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Journal of Experimental Biology

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https://www.readbyqxmd.com/read/30237241/taurine-activates-glycine-and-gaba-a-receptor-currents-in-anoxia-tolerant-painted-turtle-pyramidal-neurons
#1
Ashley Rebecca Miles, Peter John Hawrysh, Nariman Hossein-Javaheri, Leslie Thomas Buck
Unlike anoxia-intolerant mammals, painted turtles can survive extended periods without oxygen. This is partly accomplished by an anoxia-mediated increase in gamma-aminobutyric acid (GABA) release, which activates GABA receptors and mediates spike arrest in turtle neurons via shunting inhibition. Extracellular taurine levels also increase during anoxia; however, its function is unknown but speculated to involve glycine and/or GABAA/B receptors. Given the general importance of inhibitory neurotransmission in the anoxia-tolerant painted turtle brain, we investigated the function of taurine as an inhibitory neuromodulator in turtle pyramidal neurons...
September 20, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30237240/neuromechanical-coupling-within-the-human-triceps-surae-and-its-consequence-on-individual-force-sharing-strategies
#2
Marion Crouzier, Lilian Lacourpaille, Antoine Nordez, Kylie Tucker, François Hug
Little is known about the factors that influence the coordination of synergist muscles that act across the same joint, even during single-joint isometric tasks. The overall aim of this study was to determine the nature of the relationship between the distribution of activation and the distribution of force-generating capacity among the three heads of the triceps surae ( soleus [SOL], gastrocnemius medialis [GM] and lateralis [GL]). Twenty volunteers performed isometric plantarflexions during which the activation of GM, GL and SOL was estimated using electromyography (EMG)...
September 20, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30237239/interaction-between-step-to-step-variability-and-metabolic-cost-of-transport-during-human-walking
#3
Chase G Rock, Vivien Marmelat, Jennifer M Yentes, Ka-Chun Siu, Kota Z Takahashi
Minimizing metabolic cost of transport is a strong determinant of the preferred walking speed. While many factors can affect metabolic cost of transport during human walking, its interaction with step-to-step variability is unclear. Here, we aimed to determine the interaction between metabolic cost of transport and step length variability during human walking at different speeds. In particular, two aspects of step length variability were analyzed: the amount of variations (Variations) and the organization of the step-to-step fluctuations (Fluctuations)...
September 20, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30237238/frog-muscle-fibers-bear-a-larger-fraction-of-passive-muscle-tension-than-mouse-fibers
#4
Gretchen Meyer, Richard L Lieber
Differences in passive muscle mechanical properties between amphibians and mammals have led to differing hypotheses on the functional role of titin in skeletal muscle. Early studies of frog muscle clearly demonstrated intracellular load-bearing by titin, but more recent structural and biological studies in mice have shown that titin may serve other functions. Here we present biomechanical studies of isolated frog and mouse fibers and fiber bundles to compare the relative importance of intracellular vs. extracellular load bearing in these species...
September 20, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30228156/limits-to-sustained-energy-intake-xxix-the-case-of-the-golden-hamster-mesocricetus-auratus
#5
S A Ohrnberger, C Hambly, J R Speakman, T G Valencak
Golden hamster females have the shortest known gestation period among placental mammals and at the same time raise very large litters of up to 16 offspring, which are born in a naked and blind state and are able to pick up food from days 12-14 only. We quantified energy metabolism and milk production in female golden hamsters raising offspring under cold (8°C), normal (22°C) and hot (30°C) ambient temperature conditions. We monitored energy intake, subcutaneous body temperature, daily energy expenditure, litter size and pup masses over the course of lactation...
September 18, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30224371/electrical-interactions-between-photoreceptors-in-the-compound-eye-of-periplaneta-americana
#6
Paulus Saari, Esa-Ville Immonen, Andrew S French, Päivi H Torkkeli, Hongxia Liu, Kyösti Heimonen, Roman V Frolov
The compound eye of Periplaneta americana contains two spectral classes of photoreceptors: narrow-band UV-sensitive and broad-band green-sensitive. In intracellular recordings, stimulation of green-sensitive photoreceptors with flashes of relatively bright UV/violet light produced anomalous delayed depolarization after the end of the normal light response, whereas stimulation of UV-sensitive photoreceptors with green light elicited biphasic responses characterized by initial transient hyperpolarization followed by prolonged delayed depolarization...
September 17, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30224370/dietary-canthaxanthin-reduces-xanthophyll-uptake-and-red-coloration-in-adult-red-legged-partridges
#7
C Alonso-Alvarez, E García-de Blas, R Mateo
Carotenoids give color to conspicuous animal signals that are often the product of sexual selection. To know the mechanisms involved in carotenoid-based signaling is critical to understand how these traits evolve. However, these mechanisms remain partially understood. Carotenoids are usually viewed as scarce dietary antioxidants whose allocation to ornaments may trade against health. This trade-off would assure its reliability as individual quality signals. In the case of red (keto)carotenoids, the literature suggests that some species may show constraints in their uptake...
