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Journal of Experimental Biology

Oliver Baum, Carole Sollberger, Andrea Raaflaub, Adolfo Odriozola, Gunnar Spohr, Sebastian Frese, Stefan A Tschanz
To work out which microvascular remodeling processes occur in murine skeletal muscle during endurance exercise, we subjected C57BL/6-mice to voluntary running wheel training for 1 week (1wk-t) or 6 weeks (6wks-t). By means of morphometry, the capillarity as well as the compartmental and sub-compartmental structure of the capillaries were quantitatively described at the light microscopy and at the electron microscopy level, respectively, in the plantaris muscle (PLNT) of the exercising mice in comparison to untrained littermates...
December 15, 2017: Journal of Experimental Biology
S Puri, T Aegerter-Wilmsen, A Jaźwińska, C M Aegerter
The caudal fins of adult zebrafish are supported by multiple bony rays that are laterally interconnected by soft interray tissue. Little is known about the fin's mechanical properties that influence the bending in response to hydrodynamic forces during swimming. Here, we developed an experimental setup to measure the elastic properties of caudal fins in-vivo by applying micro-Newton forces to obtain bending stiffness and a tensional modulus. We detected overall bending moments of 1.5 - 4x10-9 Nm2 along the proximal-distal axis of the appendage showing a non-monotonous pattern that is not due to the geometry of the fin itself...
December 15, 2017: Journal of Experimental Biology
Ilaria Giovannini, Tiziana Altiero, Roberto Guidetti, Lorena Rebecchi
Since conditions in Continental Antarctica are highly selective and extremely hostile to life, its biota is depauperate, but well adapted to live in this region. Global climate change has the potential to impact Continental Antarctica organisms because of increasing temperatures and ultraviolet radiation. This research evaluates how ongoing climate changes will affect Antarctic species, and if Antarctic organisms will be able to adapt to the new environmental conditions. Tardigrades represent the main terrestrial components of Antarctic meiofauna; therefore the pan-Antarctic tardigrade Acutuncus antarcticus was used as model to predict the fate of Antarctic meiofauna threatened by climate changes...
December 14, 2017: Journal of Experimental Biology
A Sofia D Fernandes, C L Buckley, J E Niven
Wood ants are a model system for studying visual learning and navigation. They can forage for food and navigate to their nests effectively by forming memories of visual features in their surrounding environment. Previous studies of freely behaving ants have revealed many of the behavioural strategies and environmental features necessary for successful navigation. However, little is known about the exact visual properties of the environment that animals learn or the neural mechanisms that allow them to achieve this...
December 8, 2017: Journal of Experimental Biology
Lasse Jakobsen, John Hallam, Cynthia F Moss, Anders Hedenström
All echolocating bats and whales measured to date emit a directional bio-sonar beam that affords them a number of advantages over an omni-directional beam, i.e. reduced clutter, increased source level and inherent directional information. In this study we investigated the importance of a directional sound emission for navigation through echolocation by measuring the sonar beam of brown long-eared bats, Plecotus auritusP. auritus emits sound through the nostrils but has no external appendages to readily facility a directional sound emission as found in most nose emitters...
December 8, 2017: Journal of Experimental Biology
Andrius Pašukonis, Matthias-Claudio Loretto, Walter Hödl
Most animals move in dense habitats where distant landmarks are limited, but how they find their way around remains poorly understood. Poison frogs inhabit the rainforest understory where they shuttle tadpoles from small territories to widespread pools. Recent studies revealed their excellent spatial memory and the ability to home back from several hundred meters. It remains unclear if this homing ability is restricted to the areas that had been previously explored or if it allows the frogs to navigate from areas outside their direct experience...
December 7, 2017: Journal of Experimental Biology
Cornelia W Twining, Peter Lawrence, David W Winkler, Alexander S Flecker, J Thomas Brenna
Food availability and quality are both critical for growing young animals. In nature, swallows (Tachycineta bicolor) and other aerial insectivores feed on both aquatic insects, which are rich in omega-3 highly unsaturated fatty acids (HUFA) and terrestrial insects, which contain considerably lower amounts of omega-3 HUFA. Carnivorous mammals and fishes must obtain omega-3 HUFA from diet, as they have lost the capacity to convert the precursor omega-3 ALA into omega-3 HUFA. Thus, the relative value of aquatic versus terrestrial insects depends not only on the fatty acid composition of the prey, but also upon the capacity of consumers to convert ALA into omega-3 HUFA...
