bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Hymenopteran Skylight Compass: Matched Filtering and Parallel Coding*
Authors: Wehner Rüdiger 
Published: April 2021

ABSTRACT
In deriving compass information from the pattern of polarized light in the sky (celestial e-vector pattern), hymenopteran insects like bees and ants accomplish a truly formidable task. Theoretically, one could solve the task by going back to first principles and using spherical geometry to compute the exact position of the sun from single patches of polarized skylight. The insect, however, does not resort to such computationally demanding solutions. Instead, during its evolutionary history, it has incorporated the fundamental spatial properties of the celestial pattern of polarization in the very periphery of its nervous system, the photoreceptor layer. There, in a specialized part of the retina (POL area), the analyser (microvillar) directions of the photoreceptors are arranged in a way that mimics the e-vector pattern in the sky (matched filtering). When scanning the sky, i.e. sweeping its matched array of analysers across the celestial e-vector pattern, the insect experiences peak responses of summed receptor outputs whenever it is aligned with the symmetry plane of the sky, which includes the solar meridian, the perpendicular from the sun to the horizon. Hence, the insect uses polarized skylight merely as a means of determining the symmetry plane of the polarization pattern, and must resort to other visual subsystems to deal with the remaining aspects of the compass problem (parallel coding).
The more general message to be derived from these results is that in small brains sensory coding consists of adapting the peripheral rather than the central networks of the brain to the functional properties of the particular task to be solved. The matched peripheral networks translate the sensory information needed for performing a particular mode of behaviour into a neuronal code that can easily be understood by well-established, unspecialized central circuits. This principle of sensory coding implies that the peripheral parts of the nervous system exhibit higher evolutionary plasticity than the more central ones. Furthermore, it is reminiscent of what one observes at the cellular level of information processing, where the membrane-bound receptor molecules are specialized for particular molecular signals, but the subsequent molecular events are not.
Frameworks of analysis for the neural representation of animate objects and actions
Authors: Perrett D. I. , Harries M. H. , Bevan R. , Thomas S. , Benson P. J. , Mistlin A. J. , Chitty A. J. , Hietanen J. K. , Ortega J. E. 
Published: April 2021

ABSTRACT
A variety of cell types exist in the temporal cortex providing high-level visual descriptions of bodies and their movements. We have investigated the sensitivity of such cells to different viewing conditions to determine the frame(s) of reference utilized in processing. The responses of the majority of cells in the upper bank of the superior temporal sulcus (areas TPO and PGa) found to be sensitive to static and dynamic information about the body were selective for one perspective view (e.g. right profile, reaching right or walking left). These cells can be considered to provide viewer-centred descriptions because they depend on the observer’s vantage point. Viewer-centred descriptions could be used in guiding behaviour. They could also be used as an intermediate step for establishing view-independent responses of other cell types which responded to many or all perspective views selectively of the same object (e.g. head) or movement. These cells have the properties of object-centred descriptions, where the object viewed provides the frame of reference for describing the disposition of object parts and movements (e.g. head on top of shoulders, reaching across the body, walking forward ‘following the nose’). For some cells in the lower bank of the superior temporal sulcus (area TEa) the responses to body movements were related to the object or goal of the movements (e.g. reaching for or walking towards a specific place). This goal-centred sensitivity to interaction allowed the cells to be selectively activated in situations where human subjects would attribute causal and intentional relationships.
A Study of Diffusional Permeability of Water, Sodium and Chloride in Yolk-Sac Larvae of Cod (Gadus Morhua L.)
Authors: Tytler Peter , Bell Michael V. 
Published: April 2021

ABSTRACT
The fluxes of 3H2O, 22Na and 36Cl were simultaneously measured in yolk-sac larvae of cod (Gadus morhua L.) in 34 %o sea water at 4·5 °C. The rates of turnover of all three isotopes were higher than in adult fish. Diffusional permeability coefficients, which relate ion fluxes to surface area, were however lower, indicating that larvae are less permeable than adults. Furthermore, there is close agreement between the diffusional and osmotic permeability coefficients, which supports a previous hypothesis that relatively low drinking rates in marine fish larvae are a consequence of low integumental permeability. Estimates of the sodium and chloride concentrations derived from the equilibrium levels of 22Na, 36Cl and 3H2O indicate that yolk-sac larvae of cod regulate their body fluids hypotonic to sea water. Also, the ionic concentrations of the tissues of yolk-sac cod larvae are similar to those of adults.
Adaptational Responses of Rainbow Trout to Lowered External Nacl Concentration: Contribution of the Branchial Chloride Cell
Authors: Perry Steve F. , Laurent Pierre 
Published: April 2021

