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

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https://www.readbyqxmd.com/read/29691634/the-ctenidium-of-the-giant-clam-tridacna-squamosa-expresses-an-ammonium-transporter-1-that-displays-light-suppressed-gene-and-protein-expression-and-may-be-involved-in-ammonia-excretion
#1
Mel V Boo, Kum C Hiong, Enan J K Goh, Celine Y L Choo, Wai P Wong, Shit F Chew, Yuen K Ip
Ammonium transporters (AMTs) can participate in ammonia uptake or excretion across the plasma membrane of prokaryotic, plant and invertebrate cells. The giant clam, Tridacna squamosa, harbors nitrogen-deficient symbiotic zooxanthellae, and normally conducts light-enhanced ammonia absorption to benefit the symbionts. Nonetheless, it can excrete ammonia when there is a supply of exogenous nitrogen or exposed to continuous darkness. This study aimed to elucidate the role of AMT1 in the ctenidium of T. squamosa by cloning and characterizing the AMT1/AMT1, determining its subcellular localization, and examining changes in its transcript and protein expression levels in response to light exposure...
April 24, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29663031/urea-and-plasma-ice-nucleating-proteins-promoted-the-modest-freeze-tolerance-in-pleske-s-high-altitude-frog-nanorana-pleskei
#2
Yonggang Niu, Jianjun Wang, Shengkang Men, Yaofeng Zhao, Songsong Lu, Xiaolong Tang, Qiang Chen
The frog Nanorana pleskei (Dicroglossidae) is indigenous to the Qinghai-Tibetan Plateau. To identify its strategies in coping with the cold climate, we measured the hibernacula microhabitat temperature during winter. We also examined the freezing-induced and seasonal variation of several putative cryoprotectants in the heart, liver, brain, kidney and muscle, as well as ice-nucleating protein in plasma. Our results showed that N. pleskei survived exposure to temperatures as low as - 2.5 ± 0.40 °C during hibernation, which was lower than the body fluid freezing point (- 0...
April 16, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29623471/chronic-captopril-treatment-reveals-the-role-of-ang-ii-in-cardiovascular-function-of-embryonic-american-alligators-alligator-mississippiensis
#3
Casey A Mueller, John Eme, Kevin B Tate, Dane A Crossley
Angiotensin II (ANG II) is a powerful vasoconstrictor of the renin-angiotensin system (RAS) that plays an important role in cardiovascular regulation in adult and developing vertebrates. Knowledge of ANG II's contribution to developmental cardiovascular function comes from studies in fetal mammals and embryonic chickens. This is the first study to examine the role of ANG II in cardiovascular control in an embryonic reptile, the American alligator (Alligator mississippiensis). Using chronic low (~ 5-mg kg embryo-1 ), or high doses (~ 450-mg kg embryo-1 ) of captopril, an angiotensin-converting enzyme (ACE) inhibitor, we disrupted the RAS and examined the influence of ANG II in cardiovascular function at 90% of embryonic development...
April 6, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29623413/no-effect-of-season-on-the-electrocardiogram-of-long-eared-bats-nyctophilus-gouldi-during-torpor
#4
Shannon E Currie
Heterothermic animals regularly undergo profound alterations of cardiac function associated with torpor. These animals have specialised tissues capable of withstanding fluctuations in body temperature > 30 °C without adverse effects. In particular, the hearts of heterotherms are able to resist fibrillation and discontinuity of the cardiac conduction system common in homeotherms during hypothermia. To investigate the patterns of cardiac conduction in small insectivorous bats which enter torpor year round, I simultaneously measured ECG and subcutaneous temperature (Tsub ) of 21 Nyctophilus gouldi (11 g) during torpor at a range of ambient temperatures (Ta 1-28 °C)...
