bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acceleration Receptors in the Femoral Chordotonal Organ of the Stick Insect, Cuniculina Impigra
Authors: Hofmann T. , Koch U. T. 
Published: April 2021

ABSTRACT
The femoral chordotonal organ of the stick insect Cuniculina impigra was stimulated by moving its apodeme with staircase-like waveforms having independently controllable acceleration and velocity values. Intracellular recordings were made of receptor units in the sensory nerve. Apart from receptors encoding position and velocity (see preceding paper, Hofmann, Koch & Bassler, 1985) specific acceleration receptors and also receptors responding to both the acceleration and the velocity of the stimulus could be distinguished. The pure acceleration receptors fall into two categories: units reacting only to one sign of acceleration (e.g. onset of relaxation and end of elongation) and units reacting to both signs of accelerations. Individual thresholds for each sign of acceleration were measured and analysed. Latencies of the receptors were determined and found to be dependent on the degree of acceleration.
A possible role for the acceleration receptors in an alarm system of the animal is discussed.
Mechanical Properties Of The Octopus Aorta
Authors: Shadwick Roberte. , Gosline John M. 
Published: April 2021

ABSTRACT
The quasi-static mechanical properties of the aorta of Octopus dofleini were investigated using biaxial inflation and uniaxial force-extension tests on vessel segments in vitro. The octopus aorta is a highly compliant and non-linearly elastic structure. The elastic modulus (i.e. the stiffness) measured circumferentially (Ec) and longitudinally (EL) increased markedly with distension of the vessel wall. Ec was always greater than EL, and varied from about 104 to 2x 105 N m−2 between 2 and 5 kPa pressure respectively, the approximate range of resting blood pressure in this species. Increasing vessel wall stiffness is necessary for the aorta to be compliant at low pressure, and at the same time to be protected from ‘blowout’ at high pressure. The non-linear elasticity of the octopus aorta at physiological pressures can be attributed to the properties of the rubber-like elastic fibres which are present in the vessel wall, with little contribution from stiff collagen fibres being required until very high pressures. Dynamic mechanical properties of the aorta were measured by the method of forced oscillations. The dynamic modulus in the circumferential direction increased continuously to almost twice the static value as the frequency was raised from 0·05 to 10Hz. At the same time, the viscous damping, tan δ, increased from 0·11 to 0·27. The resilience of the octopus aorta was close to 70% at the relevant physiological frequencies. We conclude that this vessel is suitably designed to function as an efficient elastic energy storage component in the octopus circulatory system.
Calcium Absorption by the Midgut of the Blowfly, Calliphora Vicina
Authors: Taylor Colin W. 
Published: April 2021

ABSTRACT
The isolated midgut of the adult blowfly, Calliphora vicina, can be maintained under internal perfusion for over 6h, and calcium absorption measured by including 45Ca in the perfusing saline with [3H] inulin as a volume marker. The midgut has a considerable capacity to transport calcium from the lumen (L) to the bathing saline (BS) against its electro-chemical gradient and in the absence of an appreciable net water flux across the gut. Calcium absorption (L-BS) shows saturation kinetics, is totally and reversibly inhibited by metabolic poisons and is accompanied by a negligible backflux (BS-L). It is concluded that the midgut of C. vicina is capable of active calcium transport and that the entire transepithelial calcium flux occurs via a transcellular route. This contrasts with the mammalian duodenum, where absorption occurs via a combination of transcellular and paracellular routes.
Neuronal Mechanisms Underlying Crayfish Steering Behaviour as an Equilibrium Response
Authors: Takahata M. , Yoshino M. , Hisada M. 
Published: April 2021