September 17, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30224369/an-exercise-induced-improvement-in-isolated-skeletal-muscle-contractility-does-not-affect-the-performance-enhancing-benefit-of-70%C3%AE-m-caffeine-treatment
#8
Jason Tallis, Matthew F Higgins, Val M Cox, Michael J Duncan, Rob S James
This study aimed to examine the effects of exercise-induced increases in skeletal muscle contractile performance on isolated skeletal muscle caffeine sensitivity. 30-week old CD1 mice (n=28) either acted as controls or underwent eight weeks of voluntary wheel running. Following the treatment intervention, whole soleus (SOL) or a section of the costal diaphragm (DIA) was isolated from each mouse and tested to determine the effect of 70μM caffeine on work loop power output. Although caffeine elicited a significant increase in power of both the SOL and the DIA, relative to a non-caffeine control, the effect was not different between the experimental groups, despite the muscles of the trained group producing significantly greater muscle power...
September 17, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30224368/ultrasound-avoidance-by-flying-antlions-myrmeleontidae
#9
Marc W Holderied, Liam A Thomas, Carmi Korine
The acoustic arms race between insectivorous bats and their invertebrate prey has led to the convergent evolution of ultrasound hearing in seven orders of nocturnal insects. Upon hearing the echolocation calls of an approaching bat such insects take defensive action. Here we document an unknown sense of ultrasound hearing and phonotactic flight behaviour in the neuropteran family Myrmeleontidae (antlions). The antlion Myrmeleon hyalinus was presented with sound pulses at ultrasonic frequencies used by echolocating bats and its response thresholds in tethered flight determined...
September 17, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30206107/impacts-of-differences-in-nutritional-quality-of-wingless-and-winged-aphids-on-parasitoid-fitness
#10
Jennifer A-L M Pirotte, Ange Lorenzi, Vincent Foray, Thierry Hance
Winged aphids are described as hosts of lesser quality for parasitoids because a part of their resources is used to produce wings and associated muscles during their development. Host lipid content is particularly important for parasitoid larvae as they lack lipogenesis, therefore, they rely entirely on the host for this resource. The goal of this study is to determine in what extent winged and wingless aphids differ from the nutritional point of view and if these differences impact the parasitoid fitness notably the lipid content...
September 11, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30194252/aquatic-versus-terrestrial-crab-skeletal-support-morphology-mechanics-molting-and-scaling
#11
Jennifer R A Taylor
The transition from aquatic to terrestrial environments places significant mechanical challenges on skeletal support systems. Crabs have made this transition multiple times and are the largest arthropods to inhabit both environments. Furthermore, they alternate between rigid and hydrostatic skeletons, making them an interesting system to examine mechanical adaptations in skeletal support systems. I hypothesized that terrestrial crabs have modified morphology to enhance mechanical stiffness and that rigid and hydrostatic skeletons scale differently from each other, with stronger allometric relationships on land...
September 7, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30194251/controlled-feeding-experiments-with-diets-of-different-abrasiveness-reveal-slow-development-of-mesowear-signal-in-goats-capra-aegagrus-hircus
#12
Nicole L Ackermans, Daniela E Winkler, Ellen Schulz-Kornas, Thomas M Kaiser, Dennis W H Müller, Patrick R Kircher, Jürgen Hummel, Marcus Clauss, Jean-Michel Hatt
Dental mesowear is applied as a proxy to determine the general diet of mammalian herbivores based on tooth-cusp shape and occlusal relief. Low, blunt cusps are considered typical for grazers and high, sharp cusps typical for browsers. However, how internal or external abrasives impact mesowear, and the time frame the wear signature takes to develop, still need to be explored. Four different pelleted diets of increasing abrasiveness (lucerne, grass, grass and rice husks, grass, rice husks and sand) were fed to four groups of a total of 28 adult goats in a controlled feeding experiment over a six-month period...
September 7, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30194250/differences-in-motor-cortical-control-of-the-soleus-and-tibialis
#13
Benedikt Lauber, Albert Gollhofer, Wolfgang Taube
The tibialis anterior (TA) and the soleus (SOL) are both ankle joint muscles with functionally very different tasks. Thus, differences in motor cortical control between the TA and the SOL have been debated. This study compared the activity of the primary motor cortex during dynamic plantar- and dorsiflexions and compared this with measures obtained during rest. Single- and paired-pulse transcranial magnetic stimulations known as short-interval intracortical inhibition (SICI) were applied to the cortical representation of either the soleus or the tibialis muscle...
September 7, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30194249/head-width-influences-flow-sensing-by-the-lateral-line-canal-system-in-fishes
#14
Yuzo R Yanagitsuru, Otar Akanyeti, James C Liao
The architecture of the cephalic lateral line canal system, with distinct lines for the supraorbital, infraorbital, and mandibular canals, is highly conserved among fish species. Because these canals lay on a cranial platform, the sensory input they receive is expected to change based on how flow interacts with the head and how the canal pores are spatially distributed. In this study, we explore how head width, a trait that can vary greatly between species and across ontogeny, affects flow sensing. We inserted pressure sensors into physical fish head models of varying widths (narrow, intermediate, and wide) and placed these models in steady and vortical flows...
