Puncture versus capture: which stresses animals the most?
We examined the validity of the needle-threshold using the stre ss response of free-ranging snakes. Our results based on physiological markers show that blood sampling does not add any stress to that triggered by capture, and thus questions the usefulness of the needle-threshold to gauge welfare in wild animals. The specificities of studying wild species should be considered to redress captivity biased animal welfare policy. (Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology)
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 25, 2020 Category: Physiology Source Type: research

Age differences in night-time metabolic rate and body temperature in a small passerine
AbstractSpending the winter in northern climes with short days and cold ambient temperatures (Ta) can be energetically challenging for small birds that have high metabolic and heat loss rates. Hence, maintaining body temperature (Tb) inTa below thermoneutrality can be energetically costly for a small bird. We still know little about how increased heat production below thermoneutrality affects the level at whichTb is maintained, and if these patterns are age specific. To test this, we measured subcutaneous body temperature (Ts) and resting metabolic rate (RMR) simultaneously in blue tits (Cyanistes caeruleus) during winter ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 24, 2020 Category: Physiology Source Type: research

Residual vitellus and energetic state of wolf spiderlings Pardosa saltans after emergence from egg-sac until first predation
We present the first biochemical study of residual vitellus and energy expenditure during these three periods. At emergence, the mean weight of juveniles was 0.59 mg and energy stock from residual vitellus averaged 51 cal/g wet mass. During gregarious period, the weight of the juveniles aggregated on their mother did not vary significantly and juveniles utilized only 1 cal/day from their residual vitellus. During the period from dismounting until their first exogenous feed, juveniles lost weight and used 30% of their residual vitellus stock. Proteins from the residual vi tellus contributed principally to the...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 20, 2020 Category: Physiology Source Type: research

Ontogenetic expression rhythms of visual opsins in senegalese sole are modulated by photoperiod and light spectrum
AbstractIn the fish retina, rods and cones are responsible for nocturnal vision and colour perception, respectively, and exhibit a repertoire of light-sensitive opsin photopigments that permits the adaptation to different photic environment. The metamorphosis of Senegalese sole determines a migration from pelagic to benthic environments, which is accompanied by essential changes in light intensity and spectrum. In this paper, we analysed the daily expression rhythms of rod opsin and five cone opsins during sole ontogeny in animals maintained under light –dark cycles of white (LDW), blue (LDB), red (LDR) and continuou...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 11, 2020 Category: Physiology Source Type: research

White mouse pups can use torpor for energy conservation
AbstractWhite mice are ubiquitous laboratory animals and have been extensively studied. To reveal potential undiscovered traits, we tested the hypothesis that during development, when heat loss in mouse pups is high, they can use daily torpor for energy conservation. We determined at what age individual mouse pups are able to defend their body temperature at room temperature (ambient temperature,Ta = 20 °C) and whether they could use torpor from that time. Initially at 5/6 days (body mass, BM ~ 3 g), still naked mice cooled rapidly. In contrast, at ~ 14 days...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - February 6, 2020 Category: Physiology Source Type: research

The effect of temperature and meal size on the aerobic scope and specific dynamic action of two temperate New Zealand finfish Chrysophrys auratus and Aldrichetta forsteri
AbstractShallow coastal and estuarine habitats function as nurseries for many juvenile fish. In this comparative study, metabolic profiles of two New Zealand finfish, snapper (Chrysophrys auratus) and yellow-eyed mullet —YEM (Aldrichetta forsteri) that as juveniles share the same temperate coastal environments, were examined. Metabolic parameters (routine and maximum metabolic rates, and specific dynamic action —SDA) were investigated at a set of temperatures (13, 17, 21 °C) within the range juveniles both species experience annually. SDA was also determined for a range of different feed rations to inv...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 29, 2020 Category: Physiology Source Type: research

In vitro characterisation of calcium influx across skin and gut epithelia of the Pacific hagfish, Eptatretus stoutii
AbstractAlthough hagfishes osmoconform, concentrations of calcium in their extracellular fluids are maintained at levels lower than those of seawater. Ultimately, calcium homeostasis is a product of relative rates of influx and efflux into the animal, but little is known regarding these processes in hagfish. Using in vitro approaches, calcium influx across gut and skin epithelia of the Pacific hagfish,Eptatretus stoutii, was characterised. Analysis of concentration-dependent kinetics showed that accumulation into skin tissue was linear at mucosal calcium concentrations up to 10  mM. However, movement into the serosal ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 24, 2020 Category: Physiology Source Type: research

