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Şahin MK, Kuyucu AC. Thermal biology of two sympatric Lacertid lizards (Lacerta diplochondrodes and Parvilacerta parva) from Western Anatolia. J Therm Biol 2021; 101:103094. [PMID: 34879912 DOI: 10.1016/j.jtherbio.2021.103094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 09/07/2021] [Accepted: 09/14/2021] [Indexed: 11/28/2022]
Abstract
Sympatric lizard species present convenient models for studying differentiation in thermal behavior and the role of morphological differences in their thermal biology. Here we studied the thermal biology of two sympatric lizard species which occur sympatrically in the Phrygian Valley of Western Anatolia. These two species differ in body size, with Lacerta diplochondrodes being larger than Parvilacerta parva. The surface body temperatures of the individuals belonging to both species were recorded when active in the field. Additionally, several environmental parameters including solar radiation, substrate temperature, air temperature and wind speed were monitored to investigate the relative effects of these abiotic parameters on the thermal biology of the two species. The surface body temperature and temperature excess (difference between body and substrate temperature) of the two species, while being relatively close to each other, showed seasonal differences. Solar radiation, substrate temperature and air temperature were the main factors influencing their thermal biology. Additionally, although body size did not have a direct effect on body temperature or temperature excess, the interaction between body size and solar radiation on temperature excess was significant. In conclusion, our study partially supports the conservation of body temperature of related lizard species.
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Affiliation(s)
- Mehmet Kürşat Şahin
- Karamanoğlu Mehmetbey University, Department of Biology, Kamil Ozdag Faculty of Science, Karaman, Turkey.
| | - Arda Cem Kuyucu
- Hacettepe University, Department of Biology, Faculty of Science, Ankara, Turkey.
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Loehr VJ, Keswick T, Reijnders MA, Zweers IM. High-Level Inactivity Despite Favorable Environmental Conditions in the Rock-Dwelling Dwarf Tortoise Chersobius boulengeri. HERPETOLOGICA 2021. [DOI: 10.1655/herpetologica-d-20-00043.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Seddon RJ, Hews DK. Melanization, α-melanocyte stimulating hormone and steroid hormones in male western fence lizards from nine populations. Gen Comp Endocrinol 2020; 285:113287. [PMID: 31563645 DOI: 10.1016/j.ygcen.2019.113287] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/29/2019] [Accepted: 09/22/2019] [Indexed: 02/05/2023]
Abstract
Hormones can mediate suites of correlated traits. Melanocortins regulate melanin synthesis and elements of the melanocortin system can directly, and indirectly, affect a number of other traits, such as stress reactivity. Trait correlations within the melanocortin system have been studied mainly in birds and mammals but less so in reptiles. We examined adult male western fence lizards (Sceloporus occidentalis) and if melanization was correlated with plasma levels of three hormones, including peptide hormone α-melanocyte stimulating hormone (α-MSH), testosterone and corticosterone, and ectoparasite loads. This lizard is darker at higher elevations in California, and we compared five high-elevation and four low-elevation populations during comparable periods of the breeding season at each site. We first validated use of an α-MSH assay kit with lizard plasma. Since Anolis carolinensis is one of the few species with published values for α-MSH plasma levels, we assayed both Anolis and Sceloporus plasma and compared hormone values to those we generated for Anolis to the publish values. We also evaluated effects of different methods of storing spiked plasma pools on resulting α-MSH concentrations. Plasma levels of α-MSH did not differ significantly, but some populations differed significantly in mean corticosterone and mean testosterone. Combining all individuals from the nine populations, we found that individual variation in α-MSH was not associated with individual variation in melanization, but levels of α-MSH were positively associated with plasma testosterone and negatively associated with corticosterone. The lack of association between individual levels of melanization and expression of most other traits differs from a growing number of within-population studies of melanization, and we discuss what differences in physiological mechanisms could produce different hypothetical patterns. Circulating levels of -MSH are only one element of the melanocortin system; in situ synthesis of α-MSH by the skin and the diversity of melanocortin receptors could also contribute to variation in traits mediated by the melanocortin system and should be examined.
