Brain temperature regulation of panting and non-panting pigeons exposed to extreme thermal conditions

• 1.1. Brain (hypothalamic), skin and body temperatures were measured in hand-reared acclimated (Acc, n = 5) and non-acclimated (NAcc, n =7) rock pigeons (Columba livia, mean body mass 237 g) exposed to increasing ambient temperatures (T_a) (30–60°C) and low humidities.
• 2.2. In non-panting Acc birds, brain temperature gradually increased from 40.1 ± 0.4°C at 30°C to 41.2 ± 0.4°C at 60°C T_a. A mean body temperature (T_b) of 41.2 ± 0.2°C was measured at T_a up to 50°C; an increase of 1.1°C was observed at 60°C (T_b 42.2 ±0.6°C).
• 3.3. In Acc panting birds exposed for 2 hr to 60°C, T_hy was 41.9 ± 0.8°C and T_s was somewhat (but insignificantly) higher, i.e., 42.2 ± 0.7°C. It looks as if both values were increased as a result of a slight hyperthermia that developed (T_b = 43.5 ± 0.9°C).
• 4.4. The significance of the present results for evaluating neuronal thermoresponsiveness of birds' hypothalamus is discussed.

     

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.

     

Body temperature in the mouse,hamster, and rat exposed to radiofrequency radiation: An interspecies comparison

• 1.1.|Colonic temperatures of BALB/c and CBA/J mice, golden hamsters, and Sprague-Dawley rats were taken immediately after exposure for 90 min to radiofrequency (RF) radiation.
• 2.2.|Exposures were made in 2450 MHz (mouse and hamster) or 600 MHz (rat) waveguide exposure systems while the dose rate, specific absorption rate (SAR), was continuously recorded. Experiments were performed on naive, unrestrained animals at ambient temperatures (T_a) of 20 and 30°C.
• 3.3.|Body mass and T_a) were found to be significant factors in influencing the threshold SAR for the elevation of colonic temperature. The threshold SARs at T_a's of 20 and 30°C were respectively: 27.5 and 12.1 W/kg for the BALB/c mouse; 40.7 and 8.5 W/kg for the CBA/J mouse; 8.7 and 0.61 W/kg for the golden hamster; and 1.58 and 0.4 W/kg for the Sprague-Dawley rat.
• 4.4.|The relationship between threshold SAR or SAR for a 1.0°C elevation in colonic temperature vs body mass were linearly and inversely related on a double logarithmic plot. The results of this study suggest that the thermoregulatory sensitivity to RF radiation in these rodent species is heavily dependent on body mass and T_a.

     

Heat shock proteins from the lungless salamanders Eurycea bislineata and Desmognathus ochrophaeus

• 1.1. Exposing adult salamanders, Eurycea bislineata and Desmognathus ochrophaeus, to heat shocks of 1 hr at 2 or 5°C below Critical Thermhal Maximum (CTM) resulted in the induction of two heat shock proteins (hsps) of approx. M_r 70,000 and 30,000.
• 2.2. Induction patterns in response to similar heat shocks generally differed between the two species.
• 3.3. The milder heat shocks (5°C below CTM) caused different induction patterns than those from the more severe heat shocks, on a tissue-dependent basis. These results indicate that induction of the two hsps is probably independent.

     

Comparative nuclear magnetic resonance studies of diffusional water permeability of red blood cells from different species. V—Rabbit (Oryctolagus Cuniculus)

• 1.1. The diffusional water permeability (P_d) of rabbit red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulfonate (PCMBS).
• 2.2. The values of P_d were around 6.3 × 10⁻³ cm/sec at 15°C, 7.0 × 10⁻³cm/sec at 20°C, 8.0 × 10⁻³ cm/sec at 25°C, 9.1 × 10⁻³ cm/sec at 30°C and10.7 × 10⁻³ cm/sec at 37°C.
• 3.3. Systematic studies on the effects of PCMBS on water diffusion indicated that the maximal inhibition was reached in 15 min at 37°C with 0.5 mM PCMBS.
• 4.4. The values of maximal inhibition were around 71–74% at all temperatures.
• 5.5. The basal permeability to water was estimated as 1.6 × 10⁻³cm/sec at 15°C, 2.0 × 10⁻³cm/sec at 20°C, 2.4 × 10⁻³cm/sec at 25°C, 2.6 × 10⁻³cm/sec at 30°C, and 3.1× 10^{−3 cm/secat 37°C}.
• 6.6. The activation energy of water diffusion was around 18 kJ/mol and increased to 27 kcal/mol after incubation with PCMBS in conditions of maximal inhibition of water diffusion.
• 7.7. The membrane polypeptide electrophoretic pattern of rabbit RBCs has been compared with its human counterpart.
• 8.8. The rabbit membrane contained a higher amount of spectrin (bands 1 and 2), while the band 6 (glyceraldehyde-3-phosphate dehydrogenase) was markedly less intense.
• 9.9. Considerable differences in the electrophoretic patterns of the two sources of RBC membranes appeared in the bands migrating in the band 4.5 region and in front of band 7, where some polypeptides were apparent in higher amounts in the rabbit RBC membrane.

