Oxygen affinity of human and rat hemoglobins after heating the blood outside the body

The affinity of hemoglobin to oxygen increases in some rats and decreases in others after the blood warming at 45 degrees C during 5 min. After 60 min of blood warming the affinity decreases in all animals. Such reaction was not observed in human blood. These changes of hemoglobin are regarded as indirect nonspecific reaction.     

Oxygen affinity of blood in rats during cobalt-induced erythrocytic polycythemia and after its correction

Erythrocytic polycythemia in rats was produced by chronic injections of cobalt chloride. At the peak of polycythemia, i.e. after eleven weeks of cobalt injections, the P₅₀ decreased from the original, normal values 36.3 torr to 33.0 torr. Four weeks after the cessation of cobalt injection the hemoglobin concentration remained still relatively high and an additional decrease of P₅₀ to 31.0 torr was observed. Further development was characterized by a gradual return of both P₅₀ and hemoglabin levle toward the normal values.     

Oxygen affinity of the respiratory chain of Acanthamoeba castellanii.

Apparent Km values for O2 for the soil amoeba Acanthamoeba castellanii determined polarographically and by bioluminescence gave similar values (0.37 and 0.41 microM respectively). Mitochondria oxidizing succinate or NADH in the presence or absence of ADP gave values in the range 0.21-0.36 microM-O2. Oxidation of respiratory-chain components to 50% of the aerobic steady states in intact cells was observed at the following O2 concentrations: cytochrome aa3, 0.1-0.25 microM; cytochrome c, 0.3-0.6 microM; cytochrome b, 0.35-0.45 microM; flavoprotein, 2 microM. In isolated mitochondria corresponding values for a-, c- and b-type cytochromes were 0.007, 0.035-0.05 and 0.06-0.09 microM-O2. It is concluded that an O2 gradient exists between plasma membrane and mitochondria in A. castellanii.     

Oxygen affinity of red cells hemolysates of different hen breeds

Summary Oxygen affinity and number of -SH groups of hemoglobins have rather constant values for hens belonging to Leghorn, Whiterock, Rhode Island Red, Sussex and Cornish breeds, and for hybrids between Rhode Island Red and Leghorn, irrespective of the breed. Number of -SH groups in red cell hemolysates amounts to 8 per mole Hb (7,88 – 8,48) , logp₅₀=1,04–0,94; value of n for Leghorns is 1,70, for Whiterocks 2,80.This work was performed within the project 09.3.1 of Polish Academy of Sciences.     

Comparison of biochemical polymorphisms in mouflon and sheep: isoelectric differences in haemoglobins and quantitative variation of mouflon haemopexin

1. Of ten protein systems studied in mouflon (Ovis musimon), five were polymorphic (Tf, Hpx, EsA, X-protein, Cat). Electrophoretic mobilities of mouflon proteins did not differ from those of sheep. 2. Mouflon haemoglobin B and sheep haemoglobin B differed in isoelectric focusing. 3. Haemopexin levels in mouflon were determined by rocket immunoelectrophoresis. A trimodal distribution was apparent, with no haemopexin, low and high levels of the protein. The results are indicative of genetic control of haemopexin levels, one of the alleles being inactive (Hpx0).     

Kinetics of the ontogenic and reversible hemoglobin switching in the mouflon (Ovis musimon) and sheep x mouflon hybrid.

1. Hemoglobin (Hb) switching in the perinatal life of wild mouflon (Ovis musimon) was characterized by the replacement of Hb F by 60% levels of Hb C, and subsequently of Hb C by Hb B. 2. The recently discovered Hb M variant was not replaced by Hb C; thus, Hb BM heterozygote newborns synthesized 30% Hb C at the expense of Hb B. 3. Hybrid B mouflon x B sheep synthesized only 5% Hb C at birth but were able to produce 30% Hb C in adult life following induced anemia. 4. Adult BB and BM mouflons, after the same extent of induced anemia, synthesized HB C levels similar to those produced at birth. The results indicate a mouflon beta-globin gene cluster arrangement similar to those of sheep and goat, the beta C gene having an intermediate expression. Results also suggest a selective disadvantage in hybrid animals.     

