scholarly journals High altitude genetic adaptation in Tibetans: No role of increased hemoglobin–oxygen affinity

2014 ◽  
Vol 53 (1-2) ◽  
pp. 27-29 ◽  
Author(s):  
Tsewang Tashi ◽  
Tang Feng ◽  
Parvaiz Koul ◽  
Ricardo Amaru ◽  
Dottie Hussey ◽  
...  
Keyword(s):  
High Altitude ◽  
Oxygen Affinity ◽  
Genetic Adaptation ◽  
Hemoglobin Oxygen Affinity

High Altitude Genetic Adaptation In Tibetans Does Not Include Increased Hemoglobin-Oxygen Affinity

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 937-937
Author(s):  
Tsewang Tashi ◽  
Dottie Hussey ◽  
Felipe R Lorenzo V ◽  
Parvaiz Koul ◽  
Josef T. Prchal
Keyword(s):  
High Altitude ◽  
Salt Lake ◽  
Venous Blood ◽  
Salt Lake City ◽  
Oxygen Affinity ◽  
Hill Coefficient ◽  
Genetic Adaptation ◽  
Hemoglobin Oxygen Affinity ◽  
Hemoglobin Variants ◽  
Lake City

Abstract Increased hemoglobin-oxygen affinity has been shown to be an adaptive response to hypoxia in many high altitude animals such as the Andean goose, guinea pig and llamas (Reynafarje C. 1975; Hebbel R. 1978). It has been reported that people living in a high altitude, hypoxic environment have also developed a similar adaptation. Native Tibetans are known to have lived at an average of 3000-5000 meters on the Tibetan Plateau for more than 20,000 years, and have undergone genetic adaptations that have enabled them to thrive in this reduced oxygen environment. Most Tibetans are thus protected from polycythemia and other features of chronic mountain sickness. Several studies have reported higher arterial oxygen saturations among Tibetans as part of their genetic adaptation (Beall C. 1994; Moore L. 2001; Niermeyer S. 1995), thereby concluding that they have higher hemoglobin-oxygen affinity. Further, recent genomic studies have reported that beta-globin haplotypes (HBB and HBG2) have been selected in Tibetans, suggesting the presence of hemoglobin variants as a beneficial factor of Tibetan adaptation (Yi. 2010). However, some of the reports of increased hemoglobin-oxygen affinity are based on single readings of arterial oxygen measurements. Hemoglobin-oxygen affinity is more optimally measured by deriving the P50 value, which is the partial pressure of oxygen at which hemoglobin is 50% saturated with oxygen. A decreased P50 can be due to mutated globin genes resulting in high oxygen affinity hemoglobins, low 2,3 BPG, high pH or low temperature. The hemoglobin-oxygen dissociation is optimally derived by hemoximeter measurements of the percent saturation of hemoglobin at various partial pressures of oxygen. The resultant curve has a sigmoid shape due to the cooperative binding of oxygen to the four globins in the hemoglobin tetramer; this cooperative interaction can be enumerated as a Hill coefficient “n”. If a hemoximeter is not readily available, the P50 can be estimated from the venous blood gas using the measured pO2, hemoglobin oxygen percent saturation O2%, and pH (Lichtman M. 1976); however the Hill coefficient “n” cannot be derived by this method. To definitely establish whether the Tibetan adaptation to high altitude hypoxia involves increased hemoglobin-oxygen affinity, we conducted the following study of direct and indirect oxygen-hemoglobin affinity among Tibetans living at two different altitudes. We enrolled 14 healthy ethnic Tibetans and one closely related Nepalese Sherpa. There were 8 males and 7 females ages ranging 35-75 years. The first group consisted of 5 ethnic Tibetans living in Srinagar, India (1,600 meters), on whom venous blood gases were done and the P50 was derived using pH, PO2 and O2 saturation using the formula described by Lichtman and colleagues. Three were born in Tibet and two were offspring of Tibet-born parents. The second group consisted of 10 volunteers (9 Tibetans and one Nepalese Sherpa) residing in Salt Lake City, UT, (1,300 meters) whose peripheral blood was evaluated by Hemox Analyzer for obtaining P50 values and “n” Hill coefficients for hemoglobin oxygen binding. All the ethnic Tibetans in Salt Lake City were born in Tibet except for one, and the Nepalese Sherpa was born in Nepal. The results are depicted in Table. The P50 measured by venous blood gases on the Tibetan volunteers from Srinagar, India and those measured by Hemox Analyzer on the 10 volunteers from Salt Lake City, UT were normal, with values in the normal range (22-28 mmHg). No hemoglobin variants were detected by high pressure liquid chromatography in these 15 Tibetan volunteers.TableSubject IDP50 (mmHg)“n” Hill CoefficientS 0526.38n/aS 0825.95S 1326.55S 1523.68S 2722.72U 1926.962.97U 2025.162.83U 2124.202.89U 2225.462.84U 2322.502.89U 2424.062.87U 2524.282.83U 2622.352.82U 2723.292.79U 2825.992.75 We report no evidence for the presence of high hemoglobin-oxygen affinity in Tibetans as a constituent of their genetic adaptation. Our data rule out the existence of hemoglobin variants and aberrant 2,3 BPG metabolism as possible features of Tibetan high-altitude adaptation; however acquired transient metabolic alterations at high altitudes, cannot be excluded to account for possible changes in hemoglobin-oxygen affinity but these are not evolved persistent features of Tibetan genetic adaptation. Studies of Tibetans living in these extreme hypoxic environment (>4,000m) are now planned. Disclosures: No relevant conflicts of interest to declare.

