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Journal of Experimental Biology

Chelsea N Cook, Colin S Brent, Michael D Breed
Biogenic amines regulate the proximate mechanisms underlying most behavior, including those that contribute to the overall success of complex societies. For honey bees, one critical set of behaviors contributing to the welfare of a colony is involved with nest thermoregulation. Worker honeybees cool the colony by performing a fanning behavior, the expression of which is largely influenced by response thresholds modulated by the social environment. Here, we examined how changes in biogenic amines affect this group-performed thermoregulatory fanning behavior in honeybees...
March 17, 2017: Journal of Experimental Biology
David Wilby, Nicholas W Roberts
Oil droplets are spherical organelles found in the cone photoreceptors of vertebrates. They are generally assumed to focus incident light into the outer segment, and thereby improve light catch because of the droplets' spherical lens-like shape. However, using full-wave optical simulations of physiologically realistic cone photoreceptors from birds, frogs and turtles we find that pigmented oil droplets actually drastically reduce the transmission of light into the outer segment integrated across the full visible wavelength range of each species...
March 17, 2017: Journal of Experimental Biology
Kiaran K K Lawson, Mandyam V Srinivasan
Insects are magnificent fliers that are capable of performing many complex tasks such as speed regulation, smooth landings, and collision avoidance, even though their computational abilities are limited by their small brain. To investigate how flying insects respond to changes in wind speed and surrounding optic flow, the open-loop sensorimotor response of female Queensland fruit flies (Bactrocera tryoni) was examined. 136 flies were exposed to stimuli comprising sinusoidally varying optic flow and air flow (simulating forward movement) under tethered conditions in a virtual reality arena...
March 17, 2017: Journal of Experimental Biology
Jeffrey P Olberding, Stephen M Deban
Performance of muscle-powered movements depends on temperature through its effects on muscle contractile properties. In vitro stimulation of Cuban treefrog (Osteopilus septentrionalis) plantaris muscles reveals that interactions between force and temperature affect the mechanical work of muscle. At low temperatures (9 - 17°C), muscle work depends on temperature when shortening at any force, and temperature effects are greater at higher forces. At warmer temperatures (13 - 21°C), muscle work depends on temperature when shortening with intermediate and high forces (≥ 30% P0)...
March 17, 2017: Journal of Experimental Biology
Peter Olsson, Almut Kelber
A ripe strawberry looks red to our eyes in sunlight and in the green light of a forest, although the spectrum of light reflected from its surface differs dramatically. This is caused by two effects, colour constancy, and our ability to learn relative colour cues: the ripe strawberry remains relatively "redder" than an unripe green strawberry. While colour constancy - the ability to recognize colours in shifted illumination - has been studied in many animals, the use of relative colour cues is investigated more rarely...
March 16, 2017: Journal of Experimental Biology
Carol I Miles, Brianna E Allison, Michael J Losinger, Quang T Su, Ronald N Miles
This study is a physiological, anatomical, and biophysical analysis of how plant-borne vibrational signals are produced by the treehopper Umbonia crassicornis During courtship, males and females engage in a vibrational duet, with each producing a characteristic call. For males, this consists of a frequency-modulated tonal signal which is accompanied by rhythmic broad-band clicks. While previous studies described these complex signals in detail, little is known about how they are produced. By combining video recordings, electromyograms, dissections and mechanical modelling, we describe the mechanism by which the male produces his courtship signal...
March 16, 2017: Journal of Experimental Biology
Laura K Elmer, Constance M O'Connor, David P Philipp, Glen Van Der Kraak, Kathleen M Gilmour, William G Willmore, Brandon L Barthel, Steven J Cooke
Physiologically, oxidative stress is considered a homeostatic imbalance between reactive oxygen species production and absorption. From an ecological perspective, oxidative stress may serve as an important constraint to life history traits such as lifespan, reproduction, and the immune system, and is gaining interest as a potential mechanism underlying life history trade-offs. Of late, there has been much interest in understanding the role of oxidative stress in the ecology of wild animals, particularly during challenging periods such as reproduction...
