bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygenational Properties and Phosphorylated Metabolic Intermediates in Blood and Erythrocytes of the Dogfish, Squalus Acanthias
Authors: Wells Rufus M. G. , Weber Roy E. 
Published: April 2021

ABSTRACT
A typical whole blood Oz-equilibrium curve from Squalus acanthias had a P50 of 13·2 mmHg and was slightly sigmoidal, having an n value of 1·6 at 15°C, (pH = 7·85). A small Bohr effect was present (ϕ= −0·28) together with a weak Haldane effect and no Root shift.
The predominant trinucleotide, determined by thin layer chromatography, was ATP (0·44 ±0·13 S.D. mmol l−1 blood) with smaller amounts of GTP present (0·07 ± 0·02S.D. mmol 1−1). Total nucleotide concentrations, determined enzymatically, were low by comparison with teleosts. Incubation of erythrocytes with or without oxygen, or in the presence of a metabolite-enriched ‘cocktail’ showed limited potential for phosphate cofactor regulation of blood oxygen affinity.
Physiological and Behavioural Aspects of Water Balance and Respiratory Function in the Terrestrial Slug, Limax Maximus
Authors: Prior David J. , Hume Mary , Varga Dan , Hess Stephen D. 
Published: April 2021

ABSTRACT
A method is described for establishing a stable relationship between body weight and hydration (i.e. 100% hydrated) in terrestrial slugs. This allows the use of ‘% initial body weight’ as an indicator of relative body hydration. During progressive dehydration in the slug, Umax maximus (L.), the haemolymph osmolality increases exponentially. This, together with measurements of wet weight/dry weight ratios of various tissues, indicates that the water loss during the initial stages of dehydration is from the haemolymph. Although long-term (days) cyclical changes in body hydration were not observed, a daily cycle is described with highs at 12.00 midnight and lows at 12.00 noon. It is shown that the huddling behaviour of slugs can reduce evaporative water loss from individual slugs. Dehydration of a slug to about 90 % of its initial body weight initiates a rhythmic cycle of pneumostome closures. Further dehydration results in an increase in the duration of the closures and reduction of the diameter of the pneumostome when open. The absolute and relative O2 uptake by the integument and lung are presented. In quiet slugs, the lung is responsible for about 20 % of the total O2 uptake, while in active slugs it is responsible for 50 % of the total. During activity there is a greater increase of O2 uptake across the lung than across the integument.
Insects are Both Impeded and Propelled by Their Legs During Walking
Authors: Graham D. 
Published: April 2021

ABSTRACT
The kinetics of walking behaviour in stick insects differ from vertebrate walking behaviour. The differences suggest that insect locomotion consists of a hold-push-recover sequence similar to that used by a climber. This is supported by evidence from force platform measurements on free-walking insects and motor output recordings from animals walking on a treadwheel.
The Exchange of Calcium in Larvae of the Mosquito Aedes Aegypti
Authors: Barkai Amiram I. , Williams Roger W. 
Published: April 2021

ABSTRACT
The exchange of labelled calcium between the external medium and the whole body was investigated in the larva of Aedes aegypti (L.) using a closed, two-compartmental model. The transport system for the uptake of Ca2+ was found to be saturable and obeyed Michaelis-Menten kinetics. The efficiency of the inward transport of calcium from dilute solutions was markedly reduced by starvation or by ruthenium-red, a selective inhibitor of Ca2+ activated ATPase, indicating that this transport system is energy dependent. Unlike transport systems for the major monovalent ions, the Ca2+ transport system is not located in the anal papillae, since removal of these organs resulted in enhanced Ca2+ fluxes. While over 95 % of the calcium in the larva appeared to be distributed in the extracellular haemolymph, only 16 % of the total calcium was readily exchangeable with the external medium; thus the majority of the calcium is apparently bound to haemolymph constituents. The results suggest that calcium pumps consisting of Ca2+ activated ATPases play an important role in the absorption of Ca2+ from dilute solutions in the gut and its reabsorption from the urine in the rectum.
The Role of Low Molecular Weight Antifreeze Glycopeptides in the Bile and Intestinal Fluid of Antarctic Fish
Authors: O’grady S. M. , Ellory J. C. , Devries A. L. 
Published: April 2021

