bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Neural Basis Of Escape Swimming Behaviour In The Squat Lobster Galathea Strigosa III. Mechanisms For Burst Production
Authors: Sillar Keith T. , Heitler William J. 
Published: April 2021

ABSTRACT
Intracellular recordings have been made from a variety of phasic motor neurones during expression of the motor programme for backward swimming in Galathea strigosa. Fast flexor motor neurones (FFs) are driven by a large depolarization mediated by chemical synapses and are inhibited in the interburst interval. Fast extensor motor neurones (FEs) are driven by a barrage of unitary EPSPs during the extension phase and may receive unitary synaptic in-hibition while the flexors are active. FFs all have similar spike thresholds and fire bursts of spikes super-imposed upon the depolarized peak of the input. FEs show a gradation in spike threshold which is correlated with soma size. The largest FEs (type 2) have higher thresholds than smaller FEs (type 1), and fire fewer spikes. The phasic inhibitor motor neurone to flexor muscles (FI) is driven by complex central pathways and fires a single spike shortly following flexion. The extensor inhibitor (El) appears to receive the same depolarization as do the FFs, but has a low spike threshold and thus fires on the rising phase of the depolarization. Spiking in El is terminated by unitary IPSPs which occur in phase with FF activity and which may have the same origin as the interburst inhibition seen in the FEs.
The Bone Compartment in A Teleost Fish, Ictalurus Punctatus : Size, Composition and Acid-Base Response to Hypercapnia
Authors: Cameron James N. 
Published: April 2021

ABSTRACT
An estimate of the total mass of bone in the Channel catfish Ictalurus punctatus Rafinesque, was obtained by dissection. The wet weight of bone constituted 16·3 ±1·9% (± s.d.) of the total (live) wet weight, and 25·0 ± 2·1 % of the dry weight. Of the dry skeletal material, 66·3 ± 11·1 % was soluble in strong acid. The acid-soluble material was about half mineral salts, consisting of 19·5 ±2·21% Ca2+ and 27·6 + 3·22% PO43-, with minor fractions of Mg2+ (0·33 %) and CO32- (1·67 %). The pH values of fluid compartments associated with skull and vertebral bone tissues were 7·420 ± 0·026 and 7·444 ± 0·017 (± S.E.), respectively, at a normocapnie plasma pH of 7·868 ±0·020. In response to external hypercapnia (7·5 Torr), the blood response consisted of an immediate decrease in pH, and a subsequent compensatory rise in both pH and [HCO3-]. This compensatory phase was accompanied by a net apparent H+ excretion to the water. The participation of the mineral salts of the bone compartment in compensation appeared to be negligible, since there was no significant change in either blood [Ca2+] or [PO43 — ], nor any significant increase in calcium efflux to the water. The intracellular pH values of the bone compartments were only slightly higher than other tissues, and the changes in pHi during hypercapnia were similar in bone and white muscle. Thus, the bone compartment in the fish appears to be well regulated, relatively refractory to acute acid-base disturbance, and does not serve as an ion source during acid-base compensation.
Renal Excretion of Magnesium in a Freshwater Teleost, Salmo Gairdneri
Authors: Oikari A. O. J. , Rankin J. C. 
Published: April 2021

ABSTRACT
Infusion of magnesium salts into the body cavity of freshwater-adapted rainbow trout led to elevated plasma magnesium concentrations and to stimulation of renal tubular secretion of magnesium. The majority of the infused load was excreted renally, no net branchial excretion being detected. Magnesium sulphate infusion led to increased tubular secretion of sulphate. Magnesium chloride infusion led to reduced tubular reabsorption of chloride. Magnesium could either be reabsorbed or secreted in control freshwater-adapted trout, apparently as a function of nutritional status. Fish could switch from reabsorption to secretion in response to magnesium loading. It is suggested that freshwater fish eliminate excess dietary magnesium renally.
Nervous Control of the Blood Pressure in the Atlantic Cod, Gadus Morhua
Authors: Smith David G. , Nilsson Stefan , Wahlqvist Inger , Eriksson Britt-Marie 
Published: April 2021

