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Journal of Experimental Biology

Lucas J Kirschman, Marshall D McCue, Justin G Boyles, Robin W Warne
Variation in environmental conditions during larval life stages can shape development during critical windows and have lasting effects on the adult organism. Changes in larval developmental rates in response to environmental conditions, for example, can trade-off with growth to determine body size and condition at metamorphosis, which can affect adult survival and fecundity. However, it is unclear how use of energy and nutrients shape trade-offs across life stage transitions because no studies have quantified these costs of larval development and metamorphosis...
July 20, 2017: Journal of Experimental Biology
William Gilpin, Vivek N Prakash, Manu Prakash
We present a simple, intuitive algorithm for visualizing time-varying flow fields that can reveal complex flow structures with minimal user intervention. We apply this technique to a variety of biological systems, including the swimming currents of invertebrates and the collective motion of swarms of insects. We compare our results to more experimentally-difficult and mathematically-sophisticated techniques for identifying patterns in fluid flows, and suggest that our tool represents an essential "middle ground" allowing experimentalists to easily determine whether a system exhibits interesting flow patterns and coherent structures without resorting to more intensive techniques...
July 20, 2017: Journal of Experimental Biology
Agnieszka Gudowska, Bartosz W Schramm, Marcin Czarnoleski, Andrzej Antoł, Ulf Bauchinger, Jan Kozłowski
The origin of the allometric relationship between standard metabolic rate (MR) and body mass (M), often described as MR=aM (b) , remains puzzling and interpretation of the mass-scaling exponent, b may depend on the methodological approach, shapes of residuals, coefficient of determination (r(2) ) and sample size. We investigated the mass scaling of MRs within and between species of Carabidae beetles. We used ordinary least squares (OLS) regression, phylogenetically generalized least squares (PGLS) regression and standardized major axis (SMA) regression to explore the effects of different model-fitting methods and data clustering caused by phylogenetic clades (grade shift) and gas exchange patterns (discontinuous, cyclic and continuous)...
July 19, 2017: Journal of Experimental Biology
Alex S Torson, George D Yocum, Joseph P Rinehart, Sean A Nash, Kally M Kvidera, Julia H Bowsher
Exposure to stressful low temperatures during development can result in the accumulation of deleterious physiological effects called chill injury. Metabolic imbalances, disruptions in ion homeostasis, and oxidative stress contribute to the increased mortality of chill-injured insects. Interestingly, survival can be significantly increased when chill susceptible insects are exposed to a daily warm-temperature pulse during chilling. We hypothesize that warm pulses allow for the repair of damage associated with chill-injury...
July 19, 2017: Journal of Experimental Biology
Joseph P R O Orgel, Ido Sella, Rama S Madhurapantula, Olga Antipova, Yael Mandelberg, Yoel Kashman, Dafna Benayahu, Yehuda Benayahu
We report here the biochemical, molecular and ultrastructural features of a unique organization of fibrillar collagen extracted from the octocoral Sarcophyton ehrenbergi Collagen, the most abundant protein in the animal kingdom, is often defined as a structural component of extra-cellular matrices in metazoans. In the present study, collagen fibers were extracted from the mesenteries of S. ehrenbergi polyps. These fibers are organized as filaments and further compacted as coiled fibers. The fibers are uniquely long, reaching an unprecedented length of tens of centimeters...
July 13, 2017: Journal of Experimental Biology
S L Hoffmann, S M Warren, M E Porter
Hammerhead sharks (Sphyrnidae) are have a large amount of morpholigcal variation within the family, making them the focus of many studies. The size of the laterally expanded head, or cephalofoil, is inversely correlated with pectoral fin area. The inverse relation in cephalofoil and pectoral fin size in this family suggests that they might serve a complimentary role in lift generation. The cephalofoil is also hypothesized to increase olfaction, electroreception, and vision; however, little is known about how morphological variation impacts post-cranial swimming kinematics...
July 13, 2017: Journal of Experimental Biology
Claire E Newman, Jantina Toxopeus, Hiroko Udaka, Soohyun Ahn, David M Martynowicz, Steffen P Graether, Brent J Sinclair, Anthony Percival-Smith
The ability to survive and reproduce after cold exposure is important in all kingdoms of life. However, even in a sophisticated genetic model system like Drosophila melanogaster, few genes have been identified as functioning in cold tolerance. The accumulation of the Frost (Fst) gene transcript increases after cold exposure, making it a good candidate for a gene that has a role in cold tolerance. However, despite extensive RNAi knockdown analysis, no role in cold tolerance has been assigned to Fst CRISPR is an effective technique for completely knocking down genes, and less likely to produce off-target effects than GAL4-UAS RNAi systems...