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Affiliation(s)
- Ryan J Seddon
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
| | - Diana K Hews
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
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Burggren W, Filogonio R, Wang T. Cardiovascular shunting in vertebrates: a practical integration of competing hypotheses. Biol Rev Camb Philos Soc 2019; 95:449-471. [PMID: 31859458 DOI: 10.1111/brv.12572] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 10/30/2019] [Accepted: 11/07/2019] [Indexed: 12/20/2022]
Abstract
This review explores the long-standing question: 'Why do cardiovascular shunts occur?' An historical perspective is provided on previous research into cardiac shunts in vertebrates that continues to shape current views. Cardiac shunts and when they occur is then described for vertebrates. Nearly 20 different functional reasons have been proposed as specific causes of shunts, ranging from energy conservation to improved gas exchange, and including a plethora of functions related to thermoregulation, digestion and haemodynamics. It has even been suggested that shunts are merely an evolutionary or developmental relic. Having considered the various hypotheses involving cardiovascular shunting in vertebrates, this review then takes a non-traditional approach. Rather than attempting to identify the single 'correct' reason for the occurrence of shunts, we advance a more holistic, integrative approach that embraces multiple, non-exclusive suites of proposed causes for shunts, and indicates how these varied functions might at least co-exist, if not actually support each other as shunts serve multiple, concurrent physiological functions. It is argued that deposing the 'monolithic' view of shunting leads to a more nuanced view of vertebrate cardiovascular systems. This review concludes by suggesting new paradigms for testing the function(s) of shunts, including experimentally placing organ systems into conflict in terms of their perfusion needs, reducing sources of variation in physiological experiments, measuring possible compensatory responses to shunt ablation, moving experiments from the laboratory to the field, and using cladistics-related approaches in the choice of experimental animals.
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Affiliation(s)
- Warren Burggren
- Department of Biological Sciences, Developmental Integrative Biology Cluster, University of North Texas, Denton, TX, 76203-5220, U.S.A
| | - Renato Filogonio
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, 13565-905, Brazil
| | - Tobias Wang
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus C, 8000, Denmark.,Aarhus Institute of Advanced Sciences (AIAS), Aarhus University, Aarhus C, 8000, Denmark
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Seddon RJ, Hews DK. Correlates of melanization in multiple high- and low-elevation populations of the lizard,Sceloporus occidentalis: Behavior, hormones, and parasites. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 327:481-492. [DOI: 10.1002/jez.2133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/21/2017] [Accepted: 10/30/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Ryan J. Seddon
- Department of Biology; Indiana State University; Terre Haute Indiana
| | - Diana K. Hews
- Department of Biology; Indiana State University; Terre Haute Indiana
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Sirsat SKG, Dzialowski EM. Ontogeny of skeletal and cardiac muscle mitochondria oxygen fluxes in two breeds of chicken. Comp Biochem Physiol A Mol Integr Physiol 2017; 215:20-27. [PMID: 29054807 DOI: 10.1016/j.cbpa.2017.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 10/12/2017] [Accepted: 10/12/2017] [Indexed: 11/26/2022]
Abstract
From its earliest days of domestication, the domestic chicken (Gallus gallus domesticus) has been selectively bred for specific traits. Decades of genetic selection have resulted in significant dissimilarities in metabolism and growth between breeds, in particular fast-growing broilers and highly productive layers. A chicken develops the capacity to elevate metabolism in response to decreases in ambient temperature upon hatching, including well-developed methods of regulating thermogenesis. However, a differential timing between incipient endothermic capacities of broiler and layer strains exists. Although both broiler and layer chicks show the hallmark rapid attainment of endothermic capacity of precocial birds, endothermic capacity of broilers matures faster than that of layers. Here we characterized changes in morphology and mitochondria physiology during the developmental transition as the animals become endothermic. Changes in body mass occurred at a faster rate in broilers, with hatching embryos showing significant increases over embryonic body mass, while layers did not exhibit significant differences in mass until after hatch. Heart and liver both exhibited rapid growth upon hatching that occurred with little change in body mass in both breeds. Skeletal and cardiac mitochondrial respiration capacity in broilers increased from the embryonic stage through hatching. Oxidative phosphorylation was more tightly coupled to ATP production in broilers than layer muscles during external pipping. By selecting for faster growth and higher meat yield, the physiological transition from ectothermy to endothermy was also affected: differences in whole-animal, tissue, and organelle responses are evident in these two divergent breeds of chicken.
