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Journal of Experimental Biology

Jason B Ramsay, Cheryl D Wilga
Suction feeding in teleost fish is a power dependant behavior, requiring rapid and forceful expansion of the orobranchial cavity by the hypobranchial and trunk muscles. To increase power production for expansion, many species employ in-series tendons and catch mechanisms to store and release elastic strain energy. Suction feeding sharks such as Chiloscyllium plagiosum lack large in-series tendons on the hypobranchials, yet two of the hypobranchials, the coracohyoideus and coracoarcualis (CH, CA; hyoid depressors), are arranged in-series, and run deep and parallel to a third muscle, the coracomandibularis (CM, jaw depressor)...
August 14, 2017: Journal of Experimental Biology
Christopher J Mayerl, Richard W Blob
Turtles are an iconic lineage in studies of animal locomotion, typifying the use of slow, alternating footfalls during walking. Alternating movements of contralateral limbs are also typical during swimming gaits for most freshwater turtles. Here, we report a novel gait in turtles, in which the pleurodire Emydura subglobosa swims using a bounding gait that coordinates bilateral protraction of both forelimbs with bilateral retraction of both hindlimbs. Use of this bounding gait is correlated with increased limb excursion and decreased stride frequency, but not increased velocity when compared to standard swimming strokes...
August 14, 2017: Journal of Experimental Biology
Marianna Pauletto, Amélie Segarra, Caroline Montagnani, Virgile Quillien, Nicole Faury, Jacqueline Le Grand, Philippe Miner, Bruno Petton, Yannick Labreuche, Elodie Fleury, Caroline Fabioux, Luca Bargelloni, Tristan Renault, Arnaud Huvet
Double stranded RNA-mediated genetic interference (RNAi) is a widely used reverse genetic tool for determining the loss-of-function phenotype of a gene. Here, the possible induction of an immune response by long dsRNA was tested in a marine bivalve, i.e. Crassostrea gigas, as well as the specific role of the subunit 2 of the nuclear factor κB inhibitor (IκB2). This gene is a candidate of particular interest for functional investigations in the context of massive mortality oyster events as Cg-IκB2 mRNA levels exhibited significant variation depending on the amount of ostreid herpesvirus 1 (OsHV-1) DNA detected...
August 10, 2017: Journal of Experimental Biology
Dennis Kolosov, Phuong Bui, Andrew Donini, Mike P Wilkie, Scott P Kelly
This study reports on tight junction-associated MARVEL proteins of larval sea lamprey (Petromyzon marinus) and their potential role in ammocoete osmoregulation. Two Occludin isoforms (designated Ocln and Ocln-a) and a tricellulin (Tric) were identified. Transcripts encoding ocln, ocln-a, and tric were broadly expressed in larval lamprey, with greatest abundance of ocln in gut, liver and kidney, ocln-a in the gill and skin, and tric in the kidney. Ocln and Ocln-a resolved as ∼63 kDa and ∼35 kDa MW proteins respectively while Tric resolved as a ∼50 kDa protein...
August 10, 2017: Journal of Experimental Biology
Jingwei Liu, Karine Dias, Elisabeth Plagnes-Juan, Vincent Véron, Stéphane Panserat, Lucie Marandel
Environmental conditions experienced during early life play an important role in the long-term metabolic status of individuals. The present study investigated whether early hypoxia exposure (24 h, 2.5 mg·l(-1), 20% dissolved O2) during embryo stage alone (hypoxic history) or combined with a 5-day high carbohydrate diet (60%) stimulus at first-feeding (high carbohydrate diet history) can affect the glucose metabolism later in life, i.e. in fish juveniles. After 19 weeks of growth, we observed a decrease in final body weight in fish with a high carbohydrate diet history...
August 10, 2017: Journal of Experimental Biology
Cassandra M Donatelli, A P Summers, E D Tytell
Fish live in a complex world and must actively adapt their swimming behavior to a range of environments. Most studies of swimming kinematics focus on two-dimensional properties related to the bending wave that passes from head to tail. However, fish also twist their bodies in 3D around their longitudinal axis as the bending wave passes down the body. We measured and characterized this movement, which we call 'wobble', in six species of elongate fishes (Anoplarchus insignis, Xiphister mucosus, Lumpenus sagitta, Pholis laeta, Apodichthys flavidus, and Ronquilus jordani) from three different habitats (intertidal, nearshore, and subtidal) using custom video analysis software...
