O2-binding by the blood of the landhopper,Arcitalitrus dorrieni (Hunt) (Crustacea: Amphipoda)

• 1.1. The O₂-binding characteristics of the blood of the euterrestrial amphipod (landhopper) Arcitalitrus dorrieni have been studied.
• 2.2. The blood exhibited a low O₂ affinity, with a p₅₀ (at pH = 7.8) of 21.4 torr (10°C). Affinity decreased with an increase in temperature at constant pH (ΔH = − 79.4kJ/mol) but the Bohr factor (ΔlogP₅₀/Δ pH = −0.67) was unaffected.
• 3.3. The O₂-carrying capacity of the blood was moderate (1.51 ml/100 ml)
• 4.4. The results support the hypothesis that the blood of terrestrial amphipods is characterized by having a low affinity pigment.

     

Oxygen binding of intact coelomic cells and extracted hemoglobin of the echiuran Urechis caupo

• 1.1. The oxygen affinity of Urechis caupo coelomic cells is the same in normoxic and in hypoxic animals. There is no Bohr effect between pH 6.8 and 8.0.
• 2.2. The oxygen affinity of intact coelomic cells is the same as that of extracted, stripped hemoglobin. The oxygen binding properties of stripped hemoglobin are not affected by 1 mM ATP, IMP, or hydrogen ions between pH 6.8 and 8.0, nor do they clearly show cooperativity. The heat of oxygenation. ΔH, = −13.1 kcal/mol between 10 and 25 C.
• 3.3. Although U. caupo coelomic cell hemoglobin is tetrameric and intracellular, it apparently exhibits neither heterotropic nor homotropic interactions.

     

Respiration in the eastern water dragon,Physignathus lesueurii (agamidae)

• 1.1. Some aspects of the gas exchange system of a diving lizard, Physignathus lesuewii were studied.
• 2.2. Breathing patterns were analysed.
• 3.3. Breathing rate increases logarithmically with temperature and Q₁₀ = 1.8. LogBR = −0.237 + 0.0256 T.
• 4.4. Gas tensions in lung air and arterial and venous blood were measured. Arterial pH declines with increasing temperature.
• 5.5. Temperature has a marked effect on oxygen affinity of the blood (ΔH = −10.1 kcal mol⁻). A Bohr effect was also noted.
• 6.6. CO₂ equilibrium curves were drawn.
• 7.7. The results are considered with a view to anticipating the efficiency of the gas exchange system of this species under conditions of variable temperature and during diving.

     

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.

     

A comparative study of the respiratory properties and physiological function of haemocyanin in two burrowing and two non-burrowing crustaceans

• 1.1. Oxygen dissociation curves were constructed for the haemolymph of two non-burrowing, Galathea strigosa and Eupagurus bernhardus, and two burrowing crustaceans, C. cassivelaunus and Nephrops norvegicus. The p₅₀ at in vivo pH values and 10°C was 12.6 Torr in G. strigosa, 23 Torr in E. bernhardus, 3.1 Torr in C. cassivelaunus and 11.5 Torr in N. norvegicus.
• 2.2. The Bohr values (Δlogp₅₀/ΔpH) were high in all species ranging between −0.96 and −1.48. Cooperativity expressed as P₅₀ averaged 3.3, 3.8 and 3.8 in G. strigosa, E. bernhardus and N. norvegicus. respectively. A lower value of 2.2 was observed in C. cassivelaunus.
• 3.3. The oxygen affinity of the haemocyanin was relatively temperature independent, the values for ΔH at pH7.9 ranging between −5.1 and −18.1 kJmol⁻¹.
• 4.4. Haemolymph respiratory gas analysis showed values similar to those previously reported in crustaceans: p_aO₂ ranging between 44 and 107 Torr and p_vO₂ values between 18 and 24 Torr.
• 5.5. Pre-/post-branchial pH differences were small in G. strigosa, E. bernhardus and N. Norvegicus, but averaged 0.09 of a pH unit in C. cassivelaunus. p_aCO₂ and P_vCO₂ values ranged between 1.4 and 2.3 Torr.
• 6.6. In buried C. cassivelaunus both pre- and post-branchial oxygen tensions decreased, as did oxygen tension overall during respiratory pauses.
• 7.7. Cardiac output values were low, ranging between 59 and 71 ml kg⁻¹ min⁻¹ for all four species and calculated stroke volumes were realistic in terms of animal size.
• 8.8. In the non-burrowing species physically dissolved oxygen accounted for 5–21% of the oxygen transported to the tissues. In the burrowing species values of 40–77% were found.

