bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fast-Start Performance and Body form In Seven Species of Teleost Fish
Authors: Webb P. W. 
Published: April 2021

ABSTRACT
Fast-start kinematics and performance were determined for Etheostoma caeruleum, Cottus cognatus, Notropis cornutus, Lepomis macrochirus, Perca flavescens, Salmo gairdneri and a hybrid Esox sp. at an acclimation and test temperature of 15 °C. Normal three-stage kinematic patterns were observed for all species. Fast-start movements were similar in all species, except Lepomis, which had slightly higher amplitudes than expected for its length. The duration of kinematic stages was a major variable among the seven species but was a linear function of length. Acceleration rates were not functions of size. Maximum acceleration rates ranged from 22·7 to 39·5 m. s−2 with mean rates from 6·1 to 12·3 m.s−2, averaged to the completion of kinematic stage 2. Maximum velocity and distance covered in each fast-start stage varied among species but were related to length. Fast-start performance depended primarily on compromise between muscle mass as a percentage of body mass, and lateral body and fin profile. Optimal profiles provide large depth distant from the centre of mass to maximize thrust, and anterior depth enhancement to minimize recoil. The body form of Lepomis is considered optimal for multiple swimming modes.
Rebound Resilience of Tendons in the Feet of Sheep (Ovis Aries)
Authors: Cuming W. G. , Alexander R. McN. , Jayes A. S. 
Published: April 2021

ABSTRACT
The interosseous muscle of the fore foot of the sheep is multipennate, with large tendons but extremely short muscle fibres. It is believed to save energy in locomotion by elastic storage in its tendons and its sheath. Its rebound resilience (at 5−7 Hz and 20−37 °C) is about 0·62.
Physiological Discontinuity in An Epithelium with An Apparently Uniform Structure
Authors: Maddrell S. H. P. 
Published: April 2021

ABSTRACT
The lower Malpighian tubule of Rhodnius is made up of cells of apparently uniform structure. Functionally, however, this length of the Malpighian tubule consists of two distinct regions. The upper region is osmotically very permeable and plays no part in reabsorbing KC1 from the primary excretory fluid. By contrast, the lowermost 30% of the length of the lower tubule is osmotically impermeable and when stimulated absorbs KC1 from the lumen at the high rate of about 0·80 μmol cm−2 min−1. In other respects such as permeability to other solutes and the ability to transport alkaloids the two regions scarcely differ.
Depressant Action of Lithium at the Crayfish Neuromuscular Junction: Pre- And Postsynaptic Effects
Authors: Ortiz C. Leo , Junge D. 
Published: April 2021

ABSTRACT
The effects of replacement of external sodium ions with lithium have been studied at the excitatory neuromuscular junction of the crayfish. Intracellularly recorded excitatory junctional potentials fall 45 % in amplitude in the first 10 min after lithium substitution, and fail irreversibly in 48–120 min. The quantal content of extracellularly recorded excitatory junctional potentials declines 25–70% within the first 10 min of Li+ exposure. During the next 40–120 min the nerve terminal potentials and quantal release at individual synapses fail simultaneously and irreversibly. The mean amplitude of the spontaneous miniature excitatory junctional potentials (m.e.j.p.s) is reduced 13 % by Li+ substitution, but recovers upon restoration of sodium. The mean frequency of m.e.j.p.s rises steadily during Li+ exposure, and continues to increase after reintroduction of Na+. The postsynaptic response to iontophoretically applied L-glutamate falls 35–40 % in 10 min, but never falls below 45 % of the control level. The effect on the glutamate response is completely reversible with sodium restoration. The effective resistance of the postsynaptic cells is unaffected or only increased slightly by lithium substitution. Thus, the primary mechanism of transmission block by lithium appears to be decreased transmitter release and inexcitability of presynaptic terminals, probably as a result of intracellular accumulation of lithium.
The Sensitivity and Control of the Scallop Mantle Edge
Authors: Stephens Philip J. 
Published: April 2021