     

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.

     

Characteristics of Crassostrea virginica crystalline style chitin digestion

• 1.1. Fundamental chitin digestion characteristics of Crassostrea virginica crystalline style were investigated.
• 2.2. Optimum temperature and pH were 34°C and 4.8. respectively.
• 3.3. The colloidal regenerated chitin (0.56mol/0.5 ml: GlcNAc equivalents) was saturating under all enzyme levels encountered.
• 4.4. There was no evidence of end product inhibition, even after 100 hr incubation.
• 5.5. Calculated K_m for the chitinase complex was 1.19mM when determined using a 30 min assay, but was only 0.70 mM when determined using a 4.6 hr assay.
• 6.6. Both K_m values are lower than reported for similar assays in other molluscs and for most bacteria.
• 7.7. Effect of substrate preparation on the kinetics are discussed.
• 8.8. Eight peaks of chitinase activity were resolved by DEAE-Fractogel ion exchange chromatography.

     

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.

     

The effects of temperature and moisture on survival capacity,cuticular permeability,hemolymph osmoregulation and metabolism in the scorpion,Centruroides hentzi (banks) (scorpiones,buthidae)

• 1.1. The temperature and water relations of Centruroides hentzi females were investigated. At 12 and 72% relative humidity (RH), the lower and upper Lt₅₀ were -4.5 and 43.7°C, and -4.7 and 45.1°C, respectively. When exposed to high temperature stress, survivorship was significantly greater under mesic conditions.
• 2.2. Cuticular water loss was higher under xeric conditions (12% RH), ranging from 0.061 mg/cm²/hr at 30°C to 0.211 at 41°C.
• 3.3. Exposure to dry air (0–5% RH) resulted in a significant increase in hemolymph osmolality: from 441 to 688 mOsm over a 5 day period.
• 4.4. Mean oxygen consumption rates increased from 161.7 mm³/g/hr at 34°C to 541.6 at 44°C. ATPase activity was significantly higher in animals acclimated and tested at 35°C.

     

Characterization of lactoferrin binding to the MAC-T bovine mammary epithelial cell line using a biotin-avidin technique

• 1.1. A non-radioisotopic method utilizing a biotin-avidin approach was used to characterize lactoferrin binding to the clonal MAC-T bovine mammary epithelial cell line.
• 2.2. Binding of lactoferrin to MAC-T cells and isolated membranes was specific and saturable.
• 3.3. Unlabeled lactoferrin competed for and displaced biotin-labeled lactoferrin from binding sites on mammary epithelial cells. In contrast, unlabeled transferrin did not compete.
• 4.4. Scatchard analysis of lactoferrin binding to MAC-T cell crude membranes was nonlinear, revealing two classes of binding sites with association constants (K_a) of 2.36 × 10⁷ and 3.36 × 10⁶M⁻¹.
• 5.5. Binding of lactoferrin to MAC-T cells may be associated with the initial events which result in decreased MAC-T cell proliferation.

     

Binding of meso-tetra(4-sulfonatophenyl)porphine to haemopexin and albumin studied by spectroscopy methods

• 1.1. The interaction of haemopexin and albumin with TPPS₄ was studied by measuring the absorption and fluorescence spectra. Haemopexin was found to have one strong TPPS₄ binding center (K_a = 3 × 10⁷M⁻¹).
• 2.2. Haem-haemopexin complex appears to have no specific binding site for TPPS₄. Occupation of the specific binding center of haemopexin molecule by a haem abolishes TPPS₄ binding.
• 3.3. Albumin was found to possess one strong TPPS₄ binding center (K_a = 3 × 10⁶M⁻¹) besides two or three weak binding sites (K_a = 2 × 10⁵M⁻¹).
• 4.4. Haern-albumin complex possesses only one weak TPPS₄ binding site (K_a = 7 × lO⁵M⁻¹). These observations suggest identity of primary binding sites of TPPS₄ and haem on albumin molecule.