     

Characterization of hemoglobin from Phoronis architecta (phoronida)

• 1.1. Phoronis architecta hemoglobin is composed of four distinct hemoglobin subunits with minimum MW's of 16–17,000 or 17–19,000 daltons. All four hemoglobins are monomeric when oxygenated. Two of the monomers combine to form dimers when bound with carbon monoxide.
• 2.2. In cellulo, Phoronis architecta hemoglobin has a half-saturation (P₅₀) value of 1.3 ± 0.1 mm Hg, shows cooperative oxygen binding (Hill coefficient = 2.7 ± 0.3), and no Bohr effect from pH 6.6 to 7.9. In vitro, the hemoglobin has a P₅₀ of 0.76 ± 0.21 mm Hg but shows no cooperativity (0.90 ± 0.15 (SD)).
• 3.3. The oxygen dissociation constant (K_off) from hemoglobin is 2.7 ± 0.2 sec⁻¹, and the computed oxygen association constant (K_on) is 2.5 × 10⁶ M⁻¹ · sec⁻¹ (1.9–3.6 × 10⁶ M⁻¹ · sec⁻¹).

     

Functional properties of the two major hemoglobin components from Leporinus friderici (Pisces)

• 1.1. The hemoglobins of Leporinus friderici were separated by liquid chromatography on DEAE-Sepharose in order to isolate the two major electrophoretic components.
• 2.2. The chromatographic fraction I (electrophoretically slow anodic) showed no Bohr effect and no nucleoside triphosphate modulation.
• 3.3. The chromatographic fraction III (electrophoretically fast anodic) showed a normal Bohr effect and addition of nucleoside triphosphate decreased oxygen affinity but did not alter the Bohr effect.
• 4.4. The whole hemolysate showed a normal Bohr effect and phosphate modulation altered both Bohr effect and oxygen affinity.
• 5.5. No or little difference between the effect of adenosine or guanosine triphosphates on hemoglobin function was observed.

     

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.

     

Haemoglobin in male Daphnia magna

• 1.1. To define the respiratory function of haemoglobin in male Daphnia magna, the swimming activity, the depression of oxygen uptake by treatment with carbon monoxide and in vivo oxygenation of Hb at various oxygen pressures were investigated.
• 2.2. The P₅₀, values for the purified Hbs from male and female red animals were 2.0 and 2.7 torr in 0.1 M phosphate buffer (pH 7.2) at 20°C, respectively.
• 3.3. The isoelectric focusing patterns of the purified Hbs from male and female red animals showed only small differences in Hb components of high PI values.

     

Kinetics of oxygen and carbon monoxide binding to the hemoglobins of the water snakes Liophis miliaris and Helicops modestus

• 1.1. Liophis miliaris and Helicops modestus are water snakes having different respiratory adaptiations to their specific habitats. L. miliaris is more active and spends more time on land than H. modestus. Knowledge of the equilibrium and kinetics of ligand binding to their hemoglobins leads to better understanding of molecular aspects of this adaptation.
• 2.2. Both snakes contain several hemoglobin types in their blood. Studies on the kinetics of oxygen dissociation and carbon monoxide combination with these hemoglobins were performed by stopped-flow and flash-photolysis experiments at various pH values, both in the presence and absence of adenosine triphosphate.
• 3.3. The oxygen dissociation kinetics of L. miliaris hemoglobins show a strong pH dependence and cooperative interactions between chains are indicated by autocatalytic time-courses at pH 7.0. In contrast, H. moledstus hemoglobins show nearly pH independent rate constants for oxygen dissociation and cooperative interactions between chains were not apparent. The hemoglobins of H. modestus show increased pH dependence in the presence of adenosine triphosphate.
• 4.4. The carbon monoxide combination kinetics differ for the hemoglobins of L. miliaris and H. modestus in general agreement with the differences found in the kinetics and equilibria of oxygen binding. Both the kinetic and steady-state difference between these hemoglobins may be advantageous in light of the behavioral differences of these two water snakes.

     

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

     

The dynamics of the permeation of an analogue of insect juvenile hormone into nematodes

• 1.1. ¹⁴C-dichlorofarnesoate permeated rapidly into Haemonchus contortus (infective juveniles) and Panagrellus redivivus (mixed cultures) and was strongly bound by hydrophobic association (K_s > 10⁻⁴M).
• 2.2. Uptake rose linearly with increases in temperature (5–38°C) and external concentration (C₀; 0.07–2.15 × 10⁻⁴ M). Within 1 hr the internal concentration, C₁ was >C C₀.
• 3.3. The pH of the medium (6–8) did not affect uptake.
• 4.4. Efflux of dichlorofarnesoate was low: the half-time of release was > 18 hr.
• 5.5. The uptake curve approximated to the expression C₁/C₀ = a(1 − e^−bt) with a and b as constants and t in hr.
• 6.6. These results clarify previous work on the inhibitory action of juvenile hormone on the development of nematodes.

