bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of calsequestrin in atrial and ventricular muscle of thermally acclimated rainbow trout
Authors: Korajoki Hanna , Vornanen Matti 
Published: October 2009

SUMMARYCalsequestrin (CASQ) is the main Ca2+ binding protein within the sarcoplasmic reticulum (SR) of the vertebrate heart. The contribution of SR Ca2+ stores to contractile activation is larger in atrial than ventricular muscle, and in ectothermic fish hearts acclimation to low temperatures increases the use of SR Ca2+ in excitation–contraction coupling. The hypotheses that chamber-specific and temperature-induced differences in SR function are due to the increased SR CASQ content were tested in rainbow trout (Oncorhynchus mykiss)acclimated at either 4°C (cold acclimation, CA) or 18°C (warm acclimation, WA). To this end, the trout cardiac CASQ (omCASQ2) was cloned and sequenced. The omCASQ2 consists of 1275 nucleotides encoding a predicted protein of 425 amino acids (54 kDa in molecular mass, MM)with a high (75–87%) sequence similarity to other vertebrate cardiac CASQs. The transcript levels of the omCASQ2 were 1.5–2 times higher in CA than WA fish and about 2.5 times higher in the atrium than ventricle (P&lt;0.001). The omCASQ2 protein was measured from western blots using a polyclonal antibody against the amino acid sequence 174–315 of the omCASQ2. Unlike the omCASQ2 transcripts, no differences were found in the abundance of the omCASQ2 protein between CA and WA fish, nor between the atrium and ventricle (P&gt;0.05). However, a prominent qualitative difference appeared between the acclimation groups: two CASQ isoforms with apparent MMs of 54 and 59 kDa, respectively, were present in atrial and ventricular muscle of the WA trout whereas only the 54 kDa protein was clearly expressed in the CA heart. The 59 kDA isoform was a minor CASQ component representing 22% and 13% of the total CASQ proteins in the atrium and ventricle of the WA fish, respectively. In CA hearts, the 59 kDa protein was present in trace amounts (1.5–2.4%). Collectively, these findings indicate that temperature-related and chamber-specific differences in trout cardiac SR function are not related to the abundance of luminal Ca2+ buffering by cardiac CASQ.
Auditory mechanics and sensitivity in the tropical butterfly Morpho peleides (Papilionoidea, Nymphalidae)
Authors: Lucas Kathleen M. , Windmill James F. C. , Robert Daniel , Yack Jayne E. 
Published: October 2009

SUMMARY
The ears of insects exhibit a broad functional diversity with the ability to detect sounds across a wide range of frequencies and intensities. In tympanal ears, the membrane is a crucial step in the transduction of the acoustic stimulus into a neural signal. The tropical butterfly Morpho peleides has an oval-shaped membrane at the base of the forewing with an unusual dome in the middle of the structure. We are testing the hypothesis that this unconventional anatomical arrangement determines the mechanical tuning properties of this butterfly ear. Using microscanning laser Doppler vibrometry to measure the vibrational characteristics of this novel tympanum,the membrane was found to vibrate in two distinct modes, depending on the frequency range: at lower frequencies (1–5 kHz) the vibration was focused at the proximal half of the posterior side of the outer membrane,while at higher frequencies (5–20 kHz) the entire membrane contributed to the vibration. The maximum deflection points of the two vibrational modes correspond to the locations of the associated chordotonal organs, suggesting that M. peleides has the capacity for frequency partitioning because of the different vibrational properties of the two membrane components. Extracellular nerve recordings confirm that the innervating chordotonal organs respond to the same frequency range of 1–20 kHz, and are most sensitive between 2 and 4 kHz, although distinct frequency discrimination was not observed. We suggest that this remarkable variation in structure is associated with function that provides a selective advantage, particularly in predator detection.
White-throated sparrows calibrate their magnetic compass by polarized light cues during both autumn and spring migration
Authors: Muheim Rachel , Phillips John B. , Deutschlander Mark E. 
Published: October 2009