March 16, 2017: Journal of Experimental Biology
José L Zambonino-Infante, David Mazurais, A Servili, C Cahu, G Vanderplancke, N Le Bayon, C Huelvan, Guy Claireaux
Ocean warming, eutrophication and consequent decrease in oxygen lead to smaller average fish size. Although such responses are well-known in an evolutionary context, involving multiple generations, it appears to be incompatible with current rapid environmental change. Rather, phenotypic plasticity could provide a means for marine fish to cope with rapid environmental changes. However, little is known about the mechanisms underlying plastic responses to environmental conditions that favour small phenotypes.Our aim was to investigate how and why European sea bass that had experienced a short episode of moderate hypoxia during their larval stage subsequently exhibited a growth depression at the juvenile stage compared to the control group...
March 16, 2017: Journal of Experimental Biology
Antoine Stier, Andréaz Dupoué, Damien Picard, Frédéric Angelier, François Brischoux, Olivier Lourdais
The physiological mechanisms underlying the 'cost of reproduction' remain under debate, though oxidative stress has emerged as a potential candidate. The 'oxidative cost of reproduction' has received considerable attention with regards to food and antioxidant availability, however the limitation of water availability has thus far been neglected. In this study we experimentally examined the combined effect of pregnancy and water-deprivation on oxidative status in a viviparous snake (Vipera aspis), a species naturally exposed to periods of water and food deprivation...
March 14, 2017: Journal of Experimental Biology
Christopher Thomas Richards, Laura Beatriz Porro, Amber Jade Collings
The kinematic flexibility of frog hindlimbs enables multiple locomotor modes within a single species. Prior work has extensively explored maximum performance capacity in frogs; however, the mechanisms by which anurans modulate performance within locomotor modes remain unclear. We explored how Kassina maculata, a species known for both running and jumping abilities, modulates takeoff angle from horizontal to nearly vertical. Specifically, how do 3D motions of leg segments coordinate to move the center of mass (COM) upwards and forwards? How do joint rotations modulate jump angle? High-speed video was used to quantify 3D joint angles and their respective rotation axis vectors...
March 8, 2017: Journal of Experimental Biology
Stephanie G Gardner, Jean-Baptiste Raina, Peter J Ralph, Katherina Petrou
Coral bleaching is intensifying with global climate change. While the causes for these catastrophic events are well understood, the cellular mechanism that triggers bleaching is not well established. Our understanding of coral bleaching processes is hindered by the lack of robust methods for studying interactions between host and symbiont at the single-cell level. Here we exposed coral explants to acute thermal stress and measured oxidative stress, more specifically, reactive oxygen species (ROS), in individual symbiont cells...
March 8, 2017: Journal of Experimental Biology
Laura B Porro, Amber J Collings, Enrico A Eberhard, Kyle P Chadwick, Christopher T Richards
Although the red-legged running frog Kassina maculata is secondarily a walker/runner, it retains the capacity for multiple locomotor modes, including jumping at a wide range of angles (nearly 70°). Using simultaneous hind limb kinematics and single-foot ground reaction forces, we performed inverse dynamics analyses to calculate moment arms and torques about the hind limb joints during jumping at different angles in K. maculata. We show that forward thrust is generated primarily at the hip and ankle, while body elevation is primarily driven by the ankle...
March 8, 2017: Journal of Experimental Biology
Simon Wilshin, Michelle A Reeve, G Clark Haynes, Shai Revzen, Daniel E Koditschek, Andrew J Spence
Legged animals utilize gait selection to move effectively and must re-cover from environmental perturbations. We show that on rough terrain domestic dogs, Canis lupus familiaris, spend more time in longitudinal quasi-statically stable patterns of movement. Here longitudinal refers to the rostro-caudal, axis. We used an existing model in the literature to quantify the longitudinal quasi-static stability of gaits neighbouring the walk, and found that trot-like gaits are more stable. We thus hypothesized that when perturbed, the rate of return to a stable gait would depend on the direction of perturbation, such that perturbations towards less quasi-statically stable patterns of movement would be more rapid than those towards more stable patterns of movement...
March 6, 2017: Journal of Experimental Biology
Olivia Hicks, Sarah Burthe, Francis Daunt, Adam Butler, Charles Bishop, Jonathan A Green
Two main techniques have dominated the field of ecological energetics, the heart-rate and doubly labelled water methods. Although well established, they are not without their weaknesses, namely expense, intrusiveness and lack of temporal resolution. A new technique has been developed using accelerometers; it uses the Overall Dynamic Body Acceleration (ODBA) of an animal as a calibrated proxy for energy expenditure. This method provides high resolution data without the need for surgery. Significant relationships exist between rate of oxygen consumption (V̇o2) and ODBA in controlled conditions across a number of taxa; however, it is not known whether ODBA represents a robust proxy for energy expenditure consistently in all natural behaviours and there have been specific questions over its validity during diving, in diving endotherms...
