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

Capraro, Alexander; O’Meally, Denis; Waters, Shafagh A.; Patel, Hardip R.; Georges, Arthur; Waters, Paul D.

doi:10.1038/s41598-020-73706-9

Cited by 5 publications

(3 citation statements)

References 65 publications

(106 reference statements)

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“…High sugar diets, even if isocaloric, have been shown to increase the levels of triacylglycerol, acylcarnitine, and downregulate genes involved in fatty acid oxidation in rats [83]. If bearded dragons fail to metabolize these stored triacylglycerols from lack of reproduction, brumation [133], or activity, a pathological process may begin to occur. Hepatic lipidosis in bearded dragons seems to be associated with an increase in triglycerides, triglyceride-rich lipoproteins (including chylomicrons and large VLDLs), free glycerol, and lysoPC.…”

Section: Plos Onementioning

confidence: 99%

Association of plasma metabolites and diagnostic imaging findings with hepatic lipidosis in bearded dragons (Pogona vitticeps) and effects of gemfibrozil therapy

et al. 2023

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Objectives To evaluate the association between plasma metabolites, biochemical analytes, diagnostic imaging findings, and the histologic diagnosis of hepatic lipidosis in bearded dragons. To assess the effects of gemfibrozil therapy on hepatic lipid accumulation and associated diagnostic tests. Animals Fourteen bearded dragons (Pogona vitticeps) with varying severity of hepatic lipid accumulation (with and without hepatic lipidosis) were included. Procedures Animals underwent coelomic ultrasound, computed tomography (CT) scans, and coelioscopic hepatic biopsies. Clinical pathology tests included lipidologic tests, hepatic biomarkers, and mass spectrometry-based metabolomics. Animals were medicated with gemfibrozil 6mg/kg orally once a day for 2 months in a randomized blinded clinical trial prior to repeating previous diagnostic testing. Results Hounsfield units on CT were negatively associated with increased hepatic vacuolation, while ultrasound and gross evaluation of the liver were not reliable. Beta-hydroxybutyric-acid (BHBA) concentrations were significantly associated with hepatic lipidosis. Metabolomics and lipidomics data found BHBA and succinic acid to be potential biomarkers for diagnosing hepatic lipidosis in bearded dragons. Succinic acid concentrations were significantly lower in the gemfibrozil treatment group. There was a tendency for improvement in the biomarkers and reduced hepatic fat in bearded dragons with hepatic lipidosis when treated with gemfibrozil, though the improvement was not statistically significant. Conclusions These findings provide information on the antemortem assessment of hepatic lipidosis in bearded dragons and paves the way for further research in diagnosis and treatment of this disease.

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Section: Plos Onementioning

confidence: 99%

Association of plasma metabolites and diagnostic imaging findings with hepatic lipidosis in bearded dragons (Pogona vitticeps) and effects of gemfibrozil therapy

et al. 2023

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“…For example, an excellent study system is brumation (akin to hibernation) in the bearded dragon, during which thousands of genes are differentially expressed compared to individuals at non-brumating temperatures. [54,55] Comparing genome structure in cold-brumating individuals and warm individuals will reveal if the reptile genome has capacity to restructure in response to temperature. To determine if the genome is remodelled in direct response to temperature, or whether change to the underlaying epigenetic code is responsible, profiling the epigenome (ChIP-seq/CUT&RUN/bisulfite sequencing), including the detection of structural proteins such as cohesins and CTCF, in combination with Hi-C experiments in the developing reptile gonad (at different temperatures) will be key.…”

Section: Testing Thermosensitive 3d Conformation and Sexual Fatementioning

confidence: 99%

Three dimensions of thermolabile sex determination

et al. 2022

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The molecular mechanism of temperature-dependent sex determination (TSD) is a long-standing mystery. How is the thermal signal sensed, captured and transduced to regulate key sex genes? Although there is compelling evidence for pathways via which cells capture the temperature signal, there is no known mechanism by which cells transduce those thermal signals to affect gene expression. Here we propose a novel hypothesis we call 3D-TSD (the three dimensions of thermolabile sex determination).We postulate that the genome has capacity to remodel in response to temperature by changing 3D chromatin conformation, perhaps via temperature-sensitive transcriptional condensates. This could rewire enhancer-promoter interactions to alter the expression of key sex-determining genes. This hypothesis can accommodate monogenic or multigenic thermolabile sex-determining systems, and could be combined with upstream thermal sensing and transduction to the epigenome to commit gonadal fate.high-throughput chromosome conformation capture; TAD, topologically associated domain; Pg, progesterone; PRC, polycomb repressive complex.

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“…However, the prevalence of metabolic depression in squamates is unclear and its mechanisms are largely unknown. Recent studies suggest an involvement of transcription and translation inhibition (Capraro et al, 2019, 2020), membranal and mitochondrial changes (Dubinin et al, 2019), phosphorylative enzyme inhibition (Capraro et al, 2019; Storey, 1996), and possibly organ size reduction (Dubiner et al, unpublished results for Tarentola annularis ). Some aspects of this type of ectothermic metabolic depression are reminiscent of insect diapause (Hahn & Denlinger, 2011; Storey & Storey, 2012).…”

Section: Introductionmentioning

confidence: 99%

Squamate metabolic rates decrease in winter beyond the effect of temperature

Dubiner,

Jamison,

Meiri

et al. 2023

Journal of Animal Ecology

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The reptilian form of hibernation (brumation) is much less studied than its mammalian and insect equivalents. Hibernation and brumation share some basic features but may differ in others. Evidence for hypometabolism in brumating reptiles beyond the effect of temperature is sporadic and often ignored. We calculated the standard metabolic rates (SMR, oxygen uptake during inactivity), in winter and/or summer, of 156 individuals representing 59 species of Israeli squamates across all 17 local families. For 32 species, we measured the same individuals during both seasons. We measured gas exchange continuously in a dark metabolic chamber, under the average January high and low temperatures (20°C and 12°C), during daytime and nighttime. We examined how SMR changes with season, biome, body size, temperature and time of day, using phylogenetic mixed models. Metabolic rates increased at sunrise in the diurnal species, despite no light or other external cues, while in nocturnal species the metabolic rates did not increase. Cathemeral species shifted from a diurnal‐like diel pattern in winter to a nocturnal‐like pattern in summer. Regardless of season, Mediterranean species SMRs were 30% higher than similar‐sized desert species. Summer SMR of all species together scaled with body size with an exponent of 0.84 but dropped to 0.71 during brumation. Individuals measured during both seasons decreased their SMR between summer and winter by a 47%, on average, at 20°C and by 70% at 12°C. Q10 was 1.75 times higher in winter than in summer, possibly indicating an active suppression of metabolic processes under cold temperatures. Our results challenge the commonly held perception that squamate physiology is mainly shaped by temperature, with little role for intrinsic metabolic regulation. The patterns we describe indicate that seasonal, diel and geographic factors can trigger remarkable shifts in metabolism across squamate species.

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

Cited by 5 publications

References 65 publications

Association of plasma metabolites and diagnostic imaging findings with hepatic lipidosis in bearded dragons (Pogona vitticeps) and effects of gemfibrozil therapy

Association of plasma metabolites and diagnostic imaging findings with hepatic lipidosis in bearded dragons (Pogona vitticeps) and effects of gemfibrozil therapy

Three dimensions of thermolabile sex determination

Squamate metabolic rates decrease in winter beyond the effect of temperature

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