SUMMARYThe interaction and hierarchy of celestial and magnetic compass cues used by migratory songbirds for orientation has long been the topic of an intense debate. We have previously shown that migratory Savannah sparrows, Passerculus sandwichensis, use polarized light cues near the horizon at sunrise and sunset to recalibrate their magnetic compass. Birds exposed to a ±90 deg. shifted artificial polarization pattern at sunrise or sunset recalibrated their magnetic compass, but only when given full access to celestial cues, including polarized light cues near the horizon. In the current study, we carried out cue conflict experiments with white-throated sparrows, Zonotrichia albicollis, during both spring and autumn migration in a transition zone between the species' breeding and wintering areas on the south shore of Lake Ontario. We show that white-throated sparrows also recalibrate their magnetic compass by polarized light cues at sunrise and sunset. Sunrise exposure to an artificial polarization pattern shifted relative to the natural magnetic field or exposure to a shift of the magnetic field relative to the natural sky both led to recalibration of the magnetic compass, demonstrating that artificial polarizing filters do not create an anomalous, unnatural orientation response. Our results further indicate that there is no evidence for a difference in compass hierarchy between different phases of migration, confirming previous work showing that polarized light cues near the horizon at sunrise and sunset provide the primary calibration reference both in the beginning and at the end of migration.
Potential mechanism of sound production in Oreochromis niloticus(Cichlidae)
Authors: Longrie Nicolas , Van Wassenbergh Sam , Vandewalle Pierre , Mauguit Quentin , Parmentier Eric 
Published: October 2009

SUMMARY
Although acoustic communication is an integral part of cichlid behaviour,its mechanism has never been identified before. In the present study, a combination of approaches was used to investigate the sound-producing mechanism of Oreochromis niloticus. Synchronisation of high-speed video data (500 frames s–1) and cineradiographies (250 frames s–1) with the sound recordings made it possible to locate the different body parts involved in sound production in territorial males. Sounds are made during a backward movement of the pelvic and pectoral girdles and a forward movement of the second pterygiophore of the anal fin. Various electrostimulation experiments, dissections and observation of histological cross-sections revealed a set of bundles (that we call the vesica longitudinalis) situated in the hypaxial musculature, ventro-laterally to the swimbladder. Contraction of these bundles should result in compression of the rib cage and also of the swimbladder, because of its close association with the serosa and ribs. Deflation of the swimbladder resulted in a reduced sound intensity.
Waveform diversity of electric organ discharges: the role of electric organ auto-excitability inGymnotusspp.
Authors: Rodríguez-Cattáneo Alejo , Caputi Angel Ariel 
Published: October 2009

SUMMARYThis article shows that differences in the waveforms of the electric organ discharges (EODs) from two taxa are due to the different responsiveness of their electric organs (EOs) to their previous activity (auto-excitability). We compared Gymnotus omarorum endemic to Uruguay (35° South, near a big estuary), which has four components in the head to tail electric field(V1 to V4), with Gymnotus sp. endemic to the south of Brazil, Paraguay and Argentinean Mesopotamia (25° South, inland),which shows a fifth component in addition to the others (V5). We found that: (a) the innervation pattern of the electrocytes, (b) the three earlier, neurally driven, EOD components (V1 to V3), and(c) their remnants after curarisation were almost identical in the two taxa. The equivalent electromotive forces of late components (V4 and V5) increased consistently as a function of the external current associated with the preceding component and were abolished by partial curarisation in both taxa. Taken together these data suggest that these components are originated in the responses of the electrocytes to longitudinal currents through the EO. By using a differential load procedure we showed that V4 in G. omarorum responded to experimental changes in its excitation current with larger amplitude variations than V4 in Gymnotus sp. We conclude that the differences in the EOD phenotype of the two studied taxa are due to the different EO auto-excitability. This, in turn, is caused either by the different expression of a genetic repertoire of conductance in the electrocyte membrane or in the wall of the tubes forming the EO.
Insect eggs protected from high temperatures by limited homeothermy of plant leaves
Authors: Potter Kristen , Davidowitz Goggy , Woods H. Arthur 
Published: October 2009