ABSTRACTWhole-body ionic fluxes and gill chloride cell (CC) morphology were monitored in rainbow trout (Salmo gairdneri) exposed acutely or chronically to natural fresh water (NFW; [Na+]=0·120 mmol l−1; [Cl−]=0·164 mmol l−1) or artificially prepared fresh water with reduced [NaCl] (AFW; [Na+]=0·017 mmoll−1; [Cl−]=0·014mmoll−1). Net fluxes of Na+ and Cl− became extremely negative (indicating net NaCl loss to the environment) upon immediate exposure to AFW exclusively as a result of reduced NaCl influx ( and ) and were gradually restored to control rates during prolonged (30 days) exposure to AFW. The restoration of in AFW was due both to increased and to reduced Cl− efflux , whereas the primary response contributing to the restoration of was an increase of . The total apical surface area of branchial CCs exposed to the external environment increased markedly after 24 h in AFW and remained elevated for 1 month as a consequence of enlargement of individual CCs and, to a lesser extent, increased CC density. and were correlated significantly with total CC apical surface area. Plasma cortisol levels rose transiently in fish exposed to AFW. Treatment of NFW-adapted fish with cortisol for 10 days (a protocol known to cause CC proliferation) caused pronounced increases in and as measured in both NFW and AFW. These results suggest that an important adaptational response of rainbow trout to low environmental [NaCl] is cortisol-mediated enlargement of branchial epithelial CCs which, in turn, enhances the NaCl-transporting capacity of the gill as a result of the proliferation of Na+ and Cl− transport sites.
Temporal Changes in the Quality of the Song of a Bush Cricket
Authors: Hartley J. C. , Stephen R. O. 
Published: April 2021

ABSTRACT
The first songs produced by newly adult Poecilimon schmidti (Fieber) are shown to be composed of pure tone bursts. At this time the file is in its pristine condition. After a week of stridulatory activity the songs of the same individual start to be contaminated with anharmonic components, arising from wear damage that occurs to the file teeth and plectrum. The disruption of the pure tone burst adds other elements to the Fourier spectra so that they now become difficult to interpret. The number of plectrum-tooth impacts, normally 2–5, also varies with ageing. Although females responded well to old males there is a possibility that the change in song quality would enable the female to discriminate between males.
The temperature dependence of the time course of growth and decay of miniature end-plate currents in carp extraocular muscle following thermal acclimation
Authors: Harper A. A. , Shelton J. R. , Watt P. W. 
Published: April 2021

ABSTRACT
The effect of temperature (5–35°C) on the decay and growth phases of miniature end-plate currents (MEPCs) was investigated in extraocular muscle from freshwater carp acclimated to either high (28°C) or low (8°C) temperature. The temperature dependence of the time constant of decay (TD) was found to follow an Arrhenius relationship; the relationship between logTD and reciprocal of absolute temperature (1/K) being linear in both groups. The TD of MEPCs recorded from cold-acclimated carp was not statistically significant from that of the warm group. T D was moderately temperature-dependent. Regression gave a Q10 of 1·78 for the warm-acclimated carp, corresponding to an activation energy, Ea, of 41·15 ± 2·17 kJ mol−1. For the cold-acclimated carp, the Q10 was 1·79, and Ea was 41·43 ±2·46 kJ mol−1. Growth time (TG) was less susceptible than TD to temperature change. The relationship between growth time (taken as the time for MEPCs to rise from 20 to 80% of maximum) and temperature was linear for the cold-acclimated group, with a Q10 of 1·34 and Ea of 20·94 ± 4·75 kJ mol−1. The data for the warm group were, in contrast, best fitted by two linear regressions meeting at 15·1°C. At temperatures below 15·1°C Q10 was 3·16 and Ea was 82·20 ± 15·47 kJ mol−1; above 15 °C, Q10 was 1·22 and Ea was 14·15 ± 12·24 kJ mol−1. The acetylcholinesterase inhibitor neostigmine increased TD by approximately twofold and raised TG to approximately 1·4 times control values. These effects were observed across the temperature range scanned for both groups. The results are discussed with reference to the documented effects of temperature and temperature acclimation on membrane lipids and proteins.
Effects of Changes in Locomotor Intensity, Hypoxia and Hypercapnia on Locomotorrespiratory Synchrony During Walking/Running in Canada Geese
Authors: Funk Gregory D. , Valenzuela Ignacio J. , Sholomenko Geraldc N. , Steeves John D. , Milsom William K. 
Published: April 2021

