Structural Comparison of Polymorphic Hemoglobins of Deer with Those of Sheep and Other Species

The genetic basis and evolution of red blood cell sickling in deer

Crescent-shaped red blood cells, the hallmark of sickle-cell disease, present a striking departure from the biconcave disc shape normally found in mammals. Characterized by increased mechanical fragility, sickled cells promote haemolytic anaemia and vaso-occlusions and contribute directly to disease in humans. Remarkably, a similar sickle-shaped morphology has been observed in erythrocytes from several deer species, without obvious pathological consequences. The genetic basis of erythrocyte sickling in deer, however, remains unknown. Here, we determine the sequences of human β-globin orthologues in 15 deer species and use protein structural modelling to identify a sickling mechanism distinct from the human disease, coordinated by a derived valine (E22V) that is unique to sickling deer. Evidence for long-term maintenance of a trans-species sickling/non-sickling polymorphism suggests that sickling in deer is adaptive. Our results have implications for understanding the ecological regimes and molecular architectures that have promoted convergent evolution of sickling erythrocytes across vertebrates.

Studies on the blood of fallow deer (Dama dama) and red deer (Cervus elaphus): haematology, red cell enzymes, metabolic intermediates and glycolytic rates

1. Blood samples were obtained from fallow deer (Dama dama) and red deer (Cervus elaphus). Basic haematology, red cell enzymes, and metabolic intermediates and the glycolytic rate of the red cells incubated with different substrates were measured. 2. The major findings were (i) the activity of glucose phosphate isomerase was notably high in the red blood cells of the red deer; (ii) red deer cells also utilized adenosine more efficiently than those of fallow deer and (iii) red cells of both species utilized galactose more efficiently than other species of ruminants.

Multiple hemoglobin alpha-chains in the sika deer (Cervus nippon)

Investigation of the hemoglobin alpha-chains of an Asiatic deer, the sika (Cervus nippon), was prompted by the heterogenity of alpha-chain gene loci in the Virginia white-tailed deer (Odocoileus virginianus). Although electrophoresis of hemoglobin chains from 10 sika revealed only a single alpha-chain band, peptide mapping demonstrated variations in the alpha-TPIII and alpha-TPIV peptides. Substitutions at positions 15, 20, and 22 produced a minimum of five alpha-chains; two possible additional chains could noy be proven because of inseparability of the whole alpha-chains. The most common chain contains Asp-15, Lys-20 and Pro-22 but in other chains glycine is present at position 15, Asx at position 20, and either serine or Asx at position 22. The probable explanation for the large number of alpha-chains is gene duplication which may have been produced by breedings between subspecies from different geographical areas. Comparison with the alpha-chain structure of the white-tailed deer suggests that the sika may have evolved from the lineage which produced the white tailed-deer after the alpha-chain genes of the latter species had duplicated. In addition, these data provide further examples of the unusual variability of this portion of the alpha-chain.

A comparative study of haemoglobins from the Artiodactyla by isoelectric focusing

1. Isoelectric focusing on 7% acrylamide gels in 2% ampholyte of pH range 6-8 was used to fractionate the haemoglobins of 81 animals, representing 30 species from 4 families of the Order Artiodactyla. 2. Isoelectric points of the major haemoglobins were determined and the relative distribution of minor haemoglobins compared. 3. Marked haemoglobin heterogeneity was observed, with polymorphic and multiple haemoglobins. No one haemoglobin was common to all species.