scholarly journals Oxygen store depletion and the aerobic dive limit in emperor penguins

2010 ◽  
Vol 8 ◽  
pp. 237-245 ◽  
Author(s):  
PJ Ponganis ◽  
JU Meir ◽  
CL Williams
Keyword(s):  
Oxygen Store ◽  
Emperor Penguins ◽  
Store Depletion ◽  
Aerobic Dive Limit

Stroke frequencies of emperor penguins diving under sea ice

2002 ◽  
Vol 205 (24) ◽  
pp. 3769-3774 ◽  
Author(s):  
R. P. van Dam ◽  
P. J. Ponganis ◽  
K. V. Ponganis ◽  
D. H. Levenson ◽  
G. Marshall
Keyword(s):  
Sea Ice ◽  
Dive Depth ◽  
Dive Duration ◽  
Accelerometer Data ◽  
Underwater Video ◽  
Stroke Frequency ◽  
Video Footage ◽  
Ice Surface ◽  
Emperor Penguins ◽  
Aerobic Dive Limit

SUMMARYDuring diving, intermittent swim stroke patterns, ranging from burst/coast locomotion to prolonged gliding, represent potential energy conservation mechanisms that could extend the duration of aerobic metabolism and, hence,increase the aerobic dive limit (ADL, dive duration associated with onset of lactate accumulation). A 5.6 min ADL for emperor penguins had been previously determined with lactate measurements after dives of <50 m depth. In order to assess locomotory patterns during such dives, longitudinal acceleration was measured with an attached accelerometer in 44 dives of seven adult birds diving from an isolated dive hole in the sea ice of McMurdo Sound, Antarctica. Detection of wing strokes in processed accelerometer data was verified in selected birds with analysis of simultaneous Crittercam underwater video footage. Mean dive duration of birds equipped with the accelerometer and a time-depth recorder (TDR) was 5.7±2.2 min; 48% of these dives were greater than the measured 5.6 min ADL (ADLM). Highest stroke frequencies (0.92±0.31 Hz, N=981) occurred during the initial descent to 12 m depth. Swimming effort was reduced to a mean stroke frequency<0.70 Hz during other phases of the dive (while traveling below 12 m depth,during foraging ascents/descents to and from the sub-ice surface, and during final ascents to exit). The longest stroke interval (8.6 s) occurred during a feeding excursion to the undersurface of the ice. In dives>ADLM, mean stroke frequency during travel segments was significantly less than that in dives <ADLM(P<0.05). Mean stroke frequency of the entire dive correlated inversely (P<0.05) with diving duration (r=-0.67) and with mean dive depth (r=-0.43). Emperor penguins did not exhibit any significant (>10 s) periods of prolonged gliding during these shallow(<60 m) foraging dives. However, a stroke/glide pattern was evident with more than 50% of strokes associated with a stroke interval >1.6 s, and with lower stroke frequency associated with increased dive duration.

Body mass and dive duration in alcids and penguins

1999 ◽  
Vol 77 (11) ◽  
pp. 1838-1842 ◽  
Author(s):  
Yutaka Watanuki ◽  
Alan E Burger
Keyword(s):  
Body Mass ◽  
Dive Duration ◽  
Allometric Equations ◽  
Metabolic Rates ◽  
Laboratory Studies ◽  
Allometric Exponent ◽  
Oxygen Store ◽  
Mass Effects ◽  
Aerobic Dive Limit ◽  
Oxygen Stores

Interspecific allometric equations for dive duration were calculated for two groups of wing-propelled divers: penguins, which specializing in diving, and alcids, which balance demands for aerial flying with those of diving. The equations for maximum dive duration (min) were 1.433M0.702 and 3.612M0.735 (where M is body mass in kilograms) for penguins (10 species) and alcids (9 species), respectively, hence did not support a simple oxygen store/usage hypothesis based on the prediction that the mass exponent of aerobic dive limit is close to 0.25. Equations for feeding dives were 0.569M0.712 and 1.094M0.391 in penguins (9 species) and alcids (10 species), respectively. The allometric exponent for the duration of feeding dives for penguins did not match the predicted value of 0.25, but that for alcids did not differ significantly from this value. Alcids exhibited a maximum dive duration 2.5 times longer than that for penguins after mass effects were controlled for. The size of oxygen stores and metabolic rates based on laboratory studies of penguins and alcids failed to explain the longer dive duration in alcids than in penguins.