ABSTRACT
Dorsal (PDA) and ventral aortic blood pressure (PVA) and heart rate (HR) were measured in conscious resting cod, Gadus morhua L., which has been allowed 24 h recovery from surgery. Plasma adrenalin and nonadrenalin concentrations in these fish were 3·4 and 2·2 nmol 1−1 respectively, and thus lower than previously reported values from partially recovered cod. Twenty-four hours after treatment with the adrenergic neurone blocking agent bretylium, PDA was significantly reduced by 17 % compared to sham-injected controls, although PVA and heart rate were unaltered. Subsequent a-adrenoceptor blockade by phentolamine produced no further fall in PDA and no changes in PVA or HR, provided a 5-h period was allowed to over-come the acute toxic side effects of phentolamine. The effectiveness of the bretylium or phentolamine blockade was confirmed by noting the absence of any vasoconstrictor response during sympathetic nerve stimulation in perfused tails from fish used in the in vivo experiments.
Bretylium had no significant effect on the sensitivity of the isolated coeliac artery to adrenalin, but effectively blocked the adrenergic innervation of this artery or the vasculature of the tail. Evidence for a non-selective blockade of non-adrenergic nerves to the heart was also obtained.
It is concluded that the adrenergic tonus affecting the dorsal aortic blood pressure in resting cod that have recovered for 24 h following surgery is due solely to an adrenergic nervous tone.
Innervation Patterns of Inhibitory Motor Neurones in the Thorax of the Locust
Authors: Hale J. P. , Burrows M. 
Published: April 2021

ABSTRACT
The innervation pattern of inhibitory motor neurones of the locust has been revealed by intracellular recording from their cell bodies in the meso-and metathoracic ganglion and simultaneous recording from muscle fibres in a middle, or in a hind leg.
Three neurones in each ganglion, the common inhibitor (CI = CI1), the anterior inhibitor (AI = Cl2), and the posterior inhibitor (PI = CI3) inner-vate several muscles in one leg and are thus common inhibitory neurones. Metathoracic CI innervates 13 muscles in one hind leg and mesothoracic CI innervates 12 muscles in one middle leg. The muscles are all in the proximal parts of the legs and move the coxa, the trochanter and the tibia. Metathoracic Al and PI innervate four muscles in the more distal parts of one hind leg that move the tibia, the tarsus and the unguis. None of these muscles is innervated by CI. Each inhibitor innervates muscles that have different and often antagonistic actions during movements of a leg.
Al and PI receive many synaptic inputs in common and show similar patterns of spikes during imposed movements of a tibia. Tests fail, however, to reveal evidence for any electrical or synaptic coupling between them. A revised scheme of nomenclature for these inhibitory neurones is proposed.
Acetylcholine Depolarizes Barnacle Photoreceptors
Authors: Timpe Leslie C. , Stuart Ann E. 
Published: April 2021

ABSTRACT
A variety of vertebrate and invertebrate sensory cells are known to be sensitive to acetylcholine (ACh), although the purpose of ACh receptors on these cells is not understood. Acetylcholine elicits action potentials from the sensory cell of the crayfish stretch receptor organ, which receives inhibitory but not excitatory synaptic input (Wiersma, Furshpan & Florey, 1953). Among the vertebrates ACh causes spiking in several visceral and somatic sensory cells, including chemoreceptors and baroreceptors of the carotid body (von Euler, Liljestrand & Zotterman, 1941 ; Diamond, 1955), mechanoreceptors in the skin (Brown & Gray, 1948) and pain receptors (Skouby, 1951). The experiments to be described here demonstrate that ACh depolarizes the median photoreceptor of the giant barnacle, and test the possibility that the photoreceptor receives cholinergic synaptic input.
The Mechanical Properties of the Autotomy Tissues of the Holothurian Eupentacta Quinquesemita and the Effects of Certain Physico-Chemical Agents
Authors: Byrne Maria 
Published: April 2021

ABSTRACT
Evisceration in the holothurian Eupentacta quinquesemita (Selenka) results from a rapid softening of autotomy structures comprised of connective tissue. The mechanical properties of two autotomy tissues, the introvert and the retractor muscle tendon, were tested to investigate their function in the non-evisceration state and their behaviour during autotomy. The results show that these structures do not have a pre-existing mechanical weakness to account for their rapid failure during evisceration. The autotomy response was mimicked in vitro by increasing K+ concentration. The introvert exhibited viscous behaviour and the absence of Ca2+ and Mg2+ decreased introvert viscosity, whereas excess Ca2+, and low and high pH, increased viscosity. These agents may influence the mechanical properties of the autotomy structures by directly affecting connective tissue ionic interactions and may induce proteoglycan conformational changes. K+ may also exert an indirect effect through responses of cells controlling connective tissue tensility. The most likely mechanism of autotomy is through an alteration of connective tissue ionic interactions.
Free And Total Calcium Concentrations in the Blood of Rainbow Trout, Salmo Gairdneri, During ‘Stress’ Conditions
Authors: Andreasen Peter 
Published: April 2021