September 7, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30190320/dietary-antioxidants-but-not-courtship-effort-affect-oxidative-balance-in-the-testes-and-muscles-of-crickets
#15
Leigh W Simmons, Maxine Lovegrove, Samuel J Lymbery
Recent interest has focused on the role of reactive oxygen species (ROS) as universal constraints in life-history evolution. Empirical studies have examined the oxidative costs of reproduction for females, with little work conducted on males. The male germline is thought to be particularly susceptible to oxidative damage because the testes, and sperm themselves, can be prolific producers of ROS. We tested the hypothesis that protection of the male germline from oxidative damage represents a cost of reproduction for males...
September 6, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30190319/the-yellow-specialist-dronefly-eristalis-tenax-prefers-different-yellow-colours-for-landing-and-proboscis-extension
#16
Lina An, Alexander Neimann, Eugen Eberling, Hanna Algora, Sebastian Brings, Klaus Lunau
Droneflies, imagoes of the hoverfly Eristalis tenax , are known to possess a preference for yellow flowers, i.e. they prefer to visit yellow flowers and prefer to extend the proboscis to yellow colours. In this study we disentangle these colour preferences by investigating the landing reaction and proboscis reflex with particular reference to intensity, spectral purity and dominant wavelength of colour stimuli and their UV-reflection properties. In multiple choice tests naïve and non-trained flies prefer to land on yellow colours independent of its UV-reflection, but also accept blue, white and pink colours if UV-absorbing and of effectual brightness...
September 6, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30190318/aerobic-capacities-and-swimming-performance-of-polar-cod-boreogadus-saida-lepechin-under-ocean-acidification-and-warming-conditions
#17
Kristina Lore Kunz, Guy Claireaux, Hans-Otto Pörtner, Rainer Knust, Felix Christopher Mark
Polar cod, Boreogadus saida , is an important prey species in the Arctic ecosystem, yet its habitat is changing rapidly: Climate change, through rising seawater temperatures and CO2 concentrations, is projected to be most pronounced in Arctic waters. This study aimed at investigating the influence of ocean acidification and warming on maximum performance parameters of B. saida as indicators for the species' acclimation capacities under environmental conditions projected for the end of this century. After four months at four acclimation temperatures (0, 3, 6, 8°C) each combined with two P CO2 levels (390 and 1170 µatm), aerobic capacities and swimming performance of B...
September 6, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30190317/physiological-responses-of-ionotropic-histamine-receptors-pxhcla-and-pxhclb-to-neurotransmitter-candidates-in-a-butterfly-papilio-xuthus
#18
Hiroshi D Akashi, Pei-Ju Chen, Tokiho Akiyama, Yohey Terai, Motohiro Wakakuwa, Yasunori Takayama, Makoto Tominaga, Kentaro Arikawa
Histamine is the only known neurotransmitter released by arthropod photoreceptors. Synaptic transmission from photoreceptors to second order neurons is mediated by the activation of histamine-gated chloride channels (HCLs). These histaminergic synapses have been assumed to be conserved among insect visual systems. However, our understanding of the channels in question has thus far been based on studies in flies. In the butterfly Papilio xuthus , we have identified two candidate histamine-gated chloride channels, PxHCLA and PxHCLB, and studied their physiological properties using a whole-cell patch-clamp technique...
September 6, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30190316/effects-of-both-cold-and-heat-stresses-on-the-liver-of-giant-spiny-frog-quasipaa-spinosa-stress-response-and-histological-changes
#19
Ze-Peng Liu, Wen-Bin Gu, Dan-Dan Tu, Qi-Hui Zhu, Yi-Lian Zhou, Cong Wang, Lan-Zhi Wang, Miao-An Shu
Ambient temperature associated stress can affect the normal physiological functions in ectotherms. To assess the effects of cold or heat stress on amphibians, the giant spiny frogs, Quasipaa spinosa , were acclimated at 22 °C followed by being treated at 5 °C or 30 °C for 0, 3, 6, 12, 24 and 48 h, respectively. Histological alterations, apoptotic index, mitochondrial reactive oxygen species (ROS) generation, antioxidant activity indices and stress-response gene expressions in frog livers were subsequently determined...
September 6, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/30190315/no-short-term-physiological-costs-of-offspring-care-in-a-cooperatively-breeding-bird
#20
Sarah Guindre-Parker, Dustin R Rubenstein
The cost of reproduction results in a life-history trade-off where investment in current reproduction via costly parental care decreases subsequent fitness. Although this trade-off is thought to occur ubiquitously across animals, there is equivocal evidence that parental care behaviours are costly. A major challenge of studying the cost of parental care has been a lack of consensus over which physiological mechanisms underlie this trade-off. Here we compare four traits believed to mediate the cost of parental care by examining whether glucocorticoids, oxidative stress, immune function, or body condition represent a cost of performing offspring care and shape subsequent fitness...
September 6, 2018: Journal of Experimental Biology
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