June 2020
Vol 6, Issue 25

About The Cover

Cover image expansion

ONLINE COVER Most bovids (members of the cattle family) express a fetal hemoglobin isoform with higher oxygen affinity than the adult isoform, which maintains a difference in oxygen affinity that facilitates oxygen transfer across the placenta from mother to fetus. However, most bovids wouldn't be able to match the feats of the Tibetan antelope, which can sustain running speeds of more than 70 kilometers per hour over distances of greater than 100 kilometers, at altitudes where the partial pressure of oxygen is roughly half that at sea level. To investigate whether and how the Tibetan antelope evolved to express this early hemoglobin isoform into adulthood, Signore and Storz characterized the genomic organization of globin genes in Tibetan antelope and other bovids using published genome assemblies. Next, the researchers estimated how different forms of the β-globin gene influenced bovid evolutionary history, finding that the Tibetan antelope inherited the same three-part β-globin genes as goats and sheep, with the middle gene block containing βA (which corresponds to juvenile hemoglobin) later deleted. Through in vitro experiments, Signore and Storz confirmed that Tibetan antelope hemoglobin does, in fact, have a much higher oxygen affinity than that of all other bovids. [CREDIT: XI ZHINONG/MINDEN]