Oxygen equilibria studies of the hemoglobins from normal and anemic sheep and goats

Hemoglobin C in Newborn Sheep and Goats: A Possible Explanation for its Function and Biosynthesis

“…The gradual decrease in oxygen affinity (indicated by a steady increase in the P,, values from 26.5 m m H g on day 5 to approximately 36 mm H g on day 42), followed by a slow decrease to values approaching those observed in adult goats, corresponds remarkably to the disappearance of Hb-F (complete after 40 days), the increase in P C containing hemoglobins (maximal between 40 and 50 days after birth) and the gradual replacement of P C containing hemoglobins by PA containing hemoglobins. This correlation becomes even more apparent from our recent observation [28] that the oxygen affinity of blood from severely anemic goats, with 100 % P C containing hemoglobin types, is significantly decreased, while the Bohr effect is moderately increased. It appears that the large production of PC containing hemoglobin types in this animal species during the first 3 months after birth is directly responsible for the observed change in functional properties.…”

“…This protein may be the same as the ESF inhibitor observed by others [16, 30, 311. Assuming that a n activation-inhibition mechanism does operate in both animal species, it appears that the greater sensitivity for PC production in the goat could be due to a relative deficit in the formation of the feedback inhibitor in this animal. The absence of a large production of PC chain-containing hemoglobin in sheep during the postnatal period may be explained, in part, by the difference observed between the oxygen affinities of sheep hemoglobin C, which is similar to that of sheep hemoglobin A, and of goat hemoglobin C, which is considerably less than that of goat hemoglobin A a t physiological p H values [28,431. These observations would imply that the production ofhemoglobin C during the newborn period would be of no advantage to the newborn lamb, in contrast to the newborn kid.…”

“…A partial activation of this Hbpc gene will complicate the hemoglobin heterogeneity of these animals; a moderately anemic goat with a heterozygosity for the H b p~ allele will produce six distinct hemoglobin types (table IB). Oxygen dissociation curves of blood samples in uitro obtained from normal and anemic goats haveshown that Hb-C chaincontaining red blood cells of the anemic goat exhibit a decreased affinity for molecular oxygen with a concurrent increase in the Bohr effect [28].…”

Tolerance to Tick-Borne Diseases in Sheep: Highlights of a Twenty-Year Experience in a Mediterranean Environment

“…Anaemia causes a change in the type of circulating haemoglobin only in sheep carrying A-globin haplotype, where Hb A is replaced by Hb C. Pioneered by the work of van Vliet and Huismam (1964), the Hb C in Caprini species has been thoroughly studied and particularly the mechanism of reversible switching has triggered focused research in the 70's (Nienhuis and Anderson, 1972;Nienhuis and Bunn, 1974). Little information is available on the effect of Hb A replacement by Hb C. Owing to the high oxygen affinity of Hb C (Huisman and Kitchens, 1968), the reversible switch from Hb A to Hb C may be considered a way to cope with the reduced amount of oxygen available at higher altitudes and thus suggest a positive effect on the fitness of mountain Caprini. Conversely, in the case of erythropoietic stress, it was suggested (Pieragostini et al, 1994;Pieragostini et al, 2006) that Hb C might negatively affect peripheral oxygen delivery and worsen the clinical picture of sheep breeds native of areas with endemic haemotropic pathogens.…”

Effect of Hormone-Induced Premature Parturition on Hemoglobin Switching in Sheep

“…In the two lambs of the PA genotype 7-globin synthesis ceased but there was expression of the PC gene at abnormally high levels for an abnormally long period of time. It is of interest that the order of decreasing oxygen affinity of sheep Hb is Hb-F, Hb-Ac, H~-AB, and Hb-AA (31). Thus the premature lambs all expressed a Hb of higher than normal oxygen affinity in the perinatal period.…”