Transport of maternal transthyretin to the fetus in the viviparous teleost Neoditrema ransonnetii (Perciformes, Embiotocidae)
AbstractThe molecular basis of viviparity in non-mammalian species has not been widely studied.Neoditrema ransonnetii, a surfperch, is a matrotrophic teleost whose fetuses grow by ovarian cavity fluid (OCF) ingestion and by nutrient absorption via their enlarged hindgut. We performed a proteomics analysis ofN. ransonnetii plasma protein and found proteins specific to pregnant females; one of these was identified as transthyretin (TTR), a thyroid hormone distributor protein. We synthesized recombinant protein rNrTTR and raised an antibody, anti-rNrTTR, against it. Semi-quantitative analysis by western blotting using the ant...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 24, 2020 Category: Physiology Source Type: research

Salinity-dependent expression of ncc2 in opercular epithelium and gill of mummichog ( Fundulus heteroclitus )
AbstractMummichogs (Fundulus heteroclitus) can tolerate abrupt changes in environmental salinity because of their ability to rapidly adjust the activities of ionocytes in branchial and opercular epithelia. In turn, the concerted expression of sub-cellular effectors of ion transport underlies adaptive responses to fluctuating salinities. Exposure to seawater (SW) stimulates the expression of Na+/K+/2Cl− cotransporter 1 (nkcc1) andcystic fibrosis transmembrane regulator (cftr) mRNAs in support of ion extrusion by SW-type ionocytes. Given the incomplete understanding of how freshwater (FW)-type ionocytes actually operat...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 24, 2020 Category: Physiology Source Type: research

Growing up gator: a proteomic perspective on cardiac maturation in an oviparous reptile, the American alligator ( Alligator mississippiensis )
AbstractWe recently described lasting changes in the cardiac proteome of American alligators (Alligator mississippiensis) reared under hypoxic conditions, that resemble what embryos encounter in natural nests. While these changes were consistent with functional differences in cardiac performance induced by developmental hypoxia, the magnitude of this response was dwarfed by a much greater effect of development alone (76% of the total differentially abundant proteins). This means that substantial differences in relative steady-state protein expression occur in the hearts of alligators as they mature from egg-bound embryos t...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 22, 2020 Category: Physiology Source Type: research

Reverse translation: effects of acclimation temperature and acute temperature challenges on oxygen consumption, diffusive water flux, net sodium loss rates, Q 10 values and mass scaling coefficients in the rainbow trout ( Oncorhynchus mykiss )
AbstractOur understanding is limited on how fish adjust the effective permeability of their branchial epithelium to ions and water while altering O2 uptake rate (MO2) with acute and chronic changes in temperature. We investigated the effects of acclimation temperature (8  °C, 13 °C and 18 °C) and acute temperature challenges [acute rise (acclimated at 8 °C, measured at 13 °C and 18 °C), acute drop (acclimated at 18 °C, measured at 8 °C and 13 °C) and intermediate (acclimated at 13 °C, measured at 8 °C and 18 °C)] on ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 21, 2020 Category: Physiology Source Type: research

Neurons and astrocytes of the chicken hypothalamus directly respond to lipopolysaccharide and chicken interleukin-6
AbstractIn 4 –5-month-old chicken, intravenous injections of bacterial lipopolysaccharide (LPS) induced a dose-dependent fever response and a pronounced increase of circulating interleukin-6 (IL-6). To assess a possible role for IL-6 in the brain of birds, a hypothalamic neuro-glial primary culture from 1-day- old chicken was established. Each well of cultured hypothalamic cells contained some 615 neurons, 1350 astrocytes, and 580 microglial cells on average. Incubation of chicken hypothalamic primary cultures with 10 or 100 µg/ml LPS induced a dose-dependent release of bioactive IL-6 into the supernata nt...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 21, 2020 Category: Physiology Source Type: research

