bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Salivary Nitrophorin (Nitric-Oxide-Carrying Hemoprotein) in the Bedbug Cimex Lectularius
Authors: Valenzuela Jesus G. , Walker F. Ann , Ribeiro José M. C. 
Published: April 2021

ABSTRACT
Salivary gland homogenate of the bedbug Cimex lectularius caused vasodilation of the preconstricted rabbit aortic ring in the absence of endothelium. Vasodilation was augmented in the presence of superoxide dismutase and inhibited in the presence of Methylene Blue. Utilization of the Griess reaction indicated the presence of reactive nitrogen equivalents of the order of 337±57 pg equivalent NO2- per pair of salivary glands (mean ± S.E.M.; N=3). Salivary gland homogenates have a nitrosyl-hemoprotein that releases nitric oxide in a pH-dependent manner. The fraction containing the NO-carrying hemoprotein, when separated by HPLC, caused vasodilation of the preconstricted rabbit aortic strip. Furthermore, the presence of a nitrosyl-hemoprotein in Cimex lectularius salivary gland was verified by electron paramagnetic resonance spectroscopy. It is proposed that, as in the case of Rhodnius prolixus (Triatominae), Cimex lectularius salivary glands contain a hemoprotein (nitrophorin) that carries NO from the glands to the host tissues. However, because Cimex lectularius and Rhodnius prolixus belong to different hemipteran families (Cimicidae and Reduvidae) and evolved independently to blood feeding, Cimex lectularius and Rhodnius prolixus nitrophorin may be a case of convergent evolution.
Red Muscle Motor Patterns During Steady Swimming In Largemouth Bass: Effects Of Speed And Correlations With Axial Kinematics
Authors: Jayne Bruce C. , Lauder George V. 
Published: April 2021

ABSTRACT
We analyzed midline kinematics and obtained electromyograms (EMGs) from the superficial red muscle at seven longitudinal positions in four largemouth bass swimming steadily at standardized speeds of 0.7, 1.2, 1.6, 2.0 and 2.4 lengths s-1. Analysis of variance was used to test for significant variation attributable to both speed and longitudinal position. EMGs propagated posteriorly were unilateral and alternated between the left and right sides. Despite the propagation of EMGs, all the red muscle along an entire side of the fish was simultaneously active for as much as one-quarter of the locomotor cycle. When expressed as a proportion of the locomotor cycle, EMG durations at a given site did not vary significantly with speed but did vary longitudinally, ranging from values of 0.45 cycles anteriorly to 0.35 cycles posteriorly. The amplitudes of lateral displacement and bending depended on longitudinal position and also increased by a maximum of approximately 50 % with increased swimming speed, whereas for all longitudinal positions the intensity of EMGs increased approximately fourfold with increased swimming speed. Electrical activity of red muscle did not correspond simply to the time of muscle shortening. Instead, the timing of EMG onset and offset relative to both lateral bending and displacement changed significantly with both longitudinal position and increased speed, such that the phase shifts between the EMGs and kinematic values were generally greatest for posterior sites at the fastest speeds. At a single longitudinal position, the phase shift between the EMG and maximal lateral bending could change by more than one-tenth of a cycle from the slowest to the fastest swimming speed. Phase lags per body segment of EMG onset and EMG offset did not vary significantly with either swimming speed or longitudinal position. EMG offset was propagated posteriorly faster than EMG onset, and both EMG onset and EMG offset were generally propagated faster than both lateral bending and displacement. Largemouth bass have a similar number of vertebrae to carp, and these two species also have a very similar pattern of muscle activation that differs substantially from that of the trout, which has nearly twice as many vertebrae.
Ant Breathing: Testing Regulation and Mechanism Hypotheses With Hypoxia
Authors: Lighton John R. B. , Garrigan Dana 
Published: April 2021

