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Journal of Experimental Biology

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https://www.readbyqxmd.com/read/28526686/amazon-river-dolphins-inia-geoffrensis-modify-biosonar-output-level-and-directivity-during-prey-interception-in-the-wild
#1
Michael Ladegaard, Frants Havmand Jensen, Kristian Beedholm, Vera Maria Ferreira da Silva, Peter Teglberg Madsen
Toothed whales have evolved to live in extremely different habitats and yet they all rely strongly on echolocation for finding and catching prey. Such biosonar based foraging involves distinct phases of searching for, approaching, and capturing prey, where echolocating animals gradually adjust sonar output to actively shape the flow of sensory information. Measuring those outputs in absolute levels requires hydrophone arrays centred on the biosonar beam axis, but this has never been done for wild toothed whales approaching and capturing prey...
May 19, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28526685/differences-in-molecular-mechanisms-of-k-clearance-in-the-auditory-sensory-epithelium-of-birds-and-mammals
#2
Viviane Wilms, Chris Söffgen, Hans Gerd Nothwang
Mechanoelectrical transduction in the vertebrate inner ear is a highly conserved mechanism depending on K(+) influx into hair cells. Here, we investigated the molecular underpinnings of subsequent K(+) recycling in the chicken basilar papilla and compared it with those in the mammalian auditory sensory epithelium. Like mammals, the avian auditory hair cell uses KCNQ4, KCNMA1, and KCNMB1 as K(+) efflux systems. Expression of KCNQ1 and KCNE1 suggests an additional efflux apparatus in avian hair cells. Marked differences were observed for K(+) clearance...
May 19, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28515238/labrid-cleaner-fishes-show-kinematic-convergence-as-juveniles-despite-variation-in-morphology
#3
Vikram B Baliga, Ze'ev J Bernstein, Shivani Sundaram, Rita S Mehta
Cleaning, a dietary strategy in which ectoparasites or mucous are removed and consumed off other taxa, is performed facultatively or obligately in a variety of species. We explored whether species in the Labridae (wrasses, parrotfishes) of varying ecological specialization employ similar mechanisms of prey capture. In investigating feeding on attached prey among juveniles of 19 species of wrasses, we found that patterns of biting in wrasses are influenced by the interaction between the maxilla and a feature of the premaxilla which we term the maxillary crest...
May 17, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28515237/increasing-the-illumination-slowly-over-several-weeks-protects-against-light-damage-in-the-eyes-of-the-crustacean-mysis-relicta
#4
Martta L M Viljanen, Noora E Nevala, Cecilia L Calais-Granö, K Magnus W Lindström, Kristian Donner
The eyes of two glacial-relict populations of opossum shrimp Mysis relicta inhabiting the different photic environments of a deep, dark-brown freshwater lake and a variably lit bay of the Baltic Sea differ in their susceptibility to functional depression from strong light exposures. The lake population is much more vulnerable than the sea population. We hypothesized that the difference reflects physiological adaptation mechanisms operating on long time scales rather than genetically fixed differences between the populations...
May 17, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28515236/resonance-frequencies-of-honeybee-apis-mellifera-wings
#5
Christopher J Clark, Andrew M Mountcastle, Emily Mistick, Damian O Elias
During flight, insect wings bend and twist under the influence of aerodynamic and inertial forces. We tested whether wing resonance of honeybees (Apis mellifera) matches the wingbeat frequency, against the 'stiff element' hypothesis that the wing's first longitudinal mode exceeds the wingbeat frequency. Six bees were immobilized with their right wing pair outspread, and stimulated with a shaker while the normal modes were recorded with a Scanning Doppler Laser Vibrometer. The lowest normal mode of the wings was the first longitudinal bending mode, and at 602±145 Hz, greater than the wingbeat frequency of 234 Hz±13...
May 17, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28515235/insulin-like-growth-factor-signaling-regulates-developmental-trajectory-associated-with-diapause-in-embryos-of-the-annual-killifish-austrofundulus-limnaeus
#6
S Cody Woll, Jason E Podrabsky
Annual killifishes exhibit a number of unique life history characters including the occurrence of embryonic diapause, unique cell movements associated with dispersion and subsequent reaggregation of the embryonic blastomeres, and a short post-embryonic life span. Insulin-like growth factor (IGF) signaling is known to play a role in the regulation of metabolic dormancy in a number of animals but has not been explored in annual killifishes. The abundance of IGF proteins during development, and the developmental effects of blocking IGF signaling by pharmacological inhibition of the insulin-like growth factor I receptor (IGF1R) were explored in embryos of the annual killifish Austrofundulus limnaeus Blocking of IGF signaling in embryos that would normally escape entrance into diapause resulted in a phenotype that was remarkably similar to embryos entering diapause...
May 17, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28507191/lowering-metabolic-rate-mitigates-muscle-atrophy-in-western-fence-lizards
#7
J Balaban, E Azizi
Extended periods of skeletal muscle disuse can cause a significant loss of contractile proteins, which compromises the ability to generate force, mechanical work or power, thus compromising locomotor performance. Several hibernating organisms can resist muscle atrophy despite months of inactivity. This resistance has been attributed to a reduction in body temperature and metabolic rate and activation of physiological pathways that counteract pathways of protein degradation. However, in these systems such strategies are not mutually exclusive and the effects of these mechanisms can be difficult to separate...
