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1.
Mol Cells ; 43(6): 572-580, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32484163

RESUMO

Transient receptor potential ankyrin 1 from rattlesnakes (rsTRPA1) and boas (bTRPA1) was previously proposed to underlie thermo-sensitive infrared sensing based on transcript enrichment in infrared-sensing neurons and hyper-thermosensitivity expressed in Xenopus oocytes. It is unknown how these TRPA1s show thermosensitivities that overwhelm other thermoreceptors, and why rsTRPA1 is more thermosensitive than bTRPA1. Here, we show that snake TRPA1s differentially require Ca2+ for hyper-thermosensitivity and that predisposition to cytosolic Ca2+ potentiation correlates with superior thermosensitivity. Extracellularly applied Ca2+ upshifted the temperature coefficients (Q10s) of both TRPA1s, for which rsTRPA1, but not bTRPA1, requires cytosolic Ca2+. Intracellular Ca2+ chelation and substitutive mutations of the conserved cytosolic Ca2+-binding domain lowered rsTRPA1 thermosensitivity comparable to that of bTRPA1. Thapsigargin-evoked Ca2+ or calmodulin little affected rsTRPA1 activity or thermosensitivity, implying the importance of precise spatiotemporal action of Ca2+. Remarkably, a single rattlesnake-mimicking substitution in the conserved but presumably dormant cytosolic Ca2+-binding domain of bTRPA1 substantially enhanced thermosensitivity through cytosolic Ca2+ like rsTRPA1, indicating the capability of this single site in the determination of both cytosolic Ca2+ dependence and thermosensitivity. Collectively, these data suggest that Ca2+ is essential for the hyper-thermosensitivity of these TRPA1s, and cytosolic potentiation by permeating Ca2+ may contribute to the natural variation of infrared senses between rattlesnakes and boas.


Assuntos
Boidae/metabolismo , Cálcio/metabolismo , Crotalus/metabolismo , Citosol/metabolismo , Variação Genética , Temperatura , Canais de Potencial de Receptor Transitório/genética , Sequência de Aminoácidos , Animais , Cátions Bivalentes/farmacologia , Quelantes/farmacologia , Canais de Potencial de Receptor Transitório/química , Canais de Potencial de Receptor Transitório/metabolismo , Xenopus
2.
PLoS One ; 15(3): e0229667, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32119716

RESUMO

Inclusion body disease (IBD) is caused by reptarenaviruses and constitutes one of the most notorious viral diseases in snakes. Although central nervous system disease and various other clinical signs have been attributed to IBD in boid and pythonid snakes, studies that unambiguously reveal the clinical course of natural IBD and reptarenavirus infection are scarce. In the present study, the prevalence of IBD and reptarenaviruses in captive snake collections and the correlation of IBD and reptarenavirus infection with the clinical status of the sampled snakes were investigated. In three IBD positive collections, long-term follow-up during a three- to seven-year period was performed. A total of 292 snakes (178 boas and 114 pythons) from 40 collections in Belgium were sampled. In each snake, blood and buffy coat smears were evaluated for the presence of IBD inclusion bodies (IB) and whole blood was tested for reptarenavirus RNA by RT-PCR. Of all tested snakes, 16.5% (48/292) were positive for IBD of which all were boa constrictors (34.0%; 48/141) and 17.1% (50/292) were reptarenavirus RT-PCR positive. The presence of IB could not be demonstrated in any of the tested pythons, while 5.3% (6/114) were reptarenavirus positive. In contrast to pythons, the presence of IB in peripheral blood cells in boa constrictors is strongly correlated with reptarenavirus detection by RT-PCR (P<0.0001). Although boa constrictors often show persistent subclinical infection, long-term follow-up indicated that a considerable number (22.2%; 6/27) of IBD/reptarenavirus positive boas eventually develop IBD associated comorbidities.


Assuntos
Boidae/metabolismo , Infecções por Citomegalovirus/epidemiologia , Corpos de Inclusão/metabolismo , Animais , Animais de Zoológico , Arenaviridae/patogenicidade , Bélgica/epidemiologia , Comorbidade , Estudos Transversais , Corpos de Inclusão/fisiologia , Corpos de Inclusão Viral/genética , Prevalência , RNA Viral/genética , Serpentes/genética
3.
Gen Comp Endocrinol ; 288: 113375, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31874136