ABSTRACT
When the crayfish Procambarus is rolled with legs not upon a substratum, uropod opener muscles on the lifted side are activated in co-contraction whereas antagonistic closer muscles on the same side are all relaxed simultaneously. The closers are activated and the openers are relaxed on the lowered side. This reciprocal pattern is also observed in the motor neurone activity: the contraction of opener muscles on the lifted side and closer muscles on the lowered side is caused by an increase in the activity of excitatory motor neurones innervating these muscles, whereas the relaxation of their antagonists on each side is caused by a decrease in the activity of excitatory motor neurones innervating them. Deafferentation by cutting all roots of the terminal ganglion has no significant effect on the steering pattern. The decrease in the excitatory motor neurone activity during steering was found to be due to an increase in the inhibitory input to the motor neurones. During body rolling, the statocyst receptors on the lifted side increase their activity while those on the lowered side decrease it (Takahata & Hisada, 1979). We conclude that the opener motor neurones receive excitation and inhibition respectively from the ipsilateral and the contralateral statocyst, whereas the closer motor neurones receive excitation and inhibition respectively from the contralateral and ipsilateral statocyst. From these results, the connections between the motor neurones and the identified statocyst interneurones were deduced. The normal, bilaterally organized steering pattern of the uropod muscle activity seems to be produced by the statocysts of both sides, whose information is mediated by a bilateral set of interneurones having different connections to individual motor neurones.
Flight Physiology Of Flying Foxes, Pteropus Poliocephalus
Authors: Carpenter Roger E. 
Published: April 2021

ABSTRACT
Oxygen consumption was measured during flight in two flying foxes (Pteropus poliocephalus) at airspeeds of 4–8·6 ms−1. There was good agreement with the measured power input of the only previously measured large bat, and with an allometric equation predicting power input for flying vertebrates. Measurements of respiratory exchange ratios, pulmonary water loss, respiratory frequencies, heart rates and body temperatures of both bats flying at intermediate airspeeds were compared with equivalent measurements on other bats or birds in flight. Despite a high non-evaporative thermal conductance in flight, the P. poliocephalus became severely hyperthermic at ambient temperatures (Ta) above 25°C. The failure to dissipate heat as successfully as flying birds at high Ta is apparently the result of an inability to increase pulmonary ventilation rates, and thus increase rates of evaporative heat loss.
The effect of airspeed on endurance was measured systematically on one bat. Endurance was not limited by energy reserves at all airspeeds, and flight times were significantly greater at the airspeed of minimum power input (Vmp). The endurance of both bats was so reduced at the higher airspeeds that they would not achieve maximum flight range in still air at the velocity where cost of locomotion is lowest. Contrary to a common assumption, flight range would be maximized at the Vmp.
Urine Clearance Rates and Apparent Permeability of Gammarus Duebeni Exposed to Varying Conditions
Authors: Bolt Stephen R. L. 
Published: April 2021

ABSTRACT
Recent investigations indicate that some species of Crustacea have the ability to alter their apparent permeability to water in order to reduce the osmotic stress placed on the animal (Smith, 1967, 1970, 1976; Bolt, 1982; Lockwood, Bolt & Dawson, 1982). The apparent permeability to water of the amphipod Gammarus duebeni (Lilljeborg) varies dramatically when the animal is subjected to varying, salinity regimes (Lockwood, Inman & Courtenay 1973; Dawson, 1982; Bolt, 1982).
Developmental Determination of Central Connections of Sensory Neurones From Wind-Sensitive Hairs in the Locust, Schistocerca Gregaria
Authors: Bacon Jonathan , Anderson Hilary 
Published: April 2021

ABSTRACT
The nervous system of hemimetabolous insects is a favourable preparation in which to study how sensory neurones form particular projections and connections within the CNS. One reason is that the development of the sensory neurones is physically separate from the development of the CNS; sensory neurones are derived from epidermal cells under the cuticle, in contrast to interneurones and motor neurones which are derived from central neuroblasts. In addition, whereas the CNS has an almost full complement of neurones at the end of embryogenesis, neuroblast division having ceased in all but a few brain centres, sensory neurones continue to be generated from their epidermal precursors throughout the postembryonic life of the animal. Therefore transplanting pieces of epidermis during postembryonic development places sensory neurones in altered environments without surgery to the CNS. Furthermore, since sensory neurone development continues within the transplanted epidermis, the influence of these perturbations can be tested on developing as well as regenerating sensory neurones.
Neuromuscular Transmission in the Jellyfish Aglantha Digitale
Authors: Kerfoot P. A. H. , Mackie G. O. , Meech R. W. , Roberts Alan , Singla C. L. 
Published: April 2021