December 7, 2017: Journal of Experimental Biology
Natalie M D'Silva, Michael J O'Donnell
We report measurements of ion transport across the gastric caecum of larvae of Aedes aegypti, a vector of yellow fever that inhabits a variety of aquatic habitats ranging from freshwater to brackish water. We provide the first measurements of the effect of 5-hydroxytryptamine (5-HT) on transepithelial potential (TEP), luminal ion concentrations and electrochemical potentials, as well as basolateral membrane potential and H+, Na+ and K+ fluxes. TEP, basolateral membrane potential, and H+, K+, and Na+ fluxes across the gastric caeca declined within 3-6 mins after isolation of the entire midgut from the larva...
December 7, 2017: Journal of Experimental Biology
Laura E McMillan, Dylan W Miller, Shelley A Adamo
Mounting an immune response consumes resources, which should lead to increased feeding. However, activating the immune system reduces feeding (i.e. illness-induced anorexia) in both vertebrates and invertebrates, suggesting that it may be beneficial. We suggest that illness-induced anorexia may be an adaptive response to conflicts between immune defense and food detoxification. We found that activating an immune response in the caterpillar Manduca sexta increased its susceptibility to the toxin permethrin. Conversely, a sublethal dose of permethrin reduced resistance to the bacterium Serratia marcescens, demonstrating a negative interaction between detoxification and immune defense...
December 7, 2017: Journal of Experimental Biology
Delyle T Polet, Ryan T Schroeder, John E A Bertram
In gravity below Earth normal, a person should be able to take higher leaps in running. We asked ten subjects to run on a treadmill in five levels of simulated reduced gravity and optically tracked center of mass kinematics. Subjects consistently reduced ballistic height compared to running in normal gravity. We explain this trend by considering the vertical takeoff velocity (defined as maximum vertical velocity). Energetically optimal gaits should balance energetic costs of ground-contact collisions (favouring lower takeoff velocity), and step frequency penalties such as leg swing work (favouring higher takeoff velocity, but less so in reduced gravity)...
December 7, 2017: Journal of Experimental Biology
Steven J Newman, Bruce C Jayne
A central issue for understanding locomotion of vertebrates is how muscle activity and movements of their segmented axial structures are coordinated, and snakes have a longitudinal uniformity of body segments and diverse locomotor behaviors that are well suited for studying the neural control of rhythmic axial movements. Unlike all other major modes of snake locomotion, rectilinear locomotion does not involve axial bending, and the mechanisms of propulsion and modulating speed are not well understood. We integrated electromyograms and kinematics of boa constrictors to test Lissmann's decades-old hypotheses of activity of the costocutaneous superior (CCS) and inferior (CCI) muscles and the intrinsic cutaneous interscutalis (IS) muscle during rectilinear locomotion...
December 6, 2017: Journal of Experimental Biology
A A Cassidy, W R Driedzic, D Campos, W Heinrichs-Caldas, V M F Almeida-Val, A L Val, S G Lamarre
The Amazonian cichlid, Astronotus ocellatus, is highly tolerant to hypoxia, and is known to reduce its metabolic rate by reducing the activity of energetically expensive metabolic processes when oxygen is lacking in their environment. Our objectives were to determine how protein metabolism is regulated in A. ocellatus during hypoxia. Fish were exposed to a stepwise decrease in air saturation (100%, 20%, 10% and 5%) for 2 hours at each level, and sampled throughout the experiment. A flooding dose technique using a stable isotope allowed us to observe an overall decrease in protein synthesis during hypoxia in liver, muscle, gill and heart...
December 6, 2017: Journal of Experimental Biology
Jeffrey P Olberding, Jeffrey A Scales, Stephen M Deban
Many animals use elastic-recoil mechanisms to power extreme movements, achieving levels of performance that would not be possible using muscle power alone. Contractile performance of vertebrate muscle depends strongly on temperature, but the release of energy from elastic structures is far less thermally dependent, thus elastic recoil confers thermal robustness to whole-animal performance. Here we explore the role that muscle contractile properties play in the differences in performance and thermal robustness between elastic and non-elastic systems by examining muscle from two species of plethodontid salamanders that use elastically powered tongue projection to capture prey and one that uses non-elastic tongue projection...
December 6, 2017: Journal of Experimental Biology
Eric D Turenne, Jean-Michel Weber
The mobilization of mammalian lipid reserves is strongly stimulated during exercise to reach a maximum at moderate intensities, but the effects of swimming speed on fish lipolysis have never been quantified. Continuous infusion of 2-[3H]glycerol was used to measure Ra glycerol (=rate of appearance of glycerol or lipolytic rate) in rainbow trout kept at rest, or during graded exercise in a swim tunnel up to critical swimming speed (Ucrit). Results show that Ra glycerol is 1.67±0.18 µmol kg-1min-1 in control animals, and remains at a steady level of 1...