RESUMO

Plasma corticosterone (CORT) concentrations fluctuate in response to homeostatic demands. CORT is widely recognized as an important hormone related to energy balance. However, far less attention has been given to the potential role of CORT in regulating salt and water balance or responding to osmotic imbalances. We examined the effects of reproductive and hydric states on CORT levels in breeding Children's pythons (Antaresia childreni), a species with substantial energetic and hydric costs associated with egg development. Using a 2 × 2 experimental design, we examined how reproduction and water deprivation, both separately and combined, impact CORT levels and how these changes correlate with hydration (plasma osmolality) and energy levels (blood glucose). We found that reproduction leads to increased CORT levels, as does dehydration induced by water deprivation. The combined impact of reproduction and water deprivation led to the largest increases in CORT levels. Additionally, we found significant positive relationships among CORT levels, plasma osmolality, and blood glucose. Our results provide evidence that both reproductive activity and increased plasma osmolality can lead to increased plasma CORT in an ectotherm, which could be explained by either CORT having a role as a mineralocorticoid or CORT being elevated as part of a stress response to resource imbalances.


Assuntos
Boidae/metabolismo , Corticosterona/sangue , Reprodução/fisiologia , Privação de Água/fisiologia , Animais , Boidae/sangue , Boidae/fisiologia , Desidratação/sangue , Desidratação/metabolismo , Desidratação/fisiopatologia , Feminino , Masculino , Osmorregulação/fisiologia
4.
Bull Environ Contam Toxicol ; 103(4): 533-537, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31256202

RESUMO

We determined mercury (Hg) concentrations in various tissues of Burmese pythons (Python bivitattus; n = 227) caught in southwest Florida from 2012-2018 as part of a program to control this invasive species. Mercury ranged as high as 4.86 mg/kg in liver tissue from a snake that was 4.7 m long but overall averaged 0.12 ± 0.19 mg/kg in tail tips (n = 123). These levels were relatively low as compared to concentrations reported in pythons from Everglades National Park, a recognized Hg hotspot. These results show that snakes, particularly watersnakes, present another opportunity to biomonitor Hg at the aquatic-terrestrial interface. Although capturing snakes presents obvious challenges, which differ from sampling other taxa typically used in monitoring programs, taking advantage of this program to control an invasive species was cost effective and alleviated concerns about sampling and possibly reducing native snake populations.


Assuntos
Boidae/metabolismo , Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Espécies Introduzidas , Mercúrio/análise , Animais , Florida , Fígado/química
5.
Artigo em Inglês | MEDLINE | ID: mdl-30930202

RESUMO

The aim of the present study was to characterize ß-adrenergic receptors in the snake heart and lung of corn and Boa constrictor snakes. The ß-adrenergic receptor binding sites were studied in purified heart and lung membranes using the specific ß-adrenergic receptor antagonist [125J]-iodocyanopindolol (ICYP) and subtypes using selective ß1-adrenergic receptor antagonist CGP-20712A and selective ß2-adrenergic receptor antagonist ICI-118.551. A saturable and specific ß-adrenergic receptor binding site was detected in cardiac membranes with maximal receptor density (Bmax) of 43.99 ±â€¯3.86 fmol/mg protein (corn snake) and 58.07 ±â€¯2.88 fmol/mg protein (Boa constrictor) as well as KD of 24.21 ±â€¯7.38 pM (corn snake) and 21.48 ±â€¯3.85 pM (Boa constrictor) and in lung membranes (Bmax fmol/mg protein: 55.95 ±â€¯16.28 (corn snake) and 107.00 ±â€¯14.21 (Boa constrictor); KD pM: 71.25 ±â€¯21.92 (corn snake) and 55.04 ±â€¯18.68 (Boa constrictor)). Competition-binding studies showed ß-adrenergic receptors with low affinities to the ß2-selective adrenergic receptor antagonist and high affinity binding to ß1-selective adrenergic receptor antagonist in both heart and lung tissues of both snake species, suggesting the presence of high population of the post-synaptic ß1-adrenergic receptor subtype. It seems that the presence of the predominant ß1-subtype also in lung tissues may indicate the importance of the vascular system in the snake lung.