ABSTRACT
In the jellyfish Aglantha digitale escape swimming is mediated by the nearly synchronous activity of eight giant motor axons which make direct synaptic contact with contractile myoepithelial cells on the under-surface of the body wall. The delay in transmission at these synapses was 0·7 ± 0·1 ms (± S.D. ;N= 6) at 12 °C as measured from intracellular records. Transmission depended on the presence of Ca2+ in the bathing medium. It was not blocked by increasing the level of Mg2+ to 127 mmol 1−1. The myoepithelium is a thin sheet of electrically coupled cells and injection of current at one point was found to depolarize the surrounding cells. The potential change declined with distance from the current source as expected for two-dimensional current spread. The two-dimensional space constant (γ) was 770 μm for current flow in the circular direction and 177 μm for radial flow. The internal resistance of the epithelium (178–201 Ωcm) and the membrane time constant (5–10 ms) were direction independent. No propagated epithelial action potentials were observed. Spontaneous miniature synaptic potentials of similar amplitude and rise-time were recorded intracellularly at distances of up to 1 mm from the motor giant axon. Ultrastructural evidence confirms that neuro-myoepithelial synapses also occur away from the giant axons. It is likely that synaptic sites are widespread in the myoepithelium, probably associated with the lateral motor neurones as well as the giant axons. Local stimulation of lateral motor neurones generally produced contraction in distinct fields. We suppose that stimulation of a single motor giant axon excites a whole population of lateral motor neurones and hence a broad area of the myoepithelium.
Identified Muscle Fibres in a Crab. Differences in Facilitation Properties
Authors: Rathmayer W. , Hammelsbeck M. 
Published: April 2021

ABSTRACT
The superficial muscle fibres in the proximal head of the closer muscle in the crab Eriphia belong to four distinct fibre types (I-IV). By stimulating either the ‘slow’ or the ‘fast’ axon, facilitation properties of the EJPs were investigated in eight identifiable muscle fibres which represented the four fibre types. Amount, time course and frequency dependence of facilitation (f) of both ‘slow’ and ‘fast’ EJPs differed characteristically among the fibres studied, but were similar within fibres belonging to the same type. In fibres receiving double excitatory innervation through the ‘slow’ and the ‘fast’ axon (type I and II fibres), the amount of facilitation of ‘fast’ EJPs was smaller than for ‘slow’ EJPs. With the exception of type I fibres, there was an inverse relationship between facilitation and the size of both ‘slow’ and ‘fast’ EJPs. Facilitation increased with frequency and time of stimulation. In type I fibres, facilitation of ‘slow’ EJPs increased with time at low frequencies of stimulation (up to 32 Hz), but decreased at higher frequencies after an initial rise. ‘Fast’ EJPs in type I fibres showed little, if any, facilitation of frequencies below 8 Hz. At frequencies above 8 Hz, they were always depressed (negative values of f). The functional significance of different facilitation properties is discussed with regard to the participation of different muscle fibre types in the mechanical performance of the closer muscle.
Locomotor Activity of the Terrestrial Slug, Limax Maximus: Response to Progressive Dehydration
Authors: Hess Stephen D. , Prior David J. 
Published: April 2021

ABSTRACT
The circadian locomotor rhythm of the terrestrial slug, Umax maximus, was measured with activity wheels during exposure to both humid and drying conditions. Slugs kept in wet wheels (100% RH) remained fully hydrated while those in dry wheels (&lt;30% RH) experienced progressive dehydration. Transfer of slugs from a wet wheel to a dry wheel resulted in an increase in the intensity and duration of their patterned locomotor activity that persisted for 3 days. Once the slugs were returned to wet wheels, their locomotor activity returned to normal.
Plasticity and Proprioception in Insects II. Modes of Reflex Action of the Locust Metathoracic Femoral Chordotonal OrgAn
Authors: Zill Sasha N. 
Published: April 2021