ABSTRACT
Application of mechanical stimulation or crude starfish extracts to the mantle edge of Aequipecten irradians elicited afferent impulse activity in the radial pallial nerves and local movements of the stimulated mantle edge. The evoked afferent spike activity was not recorded from primary receptor cells. The local mantle edge movements were controlled by peripherally located neurones and resembled jet formation on the velum of intact scallops. The central efferent neurones that supply the adductor muscle and much of the mantle edge are situated in the visceroparietal ganglion. Cobaltous chloride back-filling of the radial pallial nerves of the right side revealed the routes of the nerve fibres and the locations of the cell bodies in the visceroparietal ganglion. One group of motor neurones has fibres that are spatio-topically arranged across the visceroparietal ganglion and play a role in jet formation on corresponding portions of the mantle edge on both valves. It is apparent that axons from this group of mantle edge efferents traverse the ganglion without chemical synaptic connection. Two groups of mantle edge efferents that control concerted movements of the mantle edge on both shells appear to have cell bodies in the lateral margins of the dorso-central lobes. One group of motor neurones controls the raising of the velum curtain to an erect position around the shell margin. The output from the second group of efferents can be synchronized with the motor output to the adductor muscle to ensure that the velum folds into the mantle cavity, and thus is protected, as the shells are closed. Fibres in the radial pallial nerves have conduction velocities of up to 2·35 m/s at a temperature of 25 °C.
Evaporative Cooling and Water Balance During Flight In Birds
Authors: Torre-Bueno Jose R. 
Published: April 2021

ABSTRACT
The rate of evaporative cooling was calculated from the rate of mass loss in starlings (Sturnus vulgaris) during 90 min flights in a wind-tunnel. Evaporative heat loss ranged from 5% of the metabolic rate at −5 °C to 19% of the metabolic rate at 29 °C. Radiation and convection accounted for the balance of the heat loss. On average, starlings dehydrated during flights at all temperatures above 7° C. The comparison of these results with data from field studies, which indicate that long-distance migrants do not dehydrate, suggests that migrants may maintain water balance by ascending to colder air in which convection carries off most of the heat produced.
Effects of Osmotic Stress on the Electrical Activities of the Giant Axon of A Marine Osmoconformer, Sabella Penicillus
Authors: Carlson A. D. , Pichon Y. , Treherne J. E. 
Published: April 2021

ABSTRACT
The giant axons of the polychaete, Sabella penicillus, can withstand, in vitro, abrupt changes in osmotic and ionic concentration of the bathing medium in the range measured in the blood of this osmoconformer (543–1236 m-osmol) at different external salinities. Isosmotic dilution of the external ions (i.e. when osmotic concentration was maintained by sucrose) induced a modest hyperpolarization of the axonal membrane and a rapid decline in the overshoot of the action potential. In contrast, abrupt hyposmotic dilution resulted in a relatively slow and complex decline in overshoot in the absence of axonal hyperpolarization. A slow potassium depolarization and rate of decrease in overshoot in sodium-free conditions suggests that there is a reduced intercellular access to the axon surfaces following exposure to hyposmotic media. It is suggested that this restricted access could provide short-term protection from fluctuations in blood osmotic concentration.
Neuronal Control of Swimming in the Medicinal Leech
Authors: Friesen W. Otto , Poon Margaret , Stent Gunther S. 
Published: April 2021

ABSTRACT
Four oscillatory interneurones that appear to be the principal components of the central swim oscillator of Hirudo medicinalis have been identified on each side of the segmental ganglia of the ventral nerve cord. During ‘swimming’ episodes of an isolated nerve cord preparation each interneurone undergoes a polarization rhythm that is phase-locked with the impulse burst rhythm of the motor neurones known to drive the swimming movement. Passage of current into any of the interneurones can shift the phase of the swim rhythm. One of the interneurones projects its axon rearward to posterior ganglia and the other three project their axons frontward to anterior ganglia. The oscillatory interneurones are connected both intra- and interganglionically to form a topologically complex intersegmental network of concatenated ring circuits that possess the feature of recurrent cyclic inhibition. Theoretical analysis and electronic analogue models show that the network is inherently oscillatory and can produce both a cycle period and intra- and intersegmental phase relations of its elements that are appropriate for generating the body wave of the swimming movement.
Long-Term Adaptations of Sabella Giant Axons Tohyposmotic Stress
Authors: Treherne J. E. , Pichon Y. 
Published: April 2021