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Affiliation(s)
- Sarah K G Sirsat
- Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, TX 76203, United States
| | - Edward M Dzialowski
- Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, TX 76203, United States.
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Barroso FM, Carretero MA, Silva F, Sannolo M. Assessing the reliability of thermography to infer internal body temperatures of lizards. J Therm Biol 2016; 62:90-96. [PMID: 27839556 DOI: 10.1016/j.jtherbio.2016.10.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 07/13/2016] [Accepted: 10/16/2016] [Indexed: 01/11/2023]
Abstract
For many years lizard thermal ecology studies have relied on the use of contact thermometry to obtain internal body temperature (Tb) of the animals. However, with progressing technology, an interest grew in using new, less invasive methods, such as InfraRed (IR) pyrometry and thermography, to infer Tb of reptiles. Nonetheless few studies have tested the reliability of these new tools. The present study tested the use of IR cameras as a non-invasive tool to infer Tb of lizards, using three differently body-sized lacertid species (Podarcis virescens, Lacerta schreiberi and Timon lepidus). Given the occurrence of regional heterothermy, we pairwise compared thermography readings of six body parts (snout, eye, head, dorsal, hind limb, tail base) to cloacal temperature (measured by a thermometer-associated thermocouple probe) commonly employed to measure Tb in field and lab studies. The results showed moderate to strong correlations (R2=0.84-0.99) between all body parts and cloacal temperature. However, despite the readings on the tail base showed the strongest correlation in all three species, it was the eye where the absolute values and pattern of temperature change most consistently followed the cloacal measurements. Hence, we concluded that the eye would be the body location whose IR camera readings more closely approximate that of the animal's internal environment. Alternatively, other body parts can be used, provided that a careful calibration is carried out. We provide guidelines for future research using thermography to infer Tb of lizards.
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Affiliation(s)
- Frederico M Barroso
- CIBIO, Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão 4485-661, Vila do Conde, Portugal; College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Miguel A Carretero
- CIBIO, Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão 4485-661, Vila do Conde, Portugal
| | - Francisco Silva
- Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre, s/n, 4169-007, Porto, Portugal
| | - Marco Sannolo
- CIBIO, Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão 4485-661, Vila do Conde, Portugal; Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre, s/n, 4169-007, Porto, Portugal.
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Goller M, Goller F, French SS. A heterogeneous thermal environment enables remarkable behavioral thermoregulation in Uta stansburiana. Ecol Evol 2014; 4:3319-29. [PMID: 25535549 PMCID: PMC4228607 DOI: 10.1002/ece3.1141] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 05/16/2014] [Accepted: 05/27/2014] [Indexed: 11/18/2022] Open
Abstract
Ectotherms can attain preferred body temperatures by selecting specific temperature microhabitats within a varied thermal environment. The side-blotched lizard, Uta stansburiana may employ microhabitat selection to thermoregulate behaviorally. It is unknown to what degree habitat structural complexity provides thermal microhabitats for thermoregulation. Thermal microhabitat structure, lizard temperature, and substrate preference were simultaneously evaluated using thermal imaging. A broad range of microhabitat temperatures was available (mean range of 11°C within 1-2 m(2)) while mean lizard temperature was between 36°C and 38°C. Lizards selected sites that differed significantly from the mean environmental temperature, indicating behavioral thermoregulation, and maintained a temperature significantly above that of their perch (mean difference of 2.6°C). Uta's thermoregulatory potential within a complex thermal microhabitat structure suggests that a warming trend may prove advantageous, rather than detrimental for this population.