December 6, 2017: Journal of Experimental Biology
Long Qing, Hong-Jie Yi, Ye-Wei Wang, Quan Zhou, Dinesh K Ariyadewa, Wei-Gang Xu
Decompression sickness (DCS) occurs when ambient pressure severely reduces during diving and aviation. Hyperbaric oxygen (HBO) pretreatment has been proven to exert beneficial effects on DCS in rats via heat-shock proteins (HSPs). We hypothesize that HBO pretreatment will also reduce DCS via HSPs in swine models. In part 1, six swine were subjected to a session of HBO treatment. HSP 32, 60, 70 and 90 were detected, before and at 6, 12, 18, 24 and 30 h following exposure in lymphocytes. In part 2, another ten swine were randomly assigned into 2 groups, 5 in each...
December 6, 2017: Journal of Experimental Biology
Le My Phuong, Do Thi Thanh Huong, Hans Malte, Jens Randel Nyengaard, Mark Bayley
The air-breathing fish Pangasianodon hypophthalmus has been shown to have highly plastic branchial surfaces whose area (SA) increases with temperature and aquatic hypoxia. This modulation occurs through development of inter-lamellar cell mass (ILCM). Paradoxically, in conditions where this fish has been shown capable of covering its entire aerobic scope from the water phase, it has been shown to have a very small branchial SA. To address this paradox, we measured the SA, harmonic mean diffusion (τh) and calculated the anatomic diffusion factor (ADF) of the branchial and swim bladder surfaces in fish ranging from 3 to 1900 g at 27ᵒC in normoxia...
November 30, 2017: Journal of Experimental Biology
Amy E Maas, Gareth L Lawson, Alexander J Bergan, Ann M Tarrant
Thecosomatous pteropods, a group of aragonite shell-bearing zooplankton, are becoming an important sentinel organism for understanding the influence of ocean acidification on pelagic organisms. These animals show vulnerability to changing carbonate chemistry conditions, are geographically widespread, and are both biogeochemically and trophically important. The objective of this study was to determine how increasing duration and severity of CO2 treatment influence the physiology of the thecosome Limacina retroversa, integrating both gene expression and organism-level (respiration and calcification) metrics...
November 30, 2017: Journal of Experimental Biology
Sergey Snigirov, Sergiy Sylantyev
Benzodiazepines, acting through ionotropic receptor of γ-aminobutyric acid (GABAA receptor, GABAR), were shown to modify feeding behaviour and increase appetite in humans and non-human subjects. However, the cellular and molecular mechanisms which underlie connected short-term behavioural fluctuations are still unclear. In the present study, we used Carassius gibelio (Prussian carp) as a model organism to research the impact of scantily explored benzodiazepine phenazepam (PNZ) on feeding behaviour and the related molecular mechanisms of PNZ action at single-cell and single-receptor levels...
November 30, 2017: Journal of Experimental Biology
David E Cade, Kelly R Barr, John Calambokidis, Ari S Friedlaender, Jeremy A Goldbogen
How fast animals move is critical to understanding their energetic requirements, locomotor capacity, and foraging performance, yet current methods for measuring speed via animal-attached devices are not universally applicable. Here we present and evaluate a new method that relates forward speed to the stochastic motion of biologging devices since tag jiggle, the amplitude of the tag vibrations as measured by high sample rate accelerometers, increases exponentially with increasing speed. We successfully tested this method in a flow tank using two types of biologging devices and tested the method in situ on wild cetaceans spanning ∼3 to >20 m in length using two types of suction cup-attached and two types of dart-attached tag...
November 30, 2017: Journal of Experimental Biology
Henry Youn, Renault David, Colinet Hervé
Crowding is a complex stress that can affect organisms' physiology, especially through decreased food quality and accessibility. Here, we evaluated the effect of larval density on several biological traits of Drosophila melanogaster An increasing gradient, from 1 to 1000 eggs per milliliter of food, was used to characterize life-history traits variations. Crowded conditions resulted in striking decreases of fresh mass (up to six-fold) and viability, as well as delayed development. Next, we assessed heat and cold tolerance in L3 larvae reared at three selected larval densities: low (LD, 5 eggs...
November 30, 2017: Journal of Experimental Biology
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