bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physiology and Behaviour of Free-Swimming Atlantic COD (Gadus Morhua) Facing Fluctuating Salinity and Oxygenation Conditions
Authors: Claireaux G. , Webber D. M. , Kerr S. R. , Boutilier R. G. 
Published: April 2021

ABSTRACT
Atlantic cod (Gadus morhua L.) acclimated to a temperature of 5 °C and 30 ‰ salinity were equipped with ultrasonic transmitters which allowed continuous monitoring of their heart rate and their position in the water column. Fish were placed in a 125 m3 tower tank which permitted various environmentally relevant modifications of the salinity and oxygenation conditions. Cod physiological and behavioural responses were followed in parallel to the environmental manipulations. Some of the experimental conditions studied in the tower tank were also reproduced in a swimming respirometer where fish oxygen consumption and heart rate were monitored at various levels of activity. Lowering salinity from 30 to 26 ‰ did not change resting oxygen consumption, but increased active oxygen consumption. Lowering salinity from 30 to 26 ‰ increased heart rate over the whole range of swimming speeds except at maximum speed. Lowering oxygen tension to 9 kPa decreased oxygen consumption over the whole range of swimming speeds and decreased resting heart rate. Low salinity did not significantly affect the relationship between heart rate and oxygen consumption. Low oxygen levels decreased the oxygen transported per heart beat. In the tower tank, bursts of activity were associated with tachycardias. In uniform conditions, fish swam more deeply during the day than at night. After an exploratory period of approximately 6 h, fish chose to remain in a low-salinity upper layer of the tank. Thereafter, high salinities were avoided. Fish tended to select low salinities if a choice was provided. Fish generally avoided zones of low oxygen (&lt;9 kPa) but continued voluntarily to enter regions with values as low as 3.0 kPa for short excursions or if food was offered.
Peptide F1, an N-Terminally Extended Analog of Fmrfamide, Enhances Contractile Activity in Multiple Target Tissues in Lobster
Authors: Worden Mary Kate , Kravitz Edward A. , Goy Michael F. 
Published: April 2021

ABSTRACT
The physiological actions of lobster peptide F1 (TNRNFLRFamide) have been examined on three different lobster nerve-muscle preparations (exoskeletal, cardiac and visceral). The peptide, which is found at high concentrations in a lobster neurosecretory gland, causes a long-lasting enhancement of contractility in each target tissue. On exoskeletal nerve-muscle preparations, peptide F1 has the following actions: (1) it potentiates transmitter release from nerve terminals innervating exoskeletal muscle, leading to an increase in both spontaneous and nerve-evoked release of transmitter; (2) it acts directly on the muscle, in the absence of nerve activity, to induce tonic contractions; and (3) it shows a potent desensitization that does not reverse with prolonged washing of the tissue. On each of the types of muscle examined, peptide F1 is active at nanomolar concentrations and is 3–4 orders of magnitude more potent than FMRFamide. These findings suggest that peptide F1 is a neurohormone with widespread myogenic actions throughout lobster peripheral tissues. The molecular mechanism(s) by which the peptide acts are not yet known, but do not appear to involve cyclic AMP or cyclic GMP.
Visual Distance Discrimination Between Stationary Targets in Praying Mantis: an Index of the Use of Motion Parallax
Authors: Poteser Michael , Kral Karl 
Published: April 2021

ABSTRACT
When larvae of the praying mantis Polyspilota sp. and Tenodera sinensis want to leave an exposed position and can choose to move between stationary objects at different distances, they usually choose the nearest. Their ability to select the nearest object is greatest when the background has horizontal stripes and is least when it has vertical stripes. Object preference is based on a successive distance comparison, which may involve content-related memory processes. Mantid larvae can determine the absolute distance to a stationary object. Vertical contrasting borders play an important role in this process. Side-to-side head movements (peering) are directly involved in the distance measurement, as shown (i) by the peering behaviour itself and (ii) by the fact that mantids can be deceived in distance measurement by arbitrary movements of target objects during the peering movement. It is supposed that the distance measurement involves the larger and faster retinal image shifts that near, as opposed to more distant, objects evoke. Mantid larvae can distinguish a black-and-white rectangle in the foreground from a black-and-white striped background, even when both are similar with respect to luminance, contrast and texture. The ability to distinguish between figures and background could be explained by motion parallaxes, i.e. by the fact that during peering movements the nearer object moves faster and by a larger angle than the background structure. From birth onwards, even when the eyes have yet to develop foveal specialization, mantids are capable of this visually controlled behaviour.
Dependence of Flight Behavior and Heat Production on air Temperature in the Green Darner Dragonfly Anax Junius (Odonata: Aeshnidae)
Authors: May Michael L. 
Published: April 2021