ABSTRACT
The role that low molecular weight antifreeze glycopeptides play in the physiology of polar fishes has been an open question. In this study, we demonstrate that antifreeze glycopeptides are present in the bile as well as the intestinal fluid of antarctic fishes. Isolation of antifreeze glycopeptides from these fluids by DEAE ion exchange chromatography followed by polyacrylamide gel electrophoresis revealed the presence of only low molecular weight glycopeptides (6, 7 and 8). Removal of the gall bladder with subsequent occlusion of the common bile duct eliminated the transport of antifreezes into the intestine. This suggests that antifreeze glycopeptides enter the intestinal lumen by biliary secretion. Measurements of reabsorption, both in vivo and in vitro, indicate that antifreeze glycopeptides are not reabsorbed as intact molecules. Our results suggest that these glycopeptides are excreted. We conclude that low molecular weight antifreeze glycopeptides are necessary to prevent the intestinal fluid from freezing and provide the first clear evidence that low molecular weight antifreeze glycopeptides have a specific biological function in polar fishes.
Motor Programme Switching in the Ventilatory System of Carcinus Maenas: the Neuronal Basis of Bimodal Scaphognathite Beating
Authors: Simmers A. John , Bush Brian M. H. 
Published: April 2021

ABSTRACT
Intracellular recordings have been made from ventilatory neurones in semi-isolated and isolated thoracic ganglia of the crab Carcinus during spontaneous switching between the two motor programmes underlying forward and reversed beating of the scaphognathites (SGs).
Ventilatory reversals are dependent upon the central activation of two subgroups of motoneurones which are normally silent, and different from those driving the same SG muscles during the forward rhythm. Two further subgroups of motoneurones remain active throughout both rhythm modes.
The results suggest that both motor output patterns are produced mainly by periodic inhibitory synaptic input from the same oscillator network, and that neural switching between the rhythm modes occurs directly at the level of the motoneurones themselves.
It appears that both sets of ‘forward’ and ‘reversal’ motoneurones are driven continuously throughout oscillator activity, and that bursting activity in these sets is gated by the selective application or removal of additional, tonic inhibition.
Cardiovascular Changes in the Exercising Emu
Authors: Grubb Barbara , Jorgensen Darwin D. , Conner Melinda 
Published: April 2021

ABSTRACT
Cardiovascular variables were studied as a function of oxygen consumption in the emu, a large, flightless ratite bird well suited to treadmill exercise. At the highest level of exercise, the birds’ rate of oxygen consumption was approximately 11·4 times the resting level (4·2 ml kg−1 min−1). Cardiac output was linearly related to , increasing 9·5 ml for each 1 ml increase in oxygen consumption. The increase in cardiac output is similar to that in other birds, but appears to be larger than in mammals. The venous oxygen content dropped during exercise, thus increasing the arteriovenous oxygen content difference. At the highest levels of exercise, heart rate showed a 3·9-fold increase over the resting rate (45·8 beats min−1). The mean resting specific stroke volume was 1·5 ml per kg body mass, which is larger than shown by most mammals. However, birds have larger hearts relative to body mass than do mammals, and stroke volume expressed per gram of heart (0·18 mlg−1) is similar to that for mammals. Stroke volume showed a 1·8-fold increase as a result of exercise in the emus, but a change in heart rate plays a greater role in increasing cardiac output during exercise.
Suppression of a Locust Visual Interneurone (DMCD) During Defensive Kicking
Authors: Heitler W. J. 
Published: April 2021

ABSTRACT
Visual stimuli presented to a locust during performance of a defensive kick fail to elicit a response from the descending contralateral movement detector (DCMD) visual interneurone. Similar control stimuli presented before the initial flexion and at least 1 s after the movement elicit a normal DCMD response (10–15 spikes). External stimuli used to elicit defensive kicking can sometimes cause suppression of the DCMD without the occurrence of kicking, but only when there is an increase in central nervous activity, or associated behavioural response. Proprioceptive stimulation similar to that occurring in a kick does not cause suppression of the DCMD unless there is an increase in central nervous activity or associated behavioural response. Extensive dorsal dissection abolishes the suppression of the DCMD.
Short Communications Initiation of Flight By an Identified Wind Sensitive Neurone (Tcg) in The Locust
Authors: Bicker Gerd , Pearson Keir G. 
Published: April 2021