Assuntos
Boidae/fisiologia , Coração/efeitos dos fármacos , Pulmão/efeitos dos fármacos , Receptores Adrenérgicos beta/genética , Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Animais , Sítios de Ligação/efeitos dos fármacos , Boidae/metabolismo , Coração/fisiologia , Imidazóis/farmacologia , Pulmão/fisiologia , Propanolaminas/farmacologia , Ligação Proteica/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos
6.
Vet Ophthalmol ; 21(2): 119-124, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28635138

RESUMO

OBJECTIVE: Assess vascular permeability of the snake spectacle to sodium fluorescein during resting and shedding phases of the ecdysis cycle. ANIMAL STUDIED: Ball python (Python regius). PROCEDURES: The snake was anesthetized, and spectral domain optic coherence tomography was performed prior to angiographic procedures. An electronically controlled digital single-lens reflex camera with a dual-head flash equipped with filters suitable for fluorescein angiography was used to make images. Sodium fluorescein (10%) solution was administered by intracardiac injection. Angiographic images were made as fluorescein traversed the vasculature of the iris and spectacle. Individually acquired photographic frames were assessed and sequenced into pseudovideo image streams for further evaluation CONCLUSIONS: Fluorescein angiograms of the snake spectacle were readily obtained. Vascular permeability varied with the phase of ecdysis. Copious leakage of fluorescein occurred during the shedding phase. This angiographic method may provide diverse opportunities to investigate vascular aspects of snake spectacle ecdysis, dysecdysis, and the integument in general.


Assuntos
Boidae/metabolismo , Olho/irrigação sanguínea , Angiofluoresceinografia/veterinária , Fluoresceína/farmacocinética , Corantes Fluorescentes/farmacocinética , Animais , Boidae/anatomia & histologia , Permeabilidade Capilar , Olho/diagnóstico por imagem , Olho/metabolismo , Feminino , Angiofluoresceinografia/métodos , Iris/diagnóstico por imagem , Iris/metabolismo , Muda
7.
Z Naturforsch C J Biosci ; 72(7-8): 265-275, 2017 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-28306545

RESUMO

Analysis by gas chromatography/mass spectrometry of the scent gland secretions of male and female Middle American burrowing pythons (Loxocemus bicolor) revealed the presence of over 300 components including cholesterol, fatty acids, glyceryl monoalkyl ethers, and alcohols. The fatty acids, over 100 of which were identified, constitute most of the compounds in the secretions and show the greatest structural diversity. They include saturated and unsaturated, unbranched and mono-, di-, and trimethyl-branched compounds ranging in carbon-chain length from 13 to 24. The glyceryl monoethers possess saturated or unsaturated, straight or methyl-branched alkyl chains ranging in carbon-chain length from 13 to 24. Alcohols, which have not previously been reported from the scent glands, possess straight, chiefly saturated carbon chains ranging in length from 13 to 24. Sex or individual differences in secretion composition were not observed. Compounds in the scent gland secretions of L. bicolor may deter offending arthropods, such as ants.


Assuntos
Álcoois/análise , Boidae/metabolismo , Ácidos Graxos/análise , Éteres de Glicerila/análise , Lipídeos/análise , Glândulas Odoríferas/metabolismo , Animais , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Masculino , Estados Unidos
8.
AAPS PharmSciTech ; 16(6): 1425-33, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25986597

RESUMO

Unprotected sunlight exposure is a risk factor for a variety of cutaneous cancers. Topically used dihydroxyacetone (DHA) creates, via Maillard reaction, chemically fixed keratin sunscreen in the stratum corneum with significant protection against UVA/Soret radiation. When used in conjunction with naphthoquinones a naphthoquinone-modified DHA Maillard reaction is produced that provides protection across the UVB/UVA/Soret spectra lasting up to 1 week, resisting sweating and contact removal. The aim of this study was to examine a simplified version of this formulation for effect on UV transmission and to determine if penetration levels merit toxicity concerns. Permeability was demonstrated for freshly prepared DHA (30 mg/mL) and lawsone (0.035 mg/mL) alone and in combination using a side-by-side diffusion apparatus at 37°C over 48 h across shed snake skin and dermatomed pig skin. These samples were then examined for effectiveness and safety. Concentrations were determined by HPLC and UPLC monitored from 250-500 nm. Lawsone flux significantly decreased across pig skin (20.8 (± 4.8) and 0.09 (± 0.1) mg/cm(2) h without and with DHA, respectively) but did not change across shed snake skin in the presence of DHA. Significantly reduced lawsone concentration was noted in donor chambers of combined solutions. Damage was not observed in any skins. Darker coloration with greater UV absorbance was observed in skins exposed to the combined solution versus individual solutions. This study confirmed that combined DHA and lawsone provided effective blocking of ultraviolet light through products bound in keratinized tissue. DHA permeation levels in pig skin suggest further in vitro and in vivo study is required to determine the safety of this system.


