Adjustments of gastric pH, motility and temperature during long-term preservation of stomach contents in free-ranging incubating king penguins

Thouzeau, Cécile; Peters, Gerrit; Bohec, Céline Le; Maho, Yvon Le

doi:10.1242/jeb.01074

Cited by 46 publications

(30 citation statements)

References 34 publications

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“…These devices record temperature during passage through the gastrointestinal tract and have been used widely on relatively large species and in humans [10,63,64]. Recording duration is determined by gut passage rate, which may vary from hours to weeks but in large ruminants devices have been retained for up to 4 years (retention time was actually improved by increasing the size of the device) [56].…”

Section: Gastrointestinal Devicesmentioning

confidence: 99%

Challenges of measuring body temperatures of free-ranging birds and mammals

2015

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The thermal physiology of most birds and mammals is characterised by considerable spatial and temporal variation in body temperature. Body temperature is, therefore, a key parameter in physiological, behavioural and ecological research. Temperature measurements on freely moving or free-ranging animals in the wild are challenging but can be undertaken using a range of techniques. Internal temperature may be sampled using thermometry, surgically implanted loggers or transmitters, gastrointestinal or non-surgically placed devices. Less invasive approaches measure peripheral temperature with subcutaneous passive integrated transponder tags or skin surface-mounted radio transmitters and data loggers, or use infrared thermography to record surface temperature. Choice of technique is determined by focal research question and region of interest that reflects appropriate physiological or behavioural causal mechanisms of temperature change, as well as welfare and logistical considerations. Particularly required are further studies that provide opportunities of continuously sampling from multiple sites from within the body. This will increase our understanding of thermoregulation and temperature variation in different parts of the body and how these temperatures may change in response to physiological, behavioural and environmental parameters. Technological advances that continue to reduce the size and remote sensing capability of temperature recorders will greatly benefit field research.

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Section: Gastrointestinal Devicesmentioning

confidence: 99%

Challenges of measuring body temperatures of free-ranging birds and mammals

2015

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“…It is known that the gastric pH in the penguin is variable. It was reported that the stomach pH of the king penguin was close to 4 at the beginning of the incubation fast, gradually increased in a few days, and could be maintained at values as high as 6 during the incubating fast (Gauthier-Clerc et al 2002;Thouzeau et al 2004). They argued that high pH might contribute to preservation of stomach contents during a long-term fast.…”

Section: Discussionmentioning

confidence: 99%

“…In the case of penguins, captured food is stored in the stomach (Croxall 1987). The gastric pH of king penguins ranges from 2 to 4 in nonfasting periods (Gauthier-Clerc et al 2002;Thouzeau et al 2003Thouzeau et al , 2004, indicating secretion of gastric acid in the stomach.…”

Section: Introductionmentioning

confidence: 99%

Metabolic Alkalosis due to Feeding Chicks in Breeding Adélie PenguinsPygoscelis adeliaeunder Natural Conditions

Sakamoto¹,

Sato²,

Kato³

et al. 2010

Physiological and Biochemical Zoology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. ABSTRACT Prolonged abnormal vomiting causes metabolic alkalosis. Many seabirds are known to feed their chicks by regurgitation. We hypothesized that metabolic alkalosis occurs in seabirds even under natural conditions during the breeding season. Adélie penguins Pygoscelis adeliae feed their chicks by regurgitating food for 50-60 d until the chicks fledge. In this study, the concentrations of Cl Ϫ , HCO 3 Ϫ , Na ϩ , K ϩ , pH, and in the Pco 2 blood of breeding Adélie penguins were measured throughout the chick-rearing season. The pH of penguin venous blood shifted from 7.54 in the guarding period to 7.47 in the crèche period. Decreasing Cl Ϫ and increasing HCO 3 Ϫ blood concentrations in parents were associated with increasing mass of their brood in the guarding period, the early phase of the rearing season, indicating that regurgitating to feed chicks causes loss of gastric acid and results in relative metabolic alkalosis. The inverse trend was observed during the crèche period, the latter phase of the rearing season, when parents spent more time at sea and have fewer opportunities for gastric acid loss. This was assumed to be the recovery phase. These results indicate that regurgitation might cause metabolic alkalosis in breeding Adélie penguins. To our knowledge, this is the first report to indicate that seabirds exhibit metabolic alkalosis due to regurgitation to feed chicks under natural conditions. The University of Chicago Press

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“…26,28 Many reports have suggested that the gastric pH varies from 2.5 to 3.7 in the fasting state due to declined secretion of hydrochloric acid by parietal cells. 26,28,29 Since the formulations of this study would be administrated under the fasting state during in vivo studies, the pH 2.5 simulated gastric juice was selected as the release media to illustrate the releases of the coated nanoemulsion, uncoated nanoemulsion, and multiple emulsion. The crosslinking complex prevented the emulsion inversion and then avoided insulin release from the inner phase in simulated gastric environment because of the tight Alg pre-gel network at low pH.…”

Section: Insulin Leakage From Coated Nanoemulsion In Simulated Gastrimentioning

confidence: 99%

Nanoemulsions coated with alginate/chitosan as oral insulin delivery systems: preparation, characterization, and hypoglycemic effect in rats

Li¹,

Qi²,

Xie³

et al. 2012

IJN

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This study aimed to prepare nanoemulsions coated with alginate/chitosan for oral insulin delivery. Uncoated nanoemulsions were prepared by homogenization of a water in oil in water (w/o/w) multiple emulsion that was composed of Labrafac ® CC, phospholipid, Span™ 80 and Cremorphor ® EL. Coating of the nanoemulsions was achieved based on polyelectrolyte cross-linking, with sequential addition of calcium chloride and chitosan to the bulk nanoemulsion dispersion that contained alginate. The particle size of the coated nanoemulsions was about 488 nm and the insulin entrapment ratio was 47.3%. Circular dichroism spectroscopy proved conformational stability of insulin against the preparative stress. In vitro leakage study indicated well-preserved integrity of the nanoemulsions in simulated gastric juices. Hypoglycemic effects were observed in both normal and diabetic rats. The relative pharmacological bioavailability of the coated nanoemulsion with 25 and 50 IU/kg insulin were 8.42% and 5.72% in normal rats and 8.19% and 7.84% in diabetic rats, respectively. Moreover, there were significantly prolonged hypoglycemic effects after oral administration of the coated nanoemulsions compared with subcutaneous (sc) insulin. In conclusion, the nanoemulsion coated with alginate/chitosan was a potential delivery system for oral delivery of polypeptides and proteins.

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Adjustments of gastric pH, motility and temperature during long-term preservation of stomach contents in free-ranging incubating king penguins

Cited by 46 publications

References 34 publications

Challenges of measuring body temperatures of free-ranging birds and mammals

Challenges of measuring body temperatures of free-ranging birds and mammals

Metabolic Alkalosis due to Feeding Chicks in Breeding Adélie PenguinsPygoscelis adeliaeunder Natural Conditions

Nanoemulsions coated with alginate/chitosan as oral insulin delivery systems: preparation, characterization, and hypoglycemic effect in rats

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