ABSTRACT
When the tarsi are not in contact with the ground, brief wind stimuli applied to the wind sensitive hairs on the head elicit flight in the locust (Weis-Fogh, 1949; Camhi, 1969). The descending interneurones mediating this reaction have not been identified but some likely candidates have been reported (Bacon & Tyrer, 1978; Simmons, 1980, 1981). The most extensively studied is the tritocerebral commissure giant (TCG) (Bacon & Tyrer, 1978; Bacon & Möhl, 1979). This large wind sensitive interneurone descends from the brain, crosses to the contralateral side of the nerve cord via the tritocerebral commissure, and makes excitatory connections with some flight motor neurones in the thoracic ganglia (Bacon & Tyrer, 1979). The location of the TCG’s axon in the tritocerebral commissure makes this neurone easily accessible for recording and stimulation in almost intact, freely moving animals. Recordings during flight, for example, have shown that the TCG discharges one or two spikes during each cycle (Bacon & Möhl, 1979). The spike activity results from rhythmic air turbulences caused by flapping of the wings and head movements during flight. This rhythmic activity may play a role in regulating motor output during flight manoeuvres, such as yaw (B. Möhl & J. Bacon, in preparation). It seems unlikely however that this is the only function for the TCG since it is capable of discharging in very high frequency bursts quite unlike those occurring in flying animals. Here we present evidence that the TCG also functions to facilitate the initiation of flight following a jump.
VAMP: A Video Activity Monitoring Processor for the Registration of Animal Locomotor Activity
Authors: Kaufmann Ruediger 
Published: April 2021

ABSTRACT
In many bioenergetic investigations, the discrimination of resting and activity metabolism represents an important problem. Personal observation, a possible solution to this problem, becomes very impractical in highly automated long-term experiments. An adequate method of measuring activity should meet the following demands : it should be able to quantify the movement of several objects simultaneously, it should be usable with animals of different shapes and sizes, and it should cause minimal disturbance to the animals.
Cardiac Output and Regional Blood Flow in Gills And Muscles After Exhaustive Exercise in Rainbow Trout (Salmo Gairdneri)
Authors: Neumann Peter , Holeton George F. , Heisler Norbert 
Published: April 2021

ABSTRACT
Rainbow trout (Salmo gairdneri) were electrically stimulated to exhausting activity and the changes in cardiac output and blood flow distribution to gills and systemic tissues resulting from the developing severe lactacidosis were repeatedly measured by the microsphere method (15 μm). Determination of cardiac output by application of the Fick principle resulted in values not significantly different from cardiac output measured by the indicator dilution technique, suggesting that cutaneous respiration, oxygen consumption, and arterio-venous shunting were insignificant under these conditions.
Following muscular activity, cardiac output was elevated by up to 60%. In the gills, the blood flow distribution in the gill arches showed a consistent pattern, even during lactacidosis, with a higher perfusion in gill arches II and III, and in the middle sections of individual gills. Blood flow to white and red muscle was increased much more than cardiac output (+230 and +490%, respectively) such that blood flow to other tissues was actually reduced.
We conclude that the elimination of lactate from muscle cells during the recovery period from strenuous exercise is delayed, not as a result of an impaired post-exercise muscle blood flow, but probably as a result of a high diffusion resistance in the cell membrane.
Motor Output of the Denervated Thoracic Ventral Nerve Cord in the Stick Insect Carausius Morosus
Authors: Bässler Ulrich , Wegner Uta 
Published: April 2021

ABSTRACT
The denervated thoracic ventral nerve cord produces a motor output which is similar to that observed in the intact animal during irregular leg movements (seeking movements) or rocking, but not walking.
When the nerves to some legs are left intact, and the animal walks on a wheel, the motor output in the protractor and retractor motor neurones of the denervated legs is modulated by the stepping frequency of the walking legs. The modulation is similar to that observed in the motor output to a not actually stepping leg of an intact walking animal.
When only the crural nerve of one leg is left intact, stimulation of the trochanteral campaniform sensilli induces protractor and retractor motor output to that leg and the leg behind it. In this case the motor output to the ipsilateral leg is in phase. Stimulation of the femoral chordotonal organ influences activity in motor neurones of the extensor tibiae (FETi and SETi) but not those of the protractor and retractor coxae muscles.
In a restrained leg of an intact animal stretching of the femoral chordotonal organ excites FETi and SETi as long as the other legs walk (as in a walking leg) and inhibits FETi and SETi (as in a seeking leg) when the other legs are unable to walk.
Respiration During Chronic Hypoxia Andhyperoxia in Larval and Adult Bullfrogs (Rana Catesbeiana) I. Morphological Responses of Lungs, Skin and Gills
Authors: Burggren Warren , Mwalukoma Anganile 
Published: April 2021