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Affiliation(s)
- Maria Goller
- Department of Biology, Utah State UniversityLogan, Utah, 84322-5305
| | - Franz Goller
- Department of Biology, University of UtahSalt Lake City, Utah, 84112-0840
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Angilletta MJ, Zelic MH, Adrian GJ, Hurliman AM, Smith CD. Heat tolerance during embryonic development has not diverged among populations of a widespread species (Sceloporus undulatus). CONSERVATION PHYSIOLOGY 2013; 1:cot018. [PMID: 27293602 PMCID: PMC4806623 DOI: 10.1093/conphys/cot018] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 05/28/2013] [Accepted: 05/31/2013] [Indexed: 05/30/2023]
Abstract
The frequency and magnitude of heat waves have increased in recent decades, imposing additional stresses on organisms in extreme environments. Most reptilian embryos are regularly exposed to thermal stress because they develop in shallow, warm soils for weeks to months. We studied cardiac performance during warming to infer lethal temperatures for embryonic lizards in the Sceloporus undulatus complex. Embryos from four populations throughout the geographical range (New Jersey, South Carolina, Colorado, and Arizona) were warmed at a rate observed in natural nests. Embryos from all populations exhibited a similar pattern of thermal sensitivity, as follows: heart rate rose between 34 and 41°C, remained stable between 41 and 44°C, and dropped sharply between 44 and 47°C. No embryos recovered from cardiac arrest, indicating that the upper lethal temperature was ≤47°C. Despite the putative selective pressures, the thermal limit to cardiac performance seems to have been conserved during the evolution of this species.
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Affiliation(s)
- Michael J. Angilletta
- Corresponding author: School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA. Tel: +1 480 727 6142.
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McWhorter TJ, Pinshow B, Karasov WH, Tracy CR. Paracellular absorption is relatively low in the herbivorous Egyptian spiny-tailed lizard, Uromastyx aegyptia. PLoS One 2013; 8:e61869. [PMID: 23596529 PMCID: PMC3626635 DOI: 10.1371/journal.pone.0061869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 03/18/2013] [Indexed: 11/19/2022] Open
Abstract
Absorption of small water-soluble nutrients in vertebrate intestines occurs both by specific, mediated transport and by non-specific, passive, paracellular transport. Although it is apparent that paracellular absorption represents a significant route for nutrient absorption in many birds and mammals, especially small, flying species, its importance in ectothermic vertebrates has not previously been explored. Therefore, we measured fractional absorption (ƒ) and absorption rate of three paracellular probes (arabinose, L-rhamnose, cellobiose) and of 3-O-methyl D-glucose (absorbed by both mediated and paracellular pathways) by the large herbivorous lizard, Uromastyx aegyptia, to explore the relative importance of paracellular and mediated transport in an ectothermic, terrestrial vertebrate. Fractional absorption of 3-O-methyl D-glucose was high (ƒ = 0.73±0.04) and similar to other vertebrates; ƒ of the paracellular probes was relatively low (arabinose ƒ = 0.31±0.03, L-rhamnose ƒ = 0.19±0.02, and cellobiose ƒ = 0.14±0.02), and decreased with molecular mass, a pattern consistent with other vertebrates. Paracellular absorption accounted for approximately 24% of total 3-O-methyl D-glucose uptake, indicating low reliance on this pathway for these herbivorous lizards, a pattern similar to that found in other terrestrial vertebrates, and different from small flying endotherms (both birds and bats).
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Affiliation(s)
- Todd J. McWhorter
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy Campus, Adelaide, SA, Australia
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Berry Pinshow
- Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - William H. Karasov
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Christopher R. Tracy
- Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia
- Department of Zoology, University of Melbourne, Parkville, VIC, Australia
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He J, Xiu M, Tang X, Wang N, Xin Y, Li W, Chen Q. Thermoregulatory and metabolic responses to hypoxia in the oviparous lizard, Phrynocephalus przewalskii. Comp Biochem Physiol A Mol Integr Physiol 2013; 165:207-13. [PMID: 23500623 DOI: 10.1016/j.cbpa.2013.03.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 02/08/2013] [Accepted: 03/05/2013] [Indexed: 11/25/2022]
Abstract
The effects of hypoxia on behavioral thermoregulation, rate of heating and cooling, hysteresis of heart rate, and standard metabolic rate (SMR) were investigated in Phrynocephalus przewalskii, a small size toad headed lizard. Preferred temperature (T(b)) descended when lizards were exposed to severe hypoxia (8% O(2) and 6% O(2)) for 22 h, and lizards were able to maintain preferred T(b) after one week at 12% and 8% O(2) respectively. The period of heating increased after being treated with hypoxia (12% and 8% O(2)) for one week. Hysteresis of heart rate appeared at any given body temperature and oxygen level except at 39 °C and 40 °C at 8% O(2). SMR significantly increased after one-week acclimatization to 12% and 8% O(2) when ambient temperature (T(a)) was 25 °C, however, it did not change at 35 °C. Thus, we suggest that P. przewalskii has special thermoregulatory and metabolic mechanisms to acclimatize to the hypoxic environment.
