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Journal of Experimental Biology

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https://www.readbyqxmd.com/read/28623226/entraining-to-the-polar-day-circadian-rhythms-in-arctic-ground-squirrels
#1
Cory T Williams, Brian M Barnes, Lily Yan, C Loren Buck
Circadian systems are principally entrained to 24h light/dark cycles, but this cue is seasonally absent in polar environments. Although some resident polar vertebrates have weak circadian clocks and are seasonally arrhythmic, the arctic ground squirrel (AGS) maintains daily rhythms of physiology and behavior throughout the summer, which includes six weeks of constant daylight. Here, we show that persistent daily rhythms in AGS are maintained through a circadian system that readily entrains to the polar day yet remains insensitive to entrainment by rapid light-dark transitions, which AGS generate naturally due to their semi-fossorial behavior...
June 16, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28623225/high-peripheral-temperatures-in-king-penguins-while-resting-at-sea-thermoregulation-versus-fat-deposition
#2
Agnes Lewden, Manfred R Enstipp, Baptiste Picard, Tessa van Walsum, Yves Handrich
Marine endotherms living in cold water face an energetically challenging situation. Unless properly insulated these animals will lose heat rapidly. The field metabolic rate of king penguins at sea is about twice that on land. However, when at sea, their metabolic rate is higher during extended resting periods at the surface than during foraging, when birds descend to great depth in pursuit of their prey. This is most likely explained by differences in thermal status. During foraging peripheral vasoconstriction leads to a hypothermic shell, which is rewarmed during extended resting bouts at the surface...
June 16, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28620015/genetic-editing-of-the-androgen-receptor-contributes-to-impaired-male-courtship-behavior-in-zebrafish
#3
Lengxob Yong, Zayer Thet, Yong Zhu
Elucidating the genes that contribute to behavioral variation has become an important endeavor in behavioral studies. While advances in genomics have narrowed down candidate genes, functionally validating them has been lagging, partly because of challenges associated with rapid gene manipulations. Consequently, few studies have demonstrated causal genetic changes linked to behaviors. The 'gene editing revolution' has offered unprecedented opportunities to interrogate candidate genes responsible for critical behaviors...
June 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28620014/the-tendinopathic-achilles-tendon-does-not-remain-iso-volumetric-upon-repeated-loading-insights-from-3d-ultrasound
#4
Leila Nuri, Steven J Obst, Richard Newsham-West, Rod S Barrett
Mid-portion Achilles tendinopathy (MAT) alters the normal three-dimensional (3D) morphology of the Achilles tendon (AT) at rest and under a single tensile load. However, how MAT changes the 3D morphology of AT during repeated loading remains unclear. This study compared the AT longitudinal, transverse and volume strains during repeated loading in MAT with those of the contralateral tendon in people with unilateral MAT. Ten adults with unilateral MAT performed 10 successive 25 second submaximal (50%) voluntary isometric plantarflexion contractions with both legs...
June 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28620013/the-evolution-of-vertical-climbing-in-primates-evidence-from-reaction-forces
#5
Jandy B Hanna, Michael C Granatosky, Pooja Rana, Daniel Schmitt
Vertical climbing is an essential behavior for arboreal animals, yet limb mechanics during climbing are poorly understood and rarely compared to those observed during horizontal walking. Primates commonly engage in both arboreal walking and vertical climbing, and this makes them an ideal taxa in which to compare these locomotor forms. Additionally, primates exhibit unusual limb mechanics compared to most other quadrupeds, with weight distribution biased towards the hindlimbs, a pattern that is argued to have evolved in response to the challenges of arboreal walking...
June 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28606898/carotenoids-buffer-the-acute-phase-response-on-fever-sickness-behavior-and-rapid-bill-color-change-in-zebra-finches
#6
Deanna R Broughton, Brent C Schneider, Kevin J McGraw, Daniel R Ardia
Carotenoids are finite resources that animals can allocate to self-maintenance, attractiveness, or reproduction. Here we test how carotenoids affect the acute phase response (APR), an intense rapid systemic response characterized by fever, sickness behavior, and production of acute phase proteins, which serves to reduce pathogen persistence. We conducted a 2x2 factorial design experiment in captive adult male and female zebra finches (Taeniopygia guttata) to determine the effects of carotenoid supplementation on the intensity of the APR...
June 12, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28606897/melatonin-attenuates-phenotypic-flexibility-of-energy-metabolism-in-a-photoresponsive-mammal-the-siberian-hamster
#7
Jan S Boratyński, Małgorzata Jefimow, Michał S Wojciechowski
The duration of melatonin (MEL) secretion conveys information about day length and initiates a cascade of seasonal phenotypic adjustments in photoresponsive mammals. With shortening days they cease reproduction, minimize energy expenditure, enhance thermoregulatory capacity and adjust functioning of the hypothalamic-pituitary-adrenal (HPA) axis to match the winter increase in energy demands. Within each season stress plays an important role in the flexible adjustments of a phenotype to environmental perturbations...