ABSTRACT
The large, endothermic dragonfly Anax junius regulates the temperatures of its thorax (Tth ) and head (Th ) during flight. At high ambient temperature (Ta ) it is able to dispose of excess heat from the thorax by increasing hemolymph circulation to the abdomen, but recent evidence suggests that heat loss to the abdomen is largely passive at Ta &lt;30 ˚C. Nevertheless, these insects continue to regulate Tth and Th at least down to 20 ˚C and probably at much lower values of Ta . As Ta declines, A. junius glide less, probably fly faster when feeding, and increase their wingbeat frequency when patrolling. Presumably as a result of these behavioral changes, heat production, and thus inferred flight metabolic rate, is inversely proportional to Ta . This is the first demonstration based on field data that an insect regulates body temperature while flying by altering heat production.
The Structure, Response Properties and Development of a Hair Plate on the Mesothoracic Leg of the Locust
Authors: Newland Philip L. , Watkins Branwen , Emptage Nigel J. , Nagayama Toshiki 
Published: April 2021

ABSTRACT
A hair plate is present on the proximal anterior face of the pro-and mesothoracic tibiae of the legs of the locust Schistocerca gregaria, but not on the metathoracic legs. The hair plate is in a depression of the cuticle and contains about 11 hairs, which are all polarised with their tips pointing towards the dorsal surface of the tibia. The hairs are all of the same trichoid sensilla type and vary in length from 90 to 140 µm. Associated with the hair plate is a pronounced distal extension of the anterior femoral coverplate, the inner face of which is concave, that makes contact with the hairs during flexion and extension movements of the tibia. During postembryonic development, no tibial hair plate hairs are present in the first four larval stages. In fifth-instar larvae just three hairs are present, while the full complement is attained only after the final moult to adulthood. The distal extension of the posterior coverplate is present through all instar stages, becoming more pronounced after each moult.
Sensory neurones innervating the hairs of an adult may be divided into two classes on the basis of their responses. The first type responds phasically to imposed deflections and is velocity-sensitive. The second type responds phasotonically and is also sensitive to the velocity of the stimulus but has an additional tonic component sensitive to maintained angular deflections. Both types of afferents are directionally sensitive and respond best to deflections against the natural bend of the hair, equivalent to extension movements of the tibia. The hairs are deflected by the coverplate only at femoro-tibial angles of less than 90 ˚. During extension movements, they will be deflected in their most sensitive directions while during flexion movements they will be deflected in their least sensitive directions.
Maximum single leg force production: cockroaches righting on photoelastic gelatin
Authors: Full R. J. , Yamauchi A. , Jindrich D. L. 
Published: April 2021