ABSTRACT
Reflex responses of tibial motoneurones were examined during mechanical stimulation of the femoral chordotonal organ, a joint angle receptor of the locust hindleg. Step displacements of the main ligament of the organ, mimicking 10–15° changes in joint angle, produced different patterns of discharge in motoneurones (1) when the leg was resting against a support and (2) when the support was removed to induce active searching movements.
Tibial motoneurones showed resistance reflex responses to oppose the apparent joint movement when the leg rested against a support. Resistance reflexes consisted of constant, short latency excitatory responses followed by discharges that varied in intensity (gain) and degree of tonic coupling. These variations were not due to simple summation with other inputs to motoneurones.
Responses changed during periods of active searching movements. Tibial flexor motoneurones fired phasically in response to apparent joint movement in any direction. Tibial extensor motoneurones were generally inhibited by chordotonal inputs. These reflex changes are not simple reflex ‘reversals’, but represent more complex changes in reflex mode.
Potential functions of each of these reflex modes and the need for plasticity in reflexes of the chordotonal organ are discussed.
Flight Mechanics of A Dragonfly
Authors: Azuma Akira , Azuma Soichi , Watanabe Isao , Furuta Toyohiko 
Published: April 2021

ABSTRACT
The steady slow climbing flight of a dragonfly, Sympetrum frequens, was filmed and analysed. By using the observed data, the mechanical characteristics of the beating wings were carefully analysed by a simple method based on the momentum theory and the blade element theory, and with a numerical method modified from the local circulation method (LCM), which has been developed for analysing the aerodynamic characteristics of rotary wings.
The results of calculations based on the observed data show that the dragonfly performs low speed flight with ordinary airfoil characteristics, instead of adopting an abnormally large lift coefficient. The observed phase advance of the hindwing, Δ δ1 ≃ 80° can be fully explained by the present theoretical calculation. Similarly, the spanwise variation of the airloading and the time variations of the horizontal force, vertical force, pitching moment and torque or power can be definitely estimated within a reasonable range of accuracy in comparison with the flight data. The distribution of loading between the fore and hind pairs of wings is also clarified by the calculations.
Post-Moult Calcification In The Blue Crab (Callinectes Sapidus): Relationships Between Apparent NET H+ Excretion, Calcium And Bicarbonate
Authors: Cameron James N. 
Published: April 2021

ABSTRACT
In the days immediately after moulting, manipulations of external pH, [HCO3−], and [Ca2+] were used to determine the nature of the rapid net Ca2+ influx and attendant apparent net H+ efflux in the blue crab (Callinectes sapidus Rathbun). Both fluxes were strongly inhibited by reductions in external [Ca2+], [HCO3−], or pH. The net Ca2+ influx was reversed at an external concentration of 2·5 mmol 1−1, and both fluxes were reversed by reducing the external [HCO3−] to 0·2 mmol 1−1. The correlation between net Ca2+ flux and apparent net H+ flux was 0·61 (P &lt; 0·01), but the variability and the time course of most experiments indicated that the link was indirect, rather than a direct coupling or cotransport. This conclusion was also borne out by acid-base disturbances that occurred in the low-[Ca2+] treatment. The results are consistent with the hypothesis that inward calcium transport is accompanied by both inward HCO3− transport and outward H+ transport, probably by separate exchanges with ions of like charge such as Na+ and Cl−. Crustecdysone (β-ecdysone) does not appear to be involved in control of these post-moult fluxes and calcification.
Control Of The Orientation Of Cilia By Atp And Divalent Cations In Triton-Glycerol-Extracted Paramecium Caudatum
Authors: Noguchi Munenori , Inoué Hiroshi , Kubo Kazumi 
Published: April 2021

ABSTRACT
The ciliary responses of Paramecium caudatum, extracted in Triton X-100 and glycerol, to the external application of ATP and various divalent cations were examined. Ciliary beating could not be reactivated, but changes in the pointing direction of the cilia (the reorientation response) could be reactivated. The free Ca2+ concentration determined the final orientation of the cilia, which was towards the front when the Ca2+ concentration was above 10−6moll−1, and towards the rear when below 10−7moll−1. The reorientation response was inhibited by vanadate. These results indicate that the mechanism for the reorientation response is separable into two components. One is the movement of cilia to change their pointing direction, which, like normal ciliary beating, is energized by Mg-ATP2–. The other is the determination of the final pointing direction of the cilia, which is Camdependent. Divalent cations can be classified into two groups according to their mode of action on the Ca2+-dependent component. Sr2+ is an agonist and Baz+, Zn2+ and Co2+ are antagonists to Ca2+ for the component.
Activity of Crayfish Abdominal-Positioning Interneurones During Spontaneous and Sensory-Evoked Movements
Authors: Jellies John , Larimer James L. 
Published: April 2021

