Adaptations to diving in the harbor seal: oxygen stores and supply

Bs, Packer; Altman, Michael L.; Ce, Cross; Hv, Murdaugh; Linta, JM; Ed, Robin

doi:10.1152/ajplegacy.1969.217.3.903

Cited by 19 publications

(4 citation statements)

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“…The hemeprotein myoglobin (Mb) is expressed in the muscle tissue of vertebrates (1)(2)(3)(4), where it functions to store oxygen (2)(3)(4)(5)(6)(7)(8). A high level of muscle Mb expression allows certain mammals to hold their breath for longer time periods, as occurs in diving mammals like whales, seals, or dolphins (9)(10)(11)(12). Genetic depletion of Mb in mice induces several compensatory mechanisms that partly overcome its loss and thus leads to viable and fertile mice (13).…”

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Myoglobin maturation is driven by the hsp90 chaperone machinery and by soluble guanylyl cyclase

et al. 2019

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Myoglobin (Mb) maturation involves heme incorporation as a final step. We investigated a role for heat shock protein (hsp) 90 in Mb maturation in C2C12 skeletal muscle myoblasts and cell lines. We found the following: 1) Hsp90 directly interacts preferentially with heme‐free Mb both in purified form and in cells. 2) Hsp90 drives heme insertion into apoprotein‐Mb in an ATP‐dependent process. 3) During differentiation of C2C12 myoblasts into myotubes, the apo‐Mb‐hsp90 complex associates with 5 cell cochaperons, Hsp70, activator of hsp90 ATPase protein 1 (Aha1), alanyl‐tRNA synthetase domain containing 1 (Aarsd1), cell division cycle 37 (Cdc37), and stress induced phosphoprotein 1 (STIP1) in a pattern that is consistent with their enabling Mb maturation. 4) Mb heme insertion was significantly increased in cells that had a functional soluble guanylyl cyclase (sGC)‐cGMP signaling pathway and was diminished upon small interfering RNA knockdown of sGCβ1 or upon overexpression of a phosphodiesterase to prevent cGMP buildup. Together, our findings suggest that hsp90 works in concert with cochaperons (Hsp70, Aha1, Aarsd1, STIP1, and Cdc37) and an active sGC‐cGMP signaling pathway to promote heme insertion into immature apo‐Mb, and thus generate functional Mb during muscle myotube formation. This fills gaps in our understanding and suggests new ways to potentially control these processes.—Ghosh, A., Dai, Y., Biswas, P., Stuehr, D. J. Myoglobin maturation is driven by the hsp90 chaperone machinery and by soluble guanylyl cyclase. FASEB J. 33, 9885–9896 (2019). http://www.fasebj.org

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Myoglobin maturation is driven by the hsp90 chaperone machinery and by soluble guanylyl cyclase

et al. 2019

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“…The lungs of phocid seals (see Glossary) are not particularly big and they will normally expire before a dive, to reduce buoyancy and avoid divers' disease (Scholander, 1940). The size of the lung oxygen stores was first estimated by Packer et al (1969) and Lenfant et al (1970) in juvenile seals and later by Burns et al (2007) in adult hooded seals. Assuming 15% oxygen in the lung air and that 50% of lung volume is expired before the dive, the lung oxygen store in hooded seals amounts to 6 ml O 2 kg −1 , compared with some 9 ml O 2 kg −1 in the fully expanded lungs of man.…”

Section: Oxygen Storesmentioning

confidence: 99%

“…This was later confirmed by Lenfant et al (1970), and subsequently by others (Box 1). Not only is the blood volume large: the hematocrit value (see Glossary), and thereby the hemoglobin content of the blood is also very high, amounting to about 60% compared with 45% in humans (Lenfant et al, 1969;Packer et al, 1969;Lenfant et al, 1970;Burns et al, 2007) (Fig. 2).…”

Section: Oxygen Storesmentioning

confidence: 99%

“…2). The oxygen-carrying capacity of the blood and hence the blood oxygen store in hooded seals may therefore be as high as 45 ml O 2 kg −1 , whereas in humans it is about 11 ml O 2 kg −1 (Packer et al, 1969;Burns et al, 2007), but this is not to say that the entire blood oxygen store is available at all times. Kooyman et al (1980) noticed a rise in aortic hemoglobin concentration in diving Weddell seals (Leptonychotes weddellii) and assumed that it was caused by release of previously sequestered red blood cells in the venous sinuses.…”

Section: Oxygen Storesmentioning

confidence: 99%

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Adaptations to deep and prolonged diving in phocid seals

Blix

2018

Journal of Experimental Biology

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This Review focuses on the original papers that have made a difference to our thinking and were first in describing an adaptation to diving, and less on those that later repeated the findings with better equipment. It describes some important anatomical peculiarities of phocid seals, as well as their many physiological responses to diving. In so doing, it is argued that the persistent discussions on the relevance and differences between responses seen in forced dives in the laboratory and those during free diving in the wild are futile. In fact, both are two sides of the same coin, aimed at protecting the body against asphyxic insult and extending diving performance.

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