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Affiliation(s)
- Jianzheng He
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, 222 Tianshui South Road, Lanzhou, 730000, PR China
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Sagonas K, Meiri S, Valakos ED, Pafilis P. The effect of body size on the thermoregulation of lizards on hot, dry Mediterranean islands. J Therm Biol 2013. [DOI: 10.1016/j.jtherbio.2012.11.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Tattersall GJ, Sinclair BJ, Withers PC, Fields PA, Seebacher F, Cooper CE, Maloney SK. Coping with Thermal Challenges: Physiological Adaptations to Environmental Temperatures. Compr Physiol 2012; 2:2151-202. [DOI: 10.1002/cphy.c110055] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Embryos in the fast lane: high-temperature heart rates of turtles decline after hatching. PLoS One 2010; 5:e9557. [PMID: 20224773 PMCID: PMC2835746 DOI: 10.1371/journal.pone.0009557] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 02/11/2010] [Indexed: 11/29/2022] Open
Abstract
In ectotherms such as turtles, the relationship between cardiovascular function and temperature may be subject to different selective pressures in different life-history stages. Because embryos benefit by developing as rapidly as possible, and can “afford” to expend energy to do so (because they have access to the yolk for nutrition), they benefit from rapid heart (and thus, developmental) rates. In contrast, hatchlings do not have a guaranteed food supply, and maximal growth rates may not enhance fitness—and so, we might expect a lower heart rate, especially at high temperatures where metabolic costs are greatest. Our data on two species of emydid turtles, Chrysemys picta, and Graptemys pseudogeographica kohnii, support these predictions. Heart rates of embryos and hatchlings were similar at low temperatures, but heart rates at higher temperatures were much greater before than after hatching.
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Are Locomotor Performances Coadapted to Preferred Basking Temperature in the Northern Map Turtle (Graptemys geographica)? J HERPETOL 2008. [DOI: 10.1670/07-1881.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Merchant M, Fleury L, Rutherford R, Paulissen M. Effects of bacterial lipopolysaccharide on thermoregulation in green anole lizards (Anolis carolinensis). Vet Immunol Immunopathol 2008; 125:176-81. [PMID: 18514328 DOI: 10.1016/j.vetimm.2008.04.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 02/06/2008] [Accepted: 04/22/2008] [Indexed: 11/29/2022]
Abstract
Fever is a non-specific host defense mechanism that comprises part of the innate immune response. Innate immune function is thought to be an important adaptive immunological response to infection because it occurs across a broad diversity of phyla. Some reptiles can mount a febrile response, despite the fact that their internal body temperatures (T(b)s) are, to some extent, controlled by the environmental temperatures in which they live. This study was undertaken to determine if LPS would induce fever in green anole lizards (Anolis carolinensis). Lizards were maintained in thermal gradients (22-45 degrees C) with a 12-h diurnal cycle. anoles were injected with LPS, pyrogen-free saline, or left untreated, and their T(b)s were recorded every 15min using internal cloacal probes. All lizards showed a diurnal periodicity in T(b) characterized by decreased temperatures during the scotophase (dark hours) and higher temperatures during the photophase (light phase). Anoles injected with LPS exhibited a hypothermic response, relative to untreated and saline-injected animals. The response varied from 2.1 to 4.6 degrees C lower than control lizards. The hypothermic response was initiated within 12-24h of LPS injection, and continued for 3 days after treatment. However, the anapyrexic response was observed primarily during scotophases, with photophase hypothermia observed only on the first day after LPS injection.
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Affiliation(s)
- Mark Merchant
- Department of Chemistry, McNeese State University, Lake Charles, LA 70609, USA.