July 13, 2017: Journal of Experimental Biology
Ryota Matsuo, Yuka Takatori, Shun Hamada, Mitsumasa Koyanagi, Yuko Matsuo
Vertebrates, cephalopods, and arthropods are equipped with eyes having the highest spatiotemporal resolution among the animal phyla. In parallel, it is only the animals in these three phyla that have visual arrestin specialized for the termination of visual signaling triggered by opsin, in addition to ubiquitously expressed β-arrestin that serves in terminating general G protein-coupled receptor signaling. Indeed, visual arrestin in Drosophila and rodents translocates to the opsin-rich subcellular region in response to light to reduce the overall sensitivity of photoreceptors in an illuminated environment (i...
July 7, 2017: Journal of Experimental Biology
Satoshi Murata, Axel Brockmann, Teiichi Tanimura
Foraging behavior is essential for all organisms to find food containing nutritional chemicals. A hungry fly of Drosophila melanogaster performs local searching behavior after drinking a small amount of sugar solution. Using video tracking we examined how the searching behavior is regulated in D. melanogaster We found that a small amount of highly concentrated sugar solution induced a long-lasting searching behavior. After the intake of sugar solution, a fly moved around in circles and repeatedly returned to the position where the sugar droplet had been placed...
July 6, 2017: Journal of Experimental Biology
Eric Krabbe Smith, Jacqueline J O'Neill, Alexander R Gerson, Andrew E McKechnie, Blair O Wolf
We examined thermoregulatory performance in seven Sonoran Desert passerine bird species varying in body mass from 10 to 70g - Lesser Goldfinch, House Finch, Pyrrhuloxia, Cactus Wren, Northern Cardinal, Abert's Towhee and Curve-billed Thrasher. Using flow-through respirometry we measured daytime resting metabolism, evaporative water loss and body temperature at air temperatures (Tair) between 30° and 52°C. We found marked increases in resting metabolism above the upper critical temperature (Tuc), which for six of the seven species fell within a relatively narrow range (36...
July 6, 2017: Journal of Experimental Biology
Alex R Quijada-Rodriguez, Aaron G Schultz, Jonathan M Wilson, Yuhe He, Garett J P Allen, Greg G Goss, Dirk Weihrauch
Freshwater organisms actively take up ions from their environment to counter diffusive ion losses due to inhabiting hypo-osmotic environments. The mechanisms behind active Na(+) uptake are quite well understood in freshwater teleosts, however, the mechanisms employed by invertebrates are not. Pharmacological and molecular approaches were used to investigate Na(+) uptake mechanisms and their link to ammonia excretion in the ribbon leech Nephelopsis obscura At the molecular level, we identified a Na(+) channel and a Na(+)/H(+)-exchanger (NHE) in the skin of N...
July 6, 2017: Journal of Experimental Biology
Michael Briga, Simon Verhulst
Basal metabolic rate (BMR) is often assumed to be indicative of the energy turnover at ambient temperatures (Ta) below the thermoneutral zone (SMR), but this assumption has remained largely untested. Using a new statistical approach, we quantified the consistency in nocturnal metabolic rate across a temperature range in zebra finches (n=3,213 measurements on 407 individuals) living permanently in eight outdoor aviaries. Foraging conditions were either benign or harsh, and body mass and mass-adjusted BMRm and SMRm were lower in individuals living in a harsh foraging environment...
July 6, 2017: Journal of Experimental Biology
Sarah Leclaire, Vincent Bourret, Francesco Bonadonna
Most studies on avian olfactory communication have focused on mate choice, and the importance of olfaction in subsequent nesting stages has been poorly explored. In particular, the role of olfactory cues in egg recognition has received little attention, despite eggs potentially being spread with parental odorous secretions known to elicit individual discrimination. Here we used behavioral choice tests to determine whether female blue petrels (Halobaena caerulea) can discriminate the odor of their own egg from the odor of a conspecific egg...