Long-term exposure to near-future ocean acidification does not affect the expression of neurogenesis- and synaptic transmission-related genes in the olfactory bulb of European sea bass ( Dicentrarchus labrax )
AbstractThe decrease in ocean pH that results from the increased concentration of dissolved carbon dioxide (CO2) is likely to influence many physiological functions in organisms. It has been shown in different fish species that ocean acidification (OA) mainly affects sensory systems, including olfaction. Impairment of olfactory function may be due to a dysfunction of the GABAergic system and to an alteration of neuronal plasticity in the whole brain and particularly in olfactory bulbs. Recent studies revealed that OA-driven effects on sensory systems are partly mediated by the regulation of the expression of genes involved...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 8, 2020 Category: Physiology Source Type: research

Calcium homeostasis during hibernation and in mechanical environments disrupting calcium homeostasis
AbstractTo maintain calcium homeostasis during physical inactivity, precise coordination is necessary between different organs of the body. There are a number of factors which alter an organism ’s calcium balance, such as growth, aging, physical inactivity and acquired or inherited disorders which ultimately lead to bone loss. In non-hibernating mammals, physical inactivity causes bone loss which may not be completely recoverable during the lifespan of an individual despite a resumption of activity. Extreme physical inactivity and nutritional deprivation are two other important factors that lead to bone loss in non-h...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 3, 2020 Category: Physiology Source Type: research

Osmoregulation and electrolyte balance in a fully marine mammal, the dugong ( Dugong dugon )
AbstractDugongs (Dugong dugon) are fully marine mammals that live independently of fresh water so must balance water and electrolytes in a hyperosmotic environment. To investigate osmoregulation, matched plasma and urine from 51 live wild dugongs were analysed for osmolality, major electrolytes (Na+, Cl−, K+), urea, creatinine, and glucose. Maximum urine osmolality (1468  mOsm kg–1) and Na+, K+, and Cl– concentrations (757, 131.3, 677  mmol L–1, respectively) indicate that dugongs are capable of concentrating urine above seawater and could potentially realise a net gain of free water ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - January 1, 2020 Category: Physiology Source Type: research

Functional and structural changes in aorta of mice divergently selected for basal metabolic rate
AbstractCardiovascular diseases (CVD) are one of the most common causes of mortality likely genetically linked to the variation in basal metabolic rate (BMR). A robust test of the significance of such association may be provided by artificial selection experiments on animals selected for diversification of BMR. Here we asked whether genetically determined differences in BMR correlate with anatomical shift in endothelium structure and if so, the relaxation and contraction responses of the aorta in mice from two lines of Swiss-Webster laboratory mice (Mus musculus) divergently selected for high or low BMR (HBMR and LBMR line...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - December 23, 2019 Category: Physiology Source Type: research

A comparison of uterine contractile responsiveness to arginine vasopressin in oviparous and viviparous lizards
AbstractNonapeptides and their receptors regulate a diverse range of physiological processes. We assessed the contractile responsiveness of uteri from the squamate viviparous-oviparous species pair,Pseudemoia entrecasteauxii andLampropholis guichenoti, as well as the bimodally reproductive species,Saiphos equalis, to arginine vasopressin (AVP). We assessed the resulting uterine contractility as a function of pregnancy status, species and parity mode. We also measured mRNA abundance for the nonapeptide receptor, oxytocin receptor (oxtr), in uteri fromP. entrecasteauxii andL. guichenoti and compared expression across pregnan...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - December 19, 2019 Category: Physiology Source Type: research

Lipid and protein catabolism contribute to aerobic metabolic responses to exhaustive exercise during the protracted spawning run of the lamprey Geotria australis
AbstractThis paper has integrated new and past data to elucidate how lipid, protein and glycogen metabolism contribute to generating the ATP required by the southern hemisphere lampreyGeotria australis during its ~  13–15 months, non-trophic upstream spawning migration. Energy is required for maintenance, swimming, the development of gonads and secondary sexual characters and spawning and post-spawning activities. Plasma and muscle metabolites were measured in animals subjected to an exercise-recovery reg ime at the commencement and completion of the spawning run. The present study demonstrated the follow...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - December 19, 2019 Category: Physiology Source Type: research

