of the thermophilic bacteria thermoactinomyces vulgaris—properties and study on the active site

• 1.1. A lipoxygenase activity was purified from Thermoactinomyces vulgaris and some of its properties were characterized.
• 2.2. The enzyme showed a temperature activity range of 40–55°C with still significant activity over 60°C.
• 3.3. The pH of activity on linoleic acid had a broad range with an optimum at pH 6.0 and a weaker one at pH 11.0.
• 4.4. On arachidonic acid the pattern was narrow bell-shaped with an optimum at pH 6.5.
• 5.5. The purified lipoxygenase from Th. vulgaris showed an apparent K_m of 1 mM and V_max of 0.84 μmol diene/min/mg protein.
• 6.6. It was inhibited by the oxidation products, 9-HPOD and 13-HPOD.
• 7.7. A 160,000 Da molecular weight of the enzyme was determined by molecular filtration. Methionine, tyrosine, tryptophan and cysteine are apparently involved in its activity.

     

Physically modeling operative temperatures and evaporation rates in amphibians

• (1)We designed a physical model that simulates the thermal and evaporative properties of live Western toads (Bufo boreas).
• (2)In controlled tests, the model tracked the body temperature of live toads with an average error of 0.3±0.03 °C (test range=4–30 °C).
• (3)It estimated the evaporative water loss of live toads with an average error of 0.35–0.65  g/h, or about 14% (test range=0.7–9 g/h).
• (4)Data collected with this physical model should provide an effective way for biologists to better understand habitat selection in toads and other amphibians

     

Oxygen consumption and haemocyanin function in the freshwater snail Marisa cornuarietis (L.)

• 1.1. The MO₂ for branchial respiration in adult snails increased from 0.24 mmol/l/O₂ kg/hr at 18°C to 0.83 mmol/l/O₂ kg/hr at 40°C. Q₁₀ values were 2.75 between 35 and 40°C and 1.8 between 18 and 30°C.
• 2.2. The haemocyanin (31.9 ± 5.8 mg/ml) has a high oxygen affinity (6.28 ± 0.8 at 25°C) with a reversed Bohr effect measured between a pH of 6.80 and 7.95 with gelchromatographed haemolymph, and measured between a pH of 7.34 and 8.10 for native haemolymph.
• 3.3. Growth rate is optimal between 27 and 30°C whilst at 24°C stunted growth was found.
• 4.4. At 25°C the same MO₂ values were found for aerial and aquatic respiration.

     

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.

     

The response of brown adipose tissue mitochondrial glycerolphosphate acyltransferase to cold-exposure in hypothyroidism,after adrenalectomy and after treatment with cycloheximide

• 1.1. Exposure to cold has previously been shown to considerably increase the activity of the mitochondrial form of glycerolphosphate acyltransferase (GPAT) in brown adipose tissue (A.C. Darnley C.A. Carpenter and E. D Saggerson, Biochem.J.253, 351–355, 1988; J.R.D. Mitchell and E.D. Saggerson. PBiochem.J.277, 665–669, 1991).
• 2.2. Both adrenalectomy and chemically-induced hypothyroidism increased mitochondrial GPAT activity in rats maintained at 21°C. This increase was similar to that caused by exposing rats to the cold (4°C) for three days. Whereas exposure of hypothyroid rats to cold (4°C) resulted in a further increase in GPAT activity, no further increase in activity was observed after exposure of adrenalectomized rats to the cold.
• 3.3. Administration of triiodothyronine (T₃) to rats maintained at 21°C had no effect on mitochondrial GPAT activity.
• 4.4. Prior treatment with cycloheximide abolished 60–70% of the increase in GPAT activity caused by cold-exposure.

     

An alkaline phosphatase from Thermus sp strain Rt41A

• 1.1. A thermostable orthophosphoric monoester phosphohydrolase (EC 3.1.3.1) from Thermus sp strain Rt41A has been purified 400-fold to give a specific activity of 25 U/mg at 60°C in IM diethanolamine (pH 11.1).
• 2.2. The enzyme has a M_r of 160,000 and is trimeric.
• 3.3. The half-life of the enzyme is 5 min at 85°C.
• 4.4. The enzyme has a wide specificity for a number of phosphate monoesters.
• 5.5. The H_m of the enzyme is pH dependent, so the pH optimum of the enzyme is affected by the substrate concentration.
• 6.6. The enzyme is inhibited 50% by 20 mM Ca²⁺ or Mg²⁺.
• 7.7. The K_i for phosphate, EDTA-di sodium salt and arsenate (in 1 M diethanolamine, pH 11.1) is approx 1.2, 1.6 and 4mM respectively.
• 8.8. Urea (200 mM) is not inhibitory.

     

The effect of temperature on the swimming of a teleost (Clupea harengus) and an ascidian larva (Dendrodoa grossularia)

• 1.1. Using a high-speed video system operating at 400 frames/sec, the effects of temperature on tail beat frequency, swimming speed and stride length were examined in newly hatched larvae of herring (Clupea harengus L.) and in tadpole larvae of the ascidian Dendrodoa grossularia van Beneden.
• 2.2. The effect of temperature was linear; the tail beat frequency of 8 mm-long herring larvae increased from 19 Hz at 5.6°C to 37 Hz at 14.9°C (Q₁₀ = 2.04); that of 2 mm-long Dendrodoa larvae increased from 10 Hz at 9.6°C to 23 Hz at 18.1°C (Q₁₀ = 2.52).
• 3.3. Burst swimming speeds of herring larvae increased from 80 mm/sec at 5°C to 150 mm/sec at 15°C, stride length remaining constant at about 0.5 of the body length for each tail beat.
• 4.4. More continuous swimming of Dendrodoa increased from 4.0 mm/sec at 10°C to 11.5 mm/sec at 18°C, the stride length increasing from about 0.15 to 0.25.