ABSTRACT
Measurements were made of the free and total calcium concentrations ([Ca2−] and Cat), acid-base status, haemoglobin concentration, haematocrit and plasma protein concentration in the blood of the rainbow trout, Salmo gairdneri. In isolated blood, [Ca2+] was proportional to Cat while log[Ca2+] was inversely proportional to pH. Similar findings have been reported from human blood. During intense activity, [Ca2+] increased by 16% without any significant change in Cat. Neither sustained exercise, hypercapnic acidosis nor hypoxia affected [Ca2+] or Cat. These data indicate that during common natural stress conditions [Ca2+] is maintained within a narrow range.
Developmental and Metabolic Constraints of the Scope for Activity in Young Rainbow Trout (Salmo Gairdneri)
Authors: Wieser Wolfgang 
Published: April 2021

ABSTRACTThe relationship between routine or ‘steady’ rate and maximum rate of metabolism after forced bursts of activity was studied in the fry and young (weight range 0·08–7 g) of Salmo gairdneri at 4 and 12 °C. The relationship between metabolic rate (y) and body weight (x) can be described by the function y = axb. The mass exponent b equals 0·96 and 0·93 for the routine rate, and 1·11 and 1·14 for the maximum rate of metabolism at 4 and 12 °C respectively, the two sets of b-values differing significantly from each other. The difference between the routine and the active rate of metabolism is called the relative scope for activity. Expressed as a percentage of the routine rate it increases from 85–166 % in the sac fry, to approximately 400% in fish weighing 10 g. Within each of four size classes there is a linear relationship between and , the slope of the relationship always being greater than one and increasing with the weight of the fish from 1·1 in the sac fry to 5·3 in the 3–7 g size class. That is, in the larger size class each increase in the steady rate of oxygen consumption by one unit adds 5·3 units to the aerobic scope for activity. It is speculated that routine and active rate of metabolism are related by a constant factor of expansion so that, up to a limiting value, an increase of the former will lead to an increase of the amount of oxygen available to each fish for additional locomotor activity.
Blood Gas Tensions and Acid-Base Regulation in the Salt-Water Crocodile, Crocodylus Porosus, at Rest and After Exhaustive Exercise
Authors: Seymour R. S. , Bennett A. F. , Bradford D. F. 
Published: April 2021

ABSTRACT
Salt-water crocodiles, Crocodylus porosus Schneider, were catheterized and , pH and lactate concentration ([lactate]) were measured in arterial blood during rest and after forced exhaustive activity at 30° C. Gas exchange ratio (R), calculated from blood and , decreased from about 1·0 to 0·3 during resting voluntary breath-holding and indicated CO2 sequestration in the body fluids. The mean value for R in undisturbed animals was 0·6, which substantiates the hypothesis that some CO2 excretion is extrapulmonary. In vitro buffer value of true plasma was – 23·5 +1·9mmol HCO2−I−1 pH−1. In vivo buffer value, determined by short-term self titration with metabolic CO2, was – 12·2 + 4·7mmolHCOs− I−1 pH−1. Exhaustive activity for 5 min in laboratory animals resulted in pronounced metabolic lactacidosis: pH decreased approximately from 7·43 to 7·11 while lactate concentration increased from 1·2 to 20–30 mmol I−1. The acidosis was reduced by respiratory compensation during the first hour of recovery and by metabolic adjustments that were practically complete after the third hour. Greater acidosis (pH down to 6·4) in larger field-captured animals was resolved over a longer period. During recovery, lactate and proton fluxes between the blood and other tissue were uncoupled. The virtual absence of the fixed-acid Bohr effect in C. porosus blood is adaptive in large individuals because it facilitates continued O2 uptake from the lung into blood which may be acidified by as much as 1 pH unit as a result of physical activity.
The Seasonal Intrinsic Cardiac Performance of a Marine Teleost
Authors: Graham Mark , Farrell Anthony 
Published: April 2021