     

Ionic currents of an identifiable giant neurone,d-rpln,of an african giant snail (Achatina fulica férussac), measured under voltage clamping—i. inward currents

• 1.1. The ionic currents of d-RPLN (dorsal-right parietal large neurone), one of the largest neurones identified in the suboesophageal ganglia of an African giant snail (Achalina fulica Ferussac), were measured under voltage clamping.
• 2.2. The present study concerns the inward currents. The electrical properties of the d-RPLN neuromembrane were: −57.8 ± 0.84 mV for the resting membrane potential (N = 79) expressed as M ± SE,
• 3.2.57 ± 0.13 MΩ for the membrane resistance (N = 12) and 48.85 ± 2.96 nF for the membrane capacitance (N = 12).
• 4.3. The maximal peak values of the inward currents in the physiological state, obtained at the command voltage (Vc)= −10mV, were: −1.02±0.06μA at the holding voltage (Vh) = −50mV and −0.98 ± 0.06 μA. at Vh = −60 mV. The peak time values of the currents at Vc = −10 mV were about 3–4 msec.
• 5.4. The outward current blocking agents, quinine (Q), at a concentration of 1.0 mM, reduced the peak inward current values and delayed their peak time, whereas tetraethylammonium chloride (TEA) at 25.0 mM and 4-aminopyridine (4-AP) at 5.0 mM were quite ineffective. Q at 0.25 mM hardly affected the same currents at all.
• 6.5. With the perfusion of the solution containing TEA at 25 mM, 4-AP at 5 mM and Q at 0.25 mM, the outward currents were reduced so that they are much smaller; the maximal peak values of calcium current (Ica), sodium current (Ina) and total inward current (Iin), which would be the sum of Ica and Ina (all were N = 4), obtained at Vc = −10 mV, were: −0.92 ± 0.05 μA for Ica, −0.30 ± 0.03 μA for Ina and −1.27±0.17μA for Iin.
• 7.6. The ratio of the maximal peak values of Ica and Ina of the neurone was about 3 to 1.
• 8.7. Tetrodotoxin at 0.1 mM completely blocked Ina of d-RPLN, whereas this substance at the same concentration had no effect on Ica.

     

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.

     

The dependence of oxygen consumption of the common whelk (Buccinum undatum) on hypoxia,salinity and air exposure

• 1.1. Oxygen consumption of low salinity (20‰) acclimated whelks decreases markedly upon acute exposure to hypoxia (P_WO₂ = 35 Torr), but almost regenerates its original level within 48 hr exposure to the hypoxic condition.
• 2.2. This ability to regain the original level of oxygen consumption is not seen in high salinity (35‰) acclimated whelks.
• 3.3. Oxygen consumption in air at 10°C is more than twice the rate shown by low salinity acclimated whelks in normoxic water (P_WO₂ = 150 Torr).
• 4.4. Q₁₀ for oxygen consumption in air is about 1.0 in the temperature range 10–20°C.

     

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.

     

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.

     

Lysosomal acid deoxyribonuclease from vervet monkey livers—II: Enzymic properties

• 1.1. Primate liver lysosomal acid DNase is an endonucleolytic enzyme.
• 2.2. The enzyme has both 3'- and 5'-nucleotidohydrolase activities.
• 3.3. The oligonucleotides produced by DNase are polymers mainly about 30 mononucleotides long.
• 4.4. The Arrhenius plot shows a discontinuity with a transition temperature at 47°C, with an activation energy of 107 kJ/mol below and 67 kJ/mol above this temperature.
• 5.5. The activation enthalpy is 104kJ/mol and the entropy −0.498 kJ/mol/K.
• 6.6. The enzyme is subject to substrate inhibition and the K_m value is 159 × 10⁻³mM DNA-P.

     

Responses of channel catfish (Ictalurus punctatus) swim-up fry to dietary calcium in soft and hard water

• 1.1. Responses of channel catfish (Ictalurus punctatus) swim-up fry to dietary calcium in soft (< 1 mg/1 as CaCO₃) and hard (> 100 mg/1 as CaCO₃) water were determined by feeding purified egg-white diets containing 0, 0.5, 1.0, or 2.0% calcium from CaCO₃ for 8 weeks.
• 2.2. Catfish fry fed the basal diet (0.03% Ca) in hard and soft water had lower whole-body ash and whole-body calcium concentrations but higher weight gain and survival than those fed calcium-supplemented diets.
• 3.3. Fry in soft water generally had lower whole-body ash, whole-body calcium, and survival, as well as a higher incidence of spinal deformities than fry in hard water.
• 4.4. Feeding higher levels of calcium to fry reared in soft water did not increase whole-body calcium levels or decrease spinal deformities to the levels observed for fry reared in hard water and fed supplemental calcium.
• 5.5. These data indicate that calcium derived solely from dietary or environmental sources was not sufficient for optimum health of channel catfish fry.