ABSTRACT
Using normoxic and hypoxic flow-through respirometry, we investigated the regulation of the closed-spiracle (C) and the nature of the fluttering-spiracle (F) phases of the discontinuous gas-exchange cycle (DGC) of the ant Camponotus vicinus. We predicted that as ambient O2 concentrations declined, DGC frequency would increase, because C phase duration would decrease (reflecting earlier hypoxic initiation of the F phase) and F phase duration would shorten (reflecting nitrogen accumulation), if convective mass inflow caused by a negative pressure gradient across the spiracles, rather than by diffusion, is the dominant F phase gas-exchange mechanism. C phase duration decreased with declining ambient O2 concentrations, as predicted. In contrast, DGC frequency decreased and F phase duration increased with decreasing ambient O2 concentrations. This was opposite to the expected trend if gas exchange in the F phase was mediated by convection, as is generally hypothesized. We therefore cannot disprove that F phase gas exchange was largely or purely diffusion-based. In addition, our data show equivalent molar rates of H2O and CO2 emission during the F phase. In contrast, during the open-spiracle phase, the duration of which was not affected by ambient O2 concentration, far more H2O than CO2 was lost. We discuss these findings and suggest that current hypotheses of F phase gas-exchange mechanisms and function in reducing respiratory water loss in adult insects may require revision.
The Role of Neurohormonal Octopamine During ‘Fight or Flight’ Behaviour in the Field Cricket Gryllus Bimaculatus
Authors: Adamo S. A. , Linn C. E. , Hoy R. R. 
Published: April 2021

ABSTRACT
Octopamine has been called the ‘fight or flight’ hormone of insects. We tested this hypothesis by measuring octopamine levels in the haemolymph of field crickets after fighting, flying, courting and escape behaviours. Octopamine levels in the cricket Gryllus bimaculatus increased during aggressive (agonistic) behaviour from baseline levels of 4.5±2.1 pg μl-1 haemolymph to 24.3±15.2 pg μl-1 haemolymph, regardless of whether the cricket won or lost the encounter. Octopamine levels also increased after 5 min of flying (to 44.6±22.3 pg μl-1) and during courtship. However, crickets did not exhibit an increase in their haemolymph octopamine levels after performing an escape run. Therefore, neurohormonal octopamine shows some, but not all, of the characteristics that would be expected if it were a component of a non-specific ‘arousal’ system. Rather, octopamine may be released as a neurohormone to prepare the animal for a period of extended activity or to assist the animal in recovering from a period of increased energy demand. Antennal contact with conspecifics may provide a sensory cue that results in the release of octopamine into the haemolymph.
Effects of Bafilomycin A1 on Cytosolic pH of sheep Alveolar and Peritoneal Macrophages: Evaluation of the pH-Regulatory Role of Plasma Membrane V-ATPases
Authors: Heming Thomas A. , Traber Daniel L. , Hinder Frank , Bidani Akhil 
Published: April 2021

ABSTRACT
The role of plasma membrane V-ATPase activity in the regulation of cytosolic pH (pHi) was determined for resident alveolar and peritoneal macrophages (mϕ) from sheep. Cytosolic pH was measured using 2′7′-biscarboxyethyl-5,6-carboxyfluorescein (BCECF). The baseline pHi of both cell types was sensitive to the specific V-ATPase inhibitor bafilomycin A1. Bafilomycin A1 caused a significant (approximately 0.2 pH units) and rapid (within seconds) decline in baseline pHi. Further, bafilomycin A1 slowed the initial rate of pHi recovery (dpHi/dt) from intracellular acid loads. Amiloride had no effects on baseline pHi, but reduced dpHi/dt (acid-loaded pHi nadir &lt;6.8) by approximately 35 %. Recovery of pHi was abolished by co-treatment of mϕ with bafilomycin A1 and amiloride. These data indicate that plasma membrane V-ATPase activity is a major determinant of pHi regulation in resident alveolar and peritoneal mϕ from sheep. Sheep mϕ also appear to possess a Na+/H+ exchanger. However, Na+/H+ exchange either is inactive or can be effectively masked by V-ATPase-mediated H+ extrusion at physiological pHi values.
The Control of Ventilatory and Cardiac Responses to Changes in Ambient Oxygen Tension and Oxygen Demand in Octopus
Authors: Wells M. J. , Wells J. 
Published: April 2021