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Seebacher F, Franklin CE. Redistribution of blood within the body is important for thermoregulation in an ectothermic vertebrate (Crocodylus porosus). J Comp Physiol B 2007; 177:841-8. [PMID: 17639414 DOI: 10.1007/s00360-007-0181-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Revised: 06/18/2007] [Accepted: 06/19/2007] [Indexed: 10/23/2022]
Abstract
Changes in blood flow are a principal mechanism of thermoregulation in vertebrates. Changes in heart rate will alter blood flow, although multiple demands for limited cardiac output may compromise effective thermoregulation. We tested the hypothesis that regional differences in blood flow during heating and cooling can occur independently from changes in heart rate. We measured heart rate and blood pressure concurrently with blood flow in the crocodile, Crocodylus porosus. We measured changes in blood flow by laser Doppler flowmetry, and by injecting coloured microspheres. All measurements were made under different heat loads, with and without blocking cholinergic and beta-adrenergic receptors (autonomic blockade). Heart rates were significantly faster during heating than cooling in the control animals, but not when autonomic receptors were blocked. There were no significant differences in blood flow distribution between the control and autonomic blockade treatments. In both treatments, blood flow was directed to the dorsal skin and muscle and away from the tail and duodenum during heating. When the heat source was switched off, there was a redistribution of blood from the dorsal surface to the duodenum. Blood flow to the leg skin and muscle, and to the liver did not change significantly with thermal state. Blood pressure was significantly higher during the autonomic blockade than during the control. Thermal time constants of heating and cooling were unaffected by the blockade of autonomic receptors. We concluded that animals partially compensated for a lack of differential heart rates during heating and cooling by redistributing blood within the body, and by increasing blood pressure to increase flow. Hence, measures of heart rate alone are insufficient to assess physiological thermoregulation in reptiles.
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Affiliation(s)
- Frank Seebacher
- School of Biological Sciences A08, The University of Sydney, NSW 2006, Sydney, Australia.
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Bicego KC, Barros RCH, Branco LGS. Physiology of temperature regulation: comparative aspects. Comp Biochem Physiol A Mol Integr Physiol 2006; 147:616-639. [PMID: 16950637 DOI: 10.1016/j.cbpa.2006.06.032] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 05/28/2006] [Accepted: 06/16/2006] [Indexed: 10/24/2022]
Abstract
Few environmental factors have a larger influence on animal energetics than temperature, a fact that makes thermoregulation a very important process for survival. In general, endothermic species, i.e., mammals and birds, maintain a constant body temperature (Tb) in fluctuating environmental temperatures using autonomic and behavioural mechanisms. Most of the knowledge on thermoregulatory physiology has emerged from studies using mammalian species, particularly rats. However, studies with all vertebrate groups are essential for a more complete understanding of the mechanisms involved in the regulation of Tb. Ectothermic vertebrates-fish, amphibians and reptiles-thermoregulate essentially by behavioural mechanisms. With few exceptions, both endotherms and ectotherms develop fever (a regulated increase in Tb) in response to exogenous pyrogens, and regulated hypothermia (anapyrexia) in response to hypoxia. This review focuses on the mechanisms, particularly neuromediators and regions in the central nervous system, involved in thermoregulation in vertebrates, in conditions of euthermia, fever and anapyrexia.
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Affiliation(s)
- Kênia C Bicego
- Department of Animal Physiology and Morfology, College of Agricultural and Veterinarian Sciences, Sao Paulo State University, Jaboticabal, São Paulo, Brazil.
| | - Renata C H Barros
- Department of General and Specialized Nursing, Nursing School of Ribeirão Preto, University of São Paulo, 14040-904, Ribeirão Preto, São Paulo, Brazil
| | - Luiz G S Branco
- Department of Morphology, Estomatology and Physiology, Dental School of Ribeirão Preto, University of São Paulo, 14040-904, Ribeirão Preto, São Paulo, Brazil
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Kovatch JJ, Reed Hainsworth F, Pease J. Analysis methods for two types of second-order thermal transients. J Therm Biol 2006. [DOI: 10.1016/j.jtherbio.2005.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Seebacher F, Franklin CE. Physiological mechanisms of thermoregulation in reptiles: a review. J Comp Physiol B 2005; 175:533-41. [PMID: 16047177 DOI: 10.1007/s00360-005-0007-1] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 04/29/2005] [Accepted: 05/20/2005] [Indexed: 10/25/2022]
Abstract
The thermal dependence of biochemical reaction rates means that many animals regulate their body temperature so that fluctuations in body temperature are small compared to environmental temperature fluctuations. Thermoregulation is a complex process that involves sensing of the environment, and subsequent processing of the environmental information. We suggest that the physiological mechanisms that facilitate thermoregulation transcend phylogenetic boundaries. Reptiles are primarily used as model organisms for ecological and evolutionary research and, unlike in mammals, the physiological basis of many aspects in thermoregulation remains obscure. Here, we review recent research on regulation of body temperature, thermoreception, body temperature set-points, and cardiovascular control of heating and cooling in reptiles. The aim of this review is to place physiological thermoregulation of reptiles in a wider phylogenetic context. Future research on reptilian thermoregulation should focus on the pathways that connect peripheral sensing to central processing which will ultimately lead to the thermoregulatory response.
