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Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology

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https://www.readbyqxmd.com/read/29150716/slow-life-histories-in-lizards-living-in-the-highlands-of-the-andes-mountains
#1
Jorgelina M Boretto, Facundo Cabezas-Cartes, Nora R Ibargüengoytía
In the highlands of the Andes, lizards must balance precisely the allocation of energy for growth and reproduction to ensure their survival. We studied the individuals' age, growth rates, age at sexual maturity, and maximum life span of the viviparous lizard Phymaturus antofagastensis, endemic of cold and harsh environments at high altitudes in the Andes Mountains of Catamarca province, Argentina. We also estimated key life history parameters like reproductive effort, lifetime reproductive effort, net reproductive rate, and relative reproductive time in P...
November 17, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29130117/correction-to-the-metabolic-cost-of-nesting-body-condition-and-blood-parameters-of-caiman-crocodilus-and-melanosuchus-niger-in-central-amazonia
#2
José António Lemos Barão-Nóbrega, Boris Marioni, Robinson Botero-Arias, António José Arsénia Nogueira, Emerson Silva Lima, William Ernest Magnusson, Ronis Da Silveira, Jaydione Luiz Marcon
Although nesting ecology is well studied in several crocodilian species, it is not known how nest attendance influences physiology and body condition of nesting females. In this study, we describe body condition and serum biochemical values of nesting female, non-nesting female and male spectacled caiman (Caiman crocodilus) and black caiman (Melanosuchus niger) in two areas of Central Amazonia. We also evaluated the effect of nest age and nest distance to water on body condition and blood parameters of nesting females...
November 13, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29124322/air-breathing-changes-the-pattern-for-temperature-induced-ph-regulation-in-a-bimodal-breathing-teleost
#3
Christian Damsgaard, Mikkel Thy Thomsen, Mark Bayley, Tobias Wang
It is well established that ectothermic vertebrates regulate a lower arterial pH when temperature increases. Typically, water-breathers reduce arterial pH by altering plasma [HCO3(-)], whilst air-breathers rely on ventilatory adjustments to modulate arterial PCO2. However, no studies have investigated whether the shift from water- to air-breathing within a species changes the mechanisms for temperature-induced pH regulation. Here, we used the striped catfish Pangasianodon hypophthalmus to examine how pH regulation is affected by water- versus air-breathing, since P...
November 9, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29119278/development-of-endothermy-in-birds-patterns-and-mechanisms
#4
REVIEW
Edwin R Price, Edward M Dzialowski
Endothermy is a conspicuous and important adaptation in birds. Even though juvenile and adult birds are endothermic and maintain a constant, high body temperature by means of internal heat production, they begin life expressing an ectothermic phenotype. Depending on where a species falls along a continuum of maturity at hatching, from precocial to altricial, they begin to express endothermic traits either close to the time of hatching or as nestlings over a period of 1-3 weeks. Developing endothermy requires attaining a high basal metabolic rate and associated aerobic scope to produce sufficient internal heat, insulation to retain the internally produced heat, and a thermostat that "turns on" heat production in response to cooling ambient temperatures...
November 8, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29075844/changes-in-thermoregulation-and-monoamine-release-in-freely-moving-rats-during-cold-exposure-and-inhibition-of-the-ventromedial-dorsomedial-or-posterior-hypothalamus
#5
Takayuki Ishiwata, Benjamin N Greenwood
The hypothalamus is critical for regulating thermogenesis, but the role of monoamines in specific hypothalamic subregions in thermogenesis is not thoroughly established. The purpose of this study was to confirm changes of body temperature (T b) and thermoregulatory parameters upon inhibition of neural activity in hypothalamic subregions in freely moving rats. In addition, the pattern of monoamine release in these nuclei was measured during active thermoregulation using microdialysis. Tetrodotoxin (TTX) was perfused into the ventromedial hypothalamus (VMH), dorsomedial hypothalamus (DMH), or posterior hypothalamus (PH) at two different ambient temperatures (5 or 23 °C)...