A characterization of the electrophysiological properties of the cardiomyocytes from ventricle, atrium and sinus venosus of the snake heart
AbstractA detailed description of the electrophysiological features of cardiomyocytes in the various contractile chambers of the vertebrate heart is essential to understand the evolution of cardiac electrical activity, yet very little is known about reptiles. The present study characterizes major ionic currents (INa, ICaL, IKr, IK1 and IKACh) and action potential (AP) configuration in cardiomyocytes from the ventricle, the right atrium and the sinus venosus (SV) of Burmese pythons (Python molurus) using sharp microelectrode and patch clamp recordings. Special attention was given to SV, since it consists of myocardial cells...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - December 18, 2019 Category: Physiology Source Type: research

Ultradian oscillations in brain temperature in sheep: implications for thermoregulatory control?
AbstractWe compared body temperature patterns and selective brain cooling (SBC) in eight adult female sheep in an indoor (22 –25 °C) and outdoor (mean ~ 21 °C) environment, by measuring brain, carotid arterial, and jugular venous blood temperatures at 5-min intervals using implanted data loggers. To investigate whether ultradian oscillations in brain temperature had thermoregulatory consequences for the sheep, w e determined the cranial arterio-venous (AV) temperature difference as an indicator of respiratory evaporative heat loss (REHL). The 24-h pattern of SBC was similar in both env...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - December 13, 2019 Category: Physiology Source Type: research

Transcriptome analyses provide the first insight into the molecular basis of cold tolerance in Larimichthys polyactis
This study may help elucidate howL. polyactis tolerates cold, which is of value for breeding cold-tolerantL. polyactis stocks for cultivation. (Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology)
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - November 25, 2019 Category: Physiology Source Type: research

Season and sex have different effects on hematology and cytokines in striped hamsters ( Cricetulus barabensis )
AbstractAnimals in the temperate zones face seasonal variations in environments and hence their immune responses change seasonally. In the current study, seasonal changes in hematological parameters and cytokines in striped hamsters (Cricetulus barabensis) were examined to test the winter immunoenhancement hypothesis, which states that immune function tends to increase in fall and winter compared with other seasons. Male and female hamsters were captured from the wild in the fall and winter of 2014 and in the spring and summer of 2015. Maximum body mass in both sexes and relative fatness in female hamsters occurred in the ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - November 15, 2019 Category: Physiology Source Type: research

Autophagy and Akt-mTOR signaling display periodic oscillations during torpor-arousal cycles in oxidative skeletal muscle of Daurian ground squirrels ( Spermophilus dauricus )
In conclusion, autophagy proteins displayed periodic oscillation in the torpor-arousal cycle, which may be advantageous in maintaining SOL muscle mass during the entire hibernation period. Furthermore, the Akt-mTOR signaling was decreased in TOR and increased in IBA group in the SOL muscle of Daurian ground squirrels during hibernation. (Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology)
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - November 15, 2019 Category: Physiology Source Type: research

From phenoloxidase to fecundity: food availability does not influence the costs of oxidative challenge in a wing-dimorphic cricket
AbstractStressed animals often struggle to maintain optimal investment into a number of fitness-related traits, which can result in some traits being more adversely affected than others. Variation in stress-related costs may also depend on the environment —costs can be facultative and only occur when resources are limited, or they may be obligate and occur regardless of resource availability. Dynamics of oxidative stress may be important in life-history evolution given their role in a range of biological processes—from reproduction to immunity to locomotion. Thus, we examined how resource (food) availability in...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - November 13, 2019 Category: Physiology Source Type: research

Can ´t beat the heat? Importance of cardiac control and coronary perfusion for heat tolerance in rainbow trout
AbstractCoronary perfusion and cardiac autonomic regulation may benefit myocardial oxygen delivery and thermal performance of the teleost heart, and thus influence whole animal heat tolerance. Yet, no study has examined how coronary perfusion affects cardiac output during warming in vivo. Moreover, while β-adrenergic stimulation could protect cardiac contractility, and cholinergic decrease in heart rate may enhance myocardial oxygen diffusion at critically high temperatures, previous studies in rainbow trout (Oncorhynchus mykiss) using pharmacological antagonists to block cholinergic and β-adrenergic regulation s...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - November 9, 2019 Category: Physiology Source Type: research

Difference in glucose tolerance between phytophagous and insectivorous bats
AbstractBats are mostly insectivorous or phytophagous. It is hypothesized that bats are evolved from small insectivorous mammals. Therefore, the digestive and metabolic systems of phytophagous and insectivorous bats must have evolved differently to adapt to their dietary habits. To investigate the difference in sugar tolerance in bats, we determined changes in blood glucose levels after intraperitoneal (i.p.) injection of glucose in three species of phytophagous and four species of insectivorous bats under resting conditions. Results showed that phytophagous bats eliminated blood glucose faster than insectivorous bats. All...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - November 5, 2019 Category: Physiology Source Type: research

