Enzymatic flux capacities in hummingbird flight muscles: a "one size fits all" hypothesis

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dc.contributor.authorFernandez, M. J.
dc.contributor.authorBozinovic, F.
dc.contributor.authorSuarez, R. K.
dc.date.accessioned2025-01-20T23:59:59Z
dc.date.available2025-01-20T23:59:59Z
dc.date.issued2011
dc.description.abstractHummingbirds (family Trochilidae) are among the smallest endothermic vertebrates representing an extreme, among birds, in their physiological design. They are unique in their ability to sustain hovering flight, one of the most energetically demanding forms of locomotion. Given that hovering metabolic rate (HMR) in hummingbirds scales allometrically as M-0.78 (M is mass), we tested the hypothesis that variation in HMR may be correlated with variation in maximal enzyme activities (V-max values) of key enzymes in glucose and fatty acid oxidation pathways in the flight muscles of four species of hummingbirds ranging in body mass from 4 to 20 g. We also estimated metabolic flux rates from respirometric data obtained during hovering flight. The data are striking in the lack of correlation between V-max values and flux rates at most steps in energy metabolism, particularly at the hexokinase and carnitine palmitoyltransferase reactions. In the context of hierarchical regulation analysis, this finding suggests that metabolic regulation (resulting from variation in substrate, product, or allosteric regulator concentrations) dominates as the proximate explanation for the interspecific variation in flux. On the other hand, we found no evidence of hierarchical regulation of flux, which results from variation in V-max and is based on variation in enzyme concentration [E]. The evolutionary conservation of pathways of energy metabolism suggests that "one size fits all" among hummingbirds.
dc.fuente.origenWOS
dc.identifier.doi10.1139/Z11-074
dc.identifier.eissn1480-3283
dc.identifier.issn0008-4301
dc.identifier.urihttps://doi.org/10.1139/Z11-074
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/95319
dc.identifier.wosidWOS:000297023100013
dc.issue.numero10
dc.language.isoen
dc.pagina.final991
dc.pagina.inicio985
dc.revistaCanadian journal of zoology
dc.rightsacceso restringido
dc.titleEnzymatic flux capacities in hummingbird flight muscles: a "one size fits all" hypothesis
dc.typeartículo
dc.volumen89
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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