SUMMARY
Virtually all aspects of insect biology are affected by body temperature,and many taxa have evolved sophisticated temperature-control mechanisms. All insects, however, begin life as eggs and lack the ability to thermoregulate. Eggs laid on leaves experience a thermal environment, and thus a body temperature, that is strongly influenced by the leaves themselves. Because plants can maintain leaf temperatures that differ from ambient, e.g. by evapotranspiration, plant hosts may protect eggs from extreme ambient temperatures. We examined the degree to which leaves buffer ambient thermal variation and whether that buffering benefits leaf-associated insect eggs. In particular, we: (1) measured temperature variation at oviposition sites in the field, (2) manipulated temperatures in the laboratory to determine the effect of different thermal conditions on embryo development time and survival, and(3) tested embryonic metabolic rates over increasing temperatures. Our results show that Datura wrightii leaves buffer Manduca sexta eggs from fatally high ambient temperatures in the southwestern USA. Moreover, small differences in temperature profiles among leaves can cause large variation in egg metabolic rate and development time. Specifically, large leaves were hotter than small leaves during the day, reaching temperatures that are stressfully high for eggs. This study provides the first mechanistic demonstration of how this type of leaf-constructed thermal refuge interacts with egg physiology.
Acoustical properties of the swimbladder in the oyster toadfish Opsanus tau
Authors: Fine Michael L. , King Charles B. , Cameron Timothy M. 
Published: October 2009

SUMMARY
Both the swimbladder and sonic muscles of the oyster toadfish Opsanus tau (Linnaeus) increase in size with fish growth making it difficult to distinguish their relative contributions to sound production. We examined acoustics of the swimbladder independent of the sonic muscles by striking it with a piezoelectric impact hammer. Amplitude and timing characteristics of bladder sound and displacement were compared for strikes of different amplitudes. Most of the first cycle of sound occurred during swimbladder compression, indicating that the bladder rapidly contracted and expanded as force increased during the strike. Harder hits were shorter in duration and generated a 30 dB increase in amplitude for a 5-fold or 14 dB range in displacement. For an equivalent strike dominant frequency, damping, bladder displacement and sound amplitude did not change with fish size, i.e. equal input generated equal output. The frequency spectrum was broad, and dominant frequency was driven by the strike and not the natural frequency of the bladder. Bladder displacement decayed rapidly (ζ averaged 0.33,equivalent to an automobile shock absorber), and the bladder had a low Q (sharpness of tuning), averaging 1.8. Sound output of an acoustic source is determined by volume velocity (surface area × velocity), and bladder surface area, muscle dimensions and contraction amplitude increase with fish size. Therefore, larger fish will be capable of producing more intense sound. Because the bladder is a low Q resonator, its output will follow muscle contraction rates independent of its size and natural frequency.
Methionine supplementation influences melanin-based plumage colouration in Eurasian kestrel,Falco tinnunculus, nestlings
Authors: Parejo Deseada , Silva Nadia 
Published: October 2009

SUMMARYThe extent to which the expression of melanin-based plumage colouration in birds is genetically or environmentally determined is controversial. Here, we performed a between-nest design supplementation with either the sulphur amino acid dl-methionine or with water to investigate the importance of the non-genetic component of melanin-based plumage colouration in the Eurasian kestrel, Falco tinnunculus. Methionine affects growth and immunity,thus we aimed to modify nestling growth and immunity before feather development. Then, we measured the effect of the experiment on colouration of two melanin-based plumage patches of nestling kestrels. We found that methionine slowed down nestling growth through treatment administration and that nestlings compensated by speeding up their growth later. We did not find any effects of methionine on nestling immunity (i.e. lymphocyte counts,natural antibody levels or complement-mediated immunity). Effects on growth seemed to be mirrored by changes in nestling colouration in the two sexes:methionine-nestlings showed less intense brown plumage on their backs compared with control nestlings. These results provide support for a non-genetic determination of a melanin-based plumage patch in the two sexes of nestling kestrels.
Whole limb kinematics are preferentially conserved over individual joint kinematics after peripheral nerve injury
Authors: Chang Young-Hui , Auyang Arick G. , Scholz John P. , Nichols T. Richard 
Published: October 2009