ABSTRACT
Octopus vulgaris can regulate its oxygen uptake down to a of around 6.7 kPa. As the tension falls from 18.6 to 6.7 kPa (140 to 50 mmHg), PV (the pressure pulse driving the ventilatory flow, measured inside the mantle cavity) can more than double while fV (the ventilation frequency) increases by a few per cent at most. Both changes are reversed when the ambient oxygen tension is returned to normal. Cutting the visceral nerves linking the hearts and gills to the brain prevents these adaptive changes in PV and fV, as does section of the branchial nerves linking the cardiac ganglia to the gills. Responses to changes in ambient oxygen tension are very fast, beginning within two or three ventilation cycles. It is concluded that changes to PV and fV depend upon receptors in the gills and on the integrity of a nervous pathway to the brain.
Changes in oxygen tension also affect the hearts, where aortic pulse amplitude (Pa) and, to a lesser extent, heartbeat frequency (fH) fall and rise with the ambient . In this case, section of the visceral or branchial nerves has no effect. Responses are again very rapid. It is concluded that the observed fall and return to normoxic values of Pa and fH are local responses to a fall and rise in the oxygen tension of blood coming from the gills into the systemic heart.
Changes to ventilation and heartbeat can also occur in normoxic water when oxygen demand rises after feeding. These responses are not prevented by section of the visceral or branchial nerves. Possible control of ventilation and heartbeat through the neurosecretory system in the anterior vena cava is discussed.
Changes in Motoneuron Membrane Potential and Reflex Activity Induced by Sudden Cooling of Isolated Spinal Cords: Differences Among Cold-Sensitive, Cold-Resistant and Freeze-Tolerant Amphibian Species
Authors: Daló Nelson L. , Hackman John C. , Storey Kenneth , Davidoff Robert A. 
Published: April 2021

ABSTRACT
The effects of sudden cooling of the spinal cord were studied in three species of amphibians – a cold-sensitive tropical toad (Bufo marinus), a cold-resistant, aquatic, hibernating frog (Rana pipiens, northern leopard frog) and a freeze-tolerant frog (Rana sylvatica, wood frog). Ventral root (motoneuron) potentials were recorded from isolated, hemisected spinal cords of each species mounted in a sucrose-gap recording apparatus and superfused with HCO3--buffered Ringer’s solution at room temperature (21 °C).
In the toad, sudden cooling to 6–8 °C produced large, sustained motoneuron depolarizations that returned slowly to baseline levels and were accompanied by extensive paroxysmal activity. Larger, but shorter-lasting, motoneuron depolarizations associated with only a limited amount of paroxysmal activity were generated by rapid cooling of the leopard frog spinal cord. Small, brief motoneuron depolarizations followed by a hyperpolarization, or hyperpolarizations not preceded by depolarizations, were seen in cooled wood frog spinal cords. The wood frog displayed a large amount of spontaneous motoneuron activity, but little paroxysmal activity in response to sudden cooling. Following prolonged cooling, rewarming the spinal cords of all three species resulted in motoneuron hyperpolarizations that slowly decayed towards the baseline value. The amplitude of the rewarming-induced response was larger and longer in toad motoneurons than in leopard frog and wood frog motoneurons. At room temperature, a single supramaximal dorsal root stimulus evoked a depolarizing ventral root potential in toad and leopard frog motoneurons that was decreased in amplitude and prolonged when the spinal cords were cooled to 8 °C or below. In contrast, at room temperature, the ventral root reflex in the wood frog was followed by a distinct hyperpolarization. Cooling the wood frog spinal cord only slightly reduced the amplitude of the ventral root potential. In contrast, the evoked hyperpolarization was blocked by sudden cooling and also by the addition of dihydro-ouabain to the Ringer’s solution. The motoneuron hyperpolarizations induced by sudden cooling in the wood frog were converted to depolarizations when Cl- in the superfusate was replaced with isethionate. The depolarizations elicited by sudden cooling were reduced by the addition of kynurenate in all three species. A dose–response curve generated by short applications of L-glutamate demonstrated that wood frog motoneurons were less sensitive than leopard frog motoneurons to L-glutamate.
In summary, three species of amphibians, differing in their adaptations to the temperature of their environments, vary in their responses to sudden reductions in temperature. The relationship of these responses to their environmental adaptations remains to be determined.
The Mode Of ATP-Dependent Microtubule–Kinesin Sliding In The Auxotonic Condition
Authors: Shirakawa I. , Oiwa K. , Chaen S. , Shimizu T. , Tanaka H. , Sugi H. 
Published: April 2021