October 26, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29071420/venous-pressures-and-cardiac-filling-in-turtles-during-apnoea-and-intermittent-ventilation
#6
William Joyce, Catherine J A Williams, Dane A Crossley, Tobias Wang
The amount of blood pumped by the heart (cardiac output) must be matched to the amount of blood returning to the heart (venous return), but the factors determining cardiac filling are sparsely understood in ectothermic vertebrates. Stroke volume is affected by heart rate along with central and peripheral venous pressures. In the present study, we investigated the heart rate dependency of cardiac filling in turtles, along with the changes in venous pressures that accompany ventilation. Experimental reductions in heart rate of anaesthetised turtles (Trachemys scripta) by the specific bradycardic agent zatebradine (2-3 mg kg(-1)) resulted in an elevation of stroke volume that compensated cardiac output...
October 25, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29067494/effects-of-water-ionic-composition-on-acid-base-regulation-in-rainbow-trout-during-hypercarbia-at-rest-and-during-sustained-exercise
#7
Katelyn J Tovey, Colin J Brauner
Aquatic hypercarbia (elevated environmental CO2) results in a blood acidosis in fish, which is compensated by the exchange of Na(+) and/or Cl(-) for its acid/base counterpart (H(+), HCO3(-)) across the gill epithelium. To date, no studies exist on how a single species, capable of inhabiting both fresh and saltwater, responds to hypercarbia, at rest or during sustained exercise. Rainbow trout was acclimated to soft water (in mmol l(- 1): Na(+), 0.08; Cl(-), 0.05; pH 6.7-6.8), hard water (in mmol l(- 1): Na(+), 2...
October 24, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29032388/ethanol-metabolism-varies-with-hypoxia-tolerance-in-ten-cyprinid-species
#8
Rashpal S Dhillon, Milica Mandic, Lili Yao, Zhen-Dong Cao, Shi-Jian Fu, Colin J Brauner, Yuxiang S Wang, Jeffrey G Richards
During periods of severe hypoxia or anoxia, Carassius spp. are known for their ability to produce ethanol as their anaerobic end product, which diffuses into the environment thereby reducing the osmotic and acidotic load associated with "anaerobic" glycolysis. However, the relationship between alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) activities, key ethanol metabolizing enzymes, and hypoxia tolerance among Carassius spp. and their closely related non-ethanol-producing cyprinids remains unclear...
October 14, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28988313/thermal-windows-and-metabolic-performance-curves-in-a-developing-antarctic-fish
#9
Erin E Flynn, Anne E Todgham
For ectotherms, temperature modifies the rate of physiological function across a temperature tolerance window depending on thermal history, ontogeny, and evolutionary history. Some adult Antarctic fishes, with comparatively narrow thermal windows, exhibit thermal plasticity in standard metabolic rate; however, little is known about the shape or breadth of thermal performance curves of earlier life stages of Antarctic fishes. We tested the effects of acute warming (- 1 to 8 °C) and temperature acclimation (2 weeks at - 1, 2, 4 °C) on survival and standard metabolic rate in early embryos of the dragonfish Gymnodraco acuticeps from McMurdo Sound, Ross Island, Antarctica...
October 7, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28988304/levels-of-plasma-and-fecal-glucocorticoid-metabolites-following-an-acth-challenge-in-male-and-female-coyotes-canis-latrans
#10
Erika T Stevenson, Eric M Gese, Lorin A Neuman-Lee, Susannah S French
Knowledge of endocrine stress responses can be advantageous for understanding how animals respond to their environment. One tool in wildlife endocrinology is to measure the adrenocortical activity as a parameter of disturbance of animals. Fecal glucocorticoid metabolites (GCMs) provide a noninvasive assessment of adrenocortical activity. Using an adrenocorticotropic hormone (ACTH) challenge administered to 28 captive coyotes (Canis latrans), we measured the levels of plasma cortisol, and fecal cortisol and corticosterone metabolites (i...