Transcript expression of inward rectifier potassium channels of Kir2 subfamily in Arctic marine and freshwater fish species
AbstractInward rectifier K+ (Kir2) channels are critical for electrical excitability of cardiac myocytes. Here, we examine expression of Kir2 channels in the heart of three Gadiformes species, polar cod (Boreogadus saida) and navaga (Eleginus nawaga) of the Arctic Ocean and burbot (Lota lota) of the temperate lakes to find out the role of Kir2 channels in cardiac adaptation to cold. Five boreal freshwater species: brown trout (Salmo trutta fario), arctic char (Salvelinus alpinus), roach (Rutilus rutilus), perch (Perca fluviatilis) and pike (Esox lucius), and zebrafish (Danio rerio), were included for comparison. Transcript...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - November 2, 2019 Category: Physiology Source Type: research

Links between muscle phenotype and life history: differentiation of myosin heavy chain composition and muscle biochemistry in precocial and altricial pinniped pups
This study investigates the rate that myosin heavy chain (MHC) composition matures in a postural and locomotor skeletal muscle for four pinniped species with different lactation lengths: hooded seals,Cystophora cristata; harp seals,Pagophilus groenlandicus; northern fur seals,Callorhinus ursinus, and Steller sea lions,Eumetopias jubatus. The ontogeny of MHC isoform expression was compared with developmental rates of myoglobin concentrations, and aerobic (citrate synthase,β-hydroxyacyl-CoA dehydrogenase) and anaerobic (lactate dehydrogenase) enzyme activities. Within taxonomic families, species with shorter lactation p...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - October 15, 2019 Category: Physiology Source Type: research

The variable heartbeat of Japanese moles ( Mogera spp.)
This report demonstrates the variable cardiac rhythm in two species of subterranean mole, the large Japanese mole (Mogera wogura) and the lesser Japanese mole (Mogera imaizumii). The phenomenon was revealed using X-ray videos ofM. wogura and investigated in detail using electrocardiogram (ECG) traces recorded with implanted electrodes in this species andM. imaizumii. Cessation of heartbeat and extendedR–R intervals were observed in the ECGs from both species during short bouts of rest in wakeful specimens of both species under normoxic conditions at room temperature. The mean durations ofR–R intervals were 288....
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - October 14, 2019 Category: Physiology Source Type: research

Calcium absorption in the fluted giant clam, Tridacna squamosa , may involve a homolog of voltage-gated calcium channel subunit α1 (CACNA1) that has an apical localization and displays light-enhanced protein expression in the ctenidium
In this study, the complete coding cDNA sequence of a homolog of voltage-gated calcium channel subunit α1 (CACNA1), which is the pore-forming subunit of L-type voltage-gated calcium channels (VGCCs), was obtained from the ctenidium (gill) of the giant clam,Tridacna squamosa. It consisted of 6081  bp and encoded a 223 kDa polypeptide with 2027 amino acids, which was characterized as the α1D subunit of L-type VGCC. Immunofluorescence microscopy demonstrated that CACNA1 had an apical localization in the epithelial cells of filaments and tertiary water channels in the ctenidium ofT. squamosa, indicating t...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - October 4, 2019 Category: Physiology Source Type: research

Ventilatory responses of the clown knifefish, Chitala ornata , to arterial hypercapnia remain after gill denervation
AbstractThe aim of this study was to corroborate the presence of CO2/H+-sensitive arterial chemoreceptors involved in producing air-breathing responses to aquatic hypercarbia in the facultative air-breathing clown knifefish (Chitala ornata) and to explore their possible location. Progressively increasing levels of CO2 mixed with air were injected into the air-breathing organ (ABO) of one group of intact fish to elevate internal PCO2 and decrease blood pH. Another group of fish in which the gills were totally denervated was exposed to aquatic hypercarbia (pH  ~ 6) or arterial hypercapnia in aquatic normocarbia...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - September 24, 2019 Category: Physiology Source Type: research