ABSTRACT
Integrating studies of mechanics, neural control and isolated muscle function are possible using arthropod legs. To evaluate leg performance, we measured the ground reaction forces generated by individual legs of the six-legged cockroach Blaberus discoidalis (3.1 g), during an emergency behavior, righting or over-turning. We used a photoelastic method to measure the forces generated by individual legs simultaneously. A gelatin track placed between crossed polarizing filters was illuminated from below, and a high-speed video camera recorded the stress-induced optical signals from above. The size and skew of the optical patterns were found to be related to the magnitude and direction of the force. We discovered that the ground reaction forces generated during the righting behavior of the death-head cockroach were eight times greater than those observed during high-speed running, supporting the possibility that relative leg forces (leg force per unit body weight) during running and maximal leg activity differ more in small arthropods than in larger vertebrates. Non-geometric scaling of relative leg force (i.e. scaling to less than body mass-0.33), along with the reduced force-generating ability of a single leg in animals with many legs, may help to explain why the maximum relative leg force production by six-legged cockroaches, as well as by some other small insects, can be similar to the relative single leg forces produced by two-and four-legged vertebrates that are almost 1000 times more massive. Leg number and body mass alone, however, appear to be insufficient to explain the variation observed in relative leg force production at a given body mass, because enormous diversity in musculo-skeletal parameters exists. The maximal relative leg force of the cockroach B. discoidalis during righting was at the low end of a 100-fold variation observed for smaller insects wedging (pushing through a small crevice) and pulling loads. Thus, this cockroach can be characterized as a moderately strong insect with the capacity for relatively high speed. Results from the present study question the predictive strength of the simple geometric scaling arguments involving a strength:weight ratio as they are applied to small arthropods and encourage further consideration of the importance of leg number, muscle force production and mechanical advantage in the derivation of general principles of leg performance.
The effects of softwater acclimation on respiratory gas transfer in the rainbow trout Oncorhynchus mykiss
Authors: Greco Anna Maria , Gilmour Kathleen M. , Fenwick James C. , Perry Steve F. 
Published: April 2021

ABSTRACT
Gill O2 uptake, CO2 excretion, ventilation and blood respiratory/acid–base variables were evaluated in control and softwater-acclimated trout (Oncorhynchus mykiss) to test the hypothesis that gill chloride cell (CC) proliferation, elicited by 2 weeks of softwater exposure, impairs the diffusion of respiratory gases across the gill. The proliferation of CCs in softwater fish was verified using light microscopy, and its impact on respiratory gas transfer was assessed in vivo by continuous monitoring of arterial blood and pH (pHa) using an extracorporeal blood circulation under conditions of normoxia and graded hypoxia [water was lowered from 20.0 kPa to 5.3 kPa within 20 min].
During normoxia, ventilation frequency was significantly higher in the softwater trout (78±4 versus 57±4 breaths min-1; mean ± S.E.M.), while ventilation amplitude was similar in both groups (1.0–1.1 cm opercular displacement). and plasma HCO3- concentration were significantly lower in the softwater fish and the blood acid–base status was characterized by a mixed respiratory alkalosis and metabolic acidosis such that blood pH was not statistically different between the two groups. CO2 excretion (2.5–2.8 mmol kg-1 h-1) and O2 uptake rates (2.3–5.1 mmol kg-1 h-1), as measured during normoxia, were unaffected by acclimation to soft water.
During hypoxia, ventilation frequency and amplitude increased in the control trout, whereas only ventilation amplitude increased in the softwater-acclimated fish. The rate of reduction during hypoxia was significantly greater in the softwater fish (0.84±0.06 versus 0.65±0.06 kPa kPa-1 ) and, at the most severe level of hypoxia , was significantly lower in the softwater fish. The rate of reduction (caused by hyperventilation) was significantly lower in the softwater-acclimated fish (0.002±0.001 versus 0.005±0.001 kPa kPa-1 ; mean ± S.E.M.; P&lt;0.06) and, indeed, was not statistically different from zero. Blood pH did not change significantly during hypoxia in either group but, through much of the hypoxic period (7–15 kPa ), pHa was statistically lower in the softwater-acclimated fish.
These results demonstrate that exposure of trout to soft water for 2 weeks is associated with proliferation of lamellar CCs and impaired branchial gas transfer. Hyperventilation was identified as a compensatory physiological adjustment.
Parasympathetic Influence on Heart Rate in Euthermic and Hibernating Ground Squirrels
Authors: Harris Michael B. , Milsom William K. 
Published: April 2021