SUMMARY
Biomechanics and neurophysiology studies suggest whole limb function to be an important locomotor control parameter. Inverted pendulum and mass-spring models greatly reduce the complexity of the legs and predict the dynamics of locomotion, but do not address how numerous limb elements are coordinated to achieve such simple behavior. As a first step, we hypothesized whole limb kinematics were of primary importance and would be preferentially conserved over individual joint kinematics after neuromuscular injury. We used a well-established peripheral nerve injury model of cat ankle extensor muscles to generate two experimental injury groups with a predictable time course of temporary paralysis followed by complete muscle self-reinnervation. Mean trajectories of individual joint kinematics were altered as a result of deficits after injury. By contrast, mean trajectories of limb orientation and limb length remained largely invariant across all animals, even with paralyzed ankle extensor muscles, suggesting changes in mean joint angles were coordinated as part of a long-term compensation strategy to minimize change in whole limb kinematics. Furthermore, at each measurement stage (pre-injury,paralytic and self-reinnervated) step-by-step variance of individual joint kinematics was always significantly greater than that of limb orientation. Our results suggest joint angle combinations are coordinated and selected to stabilize whole limb kinematics against short-term natural step-by-step deviations as well as long-term, pathological deviations created by injury. This may represent a fundamental compensation principle allowing animals to adapt to changing conditions with minimal effect on overall locomotor function.
Surgical removal of right-to-left cardiac shunt in the American alligator(Alligator mississippiensis) causes ventricular enlargement but does not alter apnoea or metabolism during diving
Authors: Eme John , Gwalthney June , Blank Jason M. , Owerkowicz Tomasz , Barron Gildardo , Hicks James W. 
Published: October 2009

SUMMARYCrocodilians have complete anatomical separation between the ventricles,similar to birds and mammals, but retain the dual aortic arch system found in all non-avian reptiles. This cardiac anatomy allows surgical modification that prevents right-to-left (R–L) cardiac shunt. A R–L shunt is a bypass of the pulmonary circulation and recirculation of oxygen-poor blood back to the systemic circulation and has often been observed during the frequent apnoeic periods of non-avian reptiles, particularly during diving in aquatic species. We eliminated R–L shunt in American alligators(Alligator mississippiensis) by surgically occluding the left aorta(LAo; arising from right ventricle) upstream and downstream of the foramen of Panizza (FoP), and we tested the hypotheses that this removal of R–L shunt would cause afterload-induced cardiac remodelling and adversely affect diving performance. Occlusion of the LAo both upstream and downstream of the FoP for ∼21 months caused a doubling of RV pressure and significant ventricular enlargement (average ∼65%) compared with age-matched,sham-operated animals. In a separate group of recovered, surgically altered alligators allowed to dive freely in a dive chamber at 23°C, occlusion of the LAo did not alter oxygen consumption or voluntary apnoeic periods relative to sham animals. While surgical removal of R–L shunt causes considerable changes in cardiac morphology similar to aortic banding in mammals, its removal does not affect the respiratory pattern or metabolism of alligators. It appears probable that the low metabolic rate of reptiles, rather than pulmonary circulatory bypass, allows for normal aerobic dives.
Ontogenetic changes in tracheal structure facilitate deep dives and cold water foraging in adult leatherback sea turtles
Authors: Davenport John , Fraher John , Fitzgerald Ed , McLaughlin Patrick , Doyle Tom , Harman Luke , Cuffe Tracy , Dockery Peter 
Published: October 2009