July 6, 2017: Journal of Experimental Biology
Tess Renahan, Ray L Hong
Nematode-insect interactions are ubiquitous, complex, and constantly changing as the host and nematode coevolve. The entomophilic nematode Pristionchus pacificus is found on a myriad beetle species worldwide, though the molecular dynamics of this relationship are largely unknown. To better understand how host cues affect P. pacificus embryogenesis, we characterized the threshold of sensitivity to the pheromone (Z)-7-tetradecen-2-one (ZTDO) by determining the minimum exposure duration and developmental window that results in P...
July 6, 2017: Journal of Experimental Biology
Rachel M Templin, Martin J How, Nicholas W Roberts, Tsyr-Huei Chiou, Justin Marshall
A combination of behavioural and electrophysiological experiments have previously shown that two species of stomatopod, Odontadactylus scyllarus and Gonodactylaceus falcatus, can differentiate between left and right handed circularly polarized light (CPL), and between CPL and linearly polarized light (LPL). It remains unknown if these visual abilities are common across all stomatopod species, and if so, how circular polarization sensitivity may vary between and within species. A sub-section of the midband, a specialized region of stomatopod eyes, contains distally placed photoreceptor cells, termed R8 (retinular cell number 8)...
June 30, 2017: Journal of Experimental Biology
Anna V Ivanina, Halina I Falfushynska, Elia Beniash, Helen Piontkivska, Inna M Sokolova
Molluscan exoskeleton (shell) plays multiple important roles including structural support, protection from predators and stressors, and physiological homeostasis. Shell formation is a tightly regulated biological process that allows mollusks to build their shells even in environments unfavorable for mineral precipitation. Outer mantle edge epithelial cells (OME) and hemocytes were implicated in this process; however, the exact functions of these cell types in biomineralization are not clear. The Pacific oysters Crassostrea gigas were used to study differences in the expression profiles of selected biomineralization-related genes in hemocytes and mantle cells, and the functional characteristics of hemocytes such as adhesion, motility and phagocytosis...
June 30, 2017: Journal of Experimental Biology
Martin Gottwald, Raya A Bott, Gerhard von der Emde
During active electrolocation the weakly electric fish Gnathonemus petersii judges distance and impedance of nearby objects. Capacitive objects, which modulate local amplitude and waveform of the fish's electric probing signals, cast amplitude- and waveform images onto the fish's electroreceptive skin. For an unambiguous estimation of the impedance and distance of an object, the animal has to deal with multiple dependencies of object- and image parameters. Based on experimentally recorded amplitude and waveform images we investigated possible strategies of the fish to unequivocally determine both the distance and the impedance of capacitive objects...
June 28, 2017: Journal of Experimental Biology
Neal J Dawson, Kenneth B Storey
Wood frogs inhabit a broad range across North America, extending from the southern tip of the Appalachian Mountains to the northern boreal forest. Remarkably they can survive the winter in a frozen state, where as much as 70% of their body water is converted into ice. During the frozen state, their hearts cease to pump blood, causing their cells to experience ischemia which can dramatically increase the production of reactive oxygen species produced within the cell. To overcome this, wood frogs have elevated levels of glutathione, a primary antioxidant...
June 28, 2017: Journal of Experimental Biology
Sabrina S Burmeister, Verónica G Rodriguez Moncalvo, Karin S Pfennig
Social behavior often includes the production of species-specific signals (e.g., mating calls or visual displays) that evoke context-dependent behavioral responses from conspecifics. Monoamines are important neuromodulators that have been implicated in context-dependent social behavior yet we know little about development of the monoaminergic systems and whether they mediate the effects of early life experiences on adult behavior. We examined the effects of diet and social signals on monoamines early in development in the Plains spadefoot toad (Spea bombifrons), a species in which diet affects the developmental emergence of species recognition and body condition affects the expression of adult mating preferences...
June 28, 2017: Journal of Experimental Biology
Natalie M D'Silva, Marjorie L Patrick, Michael J O'Donnell
Larvae of Aedes aegypti, the yellow fever vector, inhabit a variety of aquatic habitats ranging from fresh water to brackish water. This study focuses on the gastric caecum of the larvae, an organ that has not been widely studied. We provide the first measurements of H(+), K(+), and Na(+) fluxes at the distal and proximal gastric caecum, and have shown that they differ in the two regions, consistent with previously reported regionalization of ion transporters. Moreover we have shown that the regionalization of vacuolar H(+)-ATPase and Na(+)/K(+) -ATPase is altered when larvae are reared in brackish water (30% seawater) relative to fresh water...
June 28, 2017: Journal of Experimental Biology
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