ABSTRACT
The relative role of the parasympathetic nervous system during deep hibernation is enigmatic. Conflicting hypotheses exist, and both sides draw support from investigations of vagal influence on the heart. Recent studies have shown cardiac chronotropic and inotropic effects of parasympathetic stimulation and inhibition in isolated hearts and anesthetized animals at hibernating body temperatures. No studies, however, have demonstrated such occurrences in undisturbed deeply hibernating animals. The present study documents respiratory-related alterations in heart rate during euthermia and hibernation at ambient temperatures of 15, 10 and 5°C mediated by parasympathetic influence.
During quiet wakefulness, euthermic squirrels breathed continuously and exhibited a 29% acceleration in heart rate during inspiration. During deep undisturbed hibernation, at 15, 10 and 5°C ambient temperature, animals exhibited an episodic breathing pattern and body temperatures were slightly above ambient temperature. At each temperature, heart rate during the respiratory episode was greater than that during the apnea. The magnitude of this ventilatory tachycardia decreased with ambient temperature, being 108% at 15°C, 32% at 10°C and 11.5% at 5°C. Animals exposed to 3% CO2 at 5°C, which significantly increased ventilation, still exhibited an 11.7% increase in heart rate during breathing. Thus, the magnitude of the ventilation tachycardia was independent of the level of ventilation, at least over the range studied. Inhibition of vagus nerve conduction at 5°C was achieved using localized nerve block. This led to an increase in apneic heart rate and abolished the ventilatory tachycardia. The results of this study indicate that vagal projections are involved in cardiorespiratory control during deep hibernation, i.e. that parasympathetic tone is still present and is involved in homeostatic regulation during hibernation.
Active Calcium Transport in the Skin of the Frog Rana Pipiens: Kinetics and Seasonal Rhythms
Authors: Stiffler Daniel F. 
Published: April 2021

ABSTRACT
The frog Rana pipiens takes up Ca2+ against an electrochemical gradient from dilute external solutions that are similar to natural freshwater environments. The influx is dependent upon external [Ca2+] and is saturable. Kinetic analysis yielded a Km of 0.625 mmol l−1 and a Jmax of 38 nmol cm−2 h−1. These kinetic variables suggest that both the affinity and capacity are smaller than those for Na+ and Cl− transport in the skin of the same species. They are also smaller than those for Ca2+ transport in fish gill. A significant portion (20–25%) of the Ca2+ entering a frog remains in Ca2+-rich layers of the skin, with ventral skin containing about three times as much Ca2+ as dorsal skin. There are seasonal rhythms in Ca2+ exchange: although Ca2+ influx does not vary significantly over the year, efflux is minimal in July, while net flux, which is negative most of the year, appears to be positive in July. Since these fluxes do not include dietary calcium, one cannot conclude that feeding frogs are in negative Ca2+ balance.
Regulation of Na+/H+ Antiporter in Trout Red Blood Cells
Authors: Malapert Murielle , Guizouarn Helene , Fievet Bruno , Jahns Roland , Garcia-Romeu Federico , Motais Rene , Borgese Franck 
Published: April 2021

ABSTRACT
The trout red blood cell Na+/H+ antiporter (βNHE) displays two interesting properties: it is the only NHE known to be activated by cyclic AMP, and the activation process is followed by a desensitisation of the transport system itself.
Cloning and expression of βNHE have provided significant information about Na+/H+ activation, in particular that activation by cyclic AMP is directly dependent upon the presence of two protein kinase A consensus sites in the cytoplasmic tail of the antiporter. Expression of βNHE in fibroblasts demonstrates that the protein kinase A (PKA) and protein kinase C (PKC) activation pathways are independent and do not converge on a common kinase. Moreover, the hydrophilic C-terminal fragment is essential to the mediation of the various hormonal responses. NHE1 (the human ubiquitous isoform) is not activated by cyclic AMP, but a ‘NHE1 transmembrane domain/βNHE cytoplasmic domain’ chimera is fully activated by cyclic AMP.
In red cells, activation of βNHE is the result of phosphorylation by PKA of at least two independent sites. Desensitisation, inhibited by the phosphatase inhibitor okadaic acid, may consist of the dephosphorylation of one of these two sites. Furthermore, Calyculin A (ClA), another specific protein phosphatase inhibitor, induces in unstimulated cells a Na+/H+ exchange activity whose exchange properties are very different from those of the adrenergically stimulated antiporter. It is suggested that ClA may be able to revive ‘sequestered’ antiporters.
We propose that the molecular events underlying βNHE desensitisation could be similar to those involved in rhodopsin desensitisation. Antibodies were generated against trout red cell arrestin in order to analyse the binding of arrestin to the activated exchanger. Recombinant trout arrestin was produced in a protease-deficient strain of Escherichia coli and its functionality tested in a reconstituted rhodopsin assay.
The Role of Glutamate Transporters in Glutamate Homeostasis in the Brain
Authors: Takahashi Michiko , Billups Brian , Rossi David , Sarantis Monique , Hamann Martine , Attwell David 
Published: April 2021

