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  • The Company of Biologists  (5)
  • 1
    Online Resource
    Online Resource
    Mitochondrial physiology in the skeletal and cardiac muscles is altered in torrent ducks, Merganetta armata , from high altitudes in the Andes
    The Company of Biologists ; 2016
    In:  Journal of Experimental Biology
    Details
    In: Journal of Experimental Biology, The Company of Biologists
    Abstract: Torrent ducks inhabit fast-flowing rivers in the Andes from sea level to altitudes up to 4,500 m. We examined the mitochondrial physiology that facilitates performance over this altitudinal cline by comparing the respiratory capacities of permeabilized fibers, the activities of 16 key metabolic enzymes, and the myoglobin content in muscles between high- and low-altitude populations of this species. Mitochondrial respiratory capacities (assessed using substrates of mitochondrial complexes I, II, and/or IV) were higher in highland ducks in the gastrocnemius muscle – the primary muscle used to support swimming and diving – but were similar between populations in the pectoralis muscle and the left ventricle. The heightened respiratory capacity in the gastrocnemius of highland ducks was associated with elevated activities of cytochrome oxidase, phosphofructokinase, pyruvate kinase, and malate dehydrogenase (MDH). Although respiratory capacities were similar between populations in the other muscles, highland ducks had elevated activities of ATP synthase, lactate dehydrogenase, MDH, hydroxyacyl coA dehydrogenase, and creatine kinase in the left ventricle, and elevated MDH activity and myoglobin content in the pectoralis. Thus, while there was a significant increase in the oxidative capacity of the gastrocnemius that correlates with performance at high altitudes, the variation in metabolic enzyme activities in other muscles not correlated to respiratory capacity, such as the consistent up-regulation of MDH activity, may serve other functions that contribute to success at high altitudes.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.142711
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2016
    detail.hit.zdb_id: 1482461-9
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Respiratory mechanics of eleven avian species resident at high and low altitude
    The Company of Biologists ; 2017
    In:  Journal of Experimental Biology Vol. 220, No. 6 ( 2017-03-15), p. 1079-1089
    Details
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 220, No. 6 ( 2017-03-15), p. 1079-1089
    Abstract: The metabolic cost of breathing at rest has never been successfully measured in birds, but has been hypothesized to be higher than in mammals of a similar size because of the rocking motion of the avian sternum being encumbered by the pectoral flight muscles. To measure the cost and work of breathing, and to investigate whether species resident at high altitude exhibit morphological or mechanical changes that alter the work of breathing, we studied 11 species of waterfowl: five from high altitudes ( & gt;3000 m) in Perú, and six from low altitudes in Oregon, USA. Birds were anesthetized and mechanically ventilated in sternal recumbency with known tidal volumes and breathing frequencies. The work done by the ventilator was measured, and these values were applied to the combinations of tidal volumes and breathing frequencies used by the birds to breathe at rest. We found the respiratory system of high-altitude species to be of a similar size, but consistently more compliant than that of low-altitude sister taxa, although this did not translate to a significantly reduced work of breathing. The metabolic cost of breathing was estimated to be between 1 and 3% of basal metabolic rate, as low or lower than estimates for other groups of tetrapods.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.151191
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2017
    detail.hit.zdb_id: 1482461-9
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Control of breathing and respiratory gas exchange in ducks native to high altitude in the Andes
    The Company of Biologists ; 2019
    In:  Journal of Experimental Biology
    Details
    In: Journal of Experimental Biology, The Company of Biologists
    Abstract: We examined the control of breathing and respiratory gas exchange in six species of high-altitude ducks that independently colonized the high Andes. We compared ducks from high-altitude populations in Peru (Lake Titicaca at ∼3800 m above sea level; Chancay River at ∼3000-4100 m) to closely related populations or species from low altitude. Hypoxic ventilatory responses were measured shortly after capture at the native altitude. In general, ducks responded to acute hypoxia with robust increases in total ventilation and pulmonary O2 extraction. O2 consumption rates were maintained or increased slightly in acute hypoxia, despite ∼1-2°C reductions in body temperature in most species. Two high-altitude taxa – yellow-billed pintail and torrent duck – exhibited higher total ventilation than their low-altitude counterparts, and yellow-billed pintail exhibited greater increases in pulmonary O2 extraction in severe hypoxia. In contrast, three other high-altitude taxa – ruddy duck, cinnamon teal, speckled teal – had similar or slightly reduced total ventilation and pulmonary O2 extraction than low-altitude relatives. Arterial O2 saturation (SaO2) was elevated in yellow-billed pintails at moderate levels of hypoxia, but there were no differences in SaO2 in other high-altitude taxa compared to their close relatives. This finding suggests that improvements in SaO2 in hypoxia can require increases in both breathing and haemoglobin-O2 affinity, because yellow-billed pintail was the only high-altitude duck with concurrent increases in both traits compared to its low-altitude relative. Overall, our results suggest that distinct physiological strategies for coping with hypoxia can exist across different high-altitude lineages, even among those inhabiting very similar high-altitude habitats.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.198622
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2019
    detail.hit.zdb_id: 1482461-9
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Correction: Respiratory mechanics of eleven avian species resident at high and low altitude
    The Company of Biologists ; 2020
    In:  Journal of Experimental Biology Vol. 223, No. 22 ( 2020-11-15)
    Details
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 223, No. 22 ( 2020-11-15)
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.240614
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2020
    detail.hit.zdb_id: 1482461-9
    SSG: 12
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    Cardiovascular responses to progressive hypoxia in ducks native to high altitude in the Andes
    The Company of Biologists ; 2020
    In:  Journal of Experimental Biology
    Details
    In: Journal of Experimental Biology, The Company of Biologists
    Abstract: The cardiovascular system is critical for delivering O2 to tissues. Here we examine the cardiovascular responses to progressive hypoxia in four high-altitude Andean duck species compared to four related low-altitude populations in North America, tested at their native altitude. Ducks were exposed to stepwise decreases in inspired partial pressure of O2 while we monitored heart rate, O2 consumption rate, blood O2 saturation, haematocrit (Hct), and blood haemoglobin concentration [Hb]. We calculated O2 pulse (the product of stroke volume and the arterial-venous O2 content difference), blood O2 concentration, and heart rate variability. Regardless of altitude, all eight populations maintained O2 consumption rate with minimal change in heart rate or O2 pulse, indicating that O2 consumption was maintained by either a constant arterial-venous O2 content difference (an increase in the relative O2 extracted from arterial blood) or by a combination of changes in stroke volume and the arterial-venous O2 content difference. Three high-altitude taxa (yellow-billed pintails, cinnamon teal, and speckled teal) had higher Hct and [Hb] , increasing the O2 content of arterial blood, and potentially providing a greater reserve for enhancing O2 delivery during hypoxia. Hct and [Hb] between low- and high-altitude populations of ruddy duck were similar, representing a potential adaptation to diving life. Heart rate variability was generally lower in high-altitude ducks, concurrent with similar or lower heart rates than low-altitude ducks, suggesting a reduction in vagal and sympathetic tone. These unique features of the Andean ducks differ from previous observations in both Andean geese and bar-headed geese, neither of which exhibit significant elevations in Hct or [Hb] compared to their low-altitude relatives, revealing yet another avian strategy for coping with high altitude.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.211250
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2020
    detail.hit.zdb_id: 1482461-9
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
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