March 3, 2017: Journal of Experimental Biology
Dieter Wicher, Satoshi Morinaga, Lorena Halty-deLeon, Nico Funk, Bill Hansson, Kazushige Touhara, Monika Stengl
Manduca sexta females attract their mates with the release of a species-specific sex-pheromone blend with bombykal (E,Z)-10,12-hexadcadienal and (E,E,Z)-10,12,14-hexadecatrienal being the two major components. Here, we searched for the hawkmoth bombykal receptor in heterologous expression systems. The putative pheromone receptor MsexOr1 co-expressed with MsexOrco in Xenopus oocytes elicited dose-dependent inward currents upon bombykal application (10 - 300 µM), and coexpressed in HEK293 and CHO cells caused bombykal-dependent rises in the intracellular free Ca(2+) concentration...
March 2, 2017: Journal of Experimental Biology
N Traylor-Knowles, N H Rose, S R Palumbi
Previous transcriptional studies in heat stressed corals have shown that many genes are responsive to generalized heat stress whereas the expression patterns of specific gene networks after heat stress show strong correlations with variation in bleaching outcomes. However, where these specific genes are expressed is unknown. Here we employed in situ hybridization to identify patterns of spatial gene expression of genes previously predicted to be involved in general stress response and bleaching. We found that Tumor Necrosis Factor Receptors (TNFRs), known to be strong responders to heat stress, were not expressed in gastrodermal symbiont-containing cells but were widely expressed in specific cells of the epidermal layer...
March 2, 2017: Journal of Experimental Biology
Kay Lammers, Bettina Abeln, Mirko Hüsken, Christine Lehmacher, Olympia Ekaterini Psathaki, Esther Alcorta, Heiko Meyer, Achim Paululat
Drosophila harbors a simple tubular heart that ensures hemolymph circulation within the body. The heart is built by a few different cell types, including cardiomyocytes that define the luminal heart channel and ostia cells that constitute openings in the heart wall allowing hemolymph to enter the heart chamber. Regulation of flow directionality within a tube, such as blood flow in arteries or insect hemolymph within the heart lumen, requires a dedicated gate, valve, or flap-like structure that prevents backflow of fluids...
March 2, 2017: Journal of Experimental Biology
Sandya Surendran, Sebastian Hückesfeld, Benjamin Wäschle, Michael J Pankratz
Recognizing a deadly pathogen and generating an appropriate immune reaction is essential for any organism to survive in its natural habitat. Unlike vertebrates and higher primates, invertebrates depend solely on the innate immune system to defend themselves from an attacking pathogen. In this study, we report a behavioral defense strategy observed in Drosophila larvae that help them escape and limit an otherwise lethal infection. A bacterial infection in the gut is sensed by the larval central nervous system which generates an alteration in its food preference, leading them to stop feeding and move away from the infectious food source...
March 2, 2017: Journal of Experimental Biology
John Davenport
Leatherback turtles (Dermochelys coriacea) are capital breeders that accumulate blubber (33 kJ g wet mass(-1)) by hyperphagia on a gelatinous diet at high latitudes; they breed in the tropics. A jellyfish diet is energy-poor (0.1-0.2 kJ g wet mass(-1)), so leatherbacks must ingest large quantities. Two published estimates of feeding rate (50% body mass d(-1) (on Rhizostoma pulmo), 73% body mass d(-1) (on Cyanea capillata)) have been criticised as too high. Jellyfish have high salt and water contents that must be removed to access organic material and energy...
February 24, 2017: Journal of Experimental Biology
Tom Retzke, Michael Thoma, Bill S Hansson, Markus Knaden
The genetic toolbox in Drosophila offers a multitude of different effector constructs to silence neurons and neuron populations. In this study we investigated the potencies of several effector genes - when expressed in olfactory sensory neurons (OSNs) - to abolish odor-guided behavior in three different bioassays. We find that two of the tested effectors (tetanus toxin and Kir2.1) are capable of mimicking the Orco mutant phenotype in all of our behavioral paradigms. In both cases the effectiveness depended on effector expression levels as full suppression of odor-guided behavior was observed only in flies homozygous for both Gal4-driver and UAS-effector constructs...
February 24, 2017: Journal of Experimental Biology
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