Assuntos
Di-Hidroxiacetona/administração & dosagem , Naftoquinonas/administração & dosagem , Pele/efeitos dos fármacos , Protetores Solares/administração & dosagem , Animais , Boidae/metabolismo , Difusão , Suínos , Raios Ultravioleta
9.
Artigo em Inglês | MEDLINE | ID: mdl-26005204

RESUMO

Carbonic anhydrase (CA) is one of the most abundant proteins found in vertebrate erythrocytes with the majority of species expressing a low activity CA I and high activity CA II. However, several phylogenetic gaps remain in our understanding of the expansion of cytoplasmic CA in vertebrate erythrocytes. In particular, very little is known about isoforms from reptiles. The current study sought to characterize the erythrocyte isoforms from two squamate species, Python molurus and Nerodia rhombifer, which was combined with information from recent genome projects to address this important phylogenetic gap. Obtained sequences grouped closely with CA XIII in phylogenetic analyses. CA II mRNA transcripts were also found in erythrocytes, but found at less than half the levels of CA XIII. Structural analysis suggested similar biochemical activity as the respective mammalian isoforms, with CA XIII being a low activity isoform. Biochemical characterization verified that the majority of CA activity in the erythrocytes was due to a high activity CA II-like isoform; however, titration with copper supported the presence of two CA pools. The CA II-like pool accounted for 90 % of the total activity. To assess potential disparate roles of these isoforms a feeding stress was used to up-regulate CO2 excretion pathways. Significant up-regulation of CA II and the anion exchanger was observed; CA XIII was strongly down-regulated. While these results do not provide insight into the role of CA XIII in the erythrocytes, they do suggest that the presence of two isoforms is not simply a case of physiological redundancy.


Assuntos
Boidae/sangue , Anidrases Carbônicas/química , Anidrases Carbônicas/metabolismo , Eritrócitos/enzimologia , Sequência de Aminoácidos , Animais , Transporte Biológico , Boidae/genética , Boidae/metabolismo , Boidae/fisiologia , Dióxido de Carbono/metabolismo , Anidrases Carbônicas/genética , Citoplasma/enzimologia , Ingestão de Alimentos , Eritrócitos/citologia , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Dados de Sequência Molecular , Filogenia , Análise de Sequência , Transcrição Genética
10.
J Exp Biol ; 218(Pt 13): 2089-96, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25987734

RESUMO

Pythons digesting rodent meals exhibit up to 10-fold increases in their resting metabolic rate (RMR); this increase in RMR is termed specific dynamic action (SDA). Studies have shown that SDA is partially fueled by oxidizing dietary nutrients, yet it remains unclear whether the proteins and the lipids in their meals contribute equally to this energy demand. We raised two populations of mice on diets labeled with either [(13)C]leucine or [(13)C]palmitic acid to intrinsically enrich the proteins and lipids in their bodies, respectively. Ball pythons (Python regius) were fed whole mice (and pureed mice 3 weeks later), after which we measured their metabolic rates and the δ(13)C in the breath. The δ(13)C values in the whole bodies of the protein- and lipid-labeled mice were generally similar (i.e. 5.7±4.7‰ and 2.8±5.4‰, respectively) but the oxidative kinetics of these two macronutrient pools were quite different. We found that the snakes oxidized 5% of the protein and only 0.24% of the lipids in their meals within 14 days. Oxidation of the dietary proteins peaked 24 h after ingestion, at which point these proteins provided ∼90% of the metabolic requirement of the snakes, and by 14 days the oxidation of these proteins decreased to nearly zero. The oxidation of the dietary lipids peaked 1 day later, at which point these lipids supplied ∼25% of the energy demand. Fourteen days after ingestion, these lipids were still being oxidized and continued to account for ∼25% of the metabolic rate. Pureeing the mice reduced the cost of gastric digestion and decreased SDA by 24%. Pureeing also reduced the oxidation of dietary proteins by 43%, but it had no effect on the rates of dietary lipid oxidation. Collectively, these results demonstrate that pythons are able to effectively partition the two primary metabolic fuels in their meals. This approach of uniquely labeling the different components of the diet will allow researchers to examine new questions about how and when animals use the nutrients in their meals.


