Adult male northern elephant seals maintain high rates of glucose production during extended breeding fasts

2017 ◽  
Vol 187 (8) ◽  
pp. 1183-1192 ◽  
Author(s):  
Daniel E. Crocker ◽  
Brian K. Wenzel ◽  
Cory D. Champagne ◽  
Dorian S. Houser
Keyword(s):  
Adult Male ◽  
Glucose Production ◽  
Elephant Seals ◽  
Northern Elephant Seals

Gluconeogenesis is associated with high rates of tricarboxylic acid and pyruvate cycling in fasting northern elephant seals

2012 ◽  
Vol 303 (3) ◽  
pp. R340-R352 ◽  
Author(s):  
Cory D. Champagne ◽  
Dorian S. Houser ◽  
Melinda A. Fowler ◽  
Daniel P. Costa ◽  
Daniel E. Crocker
Keyword(s):  
Phosphoenolpyruvate Carboxykinase ◽  
Glucose Production ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Endogenous Glucose Production ◽  
Large Contribution ◽  
Protein Loss ◽  
Elephant Seals ◽  
Pyruvate Cycling ◽  
Northern Elephant Seals

Animals that endure prolonged periods of food deprivation preserve vital organ function by sparing protein from catabolism. Much of this protein sparing is achieved by reducing metabolic rate and suppressing gluconeogenesis while fasting. Northern elephant seals ( Mirounga angustirostris) endure prolonged fasts of up to 3 mo at multiple life stages. During these fasts, elephant seals maintain high levels of activity and energy expenditure associated with breeding, reproduction, lactation, and development while maintaining rates of glucose production typical of a postabsorptive mammal. Therefore, we investigated how fasting elephant seals meet the requirements of glucose-dependent tissues while suppressing protein catabolism by measuring the contribution of glycogenolysis, glycerol, and phosphoenolpyruvate (PEP) to endogenous glucose production (EGP) during their natural 2-mo postweaning fast. Additionally, pathway flux rates associated with the tricarboxylic acid (TCA) cycle were measured specifically, flux through phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate cycling. The rate of glucose production decreased during the fast (F1,13= 5.7, P = 0.04) but remained similar to that of postabsorptive mammals. The fractional contributions of glycogen, glycerol, and PEP did not change with fasting; PEP was the primary gluconeogenic precursor and accounted for ∼95% of EGP. This large contribution of PEP to glucose production occurred without substantial protein loss. Fluxes through the TCA cycle, PEPCK, and pyruvate cycling were higher than reported in other species and were the most energetically costly component of hepatic carbohydrate metabolism. The active pyruvate recycling fluxes detected in elephant seals may serve to rectify gluconeogeneic PEP production during restricted anaplerotic inflow in these fasting-adapted animals.

Vocalization source levels of adult male northern elephant seals (Mirounga angustirostris).

2011 ◽  
Vol 129 (4) ◽  
pp. 2505-2505
Author(s):  
Brandon L. Southall ◽  
Stephen Insley ◽  
Marla Holt ◽  
Colleen Reichmuth
Keyword(s):  
Adult Male ◽  
Mirounga Angustirostris ◽  
Elephant Seals ◽  
Northern Elephant Seals

scholarly journals Angiotensin II and Aldosterone Increase with Fasting in Breeding Adult Male Northern Elephant Seals (Mirounga angustirostris)

2006 ◽  
Vol 79 (6) ◽  
pp. 1106-1112 ◽  
Author(s):  
Rudy M. Ortiz ◽  
Daniel E. Crocker ◽  
Dorian S. Houser ◽  
Paul M. Webb
Keyword(s):  
Angiotensin Ii ◽  
Adult Male ◽  
Mirounga Angustirostris ◽  
Elephant Seals ◽  
Northern Elephant Seals

Vocal signaling among male northern elephant seals: Behavioral field studies of honesty vs. associative learning

2012 ◽  
Author(s):  
Colleen Reichmuth ◽  
Caroline Casey ◽  
Isabelle Charrier ◽  
Nicolas Mathevon ◽  
Brandon Southall
Keyword(s):  
Associative Learning ◽  
Field Studies ◽  
Elephant Seals ◽  
Northern Elephant Seals ◽  
Vocal Signaling

scholarly journals The rise and fall of dialects in northern elephant seals

2018 ◽  
Vol 285 (1892) ◽  
pp. 20182176 ◽  
Author(s):  
Caroline Casey ◽  
Colleen Reichmuth ◽  
Daniel P. Costa ◽  
Burney Le Boeuf
Keyword(s):  
Mammalian Species ◽  
Structural Complexity ◽  
Mirounga Angustirostris ◽  
Geographical Differences ◽  
Migration Patterns ◽  
Elephant Seals ◽  
The North ◽  
Vocal Behaviour ◽  
Northern Elephant Seals ◽  
The North Pacific

Vocal dialects are fundamental to our understanding of the transmission of social behaviours between individuals and populations, however few accounts trace this phenomenon among mammals over time. Northern elephant seals ( Mirounga angustirostris ) provide a rare opportunity to examine the trajectory of dialects in a long-lived mammalian species. Dialects were first documented in the temporal patterns of the stereotyped vocal displays produced by breeding males at four sites in the North Pacific in 1968 and 1969, as the population recovered from extreme exploitation. We evaluated the longevity of these geographical differences by comparing these early recordings to calls recently recorded at these same locations. While the presence of vocal dialects in the original recordings was re-confirmed, geographical differences in vocal behaviour were not found at these breeding rookeries nearly 50 years later. Moreover, the calls of contemporary males displayed more structural complexity after approximately four generations, with substantial between-individual variation and call features not present in the historical data. In the absence of measurable genetic variation in this species—owing to an extreme population bottleneck—a combination of migration patterns and cultural mutation are proposed as factors influencing the fall of dialects and the dramatic increase in call diversity.

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