October 7, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28986632/phylogenetic-analysis-of-standard-metabolic-rate-of-snakes-a-new-proposal-for-the-understanding-of-interspecific-variation-in-feeding-behavior
#11
Daniel Rodrigues Stuginski, Carlos Arturo Navas, Fábio Cury de Barros, Agustín Camacho, José Eduardo Pereira Wilken Bicudo, Kathleen Fernandes Grego, José Eduardo de Carvalho
The current proposal about the variation of standard metabolic rates (SMR) in snakes predicts that SMR is influenced by the feeding frequency (frequent or infrequent feeders). However, feeding frequency in snakes is poorly studied and hard to quantify under natural conditions. Alternatively, foraging strategy was studied for a large number of species and is usually related to the feeding frequency. In this work, we performed a meta-analysis on the SMR of compiled data from 74 species of snakes obtained from the literature and five more different species of lanceheads (genus Bothrops), after categorization according to the foraging mode (ambush or active foraging) and regarding their phylogenetic history...
October 6, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28965147/combined-effects-of-drought-and-cold-acclimation-on-phospholipid-fatty-acid-composition-and-cold-shock-tolerance-in-the-springtail-protaphorura-fimata
#12
Martin Holmstrup, Stine Slotsbo
Terrestrial arthropods' ability to survive sub-zero winter temperatures is an important factor influencing their abundance and geographic distribution. It is, therefore, important to understand their physiological mechanisms of low-temperature survival. Acclimation to moderate-low temperature can improve cold tolerance, and pre-acclimation to mild desiccation can also improve survival of a subsequent cold exposure. However, very few studies have assessed the combined actions of cold and drought acclimations...
September 30, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28942482/effects-of-seasonal-acclimatization-on-thermal-tolerance-of-inward-currents-in-roach-rutilus-rutilus-cardiac-myocytes
#13
Ahmed Badr, Hanna Korajoki, El-Sabry Abu-Amra, Mohamed F El-Sayed, Matti Vornanen
To test the hypothesis of temperature-dependent deterioration of electrical excitability (TDEE) (Vornanen, J Exp Biol 219:1941-1952, 2016), the role of sodium (I Na) and calcium (I Ca) currents in heat tolerance of cardiac excitability was examined in a eurythermic fish, the roach (Rutilus rutilus). Densities of cardiac I Ca and I Na and their acute heat tolerance were measured in winter-acclimatized (WiR) and summer-acclimatized (SuR) fish maintained in the laboratory at 4 ± 1 and 18 ± 1 °C, respectively...
September 23, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28940028/plasticity-of-skin-water-permeability-and-skin-thickness-in-the-amphibious-mangrove-rivulus-kryptolebias-marmoratus
#14
Quentin Heffell, Andy J Turko, Patricia A Wright
The skin of amphibious fishes is a multipurpose organ, important for gas and ion exchange and nitrogen excretion when fish are out of water (emersed). We tested the hypothesis that skin permeability is altered to maintain water balance through changes in water permeability and skin thickness during salinity acclimation and/or when fish emerse, using the euryhaline, amphibious fish Kryptolebias marmoratus as a model. We first recorded the behaviour of fish out of water to determine which part of the cutaneous surface was in contact with the substrate...
September 22, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28916914/the-effects-of-protein-and-fiber-content-on-gut-structure-and-function-in-zebrafish-danio-rerio
#15
Samantha C Leigh, Bao-Quang Nguyen-Phuc, Donovan P German
Chemical reactor theory (CRT) suggests that the digestive tract functions as a chemical reactor for processing food. Presumably, gut structure and function should match diet to ensure adequate nutrient and energy uptake to maintain performance. Within CRT, dietary biochemical composition is the most important factor affecting gut structure and function in vertebrates. We fed Danio rerio (zebrafish) diets ranging from high- to moderate- to low-quality (i.e., ranging from high-protein, low-fiber to low-protein, high-fiber), and observed how gut length and surface area, as well as the activity levels of digestive enzymes (amylase, maltase, trypsin, aminopeptidase, and lipase) shifted in response to these dietary changes...