A robust diving response in the laboratory mouse
In this study, telemeters that measure arterial pressure were implanted into male and female C57Bl/6J mice. These mice were trained to voluntarily dive underwater for a distance of 40  cm over a 4–6 s period. Just before the dive, the interbeat interval (IBI) was 87 ± 6 ms (mean ± SD) and diastolic pressure was 99 ± 14 mmHg. Underwater submersion caused (1) a dramatic bradycardia immediately at the onset of each dive, as IBI increased to 458 ± 104 ms, a nd (2) a large drop in diastolic pressure, to 56 &...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - September 24, 2019 Category: Physiology Source Type: research

Developmental changes in the endocrine stress response in orangutans ( Pongo pygmaeus )
This study examined the influence of age, reproductive state and environment on GC and DHEAS levels in orangutans, to test whether the GC/DHEAS ratio can provide an index of stress response in primates. We measured fecal GC (fGC) and fecal DHEAS (fDHEAS) concentrations in 7 captive orangutans from zoological parks in Japan and 22 wild orangutans from Danum Valley Conservation Area, Malaysia. We found that in a stressful condition (transportation), fDHEAS levels increased 2  days after the fGC response, which occurred 1 day after the stressor. One pregnant female had elevated levels of both hormones, and a higher ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - September 23, 2019 Category: Physiology Source Type: research

Ageing impacts phenotypic flexibility in an air-acclimated amphibious fish
AbstractThe ability to tolerate environmental change may decline as fishes age. We tested the hypothesis that ageing influences the scope for phenotypic flexibility in the mangrove rivulus (Kryptolebias marmoratus), an amphibious fish that transitions between two vastly different environments, water and land. We found that older fish (4 –6 years old) exhibited marked signs of ageing; older fish were reproductively senescent, had reduced fin regenerative capacity and body condition, and exhibited atrophy of both oxidative and glycolytic muscle fibers relative to younger adult fish (1–2 years old). Howe...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - September 13, 2019 Category: Physiology Source Type: research

Pregnancy reduces critical thermal maximum, but not voluntary thermal maximum, in a viviparous skink
In this study, we examined whether two measures of upper thermal tolerance varied among life-history stages in a viviparous New Zealand skink (Oligosoma maccanni). First, we measured voluntary thermal maxima (VTmax) and critical thermal maxima (CTmax) for four groups: late-pregnant females, newly postpartum females, males, and neonates. Second, we examined whether exposing skinks to their CTmax in late pregnancy affected success of pregnancies or size and performance of offspring. We found that both VTmax and CTmax differed among the four groups, although only CTmax differed enough to detect specific pairwise differences. ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - September 6, 2019 Category: Physiology Source Type: research

An in vitro analysis of intestinal ammonia transport in fasted and fed freshwater rainbow trout: roles of NKCC, K + channels, and Na + , K + ATPase
We examined mechanisms of ammonia handling in the anterior, mid, and posterior intestine of unfed and fed freshwater rainbow trout (Oncorhynchus mykiss), with a focus on the Na+:K+:2Cl− co-transporter (NKCC), Na+:K+-ATPase (NKA), and K+ channels. NKCC was localized by immunohistochemistry to the mucosal (apical) surface of enterocytes, and NKCC mRNA was upregulated after feeding in the anterior and posterior segments. NH4+ was equally potent to K+ in supporting NKA activity in all intestinal sections. In vitro gut sac preparations were employed to examine mucosal ammonia flux rates (Jmamm, disappearance from the muco...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - September 5, 2019 Category: Physiology Source Type: research

Participation of Na + /K + -ATPase and aquaporins in the uptake of water during moult processes in the shrimp Palaemon argentinus (Nobili, 1901)
In this study, we investigated the participation of aquaporins and Na+/K+-ATPase in cells of two potential organs responsible for the uptake of water (gills and gut) at three different stages of the moult cycle in freshwater shrimpPalaemon argentinus. We showed the participation of these two proteins with different functional patterns in gills and intestinal cells as water uptake pathways for moult and early post-moult. Our results indicate that Na+/K+-ATPase promotes the necessary osmotic gradient in the gills for water uptake through the gut cells during the pre-moult. This process, in turn, remains active during the pos...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - September 5, 2019 Category: Physiology Source Type: research

