Hibernation in reptiles—II. Changes in blood cell glucose, haemoglobin, red blood cell count, protein and non-protein nitrogen

Haggag, Gaber; Raheem, Khamis Abdel; Khalil, Fouad

doi:10.1016/0010-406x(66)90033-8

Cited by 21 publications

(8 citation statements)

References 10 publications

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“…While there are few studies of nutrient and tissue processes in hibernating reptiles, a study in cobras found that tissue catabolism for protein begins prior to hibernation, 57 suggesting that physiological preparation for hibernation can be an entrained process that could have also occurred in the lizards in our study. In addition, rapid declines in hematocrit during the first week of hibernation have been observed in snakes, suggesting that RBCs are catabolized along with protein stores in liver and muscle 58–60 . If a similar process of RBC catabolism occurred in the lizards in our study, this could account for the qualitatively more pronounced decrease in the δ 15 N values of RBCs than of plasma in both lizard species (Figure 1).…”

Section: Discussionsupporting

confidence: 56%

Nitrogen stable isotope turnover and discrimination in lizards

Warne

Wolf

2021

Rapid Comm Mass Spectrometry

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Rationale Nitrogen stable isotope ratio (δ15N) processes are not well described in reptiles, which limits reliable inference of trophic and nutrient dynamics. In this study we detailed δ15N turnover and discrimination (Δ15N) in diverse tissues of two lizard species, and compared these results with previously published carbon data (δ13C) to inform estimates of reptilian foraging ecology and nutrient physiology. Methods We quantified 15N incorporation and discrimination dynamics over 360 days in blood fractions, skin, muscle, and liver of Sceloporus undulatus and Crotaphytus collaris that differed in body mass. Tissue samples were analyzed on a continuous flow isotope ratio mass spectrometer. Results Δ15N for plasma and red blood cells (RBCs) ranged between +2.7 and +3.5‰; however, skin, muscle, and liver did not equilibrate, hindering estimates for these somatic tissues. 15N turnover in plasma and RBCs ranged from 20.7 ± 4 to 303 ± 166 days among both species. Comparison with previously published δ13C results for these same samples showed that 15N and 13C incorporation patterns were uncoupled, especially during winter when hibernation physiology could have played a role. Conclusions Our results provide estimates of 15N turnover rates and discrimination values that are essential to using and interpreting isotopes in studies of diet reconstruction, nutrient allocation, and trophic characterization in reptiles. These results also suggest that somatic tissues can be unreliable, while life history shifts in nutrient routing and metabolism potentially cause 15N and 13C dynamics to be decoupled.

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Section: Discussionsupporting

confidence: 56%

Nitrogen stable isotope turnover and discrimination in lizards

Warne

Wolf

2021

Rapid Comm Mass Spectrometry

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“…Furthermore, blood glucose has also been shown to be lower in a fasted state (such as hibernation), and higher with increased food intake in a wide range of reptiles (Haggag, Raheem, & Khalil, 1966;Khalil & Yanni, 1959;Kuckling 1981;Miller & Wurster, 1958;Moore, 1967;Moon et al, 1999;Secor & Diamond, 1997;but see Zain-ul-Abedin & Katorski, 1967).…”

Section: Introductionmentioning

confidence: 99%

“…Laboratory studies suggest that pancreatic hormones act to regulate blood glucose similarly to mammals in nonmammalian vertebrates, such as reptiles (Miller & Wurster, ; Miller, ; Sidorkiewicz & Skoczylas, ; Putti, Varano, Cavagnuolo, & Laforgia, ; Gangloff, Holden, Telemeco, Baumgard, & Bronikowski, ). Furthermore, blood glucose has also been shown to be lower in a fasted state (such as hibernation), and higher with increased food intake in a wide range of reptiles (Haggag, Raheem, & Khalil, ; Khalil & Yanni, ; Kuckling 1981; Miller & Wurster, ; Moore, ; Moon et al., ; Secor & Diamond, ; but see Zain‐ul‐Abedin & Katorski, ).…”

Section: Introductionmentioning

confidence: 99%

Convergence in reduced body size, head size, and blood glucose in three island reptiles

Sparkman

Clark

Brummett

et al. 2018

Ecology and Evolution

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Many oceanic islands harbor diverse species that differ markedly from their mainland relatives with respect to morphology, behavior, and physiology. A particularly common morphological change exhibited by a wide range of species on islands worldwide involves either a reduction in body size, termed island dwarfism, or an increase in body size, termed island gigantism. While numerous instances of dwarfism and gigantism have been well documented, documentation of other morphological changes on islands remains limited. Furthermore, we lack a basic understanding of the physiological mechanisms that underlie these changes, and whether they are convergent. A major hypothesis for the repeated evolution of dwarfism posits selection for smaller, more efficient body sizes in the context of low resource availability. Under this hypothesis, we would expect the physiological mechanisms known to be downregulated in model organisms exhibiting small body sizes due to dietary restriction or artificial selection would also be downregulated in wild species exhibiting dwarfism on islands. We measured body size, relative head size, and circulating blood glucose in three species of reptiles—two snakes and one lizard—in the California Channel Islands relative to mainland populations. Collating data from 6 years of study, we found that relative to mainland population the island populations had smaller body size (i.e., island dwarfism), smaller head sizes relative to body size, and lower levels of blood glucose, although with some variation by sex and year. These findings suggest that the island populations of these three species have independently evolved convergent physiological changes (lower glucose set point) corresponding to convergent changes in morphology that are consistent with a scenario of reduced resource availability and/or changes in prey size on the islands. This provides a powerful system to further investigate ecological, physiological, and genetic variables to elucidate the mechanisms underlying convergent changes in life history on islands.

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“…However, extended periods of cold exposure (as in winter dormancy) seems to decouple this regulation and glucose levels drop considerably. This hypoglycemic response during brumation agrees with findings in various ectotherms that endure prolonged cold exposure (e.g., Abdel-Raheem et al 1989;de Souza et al 2004;Haggag et al 1966a;Khalil and Yanni 1959;Padgaonkar and Das 2000), but contrasts with ectotherms that are capable of freeze tolerance (Costanzo et al 1993;Grenot et al 2000;Storey and Storey 1996;Voituron et al 2000). Additionally, the post-brumation increase in plasma glucose is in agreement with the upregulation of # ̇O2.…”

Section: Glucosesupporting

confidence: 87%

“…In temperate ectotherms, which endure extended periods of cold exposure (i.e., seasonal period of dormancy), CORT levels are elevated relative to baseline concentrations and oppose depressed metabolic rates under cold exposure (Brischoux et al 2016;. Circulating levels of plasma glucose positively covary with CORT at warm temperature , but temperate ectotherms also exhibit substantially reduced levels of glucose during winter dormancy when metabolic rates are depressed (Haggag et al 1966a). Under homeostatic conditions, insulin reduces the production, and promotes the uptake, of glucose into tissues .…”

Section: Introductionmentioning

confidence: 99%

Physiological ecology of stress in a terrestrial ectothermic vertebrate (garter snakes, Thamnophis spp.)

Holden¹

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Hibernation in reptiles—II. Changes in blood cell glucose, haemoglobin, red blood cell count, protein and non-protein nitrogen

Cited by 21 publications

References 10 publications

Nitrogen stable isotope turnover and discrimination in lizards

Nitrogen stable isotope turnover and discrimination in lizards

Convergence in reduced body size, head size, and blood glucose in three island reptiles

Physiological ecology of stress in a terrestrial ectothermic vertebrate (garter snakes, Thamnophis spp.)

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