Oxygen affinity of bovine haemoglobin. Relevance of electrostatic and hydrophobic interactions

We have studied the effects of organic cosolvents (monohydric alcohols and formamide) on the oxygen equilibrium of bovine haemoglobin and have compared them with the effects of the same cosolvents on the oxygen equilibrium of human haemoglobin. Our results indicate: (1) that in agreement with previous suggestions, the lower affinity of bovine haemoglobin for oxygen is not due to an increased number of salt bridges stabilizing the T structure; (2) that, following T----R transition, more hydrophobic surface is exposed to the solvent by bovine than by human haemoglobin. We suggest, therefore, that a relevant role in keeping the oxygen affinity of bovine haemoglobin lower than that of human haemoglobin is played by the higher free energy needed to expose this more hydrophobic surface to the solvent. We stress, however, that our analysis does not enable us to say which particular amino acid residues are concerned in these effects.     

Monitoring the abundance of mouflon in South France

Monitoring change in the population size of mouflon (Ovis gmelini musimon × Ovis sp.) in rugged areas is an important yet difficult task for wildlife ecologists. To assess population change of mouflon inhabiting the Caroux-Espinouse massif, France, we compared a pedestrian and helicopter survey, using counts of animals as indices of abundance. Environmental factors such as date of survey and temperature affected the detection of mouflons from the ground and the air. Both indices were sensitive to observed changes in population size. A decrease in the pedestrian index was recorded in 1994, the year following an epizootic of keratoconjunctivitis, which markedly reduced the survival rate of mouflon. Variations in pedestrian index accounted for variations in harvests when excluding epizootic events. Both surveys detected a decrease in population size, which accounted for the recent increase of harvest. Helicopter and pedestrian surveys are reliable tools to monitor annually mouflons in mountainous areas. Simulations indicated that helicopter surveys should be preferred by managers because they provide the best trade-off between cost and precision.     

Oestrid myiasis in European mouflon from Spain

From February 1992 to March 1997, 245 European mouflon (Ovis orientalis musimon) from Sierras de Cazorla, Segura y Las Villas Natural Park (southern Spain) were surveyed for oestrid larvae in order to estimate prevalence and mean intensity of parasitism by Oestrus ovis. Over 46 percent of the animals surveyed were infected, with a mean intensity of 9.6 larvae/host parasitized. No significant differences in prevalence rates between host sexes were observed, but older mouflons were infected with more larvae than younger ones.     

Oxygen dissociation of whole blood studied polarographically

The polarographic current of whole blood is in excess of that given by plasma at the same oxygen tension. The magnitude of this difference depends on (a) the oxygen content of the sample and thus is determined by the red blood cell content and by the state of oxygen saturation of hemoglobin, and (b) on the rate of dissociation of oxyhemoglobin and therefore is influenced by changes in pH, pCO₂, and temperature. The total current at 37°C. is proportional to the oxygen content of the sample and can be used to determine the latter. The theoretical basis of the studied phenomena is discussed in detail.     

Oxygen affinity and amino acid sequence of myoglobins from endothermic and ectothermic fish

Myoglobin (Mb) buffers intracellular O2 and facilitates diffusion of O2 through the cell. These functions of Mb will be most effective when intracellular PO2 is near the partial pressure of oxygen at which Mb is half saturated (P50) of the molecule. We test the hypothesis that Mb oxygen affinity has evolved such that it is conserved when adjusted for body temperature among closely related animals. We measure oxygen P50s tonometrically and oxygen dissociation rate constants with stopped flow and generate amino acid sequence from cDNA of Mbs from fish with different body temperatures. P50s for the endothermic bluefin tuna, skipjack tuna, and blue marlin at 20 degrees C were 0.62 +/- 0.02, 0.59 +/- 0.01, 0.58 +/- 0.04 mmHg, respectively, and were significantly lower than those for ectothermic bonito (1.03 +/- 0.07 mmHg) and mackerel (1.39 +/- 0.03 mmHg). Because the oxygen affinity of Mb decreases with increasing temperature, the above differences in oxygen affinity between endothermic and ectothermic fish are reduced when adjusted for the in vivo muscle temperature of the animal. Oxygen dissociation rate constants at 20 degrees C for the endothermic species ranged from 34.1 to 49.3 s(-1), whereas those for mackerel and bonito were 102 and 62 s(-1), respectively. Correlated with the low oxygen affinity and fast dissociation kinetics of mackerel Mb is a substitution of alanine for proline that would likely result in a more flexible mackerel protein.