ABSTRACT
To examine the effects of locomotor frequency and respiratory drive on the incidence of locomotor-respiratory coupling (i.e. entrainment), we examined the relationship between locomotor and ventilatory patterns in trained Canada geese that were: (1) running at three speeds (0·40, 0·52 and 0·72ms-1) on a treadmill, (2) free-running at three velocity intervals (0·40–0·72, 1·0–1·5 and 1·5–2·0ms-1) overground, and (3) breathing hypoxic (12 % O2/l % CO2) and hypercapnic (5 % CO2/30% O2) gas mixtures while running at one speed (0·52ms-1) on the treadmill.
The portion of the time that the locomotor and respiratory systems were coupled was significantly greater during overground locomotion (41·1 ±3·2%) than at comparable speeds on the treadmill (29·0 ±2·6%). In addition, a significant increase in coupling with velocity was only observed during overground locomotion (41·1 ±3·2% at 0·40–0·72ms-1 vs 57·7 ±6·3% at 1·5–2·0ms-1). This increase in entrainment appeared to be the direct result of an increase in locomotor frequency per se and not due to the increase in metabolic rate associated with greater locomotion velocity.
The effects of hypercapnia on the degree of entrainment were unclear owing to inter-animal variability; however, hypoxia caused a substantial decrease in entrainment from air-breathing values (34·8 ± 3·9 %) to levels not different from those possible due to chance alone (20%).
Thus, it appears that locomotor pattern does entrain ventilatory rhythm and that the degree of entrainment is partially dependent on limb movement frequency. However, the increased respiratory drive associated with hypoxia appears to override the influence of locomotor rhythm on respiratory pattern, with a subsequent decrease in entrainment.
An in Vitro Model of Post-Exercise Hepatic Gluconeogenesis in the Gulf Toadfish Opsanus Beta
Authors: Walsh Patrick J. 
Published: April 2021

ABSTRACT
During strenuous exercise, fish develop substantial proton and lactate loads. Although acidosis is usually rapidly corrected during recovery (1–2 h), lactate levels often remain elevated for up to 8–12 h. The quantitative role of the liver in clearance of the lactate load during recovery from exercise in fish has received little direct examination. The purposes of this study were (1) to attempt to quantify hepatic contribution to lactate clearance, and (2) to identify factors that regulate hepatic gluconeogenesis during recovery from exercise in fish. Both in vivo and in vitro (isolated hepatocytes) approaches were used. Important blood parameters (pHe, , [lactate], [glucose], [epinephrine] and [norepinephrine]) were measured in the gulf toadfish (Opsanus beta Goode and Bean) during recovery from strenuous exercise, and they conformed to the general patterns for sluggish benthic species noted in earlier studies. When toadfish hepatocytes were exposed to simulated post-exercise conditions in vitro, gluconeogenesis from lactate was stimulated by over 2·5-fold in ‘0–1 h-’ and ‘l–2h-post-exercise periods’. Variation of the extracellular parameters in controlled combinations indicated that exercise-induced changes in [glucose], [epinephrine], [norepinephrine], and [HCO3−] had no significant effects on rates of gluconeogenesis. The observed stimulation of gluconeogenesis could be induced independently by either decreased pH (which lowered Km for lactate) or increased [lactate] (by simple hyperbolic kinetic effects), but the effects were not additive. Despite this potentially adaptive stimulation of gluconeogenesis, I estimate, based on observed in vitro rates and in vivo estimates of lactate load, that hepatic gluconeogenesis accounts for less than 2 % of the lactate load clearance in toadfish.
Structure and Mechanics of Starfish Body Wall
Authors: O’Neill Patricia 
Published: April 2021