April 5, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29623412/staying-hot-to-fight-the-heat-high-body-temperatures-accompany-a-diurnal-endothermic-lifestyle-in-the-tropics
#5
Danielle L Levesque, Andrew Alek Tuen, Barry G Lovegrove
Much of our knowledge of the thermoregulation of endotherms has been obtained from species inhabiting cold and temperate climates, our knowledge of the thermoregulatory physiology of tropical endotherms is scarce. We studied the thermoregulatory physiology of a small, tropical mammal, the large treeshrew (Tupaia tana, Order Scandentia) by recording the body temperatures of free-ranging individuals, and by measuring the resting metabolic rates of wild individuals held temporarily in captivity. The amplitude of daily body temperature (~ 4 °C) was higher in treeshrews than in many homeothermic eutherian mammals; a consequence of high active-phase body temperatures (~ 40 °C), and relatively low rest-phase body temperatures (~ 36 °C)...
April 5, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29619510/variation-and-repeatability-of-cutaneous-water-loss-and-skin-resistance-in-relation-to-temperature-and-diel-variation-in-the-lizard-sceloporus-consobrinus
#6
Christopher E Oufiero, Matthew J Van Sant
Variation in rates of water loss has been proposed to be an important mechanism in the survival of terrestrial organisms, as high rates of water loss in desiccating environments may lead to hydric stress and death. Vapor density deficit, the driving force for evaporative water loss, increases exponentially as temperature increases. Acute temperature changes may be the result of daily behavioral thermoregulation of ectotherms, which may influence the among individual variation rates of water loss. The goals of this study were to determine (1) how rates of cutaneous water loss (CWL) and skin resistance (Rs ) are affected by acute temperature acclimation, (2) how rates of CWL and Rs vary throughout the day allowing behavioral thermoregulation and (3) the repeatability of CWL and Rs within and among sampling periods...
April 4, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29594459/iron-storage-disease-hemochromatosis-and-hepcidin-response-to-iron-load-in-two-species-of-pteropodid-fruit-bats-relative-to-the-common-vampire-bat
#7
Iga M Stasiak, Dale A Smith, Tomas Ganz, Graham J Crawshaw, Jutta D Hammermueller, Dorothee Bienzle, Brandon N Lillie
Hepcidin is the key regulator of iron homeostasis in the body. Iron storage disease (hemochromatosis) is a frequent cause of liver disease and mortality in captive Egyptian fruit bats (Rousettus aegyptiacus), but reasons underlying this condition are unknown. Hereditary hemochromatosis in humans is due to deficiency of hepcidin or resistance to the action of hepcidin. Here, we investigated the role of hepcidin in iron metabolism in one species of pteropodid bat that is prone to iron storage disease [Egyptian fruit bat (with and without hemochromatosis)], one species of pteropodid bat where iron storage disease is rare [straw-colored fruit bat (Eidolon helvum)], and one species of bat with a natural diet very high in iron, in which iron storage disease is not reported [common vampire bat (Desmodus rotundus)]...
March 29, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29582134/effects-of-the-recombinant-crustacean-hyperglycemic-hormones-rchh-b1-and-rchh-b2-on-the-osmo-ionic-regulation-of-the-shrimp-litopenaeus-vannamei-exposed-to-acute-salinity-stress
#8
Laura Camacho-Jiménez, Fernando Díaz, Edna Sánchez-Castrejón, Elizabeth Ponce-Rivas
The Pacific white shrimp Litopenaeus vannamei is a euryhaline organism that copes with salinity fluctuations in the environment; therefore, its osmotic and ionic regulation abilities are vital. Osmoregulation may be controlled by the crustacean hyperglycemic hormone (CHH), a neuropeptide mainly expressed in the eyestalks. In L. vannamei, CHH-B1 and CHH-B2 are CHH isoforms isolated from the eyestalks whose expression is influenced by environmental salinity. It has been suggested that they are involved in the response to salinity stress...