ABSTRACT
Sabella is a euryhaline osmoconformer which is killed by direct transfer to 50% sea water, but can adapt to this salinity with progressive dilution of the sea water. The giant axons were adapted to progressive dilution of the bathing medium (both in vivo and in vitro) and were able to function at hyposmotic dilutions (down to 50 %) sufficient to induce conduction block in unadapted axons.
Hyposmotic adaptation of the giant axon involves a decrease in intracellular potassium concentration which tends to maintain a relatively constant resting potential during adaptation despite the reduction in external potassium concentration. There is no appreciable change in the intracellular sodium concentration, but the relative sodium permeability of the active membrane increases during hyposmotic adaptation. This increase partially compensates for the reduction in sodium gradient across the axon membrane, during dilution of the bathing media, by increasing the overshoot of the action potentials recorded in hyposmotically adapted axons.
Locusts Use the Same Basic Motor Pattern in Swimming as In Jumping and Kicking
Authors: Pflüger Hans-Joachim , Burrows Malcolm 
Published: April 2021

ABSTRACT
When on the surface of water, locusts (Schistocerca or Locusta) adopt a characteristic posture with the front legs pointing forwards and the middle and hind legs backwards. Swimming is accomplished by the rapid extension of both hind tibiae. The legs move at the same time and not alternately as they do in walking. The swimming strokes are repeated at 2–3 Hz and give the locust a forward velocity of some 13 cm s-1. The motor pattern that brings about the extension of the hind tibiae is described from extracellular recording in the tibial muscles during swimming. The tibia is first flexed and held flexed by spikes of the flexor motoneurones. Then the extensor motoneurones begin to spike so that there is a period when flexor and extensor motoneurones are both spiking. This leads to cocontraction of the muscles. The flexor motoneurones then stop, but the extensors continue, with the result that the tibia extends rapidly. The same basic motor pattern for the movement of the tibia is used by the locust in jumping, kicking and swimming.
Salinity Adaptation in the Salamander Batrachoseps
Authors: Jones Ronald M. , Hillman Stanley S. 
Published: April 2021

ABSTRACT
Batrachoseps attenuatus and B. major were successfully acclimated to 600 m-osmol NaCl and 400 m-osmol sucrose solutions. Accumulation of sodium and an increased rate of synthesis of urea provide substantial increases in plasma concentrations of these solutes. Sodium concentrations in excess of 230 mM and urea concentrations in excess of 200 mm indicate that these are the two major solutes (plus anions) responsible for elevation of osmotic concentration in Batrachoseps. Batrachoseps exhibits a water balance response upon dehydration (greater than twofold increase in cutaneous uptake, 50% reduction in urine production). Urine production, estimated from bladder contents, was significantly reduced in salamanders acclimated to sucrose solutions compared to animals acclimated to tap water or saline of equivalent osmotic concentration. Plasma urea concentration was equivalent to urine urea concentration when Batrachoseps was kept in tap water and during short term saline acclimation. After long term saline acclimation, urine urea concentration was one-fourth the plasma urea concentration.
Oxygen Consumption of Moths During Rest, Pre-Flight Warm-Up, and Flight in Relation to Body Size and Wing Morphology
Authors: Bartholomew George A. , Casey Timothy M. 
Published: April 2021