ABSTRACTThe structure of the dorsal body wall of the starfish Echinaster spinulosus was studied using polarized light microscopy of frozen tissues, scanning electron microscopy and histology. The collagen fibres of the body wall form a threedimensional orthogonal web. Voids in the web contain ossicles and papulae. The orthogonal web delivers dimensional stability but allows shear necessary for ray torsion. The ossicles and fibres interact to load the fibres in tension and the ossicles in compression.Strain rates of the dorsal body wall were measured on live animals during typical movements. Uniaxial tension tests of the body wall yielded Young’s moduli of 267MPa (longitudinal), 249MPa (transverse) and 353MPa (bias); curves were essentially linear. The body wall was approximately linearly viscoelastic and showed hysteresis at 0.01 Hz. Stress relaxation over five decades of time (in seconds) yielded relaxation spectra with peaks in relaxation time at 2.96–3.35, depending on test direction. Stress relaxation caused the connective tissue to soften. The surface of fractured stress-relaxed tissue revealed wispy, dissociated fibril tufts, whereas unrelaxed fractures produced blunt-ended fibre bundles. Neural control was necessary for body wall integrity.
Short Communication Power Output from Skeletal Muscle During Linear and Sinusoidal Shortening
Authors: Josephson R. K. 
Published: April 2021

ABSTRACT
Several recent accounts have estimated the maximum sustainable mechanical power available from a skeletal muscle based on measured or assumed force–velocity characteristics of the muscle and the assumption that the muscle, when active, shortens constantly at the velocity that is optimal for power output. Curtin and Woledge (1988) used this approach in estimating how much mechanical power is available from the myotomal muscles of a dogfish to power swimming. The muscles of a fish operate cyclically, shortening and doing work for half a cycle and being lengthened, possibly absorbing work, for the other half-cycle. Curtin and Woledge allowed for the periodic nature of power output by assuming that only half the muscles were active at any time, which is equivalent to assuming that the sustainable power is half the peak power. During swimming, the shape of the trunk of a fish changes sinusoidally with time (Hess and Videler, 1984), and the shortening velocity of a trunk muscle fiber must also vary approximately sinusoidally. Thus shortening velocity cannot be at the optimum velocity for power output through the entire shortening half-cycle: the assumption of shortening at a constant, optimum velocity must overestimate the power output. Weis-Fogh and Alexander (1977) and Pennycuick and Rezende (1984) have also estimated the maximum sustainable power output of muscle based on the assumption of shortening at constant velocity. The principal muscles considered in the latter two studies were flight muscles. For flight muscles, as for swimming muscles, a sinusoidal length trajectory and a sinusoidally varying shortening velocity are more realistic assumptions than a linear length change and a constant velocity of shortening. The following analysis was begun to determine the magnitude of the error that is likely to enter into estimates of power output from the assumption that muscle shortening during normal locomotion is at constant velocity rather than at a velocity which varies sinusoidally with time. It is shown that the assumption of shortening at constant velocity overestimates maximum power output by 20 % or less.
Dactyl Sensory Influences on Rock Lobster Locomotion: II. ROLE IN INTERLEG COORDINATION
Authors: Müller U. W. E. , Clarac François 
Published: April 2021

ABSTRACT
The effects of cyclic electrical stimulation of the dactyl sensory nerve (DN) on the walking pattern of rock lobsters were examined at the two crucial points within the step cycle: the anterior extreme position (AEP) and the posterior extreme position (PEP). Stimulation during the occurrence of the PEP affected neither the movement pattern of the stimulated leg itself nor that of the ipsilateral adjacent legs. Stimulation of the same intensity during the occurrence of the AEP interrupted the oscillation of the stimulated leg and affected the phase relationships of the ipsilateral adjacent legs. The possibility that indirect influences were mediated by coupling to the substratum can be excluded. Neuronal connections may therefore exist between the funnel canal organs (FCO) of a single leg and the motor output of the adjacent legs. The discussion deals with whether the described channels alone are able to fulfil the requirements of a ‘coordinating mechanism’ as described in the literature.
A Peripheral Arterial O2-Sensitive Pathway to the Respiratory Oscillator of the Shore Crab Carcinus Maenas
Authors: Zinebi H. , Simmers J. , Truchot J. P. 
Published: April 2021