ABSTRACT
An in situ heart preparation was used to evaluate cardiac performance in the sea raven, Hemitripterus americanus, under physiological inflow and outflow pressure conditions. Winter and summer fish were subjected to an acute 10 °C temperature change from the seasonal ambient value. The maximum cardiac output under each temperature condition was determined by altering inflow pressure to the heart. Acute temperature increase produced positive chronotropic and inotropic effects in winter fish. Acute temperature decrease produced a negative chronotropic and inotropic effect in summer fish. The inotropic and chronotropic states of the heart were different in winter and summer fish. Intrinsic heart rate was higher in summer fish at all experimental temperatures. The sensitivity of the summer fish hearts to input pressure was also greater, especially during the warm experimen-tal temperatures. It was evident from heartbeat rate measurements and power output calculations that the advent of summer and winter seasons did not promote any compensatory ability in intrinsic heart function.
Three-Dimensional Reconstruction of Animal Flight Paths and the Turning Flight of Microchiropteran Bats
Authors: Rayner J. M. V. , Aldridge H. D. J. N. 
Published: April 2021

ABSTRACTA method is presented by which a microcomputer is used to reconstruct the structure of a three-dimensional object from images obtained with a pair of non-metric cameras when the images contain the vertices of a cube as test pattern and the camera—object configuration satisfies straightforward geometrical conditions. With a still camera and stroboscopic or repeating flash illumination, or with a ciné camera, this method provides a simple and economic means of recording the flight-path and wing movements of a flying animal accurately and reliably. Numerical methods for the further analysis of three-dimensional position data to determine velocity, acceleration, energy and curvature, and to interpolate and to correct for distortion due to inaccurate data records are described. The method is illustrated by analysis of a slow, powered turn of the bat Plecotus auritus (L.). Accurate reconstruction of the flight path permits mechanical forces and accelerations acting on the bat during the turn to be estimated: turning speed and radius in a narrow space are restricted by the bat’s ability to generate sufficient lift to support the weight in nonlinear level flight.
The Development of the Locust Jumping Mechanism : I. Allometric Growth and its Effect on Jumping Performance
Authors: Gabriel Julie M. 
Published: April 2021

ABSTRACTThe jump range of locusts of all instars varies throughout an instar, reaching a peak at apolysis in hoppers, and about 3 weeks after the final moult in adults. Mature adult locusts have an escape jump range three times that of young hoppers. During a period of repeated jumping, mature adults have an average jump range three times that of the hoppers. Allometric growth of the metathoracic leg occurs during development, and accounts for 25 % of the increase in range between the fourth instar and adult, the remaining increment being due to absolute size increase. The allometric changes do not, however, affect the mechanics of the femoro-tibial joint. The extensor apodeme to tarsus lever ratio remains at 27:1 in the fourth, fifth and adult stages. The extension of the joint would be expected to follow a similar pattern in the fourth instar and adult stages. The change in form of the metathoracic leg of the locust also means that the adult femur accommodates more muscle, i.e. 6·3 % of the total body weight in the adult male, as opposed to 4·3 % in the fourth instar male. Therefore relatively more force and energy may be available for use in a jump. The lengthening of the semilunar processes may be expected to have an effect on the energy storage capacity of the leg. In an escape jump, all instars use the same specific power output, which is more than the published figures for maximum specific power output (250Wkg-1, Weis-Fogh & Alexander, 1977, and 860Wkg-1, Pennycuick & Parker, 1966). This suggest that energy storage is necessary in locust hoppers.
Effects of Adrenalin on the Oxygen Consumption and Luminescence of the Photophores of the Mesopelagic Fish Argyropelecus Hemigymnus
Authors: Mallefet J. , Baguet F. 
Published: April 2021