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Affiliation(s)
- Frank Seebacher
- Integrative Physiology, School of Biological Sciences A08, University of Sydney, NSW, Australia.
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Seebacher F, Franklin CE. Integration of autonomic and local mechanisms in regulating cardiovascular responses to heating and cooling in a reptile (Crocodylus porosus). J Comp Physiol B 2004; 174:577-85. [PMID: 15340754 DOI: 10.1007/s00360-004-0446-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2004] [Indexed: 11/27/2022]
Abstract
Reptiles change heart rate and blood flow patterns in response to heating and cooling, thereby decreasing the behavioural cost of thermoregulation. We tested the hypothesis that locally produced vasoactive substances, nitric oxide and prostaglandins, mediate the cardiovascular response of reptiles to heat. Heart rate and blood pressure were measured in eight crocodiles (Crocodylus porosus) during heating and cooling and while sequentially inhibiting nitric-oxide synthase and cyclooxygenase enzymes. Heart rate and blood pressure were significantly higher during heating than during cooling in all treatments. Power spectral density of heart rate and blood pressure increased significantly during heating and cooling compared to the preceding period of thermal equilibrium. Spectral density of heart rate in the high frequency band (0.19-0.70 Hz) was significantly greater during cooling in the saline treatment compared to when nitric-oxide synthase and cyclooxygenase enzymes were inhibited. Cross spectral analysis showed that changes in blood pressure preceded heart rate changes at low frequencies (< 0.1 Hz) only. We conclude that the autonomic nervous system controls heart rate independently from blood pressure at higher frequencies while blood pressure changes determine heart rate at lower frequencies. Nitric oxide and prostaglandins do not control the characteristic heart rate hysteresis response to heat in C. porosus, although nitric oxide was important in buffering blood pressure against changes in heart rate during cooling, and inhibition caused a compensatory decrease in parasympathetic stimulation of the heart.
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Affiliation(s)
- Frank Seebacher
- Integrative Physiology, School of Biological Sciences A08, The University of Sydney, 2006 Sydney, NSW, Australia.
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22
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Importance of the limbs in the physiological control of heat exchange in Iguana iguana and Sceloporus undulatus. J Therm Biol 2004. [DOI: 10.1016/j.jtherbio.2004.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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23
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Galli G, Taylor EW, Wang T. The cardiovascular responses of the freshwater turtleTrachemys scriptato warming and cooling. J Exp Biol 2004; 207:1471-8. [PMID: 15037641 DOI: 10.1242/jeb.00912] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYSeven freshwater turtles Trachemys scripta were instrumented with flow probes and cannulated for blood pressure measurements. The turtles were warmed from 24 to 34°C, and cooled down to 24°C, with and without atropine. Animals exhibited a hysteresis of heart rate and blood flow to both the pulmonary and systemic circulations, which was not cholinergically mediated. Blood pressure remained constant during both warming and cooling,while systemic resistance decreased during heating and increased during cooling, indicating a barostatic response. There was a large right-to-left(R–L) shunt during warming and cooling in untreated animals, which remained relatively constant. Atropinisation resulted in a large L–R shunt, which decreased during warming and increased during cooling. Nevertheless, heating rates were the same in untreated and atropinised animals, and cooling rates were significantly longer in atropinised animals,indicating that shunt patterns contribute little to heat exchange.
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Affiliation(s)
- Gina Galli
- Department of Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark.