May 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28507190/the-effect-of-thermal-acclimation-on-aerobic-scope-and-critical-swimming-speed-in-atlantic-salmon-salmo-salar
#8
Malthe Hvas, Ole Folkedal, Albert Imsland, Frode Oppedal
The Atlantic salmon is extensively studied due to conservation concerns and its economic importance in aquaculture. However, a thorough report of their aerobic capacity throughout their entire thermal niche has not been described. In this study, Atlantic salmon (∼450 g) were acclimated for four weeks at 3, 8, 13, 18 or 23°C, and then tested in a large Brett-type swimming respirometer in groups of ten per trial. Both standard metabolic rate and active metabolic rate continued to increase with temperature, which resulted in an aerobic scope that also increased with temperature, but was statistically similar between 13, 18 and 23°C...
May 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28507189/oxidative-stress-affects-sperm-performance-and-ejaculate-redox-status-in-subordinate-house-sparrows
#9
Alfonso Rojas Mora, Alexandra Firth, Sophie Blareau, Armelle Vallat, Fabrice Helfenstein
Oxidative stress (OS) is the result of random cellular damage caused by reactive oxygen species that leads to cell death, ageing, or illness. Most physiological processes can result in OS, which in turn has been identified as a major cause of infertility. In promiscuous species, the fertilizing ability of the ejaculate partly determines the male reproductive success. When dominance determines access to fertile females, theory predicts that lower ranking males should increase resource investment into enhancing ejaculate quality...
May 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495874/cranking-up-the-heat-relationships-between-energetically-costly-song-features-and-the-increase-in-thorax-temperature-in-male-crickets-and-katydids
#10
B Erregger, H Kovac, A Stabentheiner, M Hartbauer, H Römer, A K D Schmidt
Sexual displays of acoustically signalling insects are used in the context of mate attraction and mate choice. While energetic investment in sound production can increase the reproductive success of the sender, this entails metabolic costs. Resource allocation into sexually selected, reproductive traits can trade off against allocation to naturally selected traits (e.g., growth, immunity) when individuals' energy budgets are limited. Estimating the magnitude of the costs invested in acoustic signalling is necessary to understand this trade-off and its influence on fitness and life-history...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495873/intestinal-digestive-enzyme-modulation-in-house-sparrow-nestlings-occurs-within-24-hours-of-a-change-in-diet-composition
#11
Katherine H Rott, Enrique Caviedes-Vidal, William H Karasov
Nestling house sparrows near fledging age (12 days) were previously found to reversibly modulate the activity of their intestinal digestive enzymes in response to changes in diet composition. However, it is not known how quickly nestlings can adjust to new diets with different substrate compositions, nor is it known how early in life nestlings can modulate their enzyme activity in response to changes in diet. In the current study, 3-day-old nestlings were captured from the wild and fed and switched among contrasting diets - one high in protein and low in carbohydrate and another higher in carbohydrate and with lower but adequate protein - in order to determine (1) how quickly house sparrow nestlings could adjust to changes in diet composition, (2) how early in life nestlings could modulate their digestive enzyme activity in response to these changes, and (3) which digestive enzymes could be modulated in house sparrow nestlings earlier in life...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495872/the-planarian-trpa1-homolog-mediates-extraocular-behavioral-responses-to-near-ultraviolet-light
#12
Taylor R Birkholz, Wendy S Beane
Although light is most commonly thought of as a visual cue, many animals possess mechanisms to detect light outside of the eye for various functions, including predator avoidance, circadian rhythms, phototaxis, and migration. Similar to C. elegans, leeches, and Drosophila larvae, we confirmed that planarians are also capable of detecting and responding to light using extraocular photoreception. We found that when either eyeless or decapitated worms were exposed to near ultraviolet (UV) light, intense wildtype photophobic behaviors were still observed...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495871/embryonic-hypoxia-programmes-postprandial-cardiovascular-function-in-adult-common-snapping-turtles-chelydra-serpentina
#13
Oliver H Wearing, Justin Conner, Derek Nelson, Janna Crossley, Dane A Crossley
Reduced oxygen availability (hypoxia) is a potent stressor during embryonic development, altering the trajectory of trait maturation and organismal phenotype. We previously documented that chronic embryonic hypoxia has a lasting impact on the metabolic response to feeding in juvenile snapping turtles (Chelydra serpentina). Turtles exposed to hypoxia as embryos (10% O2, H10) exhibited an earlier and increased peak postprandial oxygen consumption rate, compared to control turtles (21% O2, N21). In the current study, we measured central blood flow patterns to determine whether the elevated postprandial metabolic response in H10 turtles is linked to lasting impacts on convective transport...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495870/early-life-experience-drives-short-term-acclimation-of-metabolic-and-osmoregulatory-traits-in-the-leaf-eared-mouse
#14
G Cavieres, M Nuñez-Villegas, F Bozinovic, P Sabat