ABSTRACT
Larval and adult bullfrogs, Rana catesbeiana (Shaw), were exposed to 28 days of normoxia ( 150 mmHg), hypoxia ( 70–80 mmHg) or hyperoxia ( &gt; 275 mmHg) at 20–23 °C, after which the following mor phological measurements were made: (1) mass, thickness, capillary mesh density and blood-water barrier of the skin; (2) mass, volume, cava density and blood-gas barrier of lungs; and, for the larvae, (3) arch length, filament density and size, and blood-water barrier of the gills.
Chronic hypoxia induced profound morphological changes in the gas exchange organs of larvae, but not of adults. In tadpoles, the skin became thinner, with a doubling of capillary mesh density and a halving of the blood-water barrier. The gas diffusion barrier of the lungs remained un changed, but the lung volume and density of the lung wall cava both in creased significantly. The internal gills showed a marked enlargement upon hypoxic exposure, both in numbers of gill filaments and size of each fila ment. The blood-water barrier remained unchanged. Chronic hyperoxia, unlike chronic hypoxia, caused no significant changes in the morphology of the gas exchange organs of larvae.
Chronic exposure to hypoxia or hyperoxia failed to produce any sig nificant morphological changes in adult bullfrogs.
These data indicate that the great morphological plasticity of larvae, culminating in metamorphosis, also extends to profound adjustments in the gas exchange organs when oxygen transfer becomes limited, a response lacking in adults.
Respiration During Chronic Hypoxia and Hyperoxia in Larval and Adult Bullfrogs (Rana Catesbeiana) II. Changes in Respiratory Properties of Whole Blood
Authors: Pinder Alan , Burggren Warren 
Published: April 2021

ABSTRACT
Rana catesbeiana Shaw tadpoles and adults were maintained at 20–23 °C under aerial and aquatic normoxia ( 150 mmHg), hyperoxia ( 275 mmHg) and hypoxia ( 75 mmHg) for 4 weeks, after which the following blood measurements were made: haematocrit, red blood cell count, haemoglobin concentration, mean corpuscular haemoglobin concentration, O2 capacity, O2 equilibrium curve, Bohr shift, Hill’s coefficient and intraerythrocytic concentration of nucleotide triphosphates (ATP+GTP) and 2,3-DPG.
Normoxic tadpoles had much higher blood O2 affinity (P50 9–10 mmHg) than adults (P50 35 mmHg) but a lower haemoglobin concentration, haematocrit and O2 capacity. The concentration of intraerythrocytic phosphates was higher in normoxic tadpoles than in adults, indicating that the higher O2 affinity of normoxic tadpole blood was due to the haemoglobins themselves, rather than affinity modulators.
Chronic hypoxia in tadpoles produced little change in whole blood P50, and no significant change in any other blood variable. In adult bullfrogs, on the other hand, O2 capacity doubled through polycythaemia, and the P50 decreased by 11 mmHg (35%), though apparently not from any significant change in concentration of intraerythrocytic phosphates. Hyperoxia produced no haematological changes in either larvae or adults.
In adult bullfrogs exposed to chronic hypoxia, the morphology of the gas exchange organs does not change (Burggren & Mwalukomo, 1983), but instead profound adjustments occur in the blood, favouring O2 transport under these conditions. The blood of the tadpole shows little or no response to chronic hypoxia, with morphological adjustments in skin, gills and lungs constituting the major response.
Motor Control of Movements of the Antennal Flagellum in the Australian Crayfish, Euastacus Armatus
Authors: Sandeman David C. , Wilkens Lon A. 
Published: April 2021

ABSTRACT
Voluntary and reflexive antennal movements of an Australian freshwater crayfish are described. An anatomical and physiological study showed that the flagellar flexor muscle is innervated by three motor neurones (a common inhibitor and two exciters) and the flagellar extensor muscle receives four motor neurones (a common inhibitor and three exciters). The discharges of three of the motor neurones to the flexor and extensor muscles (tonic flexor, tonic extensor, common inhibitor) were recorded simultaneously with the movements of the flagellum in intact but restrained animals. Phase relationships between flexors and extensors are not simply antagonistic for all voluntary movements. The common inhibitor is more often in phase with, or leads, tonic extensor activity, than tonic flexor activity.
Haemodynamic Effects of Adrenaline on the Isolated, Perfused Head of the Dogfish ‘Pup’ (Squalus Acanthias)
Authors: Evans David H. , Claiborne J. B. 
Published: April 2021