Systemic versus tissue-level prolactin signaling in a teleost during a tidal cycle
AbstractEuryhaline Mozambique tilapia (Oreochromis mossambicus) are native to estuaries where they encounter tidal fluctuations in environmental salinity. These fluctuations can be dramatic, subjecting individuals to salinities characteristic of fresh water (FW  
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - September 4, 2019 Category: Physiology Source Type: research

Temperature affects liver and muscle metabolism in photostimulated migratory redheaded buntings ( Emberiza bruniceps )
AbstractWe investigated the transcriptional effects of temperature on metabolism in the liver and flight muscle prior to the onset of spring migration in redheaded buntings. We measured changes in body mass, cellular lipid accumulation, and transcription of metabolic genes in the liver and flight muscle, during a week of exposure to 8-h short photoperiod (SP; 8L: 16D) and 13-h-long photoperiod (LP; 13L: 11D) at 22  °C to ascertain the responsiveness to LP, and during 2.5 weeks of LP at 22 and 38 °C to examine the effect of temperature on LP-induced metabolic response. Particularly, we measured mRNA e...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - August 13, 2019 Category: Physiology Source Type: research

Effects of health status on pressure-induced changes in phocid immune function and implications for dive ability
This study investigated the functional response of ex situ immune cells from stranded phocids to in vitro increased pressure, over the course of rehabilitation. Blood samples were drawn from stranded harbor seals (Phoca vitulina), gray seals (Halichoerus grypus) and harp seals (Phoca groenlandica) at the time of admit to the Mystic Aquarium, Mystic, CT and again after rehabilitation (pre-release). Phagocytosis, lymphocyte proliferation and immune cell activation were measured in vitro, with and without exposure to 2000  psi (simulated dive depth of 1360 m). Plasma epinephrine and norepinephrine, and serum cortiso...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - July 26, 2019 Category: Physiology Source Type: research

Ocean acidification: synergistic inhibitory effects of protons and heavy metals on 45 Ca uptake by lobster branchiostegite membrane vesicles
AbstractPrevious work with isolated outer membrane vesicles of lobster branchiostegite epithelial cells has shown that45Ca2+ uptake by these structures is significantly (p 
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - July 17, 2019 Category: Physiology Source Type: research

Pulsatile urea excretion in Gulf toadfish: the role of circulating serotonin and additional 5-HT receptor subtypes
AbstractThe neurochemical serotonin (5-HT) is involved in stimulating pulsatile urea excretion in Gulf toadfish (Opsanus beta) through the 5-HT2A receptor; however, it is not known if (1) the 5-HT signal originates from circulation or if (2) additional 5-HT receptor subtypes are involved. The first objective was to test whether 5-HT may be acting as a hormone in the control of pulsatile urea excretion by measuring potential fluctuations in circulating 5-HT corresponding with a urea pulse, which would suggest circulating 5-HT may be involved with urea pulse activation. We found that plasma 5-HT significantly decreased by 38...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - July 17, 2019 Category: Physiology Source Type: research

Study of lipid reserves in Liolaemus koslowskyi (Squamata: Liolaemidae): reproductive and ecological implications
In this study, a population ofLiolaemus koslowskyi was studied to analyze the diversity and functioning of the lipid reserve structures. The specific objectives were to identify the main lipid reserve structures, and to describe their seasonal patterns; to study sexual and seasonal variations of the reserve structures; and to analyze the relation between seasonal patterns of such reserves with the sexual cycle and other biological aspects. Individuals of both sexes collected at five different times of the year were analyzed. The abdominal fat bodies, livers, tails, fat deposits of the lateral folds of the neck, the fat bod...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - July 6, 2019 Category: Physiology Source Type: research

Characterizing the influence of chronic hypobaric hypoxia on diaphragmatic myofilament contractile function and phosphorylation in high-altitude deer mice and low-altitude white-footed mice
AbstractDeer mice,Peromyscusmaniculatus, live at high altitudes where limited O2 represents a challenge to maintaining oxygen delivery to tissues. Previous work has demonstrated that hypoxia acclimation of deer mice and low altitude white-footed mice (P. leucopus) increases the force generating capacity of the diaphragm. The mechanism behind this improved contractile function is not known. Within myocytes, the myofilament plays a critical role in setting the rate and level of force production, and its ability to generate force can change in response to changes in physiological conditions. In the current study, we examined ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - July 5, 2019 Category: Physiology Source Type: research