Assuntos
Boidae/metabolismo , Proteínas na Dieta/metabolismo , Digestão/fisiologia , Animais , Metabolismo Basal , Gorduras na Dieta/metabolismo , Camundongos , Oxirredução , Período Pós-Prandial/fisiologia
11.
Artigo em Inglês | MEDLINE | ID: mdl-25553896

RESUMO

Digestion in pythons is associated with a large increase in oxygen consumption (SDA), increased cardiac output and growth in visceral organs assisting in digestion. The processes leading to the large postprandial rise in metabolism in snakes is subject to opposing views. Gastric work, protein synthesis and organ growth have each been speculated to be major contributors to the SDA. To investigate the role of food composition on SDA, heart rate (HR) and organ growth, 48 ball pythons (Python regius) were fed meals of either fat, glucose, protein or protein combined with carbonate. Our study shows that protein, in the absence or presence of carbonate causes a large SDA response, while glucose caused a significantly smaller SDA response and digestion of fat failed to affect metabolism. Addition of carbonate to the diet to stimulate gastric acid secretion did not increase the SDA response. These results support protein synthesis as a major contributor to the SDA response and show that increased gastric acid secretion occurs at a low metabolic cost. The increase in metabolism was supported by tachycardia caused by altered autonomic regulation as well as an increased non-adrenergic, non-cholinergic (NANC) tone in response to all diets, except for the lipid meal. Organ growth only occurred in the small intestine and liver in snakes fed on a high protein diet.


Assuntos
Fenômenos Fisiológicos da Nutrição Animal , Boidae/fisiologia , Frequência Cardíaca , Animais , Gasometria , Pressão Sanguínea , Boidae/crescimento & desenvolvimento , Boidae/metabolismo , Carbonatos/farmacologia , Proteínas na Dieta/farmacologia , Glucose/farmacologia , Glicogênio/análise , Lipídeos/análise , Tamanho do Órgão , Consumo de Oxigênio , Período Pós-Prandial
12.
J Exp Biol ; 217(Pt 22): 3958-61, 2014 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-25267848

RESUMO

To evaluate whether the 'oxygen and capacity limited thermal tolerance' model (OCLTT) applies to an air-breathing ectothermic vertebrate, we measured oxygen uptake (V̇(O2)), cardiac performance and arterial blood gases during a progressive rise of temperature from 30 to 40°C in the snake Python regius. V̇(O2) of fasting snakes increased exponentially with temperature whereas V̇(O2) of digesting snakes at high temperatures plateaued at a level 3- to 4-fold above fasting. The high and sustained aerobic metabolism over the entire temperature range was supported by pronounced tachycardia at all temperatures, and both fasting and digesting snakes maintained a normal acid-base balance without any indication of anaerobic metabolism. All snakes also maintained high arterial PO2, even at temperatures close to the upper lethal temperature. Thus, there is no evidence of a reduced capacity for oxygen transport at high temperatures in either fasting or digesting snakes, suggesting that the upper thermal tolerance of this species is limited by other factors.


Assuntos
Equilíbrio Ácido-Base , Boidae/metabolismo , Temperatura Alta , Oxigênio/sangue , Transporte Respiratório , Animais , Digestão/fisiologia , Jejum , Frequência Cardíaca , Consumo de Oxigênio , Estresse Fisiológico
13.
Artigo em Inglês | MEDLINE | ID: mdl-24521885

RESUMO

The few and fragmentary studies on purinergic regulation of the reptile heart have reached equivocal conclusions. Indeed, unlike fish, amphibians, and mammals, it has been suggested that the turtle heart lacks purinoceptors. Here, we study the effect of adenosine and ATP on isolated heart strips from three species of reptiles: the red-eared slider (Trachemys scripta), the ball python (Python regius) and the spectacled caiman (Caiman crocodilus). Both adenosine and ATP markedly decreased contractility in atria from all three species. This was attenuated by theophylline, suggesting that the response is mediated by P1 receptors. Ventricles were less sensitive, although high concentrations of the adenyl compounds evoked decreases in contractility. Our study suggests that cardiac purinoceptors are ubiquitous across reptiles, and may play an important and underappreciated role in reptile cardiovascular physiology.


Assuntos
Contração Miocárdica , Miocárdio/metabolismo , Receptores Purinérgicos/metabolismo , Aclimatação/efeitos dos fármacos , Adenosina/farmacologia , Trifosfato de Adenosina/farmacologia , Jacarés e Crocodilos/metabolismo , Animais , Fenômenos Biomecânicos/efeitos dos fármacos , Boidae/metabolismo , Temperatura Baixa , Ventrículos do Coração/efeitos dos fármacos , Temperatura Alta , Técnicas In Vitro , Contração Miocárdica/efeitos dos fármacos , Tartarugas/metabolismo
14.
Proc Natl Acad Sci U S A ; 110(51): 20645-50, 2013 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-24297902