ABSTRACT
The isolated, perfused head of the dogfish ‘pup’ (Squalus acanthias) maintained pressure: flow relationships near to those described for the in vivo adult for at least 3 h when perfused at a constant rate. The addition of 3% polyvinylpyrrolidone reversibly increased branchial resistance, and the postbranchial outflow (arterial + venous) equalled the inflow. 10−5M adrenaline reversibly reduced gill resistance (in some cases after a transient increase in resistance) and stimulated perfusate outflow from the dorsal aorta, at the expense of flow from the cephalic and branchial venous system. Phentolamine did not alter the effect of adrenaline on pressure and flow pattern; addition of propranolol inhibited both adrenaline effects and resulted in a slight increase in afferent pressure, indicating that a-adrenergic receptors are present, but that the dominant haemodynamic effects are mediated via β-adrenergic receptors. The isolated, perfused ‘pup’ head may provide a vehicle for investigation of transport phenomena in the elasmobranch branchial epithelium.
The Innervation of the Mesothoracic Flexor Tibiae Muscle of the Locust
Authors: Theophilidis G. , Burns M. D. 
Published: April 2021

ABSTRACT
The anatomy and innervation of the mesothoracic flexor tibiae muscle indicated a subdivision into proximal, middle and distal flexors.
The muscle is innervated by 12 excitors, two inhibitors and two dorsal unpaired median (DUM) neurones. The motor axons were identified by (a) the height of the action potentials recorded extracellularly from the flexor nerve branches of an intact locust, (b) the EPSPs or IPSPs and the tension which they produced in the muscle when they were stimulated and (c) the distribution on the muscle. There was some independent innervation of proximal, middle and distal flexors.
Conditioning Factors(s) Produced By Several Molluscan Species Promote Neurite Outgrowth in Cell Culture
Authors: Wong Richard G. , Martel Elaine C. , Kater S. B. 
Published: April 2021

ABSTRACT
The ability to correlate the behaviour of neurones in intact ganglia with events in isolation as has been shown in the leech (Ready & Nicholls, 1979; Fuchs, Nicholls & Ready, 1981), may provide insight into the intrinsic properties of individual neurones.
Antagonizing Effect of Ultraviolet and Visible Light on the Erg From the Ocellus of Spirocodon Saltatrix (Coelenterata: Hydrozoa)
Authors: Ohtsu Kohzoh 
Published: April 2021

ABSTRACT
Many anthomedusan jellyfish swim when ambient illumination is interrupted (Passano, Mackie & De Ceccatty, 1967; Ohtsu & Yoshida, 1973; Anderson & Mackie, 1977). This shadow response has been attributed to the ocelli, which are located at the margin of the bell. However, in some anthomedusae, it has been demonstrated that the motor neurones that innervate the swimming musculature are, themselves, directly photosensitive (Anderson & Mackie, 1977; Ohtsu, 1983). One species which possesses both classes of photoreceptor is Spirocodon (Ohtsu, 1983). In this animal, near ultraviolet light (u.v.) hyperpolarizes the swimming neurones and inhibits swimming. This effect is tonic, lasting long after the cessation of u.v. irradiation. However, this after-inhibition can be disinhibited by irradiation with visible light (u.v.-vis antagonism). To investigate the role of these two photoreceptor types in the behaviour of Spirocodon, the electroretinogram (ERG) of the ocelli was measured. The results described here are basically similar to those obtained from Sarsia ocelli (Weber, 1982), the only coelenterate photoreceptors investigated to date, but there are some differences.
Synchronous Vocal Response Mediated by the Amphibian Papilla in a Neotropicaltreefrog: Behavioural Evidence
Authors: Narins Peter M. 
Published: April 2021

ABSTRACT
Acoustic playback experiments with treefrogs (Eleutherodactylus coqui Thomas) in their natural habitat reveal that males readily synchronize their vocalizations with synthetic calls containing frequencies equal to or lower than their own. Low-level artificial stimuli were used in order preferentially to stimulate auditory fibres originating in the amphibian papilla while avoiding excitation of basilar papillar or saccular fibres. Moreover, the synchronous vocal response persists unabated, even when the synthetic calls were simultaneously ‘masked’ with narrow-and wide-band noise, which strongly excited a large fraction of the basilar papillar fibres. These behavioural findings support the hypothesis that the amphibian papilla alone mediates this critical vocal behaviour.