ABSTRACT
Experiments on whole crab, Carcinus maenas, as well as on two types of isolated perfused preparations were performed to locate the origin of the O2 chemosensitivity which drives hyperventilation in hypoxia and hypoventilation in hyperoxia.
Electromyographic recordings from the scaphognathite muscles confirmed the existence of strong ventilatory responses in the whole animal exposed to various water oxygen levels. Furthermore, surgical section of the circumoesophageal connectives did not suppress these responses, thereby excluding the cerebral ganglia as the only site or relay for the O2 chemosensitivity.
In semi-isolated preparations in which the thoracic ganglion and anterior arterial system were perfused by saline at various values, extracellular recordings of the motor output in the peripheral ventilatory nerves showed respiratory responses qualitatively similar, but quantitatively weaker, than those observed in the whole animal. These responses were suppressed by bilateral section of the ventilatory nerves or ligation of the anterior sternal artery.
In perfused preparations of the completely isolated thoracic ganglion, respiratory frequency was reduced under hypoxia. This is consistent with a purely metabolic response and excludes a central O2 chemosensitivity at the level of the respiratory oscillator itself.
We conclude that a population of peripheral O2-sensitive chemoreceptors is present within the arterial system in the ventral anterior region, probably around the scaphognathites. These receptors are reversibly stimulated by potassium cyanide, lobeline and almitrine bismesylate, as also are peripheral O2 chemoreceptors in vertebrates.
Mechanics of Forward Flight in Bumblebees: I. Kinematics and Morphology
Authors: Dudley R. , Ellington C. P. 
Published: April 2021

ABSTRACT
Using high-speed cinematography, bumblebees in free flight were filmed over a range of forward airspeeds. A detailed description of the wing tip and body kinematics was obtained from a three-dimensional reconstruction of the twodimensional film image. A technique for determining quantitatively the angle of attack of the wing was developed. Kinematic parameters found to vary consistently with airspeed were body angle, stroke plane angle, geometrical angle of attack, and rotational angles of the wings at the ends of half-strokes. Results of a morphological analysis of the wings and bodies of those insects filmed in free flight are presented for use in later calculations of the lift and power requirements of forward flight.
The Fast Response Mediated by The C3 Motoneurone of Helix is not Attributable to the Contained FMRFamide
Authors: Bewick G. S. , Price D. A. , Cottrell G. A. 
Published: April 2021

ABSTRACT
The C3 neurone of Helix aspersa is known to induce contraction of the ipsilateral tentacle retractor muscle. It is immunoreactive for peptides of the FMRFamide series and immunoreactive FMRFamide nerve fibres occur in the muscle.
Here we found that FMRFamide-like immunoreactivity was released from the isolated muscle following depolarization with high-potassium saline and that such release was calcium-dependent. HPLC characterization of the immunoreactive material in the muscle showed that FMRFamide itself, rather than the other FMRFamide-related peptides known from Helix, accounted for most of the immunoreactivity. Parallel radioimmunoassay (RIA) also showed that FMRFamide predominates in the C3 neurone.
The nicotinic acetylcholine (ACh) receptor antagonists benzoquinonium (10−5mol l−1) and trimetaphan (5×10−5mol l−1) reversibly reduced tension evoked in the muscle by C3 stimulation. These drugs also blocked the muscle response to bath-applied ACh. Physostigmine (5×10−8mol l−1), an acetylcholinesterase antagonist, potentiated the C3-evoked muscle response. Depolarizing excitatory junction potentials recorded in the muscle cells in response to C3 neurone stimulation corresponded 1:1 with action potentials in the C3 neurone. Whereas locally applied ACh evoked a depolarizing response in the muscle fibres, similar to that evoked by C3 neurone activation, locally applied FMRFamide, even at very high doses, did not affect the membrane potential of the muscle cells. Also, exposure of the cerebral ganglia to high-Mg2+/low-Ca2+ saline did not block the C3 neurone-evoked muscle tension. Taken together, these findings indicate that the C3 neurone makes monosynaptic connections with the tentacle retractor muscle cells and that the contraction of the muscle it induces is due, at least in part, to the release of ACh at the neuromuscular junction. The role of the FMRFamide contained in the neurone is not yet clear.