ABSTRACT
Glutamate transporters in neurones and glia, four of which have been cloned from mammals, play a crucial role in controlling the extracellular glutamate concentration in the brain. In normal conditions, they remove glutamate from the extracellular space and thereby help to terminate glutamatergic synaptic transmission and to prevent the extracellular glutamate concentration from rising to neurotoxic values. Glutamate transport on these carriers is thought to be driven by the cotransport of Na+, the counter-transport of K+, and either the cotransport of H+ or the counter-transport of OH−. Activating the transporters also activates an anion conductance in their structure, the anion flux through which is not coupled to glutamate movement and varies widely for the different transporters. During hypoxia or ischaemia, glutamate transporters can run backwards, releasing glutamate into the extracellular space, triggering the death of neurones and thus causing mental and physical handicap. The rate of glutamate release by this process is slowed by the acid pH occurring in hypoxia/ischaemia, which may help protect the brain during transient, but not sustained, ischaemia.
The Role of Antennal Sensory Cues in Female Responses to Courting Males in the Cricket Teleogryllus Oceanicus
Authors: Balakrishnan Rohini , Pollack Gerald S. 
Published: April 2021

ABSTRACT
Courtship communication in the field cricket Teleogryllus oceanicus is multimodal, involving a minimum of both acoustic and chemical cues. The acoustic signal, or courtship song, is necessary to elicit normal levels of female mounting of the male during courtship. Antennal input is also crucial since antennectomized females show highly reduced levels of mounting. Immobilization of the scape–pedicel and pedicel–flagellum joints of female antennae had no effect on mounting probability, suggesting that mechanosensory input from chordotonal organs at the base of the antenna is not necessary. The antennal flagellum is a multimodal sensory organ, which contains both mechanoreceptors and chemoreceptors. In order to dissect the roles of different flagellar modalities, we treated antennae with zinc sulphate. This suppressed a well-characterized contact-chemosensory behaviour, initiation of courtship by males, and eliminated responsiveness of most chemosensory hairs as assayed electrophysiologically. Zinc sulphate treatment had no effect on a tactile antennal reflex, indicating that it selectively silenced chemoreceptors. Treatment of antennae with zinc sulphate reduced mounting levels nearly as much as antennectomy, suggesting that the main antennal cue required for the mounting responses is chemosensory, rather than mechanosensory, in nature.
Dragonfly Flight : II. Velocities, Accelerations and Kinematics of Flapping Flight
Authors: Wakeling J. M. , Ellington C. P. 
Published: April 2021

ABSTRACT
The free flapping flight of the dragonfly Sympetrum sanguineum and the damselfly Calopteryx splendens was filmed in a large flight enclosure at 3000 frames s−1. The wingtip kinematics are described for these flights. Despite the two species being similar in size, the damselfly flew with wingbeat frequencies half those of the dragonfly. The damselfly could perform a clap and fling, and the proximity to which the wings approached each other during this manoeuvre correlated with the total force produced during the wingstroke. The dragonfly beat its wings with a set inclination of the stroke planes with respect to the londitudinal body axis; the damselfly, in contrast, showed a greater variation in this angle. Both species aligned their stroke planes to be nearly normal to the direction of the resultant force, the thrust. In order to achieve this, the dragonfly body alignment correlated with the direction of thrust. However, the damselfly body alignment was independent of the thrust direction. Velocities and accelerations were greater for the dragonfly than for the damselfly. However, non-dimensional velocities and accelerations normalised by the wingbeat periods were greater for the damselfly.