Cardiovascular and ventilatory interactions in the facultative air-breathing teleost Pangasianodon hypophthalmus
AbstractAll vertebrates possess baroreceptors monitoring arterial blood pressure and eliciting reflexive changes in vascular resistance and heart rate in response to blood pressure perturbations imposed by, e.g., exercise, hypoxia, or hemorrhage. There is considerable variation in the magnitude of the baroreflex amongst vertebrate groups, making phylogenetic trends and association with major evolutionary events such as air-breathing and endothermy, difficult to identify. In the present study, we quantified the baroreflex in the facultative air-breathing catfishPangasianodon hypophthalmus. Using a pharmacological approach, ...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - July 4, 2019 Category: Physiology Source Type: research

“Insulin-like” effects of palmitate compromise insulin signalling in hypothalamic neurons
AbstractSaturated fatty acids are implicated in the development of metabolic diseases, including obesity and type 2 diabetes. There is evidence, however, that polyunsaturated fatty acids can counteract the pathogenic effects of saturated fatty acids. To gain insight into the early molecular mechanisms by which fatty acids influence hypothalamic inflammation and insulin signalling, we performed time-course experiments in a hypothalamic cell line, using different durations of treatment with the saturated fatty acid palmitate, and the omega-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA). Western blot analysis reveal...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - May 23, 2019 Category: Physiology Source Type: research

Pheomelanin synthesis varies with protein food abundance in developing goshawks
AbstractThe accumulation of the amino acid cysteine in lysosomes produces toxic substances, which are avoided by a gene (CTNS) coding for a transporter that pumps cystine out of lysosomes. Melanosomes are lysosome-related organelles that synthesize melanins, the most widespread pigments in animals. The synthesis of the orange melanin, termed pheomelanin, depends on cysteine levels because the sulfhydryl group is used to form the pigment. Pheomelanin synthesis may, therefore, be affected by cysteine homeostasis, although this has never been explored in a natural system. As diet is an important source of cysteine, here we in...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - May 18, 2019 Category: Physiology Source Type: research

Effect of protein synthesis inhibitor cycloheximide on starvation, fasting and feeding oxygen consumption in juvenile spiny lobster Sagmariasus verreauxi
This study is the first using a protein synthesis inhibitor cycloheximide to research contribution of cycloheximide-sensitive protein synthesis to decapod crustacean metabolism. JuvenileSagmariasus verreauxi were subject to five treatments: 2-day fasted lobsters sham injected with saline; 2-day fasted lobsters injected with cycloheximide; 10-day starved lobsters injected with cycloheximide; post-prandial lobsters fed with squidNototodarus sloanii with no further treatment; and post-prandial lobsters injected with cycloheximide. Standard and routine metabolic rates in starved lobsters were reduced by 32% and 41%, respective...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - May 17, 2019 Category: Physiology Source Type: research

Within-winter flexibility in muscle and heart lipid transport and catabolism in passerine birds
AbstractSmall birds in cold climates may show within-winter metabolic flexibility to match metabolic capacities to prevailing weather conditions. This flexibility may occur over periods of days to weeks, but the underlying mechanisms for such flexibility are not well understood. Because lipids are the primary fuel for sustained thermogenesis, we examined whether lipid transport and catabolism can mediate within-winter metabolic flexibility in two small temperate-zone wintering passerine birds, dark-eyed juncos (Junco hyemalis) and house sparrows (Passer domesticus). We used simple and multiple regression analyses to test f...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - May 10, 2019 Category: Physiology Source Type: research

Effects of short- and long-term cold acclimation on morphology, physiology, and exercise performance of California mice ( Peromyscus californicus ): potential modulation by fatherhood
AbstractCalifornia mice (Peromyscus californicus) differ from most other mammals in that they are biparental, genetically monogamous, and (compared with otherPeromyscus) relatively large. We evaluated effects of cold acclimation on metabolic rate, exercise performance, and morphology of pair-housed male California mice, as well as modulation of these effects by fatherhood. In Experiment 1, virgin males housed at 5 ° or 10 °C for approximately 25 days were compared with virgins housed at standard vivarium temperature of 22 °C. Measures included resting metabolic rate (RMR), maximal oxygen consumpt...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - May 9, 2019 Category: Physiology Source Type: research