Hibernation in reptiles—III. Tissue analysis for glycogen and high energy phosphate compounds

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

doi:10.1016/0010-406x(66)90034-x

Cited by 15 publications

(4 citation statements)

References 6 publications

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“…Additionally, circulating glucose concentrations at 20C postbrumation were lower than at the same temperature pre-brumation. Though not measured here, reduced liver glycogen stores accompany hypoglycemia under the physiological demands of overwintering in other ectotherms (Barwick and Bryant, 1966;de Souza et al, 2004;Dessauer, 1955;Haggag et al, 1966b;Patterson and Davies, 1978;Zani et al, 2012). In combination with our finding of reduced post-brumation metabolic rates, this suggests that energy stores are being carefully regulated post-brumation.…”

Section: Discussionsupporting

confidence: 55%

Surviving winter: Physiological regulation of energy balance in a temperate ectotherm entering and exiting brumation

Holden

Gangloff

Gomez-Mancillas

et al. 2021

General and Comparative Endocrinology

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Section: Discussionsupporting

confidence: 55%

Surviving winter: Physiological regulation of energy balance in a temperate ectotherm entering and exiting brumation

Holden

Gangloff

Gomez-Mancillas

et al. 2021

General and Comparative Endocrinology

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“…Several previous studies have also reported that liver glycogen levels decrease substantially during winter (e.g. Dessauer, 1955;Barwick and Bryant, 1966;Haggag et al, 1966;Patterson et al, 1978;Taylor, 1986;de Souza et al, 2004). For comparison with our results, we used data reported in these previous studies (where available) to estimate liver glycogen in both winter and summer in equivalent units (Table4).…”

Section: Discussionmentioning

confidence: 71%

Glycogen, not dehydration or lipids, limits winter survival of side-blotched lizards (Uta stansburiana)

Zani

Irwin

Rollyson

et al. 2012

Journal of Experimental Biology

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SUMMARYClimate change is causing winters to become milder (less cold and shorter). Recent studies of overwintering ectotherms have suggested that warmer winters increase metabolism and decrease winter survival and subsequent fecundity. Energetic constraints (insufficient energy stores) have been hypothesized as the cause of winter mortality but have not been tested explicitly. Thus, alternative sources of mortality, such as winter dehydration, cannot be ruled out. By employing an experimental design that compared the energetics and water content of lizards that died naturally during laboratory winter with those that survived up to the same point but were then sacrificed, we attempt to distinguish among multiple possible causes of mortality. We test the hypothesis that mortality is caused by insufficient energy stores in the liver, abdominal fat bodies, tail or carcass or through excessive water loss. We found that lizards that died naturally had marginally greater mass loss, lower water content, and less liver glycogen remaining than living animals sampled at the same time. Periodically moistening air during winter reduced water loss, but this did not affect survival, calling into question dehydration as a cause of death. Rather, our results implicate energy limitations in the form of liver glycogen, but not lipids, as the primary cause of mortality in overwintering lizards. When viewed through a lens of changing climates, our results suggest that if milder winters increase the metabolic rate of overwintering ectotherms, individuals may experience greater energetic demands. Increased energy use during winter may subsequently limit individual survival and possibly even impact population persistence.

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“…Stored fats are catabolised via lipolysis, beta oxidation, and ketogenesis. In some cases, such as in hibernating reptiles like the Australian central bearded dragon (Pogona vitticeps), large amounts of stored glycogen (in the tail) are used in conjunction with stored triglycerides 3 . Hibernators must induce stress responses to mitigate physiological stress, including nutrient deficiency, compromised immune system, and oxidative-and cold-stress, that would otherwise be lethal.…”

mentioning

confidence: 99%

MicroRNA dynamics during hibernation of the Australian central bearded dragon (Pogona vitticeps)

Capraro

O’Meally

Waters

et al. 2020

Sci Rep

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Hibernation is a physiological state employed by many animals that are exposed to limited food and adverse winter conditions. Controlling tissue-specific and organism wide changes in metabolism and cellular function requires precise regulation of gene expression, including by microRNAs (miRNAs). Here we profile miRNA expression in the central bearded dragon (Pogona vitticeps) using small RNA sequencing of brain, heart, and skeletal muscle from individuals in late hibernation and four days post-arousal. A total of 1295 miRNAs were identified in the central bearded dragon genome; 664 of which were novel to central bearded dragon. We identified differentially expressed miRNAs (DEmiRs) in all tissues and correlated mRNA expression with known and predicted target mRNAs. Functional analysis of DEmiR targets revealed an enrichment of differentially expressed mRNA targets involved in metabolic processes. However, we failed to reveal biologically relevant tissue-specific processes subjected to miRNA-mediated regulation in heart and skeletal muscle. In brain, neuroprotective pathways were identified as potential targets regulated by miRNAs. Our data suggests that miRNAs are necessary for modulating the shift in cellular metabolism during hibernation and regulating neuroprotection in the brain. This study is the first of its kind in a hibernating reptile and provides key insight into this ephemeral phenotype.

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Hibernation in reptiles—III. Tissue analysis for glycogen and high energy phosphate compounds

Cited by 15 publications

References 6 publications

Surviving winter: Physiological regulation of energy balance in a temperate ectotherm entering and exiting brumation

Surviving winter: Physiological regulation of energy balance in a temperate ectotherm entering and exiting brumation

Glycogen, not dehydration or lipids, limits winter survival of side-blotched lizards (Uta stansburiana)

MicroRNA dynamics during hibernation of the Australian central bearded dragon (Pogona vitticeps)

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