March 26, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29569151/mass-scaling-of-the-resting-and-maximum-metabolic-rates-of-the-black-carp
#9
Xiao Lv, Hang Xie, Danyang Xia, Cong Shen, Jian Li, Yiping Luo
We investigated the body mass (M) scaling of resting metabolic rate (RMR), maximum metabolic rate (MMR), excess post-exercise oxygen consumption (EPOC), blood parameters, and organ masses of black carp (Mylopharyngoden piceus). The results showed that RMR scaled with M of the fish by an exponent (b) of 0.833 (bR ), which was significantly larger than 0.75. MMR scaled with M by a power of 0.775 (bM ), which was significantly lower than 1 and may be due to a small size proportion of red muscle. No difference between bR and bM or correlation between factorial aerobic scope and M was found...
March 22, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29556703/heat-flux-in-manatees-an-individual-matter-and-a-novel-approach-to-assess-and-monitor-the-thermal-state-of-florida-manatees-trichechus-manatus-latirostris
#10
Nicola Erdsack, Sophy R McCully Phillips, Sentiel A Rommel, D Ann Pabst, William A McLellan, John E Reynolds
Florida manatees (Trichechus manatus latirostris) possess an unusual suite of adaptations to accommodate both a fully aquatic lifestyle and an herbivorous diet, including a low metabolic rate and a very limited thermoneutral zone. Their relatively high lower critical temperature of around 20 °C suggests strong sensitivity to cold, thereby limiting their distribution to tropical and subtropical waters. "Cold stress syndrome" affects and kills Florida manatees every year during intense or prolonged cold weather, posing one of the major threats to manatees...
March 19, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29550887/the-cryoprotectant-system-of-cope-s-gray-treefrog-dryophytes-chrysoscelis-responses-to-cold-acclimation-freezing-and-thawing
#11
M Clara F do Amaral, James Frisbie, David L Goldstein, Carissa M Krane
Cope's gray treefrog (Dryophytes chrysoscelis) is one of few freeze-tolerant frogs that mobilize glycerol as a cryoprotectant, yet cold and freezing-induced accumulation of this and other osmolytes has received little attention in this species. This study investigated the development of freeze tolerance in D. chrysoscelis, analyzing the response of the cryoprotectant system to cold acclimation, freezing, and thawing. Glycerol production was low and unresponsive to acclimation temperature, or duration of acclimation to 5 °C, except for one cold-acclimated frog that presented elevated glycerol in plasma, liver, and skeletal muscle...
March 17, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29502263/ventilatory-responses-of-the-clown-knifefish-chitala-ornata-to-hypercarbia-and-hypercapnia
#12
Dang Diem Tuong, Brittney Borowiec, Alexander M Clifford, Renato Filogonio, Derek Somo, Do Thi Thanh Huong, Nguyen Thanh Phuong, Tobias Wang, Mark Bayley, William K Milsom
The aim of the present study was to determine the roles of externally versus internally oriented CO2 /H+ -sensitive chemoreceptors in promoting cardiorespiratory responses to environmental hypercarbia in the facultative air-breathing fish, Chitala ornata (the clown knifefish). Fish were exposed to environmental acidosis (pH ~ 6.0) or hypercarbia (≈ 30 torr PCO2 ) that produced changes in water pH equal to the pH levels of the acidotic water to distinguish the relative roles of CO2 versus H+ . We also injected acetazolamide to elevate arterial levels of PCO2 and [H+ ] in fish in normocarbic water to distinguish between internal and external stimuli...
March 3, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29480359/scaling-of-work-and-power-in-a-locomotor-muscle-of-a-frog
#13
J P Olberding, S M Deban
Muscle work and power are important determinants of movement performance in animals. How these muscle properties scale determines, in part, the scaling of performance during movements, such as jump height or distance. Muscle-mass-specific work is predicted to remain constant across a range of scales, assuming geometric similarity, while muscle-mass-specific power is expected to decrease with increasing scale. We tested these predictions by examining muscle morphology and contractile properties of plantaris muscles from frogs ranging in mass from 1...
February 26, 2018: 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
#14
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...
March 2018: 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
#15
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...
March 2018: 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
#16
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...
March 2018: 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
#17
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...
March 2018: 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
#18
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...
March 2018: 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
#19
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...
March 2018: 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
#20
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...
March 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
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