Daily and annual cycles in thermoregulatory behaviour and cardio‑respiratory physiology of black and white tegu lizards

This study was designed to determine the manner in which metabolism is suppressed during dormancy in black and white tegu lizards (Tupinambis merianae). To this end, heart rate (f H), respiration rate (f R), and deep body temperature (T b) were continuously monitored in outdoor enclosures by radio-telemetry for nine months. There was a continuous decline in nighttime breathing and heart rate, at constant T b, throughout the late summer and fall suggestive of an active metabolic suppression that developed progressively at night preceding the entrance into dormancy. During the day, however, the tegus still emerged to bask. In May, when the tegus made a behavioural commitment to dormancy, T b (day and night) fell to match burrow temperature, accompanied by a further reduction in f H and f R. Tegus, under the conditions of this study, did arouse periodically during dormancy. There was a complex interplay between changes in f H and T b associated with the direct effects of temperature and the indirect effects of thermoregulation, activity, and changes in metabolism. This interplay gave rise to a daily hysteresis in the f H/T b relationship reflective of the physiological changes associated with warming and cooling as preferred T b alternated between daytime and nighttime levels. The shape of the hysteresis curve varied with season along with changes in metabolic state and daytime and nighttime body temperature preferences

The Relationship Between Body Temperature, Heart Rate, Breathing Rate, and Rate of Oxygen Consumption, in the Tegu Lizard (Tupinambis merianae) at Various Levels of Activity

The present study determined whether EEG and/or EMG recordings could be used to reliably define activity states in the Brazilian black and white tegu lizard (Tupinambis merianae) and then examined the interactive effects of temperature and activity states on strategies for matching O2 supply and demand. In a first series of experiments, the rate of oxygen consumption (V˙O2), breathing frequency (f R), heart rate (f H), and EEG and EMG (neck muscle) activity were measured in different sleep/wake states (sleeping, awake but quiet, alert, or moving). In general, metabolic and cardio-respiratory changes were better indictors of the transition from sleep to wake than were changes in the EEG and EMG. In a second series of experiments, the interactive effects of temperature (17, 27 and 37 °C) and activity states on f R, tidal volume (V T), the fraction of oxygen extracted from the lung per breath (FIO2–FEO2), f H, and the cardiac O2 pulse were quantified to determine the relative roles of each of these variables in accommodating changes in V˙O2. The increases in oxygen supply to meet temperature- and activity-induced increases in oxygen demand were produced almost exclusively by increases in f H and f R. Regression analysis showed that the effects of temperature and activity state on the relationships between f H, f R and V˙O2 was to extend a common relationship along a single curve, rather than separate relationships for each metabolic state. For these lizards, the predictive powers of f R and f H were maximized when the effects of changes in temperature, digestive state and activity were pooled. However, the best r 2 values obtained were 0.63 and 0.74 using f R and f H as predictors of met abolic rate, respectively

Ablation of the ability to control the right-to-left cardiac shunt does not affect oxygen uptake, specific dynamic action or growth in the rattlesnake Crotalus durissus

The morphologically undivided ventricle of the heart in non-crocodilian reptiles permits the mixing of oxygen-rich blood returning from the lungs and oxygen-poor blood from the systemic circulation. A possible functional significance for this intra-cardiac shunt has been debated for almost a century. Unilateral left vagotomy rendered the single effective pulmonary artery of the South American rattlesnake, Crotalus durissus, unable to adjust the magnitude of blood flow to the lung. the higher constant perfusion of the lung circulation and the incapability of adjusting the right-left shunt in left-denervated snakes persisted over time, providing a unique model for investigation of the long-term consequences of cardiac shunting in a squamate. Oxygen uptake recorded at rest and during spontaneous and forced activity was not affected by removing control of the cardiac shunt. Furthermore, metabolic rate and energetic balance during the post-prandial metabolic increment, plus the food conversion efficiency and growth rate, were all similarly unaffected. These results show that control of cardiac shunting is not associated with a clear functional advantage in adjusting metabolic rate, effectiveness of digestion or growth rates.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Danish Research CouncilFed Univ São Paulo UNIFESP, Dept Biol, BR-09972270 Diadema, SP, BrazilUniv Birmingham, Sch Biosci, Birmingham B15 2TT, W Midlands, EnglandState Univ São Paulo UNESP, Dept Zool, BR-13506900 Rio Claro, SP, BrazilAarhus Univ, Dept Biosci, DK-8000 Aarhus C, DenmarkFed Univ São Paulo UNIFESP, Dept Biol, BR-09972270 Diadema, SP, BrazilWeb of Scienc