Heart rates of emperor penguins diving at sea: implications for oxygen store management

2014 ◽  
Vol 496 ◽  
pp. 85-98 ◽  
Author(s):  
AK Wright ◽  
KV Ponganis ◽  
BI McDonald ◽  
PJ Ponganis
Keyword(s):  
Heart Rates ◽  
Oxygen Store ◽  
Emperor Penguins ◽  
Store Management

The aerobic submersion limit of Baikal seals, Phoca sibirica

1997 ◽  
Vol 75 (8) ◽  
pp. 1323-1327 ◽  
Author(s):  
Paul J. Ponganis ◽  
Gerald L. Kooyman ◽  
Eugene A. Baranov ◽  
Philip H. Thorson ◽  
Brent S. Stewart
Keyword(s):  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Weddell Seal ◽  
Theoretical Limit ◽  
Two Phase ◽  
Oxygen Store ◽  
Weddell Seals ◽  
Aerobic Dive Limit ◽  
Duration Relationship ◽  
Free Ranging

An aerobic dive limit (ADL), the diving duration beyond which postdive lactate concentration increases above the resting level, has been estimated theoretically for many species. Such calculations have been based on an oxygen store/diving metabolic rate (MR) equation. Until now, an ADL has been determined empirically from measurements of blood lactate concentration only in the Weddell seal, Leptonychotes weddellii. We measured post-submergence plasma lactate concentrations during spontaneous voluntary submersions of three captive adult Baikal seals (Phoca sibirica). Two-phase regression analysis revealed a transition in the lactate concentration – submersion duration relationship after the animal had been diving for 15 min. Data collected in prior studies on oxygen stores and submersion metabolic rates of Baikal seals yielded a calculated aerobic limit of 16 min. As in Weddell seals, the empirically determined aerobic limit was very similar to the theoretical limit. Furthermore, most diving durations recorded during recent studies of free-ranging Baikal seals are under this limit. These data support the concept of an ADL and its estimation by means of an oxygen store/diving MR calculation.

scholarly journals Modulation of Ca2+ influx dependent on store depletion by intracellular adenine-guanine nucleotide levels.

1994 ◽  
Vol 269 (38) ◽  
pp. 23597-23602
Author(s):  
A. Gamberucci ◽  
B. Innocenti ◽  
R. Fulceri ◽  
G. Bànhegyi ◽  
R. Giunti ◽  
...  
Keyword(s):  
Guanine Nucleotide ◽  
Store Depletion

scholarly journals Effect of MgCl2 and GdCl3 on ORAI1 Expression and Store-Operated Ca2+ Entry in Megakaryocytes

2021 ◽  
Vol 22 (7) ◽  
pp. 3292
Author(s):  
Kuo Zhou ◽  
Xuexue Zhu ◽  
Ke Ma ◽  
Jibin Liu ◽  
Bernd Nürnberg ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Transcription Factor ◽  
Smooth Muscle ◽  
Kidney Disease ◽  
Protein Abundance ◽  
Rt Pcr ◽  
Calcium Sensing Receptor ◽  
Transcript Levels ◽  
Calcium Sensing ◽  
Store Depletion

In chronic kidney disease, hyperphosphatemia upregulates the Ca2+ channel ORAI and its activating Ca2+ sensor STIM in megakaryocytes and platelets. ORAI1 and STIM1 accomplish store-operated Ca2+ entry (SOCE) and play a key role in platelet activation. Signaling linking phosphate to upregulation of ORAI1 and STIM1 includes transcription factor NFAT5 and serum and glucocorticoid-inducible kinase SGK1. In vascular smooth muscle cells, the effect of hyperphosphatemia on ORAI1/STIM1 expression and SOCE is suppressed by Mg2+ and the calcium-sensing receptor (CaSR) agonist Gd3+. The present study explored whether sustained exposure to Mg2+ or Gd3+ interferes with the phosphate-induced upregulation of NFAT5, SGK1, ORAI1,2,3, STIM1,2 and SOCE in megakaryocytes. To this end, human megakaryocytic Meg-01 cells were treated with 2 mM ß-glycerophosphate for 24 h in the absence and presence of either 1.5 mM MgCl2 or 50 µM GdCl3. Transcript levels were estimated utilizing q-RT-PCR, protein abundance by Western blotting, cytosolic Ca2+ concentration ([Ca2+]i) by Fura-2 fluorescence and SOCE from the increase in [Ca2+]i following re-addition of extracellular Ca2+ after store depletion with thapsigargin (1 µM). As a result, Mg2+ and Gd3+ upregulated CaSR and blunted or virtually abolished the phosphate-induced upregulation of NFAT5, SGK1, ORAI1,2,3, STIM1,2 and SOCE in megakaryocytes. In conclusion, Mg2+ and the CaSR agonist Gd3+ interfere with phosphate-induced dysregulation of [Ca2+]i in megakaryocytes.

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