August 9, 2017: Journal of Experimental Biology
Alexa Tullis, Corinne H T Straube
Models proposed to explain sexually selected structures assume that these traits are costly. However, studies investigating the impact of such structures on locomotory costs have produced inconsistent results. Male fiddler crabs possess a large sexually selected claw and are ideal for assessing the impact of a sexually selected trait on the cost of locomotion. Here, we measure the energy expenditure of clawed, declawed, and artificially loaded crabs during sustained exercise by measuring oxygen consumption and blood lactate levels...
August 9, 2017: Journal of Experimental Biology
María José Fernández, M Ellis Driver, Tyson L Hedrick
Flight performance is fundamental to the fitness of flying organisms. Whilst airborne, flying organisms face unavoidable wing wear and wing area loss. Many studies have tried to quantify consequences of wing area loss to flight performance with varied results; suggesting that not all types of damage are equal and different species may have different means compensating for some forms of wing damage with little to no cost. Here, we investigate the cost of control during hovering flight with damaged wings, specifically wings with asymmetric and symmetric reductions in area, by measuring maximum load lifting capacity and the metabolic power of hovering flight in hawkmoths (Manduca sexta)...
August 9, 2017: Journal of Experimental Biology
Stephen M Deban, Jason C Richardson
Desmognathine salamanders possess unusual morphological features for lungless salamanders that have been proposed to aid in burrowing and biting, including well-ossified jaws and skull and a pair of robust ligaments connecting the atlas to the mandible. We evaluated the function of these and other peculiar desmognathine cranial features in biting by examining the morphology, mechanics, and in-vivo biting performance of the large Desmognathus quadramaculatus We estimated theoretical biting force using a novel geometric method that we describe...
August 7, 2017: Journal of Experimental Biology
Ryan M Jorgensen, Bruce C Jayne
The need for long-axis support is widespread among non-aquatic vertebrates and may be particularly acute for arboreal snakes when many vertebrae span sizable gaps between branches with diverse orientations. Hence, we used brown tree snakes (Boiga irregularis) bridging gaps to test how three-dimensional trajectories affected muscle activity and whether these motor patterns differed from those for the locomotion of terrestrial snakes and movements of other vertebrates. We used five trajectories: pitch angles of 90, 0 and -90 deg (downward) when yaw=0, and 90 deg yaw angles to the left and right when pitch=0 deg...
August 7, 2017: Journal of Experimental Biology
Trina Y Du, Emily M Standen
Muscle fiber types in the pectoral fins of fishes have rarely been examined, despite their morphological and functional diversity. Here we describe the distribution of fast and slow muscle fibers in the pectoral fins of Polypterus senegalus, an amphibious, basal actinopterygian. Each of the four muscle groups examined using mATPase staining show distinct fiber type regionalization. Comparison between fish raised in aquatic and terrestrial environments reveals terrestrially-reared fish possess 28% more fast muscle compared to aquatically-reared fish...
August 7, 2017: Journal of Experimental Biology
Fábio Pértille, Margrethe Brantsæter, Janicke Nordgreen, Luiz Lehmann Coutinho, Andrew M Janczak, Per Jensen, Carlos Guerrero-Bosagna
Stressful conditions are common in the environment where production animals are reared. Stress in animals is usually determined by the levels of stress-related hormones. A big challenge, however, is in determining the history of exposure of an organism to stress, because the release of stress hormones can show an acute (and recent) but not a sustained exposure to stress. Epigenetic tools provide an alternative option to evaluate past exposure to long-term stress. Chickens provide a unique model to study stress effects in the epigenome of red blood cells (RBC), a cell type of easy access and nucleated in birds...
August 7, 2017: Journal of Experimental Biology
Takafumi Furuyama, Kohta I Kobayasi, Hiroshi Riquimaroux
The vocalizations of primates contain information about the speaker individuality. Many primates, including humans, are able to distinguish conspecifics based solely on vocalizations. The purpose of this study was to investigate the acoustic characteristics used by Japanese macaques in individual vocal discrimination. Furthermore, we tested human subjects using monkey vocalizations to evaluate species specificity with respect to such discriminations. Two monkeys and five humans were trained to discriminate the coo calls of two unfamiliar monkeys...