     

Solubilization,characterization and photoaffinity labeling of the mitochondrial dihydropyridine receptor from bovine adrenal medulla

• 1.1. The mitochondrial dihydropyridine receptor was solubilized with Chaps at a detergent/ protein ratio of 2.5, during 45 min at 4°C.
• 2.2. From the rate constants of association (8.10 ± 0.25 × 10⁴ M⁻¹ min⁻¹) and dissociation (0.022 ± 0.001 min⁻¹ a K_d of 275 nM was calculated, while from saturation experiments a K_d of 270 ± 30 nM and a density of receptors of 106 ± 9 pmol/mg protein was obtained.
• 3.4. The solubilized receptors are heat-resistant, sensitive to the trypsin and to the reduction of disulfide bonds.
• 4.5. In native membranes, a polypeptide of 50 kDa was specifically photolabelled with [³H]Azidopine.

     

Effect of temperature on oxygen consumption and heart rate of the australian crayfish Cherax tenuimanus (Smith)

• 1.1. Oxygen consumption at 18°C was 60% of the rate at 22 and 26°C.
• 2.2. Critical points, where the rate of oxygen consumption changed, were defined at 22°C (2.89 mg DO) and 26°C (3.46 mg DO). Linear regressions were fitted showing that oxygen consumption declined significantly (81.5% ±4.5) below the critical point.
• 3.3. Oxygen consumption was proportional to weight. Allometric relationships resulted in variable temperature-related coefficients for respiratory dependence on weight, a reflection of the crayfish adaptation towards re-establishment of a new equilibrium state.
• 4.4. Heart beat rate was lower at 18°C, and highest at the acclimation temperature (22°C). Stress at 26°C was evident.

     

Identification and characterization of a third form (D3) of cyclic 3'5'-nucleotide phosphodiesterase from rhizobwm fredii

• 1.1. A third form (D3) of cyclic nucleotide phosphodiesterase from Rhizobiumfrediiv/as detected and characterized for the first time.
• 2.2. The enzyme could hydrolyse both cyclic AMP and cyclic GMP with apparent K_m for cyclic AMP of approx. 0.2 μM.
• 3.3. D3 cyclic nucleotide phosphodiesterase had a pH optimum of about 6.0 when hydrolysing cyclic AMP.
• 4.4. The enzyme lost almost all its activity when heated to 60°C for 20 min.
• 5.5. Gel filtration with Sephadex G-100 gave a mol. wt of approx. 42.5 kD for the native enzyme.

     

Purification of endo- and exolaminarinase and partial characterization of the exoacting form from the copepod acartia clausi (Giesbrecht, 1889)

• 1.1. The copepod Acartia clausi exhibited two laminarinases (exo- and endo-acting forms) purified by gel chromatography followed by affinity chromatography. Specific antibodies have been raised against the purified exolaminarinase antigen.
• 2.2. A single band of protein appeared on a polyacrylamide disc gel electrophoresis; its mol. wt is 21,000.
• 3.3. Biochemical properties of the purified enzyme showed a maximum activity at pH 5.2 and a temperature of 40°C with laminarin as substrate. The thermal stability of the enzyme and the effect of various cations on its activity were examined. The enzyme hydrolyses specifically the β(1–3) linked polysaccharides and had no activity against the α(1–4) or β(1–4) disaccharides or polysaccharides.
• 4.4. The kinetic parameters V_m and K_m vary with the temperature; the affinity constant (K_a) was maximum between 25–30°C. The Arrhenius plot defined two values of energy of activation: 7980 cal/mole and 17,506 cal/mole.
• 5.5. From the purification scheme the exoacting form appears to be largely dominant over the endoacting form.

     

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).

     

Changes in the activity of the adrenal cortex in fasted echidnas (Tachyglossus aculeatus) exposed to low ambient temperatures

• 1.1. The adrenal cortex is necessary for survival of echidnas at low ambient temperatures. In this study, adrenal gland activity was investigated in echidnas exposed to 2 days of cold (14°C) and fasting, alternating with 2 days at room temperature and feeding ad lib.
• 2.2. In the cold. 2.75 ± 0.29% (SD) of the initial body weight was lost daily. Plasma amino acid concentration did not change while glucose concentration decreased from 2.6 ± 0.3 to 1.5 ± 0.3 mmol/l with consecutive sessions of cold.
• 3.Plasma concentrations of corticosterone (7.2 ± 1.4 nmol/l) and cortisol (4.4 ± 1.9 nmol/l) were unchanged by repeated cold exposure. However, the adrenal response to ACTH stimulation decreased and the clearance of corticosteroids increased after cold exposure.
• 4.It was concluded that exposure to cold increases the utilization of glucocorticoids and decreases the capacity for their biosynthesis.