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Zaar M, Larsen E, Wang T. Hysteresis of heart rate and heat exchange of fasting and postprandial savannah monitor lizards (Varanus exanthematicus). Comp Biochem Physiol A Mol Integr Physiol 2004; 137:675-82. [PMID: 15123175 DOI: 10.1016/j.cbpb.2004.01.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Revised: 01/23/2004] [Accepted: 01/28/2004] [Indexed: 11/29/2022]
Abstract
Reptiles are ectothermic, but regulate body temperatures (T(b)) by behavioural and physiological means. Body temperature has profound effects on virtually all physiological functions. It is well known that heating occurs faster than cooling, which seems to correlate with changes in cutaneous perfusion. Increased cutaneous perfusion, and hence elevated cardiac output, during heating is reflected in an increased heart rate (f(H)), and f(H), at a given T(b), is normally higher during heating compared to cooling ('hysteresis of heart rate'). Digestion is associated with an increased metabolic rate. This is associated with an elevated f(H) and many species of reptiles also exhibited a behavioural selection of higher T(b) during digestion. Here, we examine whether digestion affects the rate of heating and cooling as well as the hysteresis of heart rate in savannah monitor lizards (Varanus exanthematicus). Fasting lizards were studied after 5 days of food deprivation while digesting lizards were studied approximately 24 h after ingesting dead mice that equalled 10% of their body mass. Heart rate was measured while T(b) increased from 28 to 38 degrees C under a heat lamp and while T(b) decreased during a subsequent cooling phase. The lizards exhibited hysteresis of heart rate, and heating occurred faster than cooling. Feeding led to an increased f(H) (approximately 20 min(-1) irrespective of T(b)), but did not affect the rate of temperature change during heating or cooling. Therefore, it is likely that the increased blood flows during digestion are distributed exclusively to visceral organs and that the thermal conductance remains unaffected by the elevated metabolic rate during digestion.
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Affiliation(s)
- Morten Zaar
- Department of Zoophysiology, Institute of Biology, Aarhus University, Building 131, Universitetsparken, 8000 Aarhus C, Denmark
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Franklin CE, Seebacher F. The effect of heat transfer mode on heart rate responses and hysteresis during heating and cooling in the estuarine crocodile Crocodylus porosus. J Exp Biol 2003; 206:1143-51. [PMID: 12604574 DOI: 10.1242/jeb.00222] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effect of heating and cooling on heart rate in the estuarine crocodile Crocodylus porosus was studied in response to different heat transfer mechanisms and heat loads. Three heating treatments were investigated. C. porosus were: (1) exposed to a radiant heat source under dry conditions; (2) heated via radiant energy while half-submerged in flowing water at 23 degrees C and (3) heated via convective transfer by increasing water temperature from 23 degrees C to 35 degrees C. Cooling was achieved in all treatments by removing the heat source and with C. porosus half-submerged in flowing water at 23 degrees C. In all treatments, the heart rate of C. porosus increased markedly in response to heating and decreased rapidly with the removal of the heat source. Heart rate during heating was significantly faster than during cooling at any given body temperature, i.e. there was a significant heart rate hysteresis. There were two identifiable responses to heating and cooling. During the initial stages of applying or removing the heat source, there was a dramatic increase or decrease in heart rate ('rapid response'), respectively, indicating a possible cardiac reflex. This rapid change in heart rate with only a small change or no change in body temperature (<0.5 degrees C) resulted in Q(10) values greater than 4000, calling into question the usefulness of this measure on heart rate during the initial stages of heating and cooling. In the later phases of heating and cooling, heart rate changed with body temperature, with Q(10) values of 2-3. The magnitude of the heart rate response differed between treatments, with radiant heating during submergence eliciting the smallest response. The heart rate of C. porosus outside of the 'rapid response' periods was found to be a function of the heat load experienced at the animal surface, as well as on the mode of heat transfer. Heart rate increased or decreased rapidly when C. porosus experienced large positive (above 25 W) or negative (below -15 W) heat loads, respectively, in all treatments. For heat loads between -15 W and 20 W, the increase in heart rate was smaller for the 'unnatural' heating by convection in water compared with either treatment using radiant heating. Our data indicate that changes in heart rate constitute a thermoregulatory mechanism that is modulated in response to the thermal environment occupied by the animal, but that heart rate during heating and cooling is, in part, controlled independently of body temperature.
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Affiliation(s)
- Craig E Franklin
- Department of Zoology and Entomology, University of Queensland, St Lucia, Qld 4072, Australia
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