September 15, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28447151/rhythms-in-the-endocrine-system-of-fish-a-review
#16
REVIEW
Mairi Cowan, Clara Azpeleta, Jose Fernando López-Olmeda
The environment which living organisms inhabit is not constant and many factors, such as light, temperature, and food availability, display cyclic and predictable variations. To adapt to these cyclic changes, animals present biological rhythms in many of their physiological variables, timing their functions to occur when the possibility of success is greatest. Among these variables, many endocrine factors have been described as displaying rhythms in vertebrates. The aim of the present review is to provide a thorough review of the existing knowledge on the rhythms of the endocrine system of fish by examining the hormones that show rhythmicity, how environmental factors control these rhythms and the variation in the responses of the endocrine system depending on the time of the day...
December 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28444441/the-activity-of-the-rectal-gland-of-the-north-pacific-spiny-dogfish-squalus-suckleyi-is-glucose-dependent-and-stimulated-by-glucagon-like-peptide-1
#17
Courtney A Deck, W Gary Anderson, J Michael Conlon, Patrick J Walsh
Elasmobranchs possess a specialised organ, the rectal gland, which is responsible for excreting sodium chloride via the posterior intestine. Previous work has indicated that the gland may be activated by a number of hormones, some of which are likely related to the salt or volume loads associated with feeding. Furthermore, evidence exists for the gland being glucose dependent which is atypical for an elasmobranch tissue. In this study, the presence of sodium-glucose co-transporters (SGLTs) in the rectal gland and their regulation by feeding were investigated...
December 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28439669/effects-of-desiccation-and-starvation-on-thermal-tolerance-and-the-heat-shock-response-in-forest-ants
#18
Andrew D Nguyen, Kerri DeNovellis, Skyler Resendez, Jeremy D Pustilnik, Nicholas J Gotelli, Joel D Parker, Sara Helms Cahan
Temperature increases associated with global climate change are likely to be accompanied by additional environmental stressors such as desiccation and food limitation, which may alter how temperature impacts organismal performance. To investigate how interactions between stressors influence thermal tolerance in the common forest ant, Aphaenogaster picea, we compared the thermal resistance of workers to heat shock with and without pre-exposure to desiccation or starvation stress. Knockdown (KD) time at 40.5 °C of desiccated ants was reduced 6% compared to controls, although longer exposure to desiccation did not further reduce thermal tolerance...
December 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28421289/adult-male-northern%C3%A2-elephant-seals-maintain-high-rates-of-glucose-production-during-extended-breeding-fasts
#19
Daniel E Crocker, Brian K Wenzel, Cory D Champagne, Dorian S Houser
Many species undergo natural fasts as part of their life histories. Extended fasting is associated with increased β-oxidation of fatty acids and reduced oxidation of glucose to minimize commitment of body protein to gluconeogenesis. However, the metabolic strategies used to sustain extended fasts simultaneous with high rates of energy expenditure are not well understood. Studies in fasting adult female and weanling northern elephant seals (NES) have revealed high rates of endogenous glucose production (EGP) under constraints of high nutrient demand for lactation or development but relatively low rates of metabolism...
December 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28409226/daily-thermal-fluctuations-to-a-range-of-subzero-temperatures-enhance-cold-hardiness-of-winter-acclimated-turtles
#20
James M Wiebler, Manisha Kumar, Timothy J Muir
Although seasonal increases in cold hardiness are well documented for temperate and polar ectotherms, relatively little is known about supplemental increases in cold hardiness during winter. Because many animals are exposed to considerable thermal variation in winter, they may benefit from a quick enhancement of cold tolerance prior to extreme low temperature. Hatchling painted turtles (Chrysemys picta) overwintering in their natal nests experience substantial thermal variation in winter, and recently, it was found that brief subzero chilling of winter-acclimated hatchlings decreases subsequent chilling-induced mortality, increases blood concentrations of glucose and lactate, and protects the brain from cryoinjury...
December 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
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