RESUMO

Snakes possess many extreme morphological and physiological adaptations. Identification of the molecular basis of these traits can provide novel understanding for vertebrate biology and medicine. Here, we study snake biology using the genome sequence of the Burmese python (Python molurus bivittatus), a model of extreme physiological and metabolic adaptation. We compare the python and king cobra genomes along with genomic samples from other snakes and perform transcriptome analysis to gain insights into the extreme phenotypes of the python. We discovered rapid and massive transcriptional responses in multiple organ systems that occur on feeding and coordinate major changes in organ size and function. Intriguingly, the homologs of these genes in humans are associated with metabolism, development, and pathology. We also found that many snake metabolic genes have undergone positive selection, which together with the rapid evolution of mitochondrial proteins, provides evidence for extensive adaptive redesign of snake metabolic pathways. Additional evidence for molecular adaptation and gene family expansions and contractions is associated with major physiological and phenotypic adaptations in snakes; genes involved are related to cell cycle, development, lungs, eyes, heart, intestine, and skeletal structure, including GRB2-associated binding protein 1, SSH, WNT16, and bone morphogenetic protein 7. Finally, changes in repetitive DNA content, guanine-cytosine isochore structure, and nucleotide substitution rates indicate major shifts in the structure and evolution of snake genomes compared with other amniotes. Phenotypic and physiological novelty in snakes seems to be driven by system-wide coordination of protein adaptation, gene expression, and changes in the structure of the genome.


Assuntos
Adaptação Fisiológica/fisiologia , Boidae , Evolução Molecular , Regulação da Expressão Gênica/fisiologia , Genoma/fisiologia , Transcrição Genética/fisiologia , Animais , Boidae/genética , Boidae/metabolismo , Ciclo Celular/fisiologia , Humanos , Especificidade de Órgãos/fisiologia
15.
Vet Rec ; 173(14): 345, 2013 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-24068697

RESUMO

Despite the popularity of keeping snakes in captivity, there has been limited investigation into the effects of UV radiation on vitamin D levels in snakes. The aim of this study was to investigate the effects of UV-b radiation on plasma 25-hydroxyvitamin D3 levels and ionised calcium concentrations in ball pythons (Python regius). Blood samples were taken from 14 ball pythons, which had never been exposed to UV-b light, to obtain baseline 25-hydroxyvitamin D3 levels and ionised calcium concentrations. Blood samples were then taken again from the same snakes 70 days later after one group (Group 1, n=6 females) were exposed to UV-b radiation daily, and the other group (Group 2, n=5 males and 3 females) were exposed to no UV-b radiation. Mean±sd 25-hydroxyvitamin D3 levels on day 0 in Group 1 were 197±35 nmol/l, and on day 70 were 203.5±13.8 nmol/l. Mean±sd 25-hydroxyvitamin D3 levels in Group 2 on day 0 were 77.7±41.5 nmol/l, and on day 70 were 83.0±41.9 nmol/l. Mean±sd ionised calcium levels at day 0 were 1.84±0.05 mmol/l for Group 1, and on day 70 were 1.78±0.07 mmol/l. Mean±sd ionised calcium levels at day 0 were 1.79±0.07 mmol/l for Group 2, and on day 70 were 1.81±0.05 mmol/l. No association was demonstrated between exposure to UV-b radiation and plasma 25-hydroxyvitamin D3 and ionised calcium concentrations. These results may provide baseline parameters for future studies in this and other snake species to determine ability to utilise UV-b light for vitamin D production.


Assuntos
Boidae/metabolismo , Calcifediol/efeitos da radiação , Cálcio/efeitos da radiação , Raios Ultravioleta , Animais , Animais de Zoológico , Boidae/sangue , Calcifediol/sangue , Cálcio/metabolismo , Feminino , Masculino
16.
Gen Comp Endocrinol ; 193: 178-84, 2013 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-23948369

RESUMO

To cope with environmental challenges, organisms have to adjust their behaviours and their physiology to the environmental conditions they face (i.e. allostasis). In vertebrates, such adjustments are often mediated through the secretion of glucocorticoids (GCs) that are well-known to activate and/or inhibit specific physiological and behavioural traits. In ectothermic species, most processes are temperature-dependent and according to previous studies, low external temperatures should be associated with low GC concentrations (both baseline and stress-induced concentrations). In this study, we experimentally tested this hypothesis by investigating the short term influence of temperature on the GC stress response in a squamate reptile, the Children's python (Antaresia childreni). Snakes were maintained in contrasting conditions (warm and cold groups), and their corticosterone (CORT) stress response was measured (baseline and stress-induced CORT concentrations), within 48h of treatment. Contrary to our prediction, baseline and stress-induced CORT concentrations were higher in the cold versus the warm treatment. In addition, we found a strong negative relationship between CORT concentrations (baseline and stress-induced) and temperature within the cold treatment. Although it remains unclear how cold temperatures can mechanistically result in increased CORT concentrations, we suggest that, at suboptimal temperature, high CORT concentrations may help the organism to maintain an alert state.