     

Effect of temperature and salinity on the oxygen consumption of laboratory produced Penaeus californiensis postlarvae

• 1.1. The oxygen consumption by P. californiensis postlarvae (mean wt = 0.38 g) was determined at five different temperatures and four salinities.
• 2.2. The O₂ in each chamber was recorded at 10 min intervals for 1 hr. The time course of oxygen depletion was independent of O₂ concentration down to 1.6 mg/l.
• 3.3. Oxygen consumption increased with temperature from 0.0045 mg/g/min at 19°C, to 0.0142 mg/g/min at 35°C. The thermal coefficient (Q₁₀) indicated a very high sensitivity of the postlarvae to temperature variations at 19–23°C.
• 4.4. The results show that oxygen consumption significantly depends on temperature (P < 0.001) while salinity has only a marginal effect.

     

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.

     

The pH dependence of the affinity,kinetics and cooperativity of ligand binding to the root effect haemoglobin of the goldfish Carassius auratus

• 1.1. The binding of O₂ to goldfish haemoglobin showed a strong pH dependence P₅₀=5.5 mmHg; n = 2.4 at pH 8.0 and P₅₀ = 170 mmHg; n = 1.0 at pH 5.5 such that the protein is only 50% saturated in a solution of air equilibrated buffer at pH 5.5.
• 2.2. The binding of CO is cooperative at high pH (n = 2.8; L = 1000; K_R = 0.1 μM; K_T = 4 μM) and non-cooperative (n = 1) at pH 5.5.
• 3.3. The rate of O₂ dissociation is extremely fast and pH dependent; being 30 sec⁻¹ at pH 8.0 and 400 sec⁻¹ at pH 6.0 at 1°C. At 23°C the rate of this process is too fast to obtain accurate data using stopped-flow techniques.
• 4.4. Partial photolysis of the oxyhaemoglobin species leads to homogeneous recombination kinetics at pH 8.0 with an associated rate constant of 4.7 × 10⁷ M⁻¹ sec⁻¹. At pH < 7.5 the recombination process occurs in two steps. One rate is equal to that observed at pH 8.0. The slower process is favoured at low pH.
• 5.5. Photolysis of the CO haemoglobin complex indicates that, at high pH, combination of CO with deoxyhaemoglobin is cooperative, whilst recombination with Hb(CO)₃ is non-cooperative and occurs at a rate of 1.2 × 10⁶ M⁻¹ sec⁻¹.
• 6.6. At neutral pH recombination of CO with partially linganded haemoglobin occurs in a two-step process. The proportion contributed by each of these two steps in pH dependent.
• 7.7. The functioning of this Root effect haemoglobin is discussed in terms of the two state-model of cooperativity in which the αβ chain heterogeneity is minimal

     

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.

     

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.

     

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.

     

Changes in high-energy phosphate metabolism in the water scorpion,Ranatra chinensis,under cold water-warm water stress

• 1.1. To evaluate changes in high-energy phosphate metabolism in the water scorpion (Ranatra chinensis) under restraint and cold water-warm water stresses, in vivo [³¹P]NMR spectra were obtained.
• 2.2. Under restraint stress, arginine phosphate (Arg-P) decreased by 10% after 1 hr and remained at that level thereafter, while β-ATP showed negligible changes over 6 hr.
• 3.3. As the water temperature gradually increased or decreased, the relative concentration of Arg-P decreased due to enzyme regulation.
• 4.4. Repeated cold water-warm water stress, which consisted of repeated 15 min exposures to cold water (5°C) followed by 15 min exposures to warm water (30°C) caused distinct decreases in Arg-P and β-ATP concentration. These decreases were dependent on the frequency of exposure.
• 5.5. Phosphomonoesters (PME) increased not only with restraint stress but also with cold water-warm water stress.
• 6.6. The effect of cold water-warm water stress on high-energy phosphate metabolism was greater than that of restraint stress.

     

Acute toxicity and bioaccumulation of endosulfan in rotifer (Brachionus calyciflorus)

• 1.1. The acute toxicity of endosulfan was determined for the freshwater rotifer Brachionus calyciflorus.
• 2.2. The mean 24 hr lc₅₀ value for endosulfan was 5.15 ppm with a coefficient of variation of 14.7%.
• 3.3. Rotifers were exposed at two sublethal concentrations (1.5–2.0 ppm) of endosulfan for bioaccumulation experiments, for an exposure time of 24, 48, 72 and 96 hr. The rotifers were fed with Nannochloris oculata (5 × 10⁵cell/ml).
• 4.4. The highest accumulation of endosulfan was found 24 hr after the start of the exposure to 1.5 ppm of the toxicant. A steady-state concentration in rotifer was reached between 24–48 hr, followed by a gradual decrease until 96 hr.