ABSTRACT
Insect pollinators, such as the tobacco hawkmoth Manduca sexta, are known for locating flowers and learning floral odors by using their antennae. A recent study revealed, however, that the tobacco hawkmoth additionally possesses olfactory sensilla at the tip of its proboscis. Here, we asked whether this second ‘nose’ of the hawkmoth is involved in odor learning, similar to the antennae. We first show that M. sexta foraging efficiency at Nicotiana attenuata flowers increases with experience. This raises the question whether olfactory learning with the proboscis plays a role during flower handling. By rewarding the moths at an artificial flower, we show that, although moths learn an odor easily when they perceive it with their antennae, experiencing the odor just with the proboscis is not sufficient for odor learning. Furthermore, experiencing the odor with the antennae during training does not affect the behavior of the moths when they later detect the learned odor with the proboscis only. Therefore, there seems to be no cross-talk between the antennae and proboscis, and information learnt by the antennae cannot be retrieved by the proboscis.
Morphometries and oxygen consumption were studied in about 35 sphingids, 50 satumiids, and 20 other heterothermic moths belonging to various families. For the pooled data of all species the regression of oxygen consumption on mass in grams is described by the following equations: at rest, cm3/h = 0·402 g0·775 ; during hovering flight, cm3/h = 59·430·818; during warm-up, cm3 = 1·1g0·896. Similar equations are presented for the families Saturniidae and Sphingidae. In sphingids and satuniids thoracic mass, wing length, and wing area increased with body mass, whereas wing loading and aspect ratio were independent of body mass. The sphingids had higher wing loading, aspect ratio, and wing beat frequency during flight than the saturniids. Wing beat frequency was more tightly coupled to morphological parameters in sphingids than in saturniids. The allometry of resting and active aerobic metabolism in heterothermic moths is compared with that of reptiles, mammals and birds. The scaling of oxygen consumption during flight in the moths is almost identical to that of bats and birds.
Patterns of Activity and the Effects of Activation of the Fast Conducting System on the Behaviour of Unrestrained Leeches
Authors: Magni Franco , Pellegrino Mario 
Published: April 2021

ABSTRACT
The neural activity of the nerve cord of Hirudo medicinalis has been recorded in unrestrained animals by means of chronically implanted electrodes. The Fast Conducting System (FCS) is inactive both in motionless animals and during various kinds of active behaviour (creeping, swimming, ventilation). Photic and tactile stimuli applied to a motionless animal elicit a FCS discharge, which may be followed by generalized shortening. Photic and tactile stimuli applied during ventilation are followed by a reversible blockade of the ongoing activity only if they are able to elicit a FCS discharge. No such effect is observed on swimming. An explanation of these findings in terms of the known connexions of leech neurones is offered and a role in the control of reafferent inputs is attributed to the rectifying synapses made by FCS and T cells on the L motor neurones.
Evidence For One-Way Valves in the Water-Flow System of Sponges
Authors: Vogel Steven 
Published: April 2021

ABSTRACT
A water current over a marine sponge can increase flow through the sponge ; even a current below the active pumping rate is effective. To investigate the structural correlates of such flow induction, two series of models were tested in a flow tank. These models were hollow cylinders with either wall perforations serving as ostia or an apical orifice as osculum. They were connected to an external reservoir which acted as a water source with the osculum exposed to flow, or as a sink where ostia were exposed. The reservoir could be raised or lowered to simulate active pumping. The models differed from intact sponges in showing much lower flow induction in general and no induction with ambient currents much below the active pumping rate.
The magnitude of flow induction could be raised to near normal by the addition of one-way valves in the model ostia. These valves prevented backflow out of the ostia lateral and downstream to the current while permitting the positive pressure on the upstream ostia to augment flow. To be effective at low ambient currents, the valves had to be isolated from the active pump ; if the valves were located in the ‘dermis’, the ‘subdermal space’ provided the requisite isolation.
Direct evidence for functional valves was obtained by cannulating freshly collected Haliclona viridis and observing that water could be more easily drawn out of an osculum than forced into it.
Axonal Adaptations to Osmotic and Ionic Stress in an Invertebrate Osmoconformer (Mercierella Enigmatica Fauvel)
Authors: Benson J. A. , Treherne J. E. 
Published: April 2021