We studied the putative effect of early experience on the physiological flexibility of metabolic and osmoregulatory traits in the leaf-eared mouse Phyllotis darwini, an altricial rodent inhabiting seasonal mediterranean environments. Adult individuals were collected in central Chile and maintained in breeding pairs. Pups were isolated after weaning and acclimated to different temperature (cold or warm) and water availability (unrestricted and restricted) until adulthood. Subsequently, individuals were re-acclimated to the opposite treatment...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495869/kinematics-of-ram-filter-feeding-and-beat-glide-swimming-in-the-northern-anchovy-engraulis-mordax
#15
Nicholas Carey, Jeremy A Goldbogen
In the dense aquatic environment, the most adept swimmers are streamlined to reduce drag and increase the efficiency of locomotion. However, because they open their mouth to wide gape angles to deploy their filtering apparatus, ram filter feeders apparently switch between diametrically opposite swimming modes; highly efficient, streamlined 'beat-glide' swimming, and ram filter feeding, which has been hypothesized to be a high-cost feeding mode because of presumed increased drag. Ram filter feeding forage fish are thought to play an important role in the flux of nutrients and energy in upwelling ecosystems, however the biomechanics and energetics of this feeding mechanism remain poorly understood...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495868/transforming-growth-factor-beta-1-tgf-%C3%AE-1-stimulates-collagen-synthesis-in-cultured-rainbow-trout-cardiac-fibroblasts
#16
Elizabeth F Johnston, Todd E Gillis
Cold acclimation of rainbow trout, Oncorhynchus mykiss, causes collagen to increase within the extracellular matrix (ECM) of the myocardium, while warm acclimation has the opposite effect. The mechanism responsible for this remodeling response is not known. In mammals, transforming growth factor beta-1 (TGF-β1) stimulates collagen deposition within the myocardial ECM. Therefore, we hypothesized that TGF-β1 regulates trout myocardial ECM turnover and predicted that TGF-β1 would induce collagen deposition in cultured rainbow trout cardiac fibroblasts...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495867/sex-differences-in-the-utilization-of-essential-and-non-essential-amino-acids-in-a-lepidoptera
#17
Eran Levin, Marshall D McCue, Goggy Davidowitz
The different reproductive strategies of males and females underlie differences in behavior that may also lead to differences in nutrient use between the two sexes. We study sex differences in the utilization of two essential amino acids (EAAs) and one non-essential amino-acid (NEAA) by the Carolina sphinx moth (Manduca sexta). On day one post-eclosion from the pupae, adult male moths oxidized greater amounts of larval-derived AAs than females, and more nectar derived AAs after feeding. After four days of starvation the opposite pattern was observed; adult females oxidized more larval-derived AAs than males...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495866/sources-of-variance-in-immunological-traits-evidence-of-congruent-latitudinal-trends-across-species
#18
Hendrik Meister, Toomas Tammaru, Siiri-Lii Sandre, Dalial Freitak
Among-population differences in immunological traits allow to assess both evolutionary and plastic changes in organisms' resistance to pathogens. Such knowledge also provides information necessary to predict responses of such traits to environmental changes. Studies on latitudinal trends in insect immunity have so far yielded contradictory results, suggesting that multispecies approaches with highly standardised experimental conditions are needed. Here, we studied among-population differences of two parameters reflecting constitutive immunity - phenoloxidase (PO) and lytic activity - using common garden design on three distantly related moth species represented by populations ranging from northern Finland to Georgia (Caucasus)...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28495865/ceramide-counteracts-the-effects-of-ghrelin-on-the-metabolic-control-of-food-intake-in-rainbow-trout
#19
Cristina Velasco, Guillermo Moreiras, Marta Conde-Sieira, José M Leao, Jesús M Míguez, José L Soengas
In mammals ceramides are involved in the modulation of the orexigenic effects of ghrelin (GHRL). We previously demonstrated in rainbow trout that intracerebroventricular (ICV) treatment with ceramide (2.5 µg/100g fish) resulted in an anorexigenic response, i.e. a response opposed to that described in mammals where ceramide treatment is orexigenic. Therefore, we hypothesize that the putative interaction between GHRL and ceramide must be different in fish. Accordingly, in a first experiment we observed that ceramide levels in hypothalamus of rainbow trout did not change after ICV treatment with GHRL...
May 11, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28476894/rates-of-hypoxia-induction-alter-mechanisms-of-o2-uptake-and-the-critical-o2-tension-of-goldfish
#20
Matthew D Regan, Jeffrey G Richards
The rate of hypoxia induction (RHI) is an important but overlooked dimension of environmental hypoxia that may affect an organism's survival. We hypothesized that, compared with rapid RHI, gradual RHI will afford an organism more time to alter plastic phenotypes associated with O2 uptake and subsequently reduce the critical O2 tension (Pcrit) of O2 uptake rate (ṀO2). We investigated this by determining Pcrit values for goldfish exposed to short (∼24 min), typical (∼84 min) and long (∼480 min) duration Pcrit trials to represent different RHIs...
May 5, 2017: Journal of Experimental Biology
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