ABSTRACT
Kinesin is a motor protein that converts chemical energy derived from ATP hydrolysis into mechanical work to transport cellular components along microtubules. We studied the properties of ATP-dependent microtubule– kinesin sliding with two different in vitro assay systems. In one assay system, a kinesin-coated glass microneedle (elastic coefficient, 1–2.5 pN μm−1) was made to slide along an axoneme. Using this system, we obtained the relationship between the force (=load) on the microneedle and the velocity of microneedle–kinesin sliding in the auxotonic condition, in which the load on the microtubule–kinesin contacts increased as sliding progressed. The force–velocity curve was upwardly convex (maximum velocity Vmax, 0.58±0.15 μm s−1; maximum isometric force P0, 5.0±1.6 pN) and was similar to that of in vitro actin–myosin sliding in the auxotonic condition, suggesting that the two motor protein systems have fundamental kinetic properties in common. In the other assay system, an axoneme attached to a glass microneedle (elastic coefficient, 4–5 pN μm−1) was made to slide on a kinesin-coated glass surface (Vmax, 0.68±0.17 μm s−1; P0, 46.1±18.6 pN). The change in shape of the axoneme indicated an enormous flexibility of randomly oriented kinesin molecules.
The Wind-Evoked Escape Behavior of the Cricket Gryllus Bimaculatus: Integration of Behavioral Elements
Authors: Tauber Eran , Camhi Jeffrey M. 
Published: April 2021

ABSTRACT
The wind-evoked escape behavior of freely ranging crickets (Gryllus bimaculatus) was studied using high-speed video and film analysis. The escape response can be of three types: a turn, a jump or a turn + jump. Any of these can be followed by running.
The turn is similar to that of the cockroach, in terms of the details of body and leg movements. A jump occurs only when the cricket has its back to the wind, either because the stimulus came approximately from behind or because the cricket had first turned away from the wind and then jumped.
The jump, like that of locust, requires some form of energy storage and quick release to obtain the necessary power. Locusts use long-term co-activation of antagonistic leg motor neurons to produce mechanical energy storage. By contrast, crickets do not appear to co-activate antagonistic leg motor neurons. Possible alternative energy storage and release mechanisms are discussed.
Dynamic Properties of Orientation to Turbulent air Current by Walking Carrion Beetles
Authors: Böhm Hartmut 
Published: April 2021

ABSTRACT
A beetle orients its walk with respect to the direction of even a brief air current lasting only a few seconds. In a discontinuous current, the degree of orientation increases with the proportion of time during which the air flows. In the absence of wind, a walking beetle generates its own opposing airstream, the velocity of which is rhythmically modulated.
Sinusoidal modulation of the wind direction elicits approximately sinusoidal changes in walking direction. The amplitude of the following response at frequencies below 0.1 s−1 is almost as large as the amplitude of the change in wind direction. As the stimulus frequency increases, the response amplitude decreases. The Bode plot shows that at frequencies above 1 s−1 the phase of the following response lags by almost 360°.
The dynamic temporal behaviour of the wind-orientation system is comparable with that of a control mechanism having low-pass characteristics of at least second order. It follows that rapid changes in wind direction do not immediately affect orientation behaviour. The wind-orientation system is thus well adapted to the air currents recorded in nature which, at the level of a walking beetle, can change very quickly and erratically in both direction and velocity.
Visual Navigation in Insects: Coupling of Egocentric and Geocentric Information
Authors: Wehner Rüdiger , Michel Barbara , Antonsen Per 
Published: April 2021

