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Journal of Experimental Biology

Ravi Theja V Chintapalli, Julián F Hillyer
The wings of insects are composed of membranes supported by interconnected veins. Within these veins are epithelial cells, nerves and tracheae, and their maintenance requires the flow of hemolymph. For this purpose, insects employ accessory pulsatile organs (auxiliary hearts) that circulate hemolymph throughout the wings. Here, we used correlative approaches to determine the functional mechanics of hemolymph circulation in the wings of the malaria mosquito, Anopheles gambiae Examination of sectioned tissues and intravital videos showed that the wing heart is located underneath the scutellum and is separate from the dorsal vessel...
October 14, 2016: Journal of Experimental Biology
Alexandra Jochmans-Lemoine, Manju Shahare, Jorge Soliz, Vincent Joseph
We previously reported that rats and mice that have been raised for more than 30 generations in La Paz, Bolivia (3600m), display divergent physiological responses to high altitude (HA), including improved respiratory and metabolic control in mice. In the present study we asked whether these traits would also be present in response to hypoxia at sea level (SL). To answer this question, we exposed rats (SD) and mice (FVB) to normoxia (21% O2) or hypoxia (15 and 12% O2) for 6 hours and measured ventilation and metabolic rate (whole body plethysmography), and expression of the transcription factor HIF-1α (ELISA and Mass Spectrometry) and other proteins whose expression are regulated by hypoxia (Glucose Transporter 1, Pyruvate Dehydrogenase Kinase 1, and Angiopoietin 2 - Mass Spectrometry) in the brainstem...
October 14, 2016: Journal of Experimental Biology
David Taylor
Experiments and observations were carried out to investigate the response to impact of the shells of the limpet Patella vulgata. Dropped-weight impact tests were conducted, creating damage which usually took the form of a hole in the shell's apex. Similar damage was found to occur naturally, presumably as a result of stones propelled by the sea during storms. Apex holes were usually fatal, but small holes were sometimes repaired, and the repaired shell was as strong as the original, undamaged shell.The impact strength (energy to failure) of shells tested in situ was found to be 3...
October 14, 2016: Journal of Experimental Biology
Astra S Bryant, Anna K Greenwood, Scott A Juntti, Allie E Byrne, Russell D Fernald
Dopamine regulates reproduction in part by modulating neuronal activity within the hypothalamic-pituitary-gonadal (HPG) axis. Previous studies suggested numerous mechanisms by which dopamine exerts inhibitory control over the HPG axis, ultimately changing the levels of sex steroids that regulate reproductive behaviors. However, it is not known whether these mechanisms are conserved across vertebrate species. In particular, it is unknown whether mechanisms underlying dopaminergic control of reproduction are shared between mammals and teleost fish...
October 14, 2016: Journal of Experimental Biology
Marie N Hansen, Jon O Lundberg, Mariacristina Filice, Angela Fago, Nanna M G Christensen, Frank B Jensen
In mammals, treatment with low doses of nitrite have cytoprotective effects in ischemia/reperfusion events, due to nitric oxide formation and S-nitrosation of proteins. Interestingly, anoxia-tolerant lower vertebrates possess an intrinsic ability to increase intracellular [nitrite] during anoxia in tissues with high myoglobin and mitochondria contents, such as the heart. Here we test the hypothesis that red and white skeletal muscle develops different nitrite levels in crucian carp exposed to deep hypoxia and whether this correlates with myoglobin concentration...
October 14, 2016: Journal of Experimental Biology
A D Vaudo, D Stabler, H M Patch, J F Tooker, C M Grozinger, G A Wright
Bee population declines are linked to reduction of nutritional resources due to land-use intensification, yet we know little about the specific nutritional needs of many bee species. Pollen provides bees their primary source of protein and lipids, but nutritional quality varies widely among host-plant species. Therefore, bees may be adapted to assess resource quality and adjust their foraging behavior to balance nutrition from multiple food sources. We tested the ability of two bumble bee species, Bombus terrestris and B...
October 14, 2016: Journal of Experimental Biology
Volker Berendes, Sasha N Zill, Ansgar Büschges, Till Bockemühl
In insects, the coordinated motor output required for walking is based on the interaction between local pattern-generating networks providing basic rhythmicity and leg sensory signals which modulate this output on a cycle-to-cycle basis. How this interplay changes speed-dependently and thereby gives rise to the different coordination patterns observed at different speeds is understood insufficiently. Here, we used amputation to reduce sensory signals in single legs and decouple them mechanically during walking in Drosophila...
