1. Cardiac adaptations to high altitude in bar-headed geese.
Cardiac adaptations to high altitude in bar-headed geese. (A) Capillary density is enhanced in the hearts (left ventricle) of bar-headed geese compared with low-altitude geese. Insets are representative images of capillary staining in bar-headed geese (left), pink-footed geese (centre) and barnacle geese (right). Scale bar, 100 μm. (B) Cytochrome c oxidase (COX) from the hearts of bar-headed geese has a different maximal activity (lower Vmax) and substrate kinetics (lower Km for cytochrome c [Fe2+], cytochrome c in its reduced state) than COX from the two species of low-altitude geese. Asterisk represents a significant difference from both low-altitude species. (C) COX subunit 3 (COX3) of bar-headed geese contains a single amino acid mutation at a site that is otherwise conserved across all vertebrates (Trp-116 to Arg) and is predicted by structural modeling to alter the interaction between COX3 and COX1. Modified from Scott et al. (Scott et al., 2011).
Graham R. Scott J Exp Biol 2011;214:
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