August 4, 2017: Journal of Experimental Biology
Harvey B Lillywhite
An important question related to survival of dehydrating animals is whether feeding provides a net gain of water - contributing postprandial free water and metabolic water - or, alternatively, whether digestion and assimilation of ingested food incur a net loss of water because of requirements for digestion and the excretion of resulting metabolic wastes. Here I address the question whether voluntary drinking increases or decreases following the ingestion of food. Increased postprandial drinking implies that food consumption increases rather than decreases the requirement for free water, whereas decreased postprandial drinking suggests there is a net profit of water from food...
August 4, 2017: Journal of Experimental Biology
William A Talbot, Todd J McWhorter, Alexander R Gerson, Andrew E McKechnie, Blair O Wolf
Birds in the order Caprimulgiformes (nightjars and allies) have a remarkable capacity for thermoregulation over a wide range of environmental temperatures, exhibiting pronounced heterothermy in cool conditions and extreme heat tolerance at high environmental temperatures. We measured thermoregulatory responses to acute heat stress in three species of caprimulgiforms that nest in areas of extreme heat and aridity, the common poorwill (Phalaenoptilus nuttallii: Caprimulgidae) and lesser nighthawk (Chordeiles acutipennis: Caprimulgidae) in the Sonoran Desert of Arizona, and the Australian owlet-nightjar (Aegotheles cristatus: Aegothelidae) in the mallee woodlands of South Australia...
July 31, 2017: Journal of Experimental Biology
Lidiya Misyura, Gil Y Yerushalmi, Andrew Donini
The mosquito, Aedes aegypti, is the primary vector for arboviral diseases such as Zika fever, dengue fever, chikungunya, and yellow fever. The larvae reside in hypo-osmotic freshwater habitats, where they face dilution of their body fluids from osmotic influx of water. The Malpighian tubules help maintain ionic and osmotic homeostasis by removing excess water from the hemolymph, but the transcellular pathway for this movement remains unresolved. Aquaporins are transmembrane channels thought to permit transcellular transport of water from the hemolymph into the Malpighian tubule lumen...
July 31, 2017: Journal of Experimental Biology
Tristan J McArley, Anthony J R Hickey, Neill A Herbert
Intertidal fish species face gradual chronic changes in temperature and greater extremes of acute thermal exposure through climate induced warming. As sea temperatures rise it has been proposed that whole animal performance will be impaired through oxygen and capacity limited thermal tolerance (OCLTT, reduced aerobic metabolic scope-MS) and, on acute exposure to high temperatures, thermal safety margins may be reduced due to constrained acclimation capacity of upper thermal limits. Using the New Zealand triplefin fish (Forsterygion lapillum), this study addressed how performance in terms of growth and metabolism (MS) and upper thermal tolerance limits would be affected by chronic exposure to elevated temperature...
July 31, 2017: Journal of Experimental Biology
Yao Li, Feng Cao, Tat Thang Vo Doan, Hirotaka Sato
In flight, many insects fold their forelegs tightly close to the body, which naturally decreases drag or air resistance. However, flying beetles stretch out their forelegs for some reason. Why do they adopt this posture in flight? Here, we show the role of the stretched forelegs in beetle Mecynorrhina torquata flight. Using leg motion tracking and electromyography in flight, we found that the forelegs were voluntarily swung clockwise in yaw to induce counter-clockwise rotation of the body for turning left, and vice versa...
July 28, 2017: Journal of Experimental Biology
Timothy D Clark, Dominique G Roche, Sandra A Binning, Ben Speers-Roesch, Josefin Sundin
Theoretical models predict that ocean acidification, caused by increased dissolved CO2, will reduce the maximum thermal limits of fishes, thereby increasing their vulnerability to rising ocean temperatures and transient heatwaves. Here, we test this prediction in three species of damselfishes on the Great Barrier Reef, Australia. Maximum thermal limits were quantified using critical thermal maxima (CTmax) tests following acclimation to either present-day or end-of-century levels of CO2 for coral reef environments (∼500 or ∼1,000 µatm, respectively)...
July 28, 2017: Journal of Experimental Biology
Maria Wilson, Anton D Tucker, Kristian Beedholm, David A Mann
To improve conservation strategies for threatened sea turtles more knowledge on their ecology, behavior, and how they cope with severe and changing weather conditions is needed. Satellite and animal motion datalogging tags were used to study the inter-nesting behavior of two female loggerhead turtles in the Gulf of Mexico, which regularly has hurricanes and tropical storms during nesting season. We contrast the behavioral patterns and swimming energetics of two turtles, the first tracked in calm weather and a second tracked before, during, and after a tropical storm...
July 28, 2017: Journal of Experimental Biology
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