June 12, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28596215/reproductive-and-metabolic-state-differences-in-olfactory-responses-to-amino-acids-in-a-mouth-brooding-african-cichlid-fish
#8
Alexandre A Nikonov, Julie M Butler, Karen E Field, John Caprio, Karen P Maruska
Olfaction mediates many crucial life-history behaviors such as prey detection, predator avoidance, migration, and reproduction. Olfactory function can also be modulated by an animal's internal physiological and metabolic states. While this is relatively well-studied in mammals, little is known about how internal state impacts olfaction in fishes, the largest and most diverse group of vertebrates. Here we apply electro-olfactograms (EOGs) in the African cichlid fish Astatotilapia burtoni to test the hypothesis that olfactory responses to food-related cues (i...
June 8, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28596214/changes-in-mechanical-work-during-neural-adaptation-to-asymmetric-locomotion
#9
Brian P Selgrade, Montakan Thajchayapong, Gloria E Lee, Megan E Toney, Young-Hui Chang
Minimizing whole body metabolic cost has been suggested to drive the neural processes of locomotor adaptation. Mechanical work performed by the legs should dictate the major changes in whole body metabolic cost of walking while providing greater insight into temporal and spatial mechanisms of adaptation. We hypothesized changes in mechanical work by the legs during an asymmetric split-belt walking adaptation task could explain previously observed changes in whole body metabolic cost. We predicted subjects would immediately increase mechanical work performed by the legs when first exposed to split-belt walking, followed by a gradual decrease throughout adaptation...
June 8, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28596213/chamber-music-an-unusual-helmholtz-resonator-for-song-amplification-in-a-neotropical-bush-cricket-orthoptera-tettigoniidae
#10
Thorin Jonsson, Benedict D Chivers, Kate Robson Brown, Fabio A Sarria-S, Matthew Walker, Fernando Montealegre-Z
Animals use sound for communication, with high-amplitude signals being selected for attracting mates or deterring rivals. High amplitudes are attained by employing primary resonators in sound producing structures to amplify the signal (e.g., avian syrinx). Some species actively exploit acoustic properties of natural structures to enhance signal transmission by using these as secondary resonators (e.g., tree-hole frogs). Male bush-crickets produce sound by tegminal stridulation and often use specialised wing areas as primary resonators...
June 8, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28596212/rapid-growth-causes-abnormal-vaterite-formation-in-farmed-fish-otoliths
#11
T Reimer, T Dempster, A Wargelius, P G Fjelldal, T Hansen, K A Glover, M F Solberg, S E Swearer
Sagittal otoliths are essential components of the sensory organs that enable all teleost fish to hear and maintain balance, and are primarily composed of calcium carbonate. A deformity, where aragonite (the normal crystal form) is replaced with vaterite, was first noted over 50 years ago but its underlying cause is unresolved. We evaluated the prevalence of vateritic otoliths from two captive rearing studies which suggested that fast growth, due to environmental rather than genetic control, led to vaterite development...
June 8, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28596211/low-levels-of-extracellular-glucose-limit-cardiac-anaerobic-metabolism-in-some-species-of-fish
#12
Kathy A Clow, Connie E Short, William R Driedzic
There is a wide interspecific range in plasma glucose levels in teleosts from less than 0.5 to greater than 10 mmol l(-1) Here it is assessed how glucose availability influences glucose metabolism in hearts of Atlantic cod (Gadus morhua), rainbow trout (Oncorhynchus mykiss), lumpfish (Cyclopterus lumpus) and short-horned sculpin (Myoxocephalus scorpius) under normoxic and hypoxic conditions. These species had plasma glucose levels of 5.1, 4.8, 0.9 and 0.5 mmol l(-1), respectively. Rates of glucose metabolism and lactate production were determined in isolated hearts perfused with media containing physiological levels of glucose...
June 8, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28576824/pre-settlement-coral-reef-fish-larvae-respond-to-magnetic-field-changes-during-the-day
#13
Jack O'Connor, Rachel Muheim
Observations of coral-reef fish larvae have revealed remarkably consistent orientation behaviour while swimming offshore, requiring large-scale orientation cues. However, the mechanisms underlying this behaviour are still being investigated. One potential large-scale cue for orientation is the Earth's geomagnetic field. Here, we examined the effect of magnetic field manipulations on the orientation behaviour of coral-reef fish during the pelagic larval phase. In the absence of visual cues, individual larvae responded to a 90° shift of the horizontal component of the magnetic field within a Helmholtz coil with a comparable shift in orientation, demonstrating that they use a magnetic compass for orientation...
June 2, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28576823/heart-rate-dynamics-in-a-marsupial-hibernator
#14
Steven J Swoap, Gerhard Körtner, Fritz Geiser
The eastern pygmy-possum (Cercartetus nanus) is a small marsupial that can express spontaneous short bouts of torpor, as well as multi-day bouts of deep hibernation. To examine heart rate (HR) control at various stages of torpor in a marsupial hibernator, and to see whether HR variability differs from deep placental hibernators, we used radiotelemetry to measure ECG and Tb while measuring the rate of O2 consumption and ventilation. The HR and rate of O2 consumption during euthermia was at its minimum (321±34 bpm, 0...