SUMMARYAdult leatherbacks are large animals (300–500 kg), overlapping in size with marine pinniped and cetacean species. Unlike marine mammals, they start their aquatic life as 40–50 g hatchlings, so undergo a 10,000-fold increase in body mass during independent existence. Hatchlings are limited to the tropics and near-surface water. Adults, obligate predators on gelatinous plankton, encounter cold water at depth (&lt;1280 m) or high latitude and are gigantotherms that maintain elevated core body temperatures in cold water. This study shows that there are great ontogenetic changes in tracheal structure related to diving and exposure to cold. Hatchling leatherbacks have a conventional reptilian tracheal structure with circular cartilaginous rings interspersed with extensive connective tissue. The adult trachea is an almost continuous ellipsoidal cartilaginous tube composed of interlocking plates, and will collapse easily in the upper part of the water column during dives, thus avoiding pressure-related structural and physiological problems. It is lined with an extensive, dense erectile vascular plexus that will warm and humidify cold inspired air and possibly retain heat on expiration. A sub-luminal lymphatic plexus is also present. Mammals and birds have independently evolved nasal turbinates to fulfil such a respiratory thermocontrol function; for them, turbinates are regarded as diagnostic of endothermy. This is the first demonstration of a turbinate equivalent in a living reptile.
Thermomechanical finite element analysis and experimental investigation of single-pass single-sided submerged arc welding of C—Mn steel plates
Authors: Biswas P , Mandal N R 
Published: October 2009

Determination of distortions are important while designing the arc-welded joints. These distortions occur in a varied way in almost every type of welded joint, depending on several parameters, i.e. welding speed, plate thickness, welding current and voltage, restraints applied to the job while welding, thermal history, etc. In the present work a numerical model based on the finite element package ANSYS was developed for single-pass single-sided submerged arc welding of square butt joints. Suitable macros were developed to simulate the situation of a moving distributed heat source, metal deposition to account for top and bottom reinforcements, a time step, and a meshing scheme. In this model the effect of bead geometry was incorporated. The effect of filler metal deposition was taken into account by implementing the element birth and death technique. Submerged arc welding (SAW) can be conveniently used to weld a range of plate thicknesses in a single run using a suitable backing strip achieving adequate top and bottom reinforcements. The welding methodology established in the present work resulted in minimizing angular distortions in butt welds. The numerical model yielded results comparing well with those of the experimental ones.
Δ9-Tetrahydrocannabinol (THC), 11-Hydroxy-THC, and 11-Nor-9-carboxy-THC Plasma Pharmacokinetics during and after Continuous High-Dose Oral THC
Authors: Schwilke Eugene W , Schwope David M , Karschner Erin L , Lowe Ross H , Darwin William D , Kelly Deanna L , Goodwin Robert S , Gorelick David A , Huestis Marilyn A 
Published: October 2009

AbstractBackground: Δ9-Tetrahydrocannabinol (THC) is the primary psychoactive constituent of cannabis and an active cannabinoid pharmacotherapy component. No plasma pharmacokinetic data after repeated oral THC administration are available.Methods: Six adult male daily cannabis smokers resided on a closed clinical research unit. Oral THC capsules (20 mg) were administered every 4–8 h in escalating total daily doses (40–120 mg) for 7 days. Free and glucuronidated plasma THC, 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH) were quantified by 2-dimensional GC-MS during and after dosing.Results: Free plasma THC, 11-OH-THC, and THCCOOH concentrations 19.5 h after admission (before controlled oral THC dosing) were mean 4.3 (SE 1.1), 1.3 (0.5), and 34.0 (8.4) μg/L, respectively. During oral dosing, free 11-OH-THC and THCCOOH increased steadily, whereas THC did not. Mean peak plasma free THC, 11-OH-THC, and THCCOOH concentrations were 3.8 (0.5), 3.0 (0.7), and 196.9 (39.9) μg/L, respectively, 22.5 h after the last dose. Escherichia coli β-glucuronidase hydrolysis of 264 cannabinoid specimens yielded statistically significant increases in THC, 11-OH-THC, and THCCOOH concentrations (P &lt; 0.001), but conjugated concentrations were underestimated owing to incomplete enzymatic hydrolysis.Conclusions: Plasma THC concentrations remained &gt;1 μg/L for at least 1 day after daily cannabis smoking and also after cessation of multiple oral THC doses. We report for the first time free plasma THC concentrations after multiple high-dose oral THC throughout the day and night, and after Escherichia coli β-glucuronidase hydrolysis. These data will aid in the interpretation of plasma THC concentrations after multiple oral doses.