Assuntos
Boidae/metabolismo , Corticosterona/metabolismo , Animais , Boidae/fisiologia , Glucocorticoides/metabolismo , Estresse Fisiológico , Temperatura
17.
J Exp Biol ; 215(Pt 1): 185-96, 2012 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-22162867

RESUMO

Snakes exhibit an apparent dichotomy in the regulation of gastrointestinal (GI) performance with feeding and fasting; frequently feeding species modestly regulate intestinal function whereas infrequently feeding species rapidly upregulate and downregulate intestinal function with the start and completion of each meal, respectively. The downregulatory response with fasting for infrequently feeding snakes is hypothesized to be a selective attribute that reduces energy expenditure between meals. To ascertain the links between feeding habit, whole-animal metabolism, and GI function and metabolism, we measured preprandial and postprandial metabolic rates and gastric and intestinal acid-base secretion, epithelial conductance and oxygen consumption for the frequently feeding diamondback water snake (Nerodia rhombifer) and the infrequently feeding Burmese python (Python molurus). Independent of body mass, Burmese pythons possess a significantly lower standard metabolic rate and respond to feeding with a much larger metabolic response compared with water snakes. While fasting, pythons cease gastric acid and intestinal base secretion, both of which are stimulated with feeding. In contrast, fasted water snakes secreted gastric acid and intestinal base at rates similar to those of digesting snakes. We observed no difference between fasted and fed individuals for either species in gastric or intestinal transepithelial potential and conductance, with the exception of a significantly greater gastric transepithelial potential for fed pythons at the start of titration. Water snakes experienced no significant change in gastric or intestinal metabolism with feeding. Fed pythons, in contrast, experienced a near-doubling of gastric metabolism and a tripling of intestinal metabolic rate. For fasted individuals, the metabolic rate of the stomach and small intestine was significantly lower for pythons than for water snakes. The fasting downregulation of digestive function for pythons is manifested in a depressed gastric and intestinal metabolism, which selectively serves to reduce basal metabolism and hence promote survival between infrequent meals. By maintaining elevated GI performance between meals, fasted water snakes incur the additional cost of tissue activity, which is expressed in a higher standard metabolic rate.


Assuntos
Boidae/fisiologia , Colubridae/fisiologia , Equilíbrio Ácido-Base , Animais , Metabolismo Basal , Boidae/metabolismo , Colubridae/metabolismo , Digestão , Eletrofisiologia , Comportamento Alimentar , Conteúdo Gastrointestinal/química , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/fisiologia , Oxigênio/metabolismo , Período Pós-Prandial
18.
J Exp Zool B Mol Dev Evol ; 316(8): 598-608, 2011 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-21932327

RESUMO

The molecular and developmental factors that regulate tooth morphogenesis in nonmammalian species, such as snakes and lizards, have received relatively little attention compared to mammals. Here we describe the development of unicuspid and bicuspid teeth in squamate species. The simple, cone-shaped tooth crown of the bearded dragon and ball python is established at cap stage and fixed in shape by the differentiation of cells and the secretion of dental matrices. Enamel production, as demonstrated by amelogenin expression, occurs relatively earlier in squamate teeth than in mouse molars. We suggest that the early differentiation in squamate unicuspid teeth at cap stage correlates with a more rudimentary tooth crown shape. The leopard gecko can form a bicuspid tooth crown despite the early onset of differentiation. Cusp formation in the gecko does not occur by the folding of the inner enamel epithelium, as in the mouse molar, but by the differential secretion of enamel. Ameloblasts forming the enamel epithelial bulge, a central swelling of cells in the inner enamel epithelium, secrete amelogenin at cap stage, but cease to do so by bell stage. Meanwhile, other ameloblasts in the inner enamel epithelium continue to secrete enamel, forming cusp tips on either side of the bulge. Bulge cells specifically express the gene Bmp2, which we suggest serves as a pro-differentiation signal for cells of the gecko enamel organ. In this regard, the enamel epithelial bulge of the gecko may be more functionally analogous to the secondary enamel knot of mammals than the primary enamel knot.