September 29, 2016: Journal of Experimental Biology
J Ryan Shipley, Polly Campbell, Jeremy B Searle, Bret Pasch
Aerobic respiration is a fundamental physiological trait dependent on coordinated interactions between gene products of the mitochondrial and nuclear genomes. Mitonuclear mismatch in interspecific hybrids may contribute to reproductive isolation by inducing reduced viability (or even complete inviability) due to increased metabolic costs. However, few studies have tested for effects of mitonuclear mismatch on respiration at the whole organism level. We explored how hybridization affects metabolic rates in closely related species of grasshopper mice (genus Onychomys) to better understand the role of metabolic costs in reproductive isolation...
September 29, 2016: Journal of Experimental Biology
Zachary C DeVries, Russell Mick, Coby Schal
Host location in bed bugs is poorly understood. Of the primary host-associated cues known to attract bed bugs - CO2, odors, heat - heat has received little attention as an independent stimulus. We evaluated the effects of target temperatures ranging from 23-48°C on bed bug activation, orientation, and feeding. Activation and orientation responses were assessed using a heated target in a circular arena. All targets heated above ambient temperature activated bed bugs (initiated movement) and elicited oriented movement toward the target, with higher temperatures generally resulting in faster activation and orientation...
September 29, 2016: Journal of Experimental Biology
Benjamin J Knörlein, David B Baier, Stephen M Gatesy, J D Laurence-Chasen, Elizabeth L Brainerd
Marker-based XROMM requires software tools for: 1) correcting fluoroscope distortion; 2) calibrating X-ray cameras; 3) tracking radio-opaque markers; and 4) calculating rigid body motion. In this paper we describe and validate XMALab, a new open-source software package for marker-based XROMM (C++ source and compiled versions on Bitbucket). Most marker-based XROMM studies to date have used XrayProject in MATLAB. XrayProject can produce results with excellent accuracy and precision, but it is somewhat cumbersome to use and requires a MATLAB license...
September 21, 2016: Journal of Experimental Biology
Anna V Ivanina, Inna M Sokolova
Oxygen fluctuations represent a common stressor in estuarine and intertidal environments and can compromise the mitochondrial integrity and function in marine organisms. We assessed the role of mitochondrial protection mechanisms (ATP-dependent and ATP-independent mitochondrial proteases, and antioxidants) in tolerance to intermittent hypoxia or anoxia in three species of marine bivalves: the hypoxia tolerant hard clams (Mercenaria mercenaria) and oysters (Crassostrea virginica), and a hypoxia-sensitive subtidal scallop (Argopecten irradians)...
September 21, 2016: Journal of Experimental Biology
Julia Machon, Juliette Ravaux, Magali Zbinden, Philippe Lucas
Antennular chemoreception in aquatic decapods is well-studied via the recording of single chemoreceptor neuron activity in the antennule, but global responses of the antennule (or antennae in insects) by electroantennography (EAG) was so far mainly restricted to aerial conditions. We present here a well-established underwater EAG method to record the global antennule activity in the marine shrimp Palaemon elegans in natural (aqueous) conditions. EAG responses to food extracts, recorded as net positive deviations of the baseline, are reproducible, dose-dependent and exhibit sensory adaptation...
September 16, 2016: Journal of Experimental Biology
Emily A Mistick, Andrew M Mountcastle, Stacey A Combes
Insect wings do not contain intrinsic musculature to change shape, but rather bend and twist passively during flight. Some insect wings feature flexible joints along their veins that contain patches of resilin, a rubber-like protein. Bumblebee wings exhibit a central resilin joint (1m-cu) that has previously been shown to improve vertical force production during hovering flight. In this study, we artificially stiffened bumblebee (Bombus impatiens) wings in vivo by applying a micro-splint to the 1m-cu joint, and measured the consequences for body stability during forward flight in both laminar and turbulent airflow...
September 16, 2016: Journal of Experimental Biology
Lucas A Zena, Glauber S F da Silva, Luciane H Gargaglioni, Kênia C Bícego
Anurans regulate short-term oscillations in blood pressure through changes in heart rate (fH), vascular resistance and lymph hearts frequency. Lung ventilation in anurans is linked to blood volume homeostasis by facilitating lymph return to the cardiovascular system. We hypothesized that the arterial baroreflex modulates pulmonary ventilation in the Cururu toad Rhinella schneideri, and that this relationship is temperature-dependent. Pharmacologically induced hypotension (sodium nitroprusside) and hypertension (phenylephrine) increased ventilation (25°C: 248...