A UME e a projecção da Europa no mundo : referência à posição portuguesa

A projecção da Europa no Mundo depende grandemente da consolidação do processo de integração económica que tem vindo a ser impulsionado pela globalização e pelo lançamento da moeda única europeia. Em particular, vai depender da imagem de credibilidade do euro, das reformas estruturais necessárias à competitividade e à atractividade dos mercados europeus, da adopção de polí- ticas pan-europeias de segurança e de defesa e das reformas institucionais indispensáveis para o avanço do alargamento. No caso de Portugal, o nosso País enfrenta hoje uma situação complexa, marcada por alguns desequilíbrios macro-económicos insustentáveis a prazo – déficit externo e finanças públicas – e por bloqueios estruturais que estão a travar o crescimento e o desenvolvimento económicos. O modo como os ultrapassarmos condicionará a nossa posição na União e no Mund

Cardiac hypertrophy and structural and metabolic remodeling related to seasonal dormancy in the first annual cycle in tegu lizards

AbstractMorpho-functional adjustments in the heart of juvenile tegu lizards (Tupinambis merianae) were analyzed at distinct seasonal periods to investigate how the demands of growth and of energy saving are reconciled during the first annual cycle. The relative ventricular mass (Mv) was 31% and 69% larger in late autumn and winter dormancy, respectively, compared to early autumn. This effect did not persist during unfed arousal, suggesting that protein accumulates in the heart during hypometabolism and is degraded on arousal. Both the hypertrophy and the atrophy were disproportionate in the largest individuals. In contrast, Mv was smaller in lizards that were starved during spring activity compared to fed lizards, this effect being larger in smaller individuals. In late autumn and winter dormancy the spongy myocardium had 8% of the section area covered by lacunary spaces, which expanded after food intake during arousal and reached 29% in spring activity together with higher density of cardiomyocytes. Total and soluble proteins per mass unity were unchanged, and maximum activities of selected enzymes suggest sustained glycolytic and aerobic capacities during hypometabolism. Results indicate that important structural adjustments occur in the heart in anticipation of dormancy, and that the protein balance in the tissue is maintained at winter temperatures ~17°C

An appraisal of the use of an infrared digital monitoring system for long-term measurement of heart rate in reptilian embryos

Made available in DSpace on 2018-11-26T16:16:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-10-01Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)National Science FoundationMeasurement of heart rate (f(H)) in embryonic reptiles has previously imposed some degree of invasive treatment on the developing embryo. Recently a non-invasive technique of f(H) detection from intact eggs was developed for commercial avian breeders and has since been used in biological research. This device uses infrared light, enabling it to detect heartbeats in very early embryos. However, infrared light is a source of heat and extended enclosure of an egg in the device is likely to affect temperature with consequent effects on physiological processes, including f(H). We studied the effect of use of the monitor on the temperature of eggs and on fH in two species of reptiles, the snapping turtle (Chelydra serpentina) and the green iguana (Iguana iguana). Egg temperature increased from a room temperature of 27-28 degrees C, by 26% in turtles and 14% in iguanas over 1 h of enclosure, resulting in an increase in f(H) of 76-81% in turtles and 35-50% iguanas. These effects on f(H) can either be avoided by brief enclosure of each egg in the monitor or measured and accounted for during the design of long-term experiments. (C) 2015 Elsevier Inc. All rights reserved.Univ Estadual Paulista, Inst Biociencias, Dept Zool, Rio Claro, SP, BrazilUniv Birmingham, Sch Biosci, Birmingham B15 2TT, W Midlands, EnglandUniv N Texas, Dept Biol Sci, Dev Integrat Biol Cluster, Denton, TX 76203 USAUniv Estadual Paulista, Inst Biociencias, Dept Zool, Rio Claro, SP, BrazilFAPESP: 2012/06938-8FAPESP: 2012/16537-0National Science Foundation: IOS-084574