ABSTRACT
Photophores isolated from the mesopelagic fish Argyropelecus hemigymnus consume oxygen at a rate of 1·22± 0·17 nmol min-1 in saline at 20°C. In the presence of 5 x 10−4moll-1 adrenalin the preparations that responded by a long-lasting luminescence showed a significant decrease of their resting respiration rate. After the adrenalin had been washed out, oxygen consumption increased immediately to the previous resting level and was inhibited by 5 x 10−4moll-1 KCN. It is suggested that the mechanism of light production by isolated photophores of the epipelagic fish Porichthys and the mesopelagic fish Argyropelecus are different.
Further Studies of Crayfish Escape Behaviour : I. The Role of the Appendages and the Stereotyped Nature of Non-Giant Escape Swimming
Authors: Cooke Ian R. C. , Macmillan David L. 
Published: April 2021

ABSTRACT
High-speed cinematography of the escape behaviour of freelymoving crayfish showed that the thoracic and abdominal appendages exhibit stereotyped movements in giant axon-mediated tail flips and in non-giant flips. Three distinct classes of non-giant tail flips were recognized in this study: linear, pitching and twisting flips. In medial giant flips and linear non-giant flips the chelipeds and pereiopods were promoted and extended in a manner which minimized the hydrodynamic resistance of the animal. The exopodites of the uropods were promoted. In lateral giant flips and pitching non-giant flips the thoracic appendages moved only passively. The uropod protopodites were promoted but the exopodites remained remoted. When giant axon-mediated tailflips were elicited with natural stimuli they were followed by sequences of non-giant flips which appeared quite stereotyped.
Viscoelastic Behaviour and Wet Supercontraction of Major Ampullate Silk Fibres of Certain Orb-Web-Building Spiders (Araneae)
Authors: Work Robert W. 
Published: April 2021

ABSTRACT
The axial retractive stresses that cause the supercontraction of wetted major ampullate silk fibres and the stresses developed upon reextension from the supercontracted condition are quantified and illustrated. The viscoelastic behaviour of major ampullate silk fibres, subjected to the amounts of elongation that would be produced by a spider on its dragline, is described and illustrated. When major ampullate silk fibres are either wet elongated from supercontraction or when dry from initial lengths, viscoelastic stress relaxations are found to be functions of the logarithms of time. Regression curves illustrate these relationships and normalized results are subjected to statistical analyses. Viscoelastic memory of major ampullate silk fibres is illustrated. The characteristics of viscoelastic stress relaxation and viscoelastic memory of major ampullate silk fibres appear not to be associable with taxonomy. Examples are suggested in which supercontraction and stress relaxation act in the formation and placement of major apipullate silk fibres as structural elements of the orb web.
Frequency Selectivity in the Ampullary System of an Elasmobranch Fish (Scyliorhinus Canicula)
Authors: Peters R. C. , Evers H. P. 
Published: April 2021

ABSTRACT
Frequency characteristics of the electroreceptive system in Scylior-hinus canicula were determined both by electrophysiological recording of the primary afferent responses and by optical recording of respiratory reflexes after electrical stimulation. The frequency response of the primary afferents shows a maximum gain at about 5 Hz, with slopes of +2·3 and — 3·4dBoctave−1 at the low and high frequency side respectively. The phase changes from +60° at 0·03 Hz to -120° at 15 Hz. The sensitivity curve determined by recording the respiratory reflex has a plateau from 0·1 to 1 Hz, with slopes of + 2·8 and — 11·4dBoc-tave−1. The highest sensitivity for sinusoidal electrical stimuli was 40 nV cm−1 peak-to-peak, in the frequency range 0·1 to 1 Hz. We suggest that the difference between the two curves reflects the convergence of primary afferents on to secondary neurones. We conclude that the low pass filter properties are not imposed by the time constant of the ampulla wall. The low frequency slope found in the behavioural curve presumably represents the slope of the receptor-cell-synapse complex. The Lorenzinian ampullae apparently act as peripheral filters with different tuning curves; these must play a part in frequency discrimination.
Attack Behaviour and Distance Perception in the Australian Bulldog Ant Myrmecia Nigriceps
Authors: Eriksson E. Sture 
Published: April 2021

ABSTRACT
The behaviour of the Australian bulldog ant Myrmecia nigriceps (Fr. Smith) has been studied by using moving targets characterized by sizedistance equivalence in relation to a stationary zero-point. The attack behaviour of freely moving animals demonstrated that the ants can discriminate between different targets, in the range of 5–80 cm, using movement parallax to extract information about the targets. By studying the antenna response it was possible to demonstrate that the stationary bulldog ant can utilize binocular disparity information and that this mechanism has an effective range of about 90 mm.