September 15, 2016: Journal of Experimental Biology
Shelley Anne Adamo, Ilya Kovalko, Kurtis F Turnbull, Russell H Easy, Carol I Miles
Some parasites alter the behaviour of their hosts. The larvae of the parasitic wasp Cotesia congregata develop within the body of the caterpillar Manduca sexta During the initial phase of wasp development, the host's behaviour remains unchanged. However, once the wasps begin to scrape their way out of the caterpillar, the caterpillar host stops feeding and moving spontaneously. We found that the caterpillar also temporarily lost sensation around the exit hole created by each emerging wasp. However, the caterpillars regained responsiveness to nociception in those areas within 1 day...
September 15, 2016: Journal of Experimental Biology
François Therrien, Annie Quinney, Kohei Tanaka, Darla K Zelenitsky
Mandibular force profiles apply the principles of beam theory to identify mandibular biomechanical properties that reflect the bite force and feeding strategies of extant and extinct predators. While this method uses external dimensions of the mandibular corpus to determine its biomechanical properties, more accurate results could potentially be obtained by quantifying its internal cortical bone distribution. To test this possibility, mandibular force profiles were calculated using both external mandibular dimensions ('solid mandible model') and quantification of internal bone distribution of the mandibular corpus obtained from CT scans ('hollow mandible model') for five carnivorans (Canis lupus, Crocuta crocuta, Panthera leo, Neofelis nebulosa, and the extinct Canis dirus)...
September 15, 2016: Journal of Experimental Biology
Gabriel Cerqueira Alves Costa, Adriana Coelho Soares, Marcos Horácio Pereira, Nelder Figueiredo Gontijo, Maurício Roberto Viana Sant'Anna, Ricardo Nascimento Araujo
Ornithodoros rostratus is an argasid tick and its importance is based on its hematophagy and the resulting transmission of pathogens such as Rickettsia rickettsii and Coxiella burnetii unto its vertebrate hosts. In the face of a lack of physiological studies related to hematophagy in argasid ticks, this paper aims to identify and characterize the events that occur throughout the feeding by O. rostratus on live hosts. Electrical signals and alterations on the feeding site were monitored using intravital microscopy and electromyography...
September 13, 2016: Journal of Experimental Biology
Neal J Dawson, Catherine M Ivy, Luis Alza, Rebecca Cheek, Julia M York, Beverly Chua, William K Milsom, Kevin G McCracken, Graham R Scott
Torrent ducks inhabit fast-flowing rivers in the Andes from sea level to altitudes up to 4,500 m. We examined the mitochondrial physiology that facilitates performance over this altitudinal cline by comparing the respiratory capacities of permeabilized fibers, the activities of 16 key metabolic enzymes, and the myoglobin content in muscles between high- and low-altitude populations of this species. Mitochondrial respiratory capacities (assessed using substrates of mitochondrial complexes I, II, and/or IV) were higher in highland ducks in the gastrocnemius muscle - the primary muscle used to support swimming and diving - but were similar between populations in the pectoralis muscle and the left ventricle...
September 12, 2016: Journal of Experimental Biology
Cassondra L Williams, James W Hicks
Mammals and birds maintain high arterial partial pressure of oxygen (P O2) values in order to preserve near complete hemoglobin (Hb) oxygen (O2) saturation. In diving mammals and birds, arterial O2 follows a primarily monotonic decline and then recovery quickly after dives. In laboratory studies of submerged freshwater turtles, arterial O2 depletion typically follows a similar pattern. However, in these studies, turtles were disturbed, frequently tethered to external equipment and either confined to small tanks or breathing holes...
September 12, 2016: Journal of Experimental Biology
Gloria Ruiz-Guzmán, José Ramos-Castañeda, Angélica Hernández-Quintero, Jorge Contreras-Garduño
Parasites can be transmitted either or both, vertically or horizontally, but the costs or benefits for the host due to infection have only been tested after horizontal transmission. Here as far as we know, is reported for the first time the survival, reproduction and infection of Aedes aegypti during vertical and horizontal transmission of Dengue virus 2 (DENV-2). Females infected horizontally produced more eggs with a sex ratio skewed to males compared to uninfected controls. However, there was a not significant difference on the number of emerging adults or mothers survival...
September 12, 2016: Journal of Experimental Biology
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