June 2, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28576822/ammonia-exposure-affects-the-mrna-and-protein-expression-levels-of-certain-rhesus-glycoproteins-in-the-gills-of-climbing-perch
#15
Xiu L Chen, Biyan Zhang, You R Chng, Jasmine L Y Ong, Shit F Chew, Wai P Wong, Siew H Lam, Tsutomu Nakada, Yuen K Ip
The freshwater climbing perch, Anabas testudineus, is an obligate air-breathing and euryhaline teleost capable of active ammonia excretion and tolerance of high concentrations of environmental ammonia. As Rhesus glycoproteins (RhGP/Rhgp) are known to transport ammonia, this study aimed to obtain the complete cDNA coding sequences of various rhgp isoforms from the gills of A. testudineus, and to determine their mRNA and protein expression levels during 6 days of exposure to 100 mmol l(-1) NH4Cl. The subcellular localization of Rhgp isoforms in the branchial epithelium was also examined in order to elucidate the type of ionocyte involved in active ammonia excretion...
June 2, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28576821/contraction-induced-enhancement-of-relaxation-during-high-force-contractions-of-mouse-lumbrical-muscle-at-37%C3%A2-c
#16
Ian C Smith, Rene Vandenboom, A Russell Tupling
Repeated stimulation of unfatigued rodent fast twitch skeletal muscle accelerates the kinetics of tension relaxation through an unknown mechanism. This effect varies with muscle type and stimulation parameters, and has been observed at physiological temperatures for submaximal but not maximal contractions. The purpose of this study was to compare relaxation kinetics of C57BL/6 mouse lumbrical muscles ex vivo from maximal isometric force (500 Hz for 20 ms) when evoked before (Pre) and after (Post) an intervening tetanic contraction at 37°C...
June 2, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28576820/mir-210-expression-is-associated-with-methionine-induced-differentiation-of-trout-satellite-cells
#17
M Latimer, N Sabin, A Le Cam, I Seiliez, P Biga, J C Gabillard
In fish, data on miRNAs involved in myogenesis are scarce. In order to identify miRNAs involved in satellite cell differentiation, we used a methionine depletion/replenishment protocol to synchronize myogenic cell differentiation. Our results validated that methionine removal (72H) from the medium strongly decreased myoD1 and myogenin expression indicating differentiation arrest. In contrast, methionine replenishment rescued expression of myoD1 and myogenin showing a resumption of differentiation. We performed a miRNA array analysis of myogenic cells from three conditions: presence of methionine (CTRL), absence of methionine during 72h (Meth-) and absence of methionine during 48H with 24H of methionine replenishment (Meth -/+)...
June 2, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28546509/behavioral-color-vision-in-a-cichlid-fish-metriaclima-benetos
#18
Daniel Escobar-Camacho, Justin Marshall, Karen L Carleton
Color vision is the capacity of discriminating color regardless of brightness. It is essential for many fish species as they rely on color discrimination for numerous ecological tasks. The study of color vision is important because it can unveil the mechanisms that shape coloration patterns, visual system sensitivities and hence, visual signals. In order to understand better the mechanisms underlying color vision an integrative approach is necessary. This usually requires combining behavioral, physiological, and genetic experiments with quantitative modeling, resulting in a distinctive characterization of the visual system...
May 25, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28546508/stable-carbon-isotopes-in-breath-reveal-fast-incorporation-rates-and-seasonally-variable-but-rapid-fat-turnover-in-the-common-shrew-sorex-araneus
#19
Lara Keicher, M Teague O'Mara, Christian C Voigt, Dina K N Dechmann
Small non-migratory mammals with Northern distribution ranges apply a variety of behavioural and physiological wintering strategies. A rare energy saving strategy is Dehnel's phenomenon, involving a reduction and later regrowth of the body, several organs and parts of the skeleton in red-toothed shrews (Soricidae). The size extremes coincide with major life stages. Yet, the physiological consequences for the shrews' metabolism remain poorly understood. In keeping with the energetic limitations that may induce the size changes, we hypothesized that metabolic incorporation rates should remain the same across the shrews' lifetime...
May 25, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28546507/individual-quality-as-sensitivity-to-cysteine-availability-in-a-melanin-based-honest-signalling-system
#20
Ismael Galván, Carlos Alonso-Alvarez
The evolution of honest animal communication is mostly understood through the handicap principle, which is intrinsically dependent on the concept of individual quality: low-quality individuals are prevented from producing high-quality signals because if they did so, they would pay greater production costs than high-quality individuals. We tested an alternative explanation for the black bib size of male house sparrows Passer domesticus, an honest signal of quality whose expression is negatively related to levels of the pigment pheomelanin in its contituent feathers...
May 25, 2017: Journal of Experimental Biology
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