NTP pattern of avian embryonic red cells: role of RNA degradation and AMP deaminase/5′-nucleotidase activity

2003 ◽  
Vol 284 (3) ◽  
pp. R771-R779 ◽  
Author(s):  
Rosemarie Baumann ◽  
Robert Götz ◽  
Stefanie Dragon
Keyword(s):  
Hormonal Regulation ◽  
Oxygen Affinity ◽  
Erythroid Differentiation ◽  
Rna Degradation ◽  
Amp Deaminase ◽  
Key Enzymes ◽  
Allosteric Effectors ◽  
Hemoglobin Oxygen Affinity ◽  
Adult Hemoglobin

During terminal erythroid differentiation, degradation of RNA is a potential source for nucleotide triphosphates (NTPs) that act as allosteric effectors of hemoglobin. In this investigation, we assessed the developmental profile of RNA and purine/pyrimidine trinucleotides in circulating embryonic chick red blood cells (RBC). Extensive changes of the NTP pattern are observed which differ significantly from what is observed for adult RBC. The biochemical mechanisms have not been identified yet. Therefore, we studied the role of AMP deaminase and IMP/GMP 5′-nucleotidase, which are key enzymes for the regulation of the purine nucleotide pool. Finally, we tested the effect of major NTPs on the oxygen affinity of embryonic/adult hemoglobin. The results are as follows. 1) Together with ATP, UTP and CTP serve as allosteric effectors of hemoglobin. 2) Degradation of erythroid RNA is apparently a major source for NTPs. 3) Developmental changes of nucleotide content depend on the activities of key enzymes (AMP deaminase, IMP/GMP 5′-nucleotidase, and pyrimidine 5′-nucleotidase). 4) Oxygen-dependent hormonal regulation of AMP deaminase adjusts the red cell ATP concentration and therefore the hemoglobin oxygen affinity.

Exchange transfusion in the newborn infant with fresh and “old” blood: The role of storage on 2,3-diphosphoglycerate, hemoglobin-oxygen affinity, and oxygen release

1971 ◽  
Vol 79 (6) ◽  
pp. 898-903 ◽  
Author(s):  
Maria Delivoria-Papadopoulos ◽  
Grant Morrow ◽  
Frank A. Oski ◽  
Richard Cohen ◽  
Patricia O'Neal
Keyword(s):  
Newborn Infant ◽  
Exchange Transfusion ◽  
Oxygen Affinity ◽  
Oxygen Release ◽  
Hemoglobin Oxygen Affinity

scholarly journals Engineering Ascaris hemoglobin oxygen affinity in sperm whale myoglobin: role of tyrosine B10

FEBS Letters ◽  
1994 ◽  
Vol 352 (1) ◽  
pp. 63-66 ◽  
Author(s):  
Carlo Travaglini Allocatelli ◽  
Francesca Cutruzzolà ◽  
Andrea Brancaccio ◽  
Beatrice Vallone ◽  
Maurizio Brunori
Keyword(s):  
Oxygen Affinity ◽  
Sperm Whale ◽  
Hemoglobin Oxygen Affinity ◽  
Sperm Whale Myoglobin
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