Assuntos
Amelogenina/metabolismo , Dente Pré-Molar/crescimento & desenvolvimento , Boidae/embriologia , Boidae/metabolismo , Proteína Morfogenética Óssea 2/metabolismo , Dente Canino/crescimento & desenvolvimento , Coroa do Dente/crescimento & desenvolvimento , Ameloblastos/metabolismo , Animais , Dente Pré-Molar/embriologia , Boidae/anatomia & histologia , Diferenciação Celular/fisiologia , Dente Canino/embriologia , Esmalte Dentário/metabolismo , Órgão do Esmalte/citologia , Órgão do Esmalte/metabolismo , Epitélio/metabolismo , Morfogênese/fisiologia , Odontogênese/fisiologia , Coroa do Dente/embriologia
19.
Artigo em Inglês | MEDLINE | ID: mdl-21884815

RESUMO

Reproductive effort has been defined as the proportion of an organism's energy budget that is allocated to reproduction over a biologically meaningful time period. Historically, studies of reproductive bioenergetics considered energy content of gametes, but not costs of gamete production. Although metabolic costs of vitellogenesis (MCV) fundamentally reflect the primary bioenergetic cost of reproductive allocation in female reptiles, the few investigations that have considered costs of reproductive allocation have focused on metabolic costs of pregnancy (MCP) in viviparous species. We define MCP as energetic costs incurred by pregnant females, including all costs of maintaining gestation conditions necessary for embryogenesis. MCP by our definition do not include fetal costs of embryogenesis. We measured metabolic rates in five species of viviparous snakes (Agkistrodon contortrix, Boa constrictor, Eryx colubrinus, Nerodia sipedon, and Thamnophis sirtalis) during vitellogenesis and pregnancy in order to estimate MCV and MCP. Across all species, MCV were responsible for 30% increases in maternal metabolism. Phylogenetically-independent contrasts showed that MCV were significantly greater in B. constrictor than in other species, likely because B. constrictor yolk energy content was greater than that of other species. Estimates of MCP were not significantly different from zero in any species. In viviparous snakes, MCV appear to represent significant bioenergetic expenditures, while MCP do not. We suggest that MCV, together with yolk energy content, represent the most significant component of reptilian reproductive effort, and therefore deserve greater attention than MCP in studies of reptilian reproductive bioenergetics.


Assuntos
Metabolismo Energético/fisiologia , Reprodução/fisiologia , Serpentes/fisiologia , Vitelogênese/fisiologia , Viviparidade não Mamífera/fisiologia , Animais , Boidae/metabolismo , Boidae/fisiologia , Estradiol/metabolismo , Feminino , Progesterona/metabolismo , Répteis/metabolismo , Répteis/fisiologia , Serpentes/metabolismo
20.
J Zoo Wildl Med ; 42(3): 444-50, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22950317

RESUMO

The objective of this study was to determine the pharmacokinetics of a long-acting formulation of ceftiofur crystalline-free acid (CCFA) following intramuscular injection in ball pythons (Python regius). Six adult ball pythons received an injection of CCFA (15 mg/kg) in the epaxial muscles. Blood samples were collected by cardiocentesis immediately prior to and at 0.5, 1, 2, 4, 8, 12, 18, 24, 48, 72, 96, 144, 192, 240, 288, 384, 480, 576, 720, and 864 hr after CCFA administration. Plasma ceftiofur concentrations were determined by high-performance liquid chromatography. A noncompartmental pharmacokinetic analysis was applied to the data. Maximum plasma concentration (Cmax) was 7.096 +/- 1.95 microg/ml and occurred at (Tmax) 2.17 +/- 0.98 hr. The area under the curve (0 to infinity) for ceftiofur was 74.59 +/- 13.05 microg x h/ml and the elimination half-life associated with the terminal slope of the concentration-time curve was 64.31 +/- 14.2 hr. Mean residence time (0 to infinity) was 46.85 +/- 13.53 hr. CCFA at 15 mg/kg was well tolerated in all the pythons. Minimum inhibitory concentration (MIC) data for bacterial isolates from snakes are not well established. For MIC values of < or =0.1 microg/ml, a single dose of CCFA (15 mg/kg) provides adequate plasma concentrations for at least 5 days in the ball python. For MICs > or =0.5 microg/ml, more frequent dosing or a higher dosage may be required.


Assuntos
Antibacterianos/farmacocinética , Boidae/sangue , Boidae/metabolismo , Cefalosporinas/farmacocinética , Animais , Antibacterianos/administração & dosagem , Antibacterianos/sangue , Área Sob a Curva , Cefalosporinas/administração & dosagem , Cefalosporinas/sangue , Meia-Vida , Injeções Intramusculares
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