ABSTRACT
The giant axon of this extreme euryhaline osmoconformer possess an unusual ability to produce action potentials of large amplitude over a wide range of ionic dilution when constant osmotic concentration is maintained by the addition of mannitol to the bathing medium. Ionic dilution under these circumstances causes a decline in the overshoot of the action potential (resulting largely from reduction in [Na+]0) and an appreciable axonal hyperpolarization (primarily as a result of decrease in [K+]0). This hyperpolarization tends to compensate for the reduction in the extent of the overshoot and so maintains the amplitude of the sodium-mediated action potentials during isosmotic dilution of the bathing medium. The axonal hyperpolarization also appears to reduce sodium inactivation so as to maintain a rapid rate of rise of the action potential despite drastic reduction in the ionic concentration of the bathing medium. Prolonged exposure to reduced ionic concentrations appears to induce a ouabain sensitive reduction in intracellular sodium concentration which increases the sodium gradient across the axon membrane during isosmotic dilution of the external medium.
Axonal Adaptation to Osmotic and Ionic Stress in An Invertebrate Osmoconformer (Mercierella Enigmatica Fauvel)
Authors: Benson J. A. , Treherne J. E. 
Published: April 2021

ABSTRACT
The giant axons of this extreme osmoconformer were adapted, in vitro, to progressive hyposmotic dilution of the bathing medium (from 1024 m-Osmol to concentrations as low as 76·8 m-Osmol). Hyposmotic adaptation is associated with reductions in the intracellular concentrations of both sodium and potassium ions. These reductions do not appear to result from appreciable axonal swelling. The different electrical responses to isosmotic and hyposmotic dilution suggest that reduction in [Na+]1 results from ouabain-dependent sodium extrusion, in response to ionic dilution, and that reduction in [K+]1 is induced by a combination of ionic and osmotic dilution. The reduced level of intracellular potassium achieved during hyposmotic adaptation represents a balance between the necessity to contribute to osmotic equilibration and to maintain a potassium gradient across the axon membrane sufficient to produce appreciable axonal hyperpolarization during dilution of the bathing medium. This hyperpolarization tends to maintain the amplitude of the action potential, by compensating for reduction in overshoot (with decline in ENa), and by reducing sodium inactivation. This, together with the reduction in [Na+]1, enables over shooting action potentials of relatively large amplitude and rapid rise time to be maintained during more than tenfold dilution of the ionic and osmotic concentration of the bathing medium.
Multiple Sites of Spike Initiation in A Bifurcating Locust Neurone
Authors: Heitler W. J. , Goodman Corey S. 
Published: April 2021

ABSTRACT
Recordings were made from the metathoracic dorsal unpaired median neurone to the extensor tibiae muscle (DUMETi) in the locust. This is a bifurcating neurone with axons exiting both sides of the ganglion, whose soma can support a full action potential. Four different spike types were recorded in the soma, each of which we associate with a different region of the neurone. These were (1) a soma (S) spike of 70−90 mV (2) a neurite (N) spike of 20−40 mV, occurring between the axon hillock and axon branch point, (3) and (4) axon (A) spikes of 8−15 mV, occurring distal to the branch point on the left and right axons. Each of these regions must therefore have its own spike initiation site.
At spike frequencies greater than about 10 Hz at room temperature or 1−5 Hz at 32 °C (the preferred environmental temperature of the locust) the S-spike may fail, revealing A-spikes, or more rarely N-spikes. A-spikes usually consist of two more-or-less separate components, Al and Ar, which can be correlated with action potentials in the left and right axon branches by recording spikes extracellularly in the peripheral nerves on each side. Occasionally single component A-spikes occur when an action potential is initiated in only one axon, and fails to propagate across the branch point to the contralateral axon. Thus, action potentials may occur independently in the branches of this bifurcating neurone. After unilateral axotomy only S-spikes and N-spikes are recorded, indicating that action potentials no longer fail to propagate across the branch point. Anatomical asymmetries in the axon branches of DUMETi have been correlated with physiological asymmetries recorded in the soma of the same neurone.