ABSTRACT
Social hymenopterans such as bees and ants are central-place foragers; they regularly depart from and return to fixed positions in their environment. In returning to the starting point of their foraging excursion or to any other point, they could resort to two fundamentally different ways of navigation by using either egocentric or geocentric systems of reference. In the first case, they would rely on information continuously collected en route (path integration, dead reckoning), i.e. integrate all angles steered and all distances covered into a mean home vector. In the second case, they are expected, at least by some authors, to use a map-based system of navigation, i.e. to obtain positional information by virtue of the spatial position they occupy within a larger environmental framework.
In bees and ants, path integration employing a skylight compass is the predominant mechanism of navigation, but geocentred landmark-based information is used as well. This information is obtained while the animal is dead-reckoning and, hence, added to the vector course. For example, the image of the horizon skyline surrounding the nest entrance is retinotopically stored while the animal approaches the goal along its vector course. As shown in desert ants (genus Cataglyphis), there is neither interocular nor intraocular transfer of landmark information. Furthermore, this retinotopically fixed, and hence egocentred, neural snapshot is linked to an external (geocentred) system of reference.
In this way, geocentred information might more and more complement and potentially even supersede the egocentred information provided by the path-integration system. In competition experiments, however, Cataglyphis never frees itself of its homeward-bound vector – its safety-line, so to speak – by which it is always linked to home. Vector information can also be transferred to a longer-lasting (higher-order) memory. There is no need to invoke the concept of the mental analogue of a topographic map – a metric map – assembled by the insect navigator. The flexible use of vectors, snapshots and landmark-based routes suffices to interpret the insect’s behaviour.
The cognitive-map approach in particular, and the representational paradigm in general, are discussed.
Distance Estimation by Foraging Honeybees
Authors: Esch Harald E. , Burns John E. 
Published: April 2021

ABSTRACT
Honeybees are widely believed to assess feeder distances by the energy spent on foraging flights. However, a critical review of this ‘energy hypothesis’ reveals many inconsistencies in the experiments from which it was derived. In fact, new evidence shows that the energy hypothesis cannot be correct. Foragers loaded with weights do not overestimate distance, as indicated by their waggle dances performed upon return to the hive. Bees that climb to a feeder on top of a high building (50 m) signal the same distance as hive mates that visit an equidistant feeder at ground level. Foragers visiting a feeder suspended from a balloon at 70 m from their hive underestimate the distance flown dramatically when the balloon lifts the feeder from ground level to 90 m, even though the energy required to reach the feeder increases considerably. Foragers from a hive situated on a high building (50 m) that fly to a feeder on the roof of another high building (34 m) signal a much shorter distance than the actual distance flown. We propose instead an ‘optical flow hypothesis’: bees use the speed of retinal image motion perceived from the ground to estimate the distance flown. Flight altitude is important for distance estimation by retinal image flow, because objects move faster and farther across the retina when the bee flies closer to the ground. When the forager’s flight behavior is considered, the optical flow hypothesis does not conflict with previous findings.
Landmark Stability: Studies Exploring Whether the Perceived Stability of the Environment Influences Spatial Representation
Authors: Biegler Robert , Morris Richard G. M. 
Published: April 2021

ABSTRACT
To investigate whether spatial learning complies with associative learning theories or with theories of cognitive mapping, rats were trained in three experiments exploring the effect of variations in spatial predictive relationships.
In experiment 1, it was found that making one of two landmarks the sole spatial predictor of reward, by varying the spatial relationship between reward and other cues, reduced the control over search exerted by that landmark compared with that observed when the landmark and context cues were both reliable predictors of reward location. This requirement for landmark stability rather than predictive power appears to contradict results obtained in conventional conditioning paradigms. Discrimination learning was unaffected, suggesting a dissociation between discrimination and spatial learning with respect to the influence of geometric stability. Further experiments used arrays of both single and multiple landmarks. Experiment 2 revealed that the stability of a single landmark improved accuracy of search, but also showed that local stability between a pair of landmarks that moved around the arena together was sufficient to support spatial learning. Experiment 3 examined landmark stability using fixed directional cues in the absence of vestibular disorientation. This also revealed a relative advantage of stable landmarks, but animals presented with a landmark that moved from trial to trial did show some evidence of learning.
Parametric manipulation of landmark stability offers an intriguing way of influencing the process of spatial representation and thus understanding better the processes through which egocentric representations of perceived space are transformed into allocentric representations of the real world.