The progressive onset of cholinergic and adrenergic control of heart rate during development in the green iguana, Iguana iguana

Made available in DSpace on 2018-11-26T16:16:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-10-01INCT in Comparative PhysiologyFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)National Science FoundationThe autonomic control of heart rate was studied throughout development in embryos of the green iguana, Iguana iguana by applying receptor agonists and antagonists of the parasympathetic and sympathetic systems. Acetylcholine (Ach) slowed or stopped the heart and atropine antagonized the response to Ach indicating the presence of muscarinic cholinoceptors on the heart of early embryos. However, atropine injections had no impact on heart rate until immediately before hatching, when it increased heart rate by 15%. This cholinergic tonus increased to 34% in hatchlings and dropped to 24% in adult iguanas. Although epinephrine was without effect, injection of propranolol slowed the heart throughout development, indicating the presence of beta-adrenergic receptors on the heart of early embryos, possibly stimulated by high levels of circulating catecholamines. The calculated excitatory tonus varied between 33% and 68% until immediately before hatching when it fell to 25% and 29%, a level retained in hatchlings and adults. Hypoxia caused a bradycardia in early embryos that was unaffected by injection of atropine indicating that hypoxia has a direct effect upon the heart. In later embryos and hatchlings hypoxia caused a tachycardia that was unaffected by injection of atropine. Subsequent injection of propranolol reduced heart rate both uncovering a hypoxic bradycardia in late embryos and abolishing tachycardia in hatchlings. Hypercapnia was without effect on heart rate in late stage embryos and in hatchlings. (C) 2015 Elsevier Inc All rights reserved.Univ Estadual Paulista, Inst Biociencias, Dept Zool, Rio Claro, SP, BrazilUniv Fed Sao Carlos, Dept Ciencias Fisiol, BR-13560 Sao Carlos, SP, BrazilUniv N Texas, Dept Biol Sci, Dev Integrat Biol Cluster, Denton, TX 76203 USAUniv Birmingham, Sch Biosci, Birmingham B15 2TT, W Midlands, EnglandUniv Estadual Paulista, Inst Biociencias, Dept Zool, Rio Claro, SP, BrazilINCT in Comparative Physiology: CNPq 573921/2008-3INCT in Comparative Physiology: FAPESP 2008/57712-4FAPESP: 2012/06938-8FAPESP: 2012/16537-0National Science Foundation: IBN-IOS 084574

Convective oxygen transport during development in embryos of the snapping turtle Chelydra serpentina

This article describes a study investigating the maturation of convective oxygen transport in embryos of the snapping turtle (Chelydra serpentina). Measurements included: mass, oxygen consumption, heart rate, blood oxygen content and affinity and blood flow distribution at 50%, 70% and 90% of the incubation period

The Semileptonic BB to K1(1270,1400)K_1(1270,1400) Decays in QCD Sum Rules

We analyze the semileptonic rare decays of $B$ meson to $K_{1} (1270)$ and $K_{1} (1400)$ axial vector mesons. The $B\to K_{1} (1270,1400) \ell^+ \ell^-$ decays are significant flavor changing neutral current decays of the $B$ meson. These decays are sensitive to the new physics beyond SM, since these processes are forbidden at tree level at SM. These decays occurring at the quark level via $b\to s \ell^+ \ell^-$ transition, also provide new opportunities for calculating the CKM matrix elements $V_{bt}$ and $V_{ts}$. In this study, the transition form factors of the $B\to K_{1} (1270,1400) \ell^+ \ell^-$ decays are calculated using three-point QCD sum rules approach. The resulting form factors are used to estimate the branching fractions of these decays.Comment: 18 pages, 7 figures, version to appear in JP

Estimating the inelasticity with the information theory approach

Using the information theory approach, in both its extensive and nonextensive versions, we estimate the inelasticity parameter $K$ of hadronic reactions together with its distribution and energy dependence from $p\bar{p}$ and $pp$ data. We find that the inelasticity remains essentially constant in energy except for a variation around $K\sim 0.5$, as was originally expected.Comment: 14 pages, 8 figures. Misprints correcte