ABSTRACT
The premotor interneurones that produce coordinated abdominal movements in crayfish (Procambarus) when stimulated directly, are also ‘sensorimotor’. Sets of these interneurones respond in predictable ways to touching the body surface. One set of interneurones (type I) is activated to spiking by touch, while another (type II) receives only subthreshold influences. Several of these interneurones have overlapping receptive fields on the body surface. Touching areas of overlap activates groups of interneurones which discharge at low to moderate frequencies, rather than producing a high-frequency discharge of a single cell. No single positioning interneurone has been identified which is solely responsible for a ‘voluntary’ (spontaneous) motor programme. When active, the positioning interneurones contribute to the production of the behaviour as a member of a constellation of such cells. The results show that this motor system comprises interneurones with sensory as well as motor properties. Although single cells can produce coordinated movements when stimulated at high frequencies, these positioning interneurones appear to function as ‘command elements’ within a large ‘command system’ and not as individual units.
The Influence Of Blood Gas Properties On Gas Tensions And Ph Of Ventral And Dorsal Aortic Blood In Free-SwimmingTuna, Euthynnus Affinis
Authors: Jones David R. , Brill Richard W. , Mense Dennis C. 
Published: April 2021

ABSTRACT
We have developed a technique for capture, anaesthetization, instrumentation and release of tuna and have made the first determinations of blood gas values in dorsal and ventral aortae of free-swimming tuna. Dorsal aortic varied from 34·5 to 91·7 mmHg, and ranged from 3·7 to 7 mmHg. Dorsal aortic blood [pHa = 7·77 ± 0·04 (8), mean ± one S.E.M. (N)] was more alkaline than ventral aortic blood [pHv = 7·65 ± 0·02 (7)]. Warming dorsal aortic blood from 25 to 35 °C in a closed system caused and to rise and pH to fall. Oxygen-combining curves for whole blood were sigmoid [mean Hill’s number = 1·72 ± 0·05 (11), range 1·57–2·0] and P50 over the pH range found in free-swimming animals was 21 ±1·75 (8) mmHg. The CO2-induced Bohr coefficient (ΔlogP50/Δ pH) was –0·59 ± 0·046 (30). Unusual features of CO2-combining curves are attributed to a significant Root effect. Although these in vitro properties of tuna whole blood are at variance with other published data on tuna they nevertheless substantiate our determinations made in vivo.
Respiratory, Circulatory And Metabolic Adjustments During Swimming In The Tufted Duck, Aythya Fuligula
Authors: Woakes A. J. , Butler P. J. 
Published: April 2021

ABSTRACT
Respiratory, and some cardiovascular and metabolic, variables were measured in tufted ducks swimming at different velocities. There were no substantial changes in any of the measured variables up to a swimming speed of 0·5 m s−1. Above this speed there were progressive increases in heart rate, oxygen uptake and respiratory minute volume. At the middle of the maximum speed range (0·8ms−1) these variables were 1·7 times, 2·7 times, and 3·4 times their resting values respectively. There was, therefore, an excessive increase in ventilation (hyperventilation), compared with the extra demand for oxygen, and this was evident as a significant decrease in oxygen extraction and as a significant fall in in arterial blood.
The possible causes of the hyperventilation are not obvious as there was no hyperthermia and no change in pH of the arterial blood; a 2·3 times increase in lactic acid was balanced by the reduction in .There was some evidence of locomotor-respiratory coupling at the highest swimming speeds (leg beat frequency: respiratory frequency, 6:1), which appeared to constrain any further rise in respiratory frequency. At the highest swimming speed tidal volume, for the first time, increased above the resting value and the level of hyperventilation was increased. Hyperventilation may, therefore, serve to maintain arterial pH in the face of a metabolic acidosis.
Arterial blood pressure, and haematocrit did not change during swimming. There was a doubling in the level of plasma adrenalin with little change in noradrenalin. The possible effects of these increases are discussed.