bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinematics and Performance Capacity for the Concertina Locomotion of A Snake (Coluber Constrictor)
Authors: Jayne Bruce C. , Davis James D. 
Published: April 2021

ABSTRACTWe used a motorized treadmill to determine the endurance (from 4.2 to 5.6cm s−1) and burst speed of five Coluber constrictor Linnaeus performing concertina locomotion in tunnels 3, 5 and 7cm wide. The snakes had greatest average endurance at 4.2cms−1 within the 5cm wide tunnel (80min), and the average endurance of snakes moving in the 3 cm tunnel (24 min) was significantly lower than that observed for either the 5 or 7 cm tunnel at the same speed. In contrast to endurance capacity, there was no statistically significant effect of tunnel width on burst speed, and mean values ranged from 13.5 to 16.8 cm s−1. The fastest burst speed observed was 20.8 cm s−1 in a 7 cm tunnel. Analysis of variance on kinematic variables measured from videotapes made of the endurance trials revealed highly significant effects of both speed and tunnel width on kinematics. As the tread speed increased among different endurance trials, the snakes primarily increased the frequency of movements and increased the average forward speed during the moving phase. However, the snakes did not significantly alter either the distance moved per cycle or the proportion of time spent moving in response to different tread speeds used in the endurance trials. Decreased tunnel width caused snakes (1) to move a smaller distance per cycle, (2) to use more regions of static contact with the sides of the tunnel, and (3) to orient the convoluted portions of the body at a smaller angle relative to the sides of the tunnel. Decreased tunnel width did not affect the average forward speed during the moving phase. Hence, tread speed and tunnel width affected different kinematic variables. Significant changes in kinematics did not always cause significant changes in locomotor performance capacity.
Myocardial Oxygen Consumption and Lactate Release by the Hypoxic Hagfish Heart
Authors: Forster M. E. 
Published: April 2021

ABSTRACT
Myocardial oxygen consumption and lactic acid release were measured in the isolated heart of a hagfish (Eptatretus cirrhatus Forster) perfused in vitro. Two different ranges of partial pressures of oxygen were employed ( 3.87–5.87 and 1.60–2.67kPa). All hearts released lactate into the perfusate, but the rate of release was greater and was depressed at the lower .
When energy production through the glycolytic pathway to lactate is converted to oxygen equivalents and added to measured oxygen consumption rates, over a wide range of power outputs and different values of , the data can be fitted to a single linear regression line. The rate of oxygen consumption of the hagfish myocardium, so obtained, is similar to values reported for teleost fish. The unusual ability of the hagfish myocardium to support perhaps up to 50% of its maximal power output through anaerobic metabolism is related to its extremely low cardiac energy demand.
The Heart Rate Variability Signal in Rainbow Trout (Oncorhynchus Mykiss)
Authors: Vera Luis De , Priede Imants G. 
Published: April 2021

ABSTRACT
Records of heart rate often show short-term variation in beat-to-beat interval which can be plotted as a heart rate variability signal (HRVS). It has been suggested that, in mammals, analysis of the HRVS can be used as a quantitative means of investigating control of cardiac function (McDonald, 1980). An HRVS can be recognised in the electrocardiograms (ECGs) of teleost fishes (Armstrong et al. 1989a) and these signals have been recorded by telemetry from free-living fish in their natural environment (Armstrong et al. 1989b). Regulation of the heart is usually studied by blocking components of the system by surgical or pharmacological intervention or using in vitro isolated preparations (Farrel, 1984). Analysis of the HRVS may provide a unique insight into the function of the intact system and should be applicable to free-swimming fish in their natural environment.
Centrally Generated Rhythmic and Non-Rhythmic Behavioural Responses inRana TemporariaEmbryos
Authors: Soffe S. R. 
Published: April 2021

ABSTRACTEmbryos of the frog Rana temporaria up to and around the time of hatching show a range of rhythmic and non-rhythmic movements. These may occur spontaneously or in response to lightly touching the skin of the trunk or head. The first response to touching one side is usually on the opposite side. Non-rhythmic movements range from weak twitches centred on the mid trunk to strong flexions along much of one side of the body and part of the tail, which result in the animal becoming tightly coiled. Rhythmic movements range from slow, high-amplitude ‘lashing’ movements to faster, lower-amplitude ‘swimming’ movements. During rhythmic movements, a wave of bending passes along the animal from head to tail. The longitudinal phase delay in bending is constant for a range of cycle periods (88–193 ms) but is not uniform along the whole body. Bending is maximal along the body and rostral part of the tail, decreases towards the tip of the tail and is lowest at the head. Lateral displacement during rhythmic movements is lowest 0.2 body lengths from the snout, increases rostral and caudal to this level and is highest at the tip of the tail.In animals immobilised with curare, a range of patterns of motor discharge can be recorded in response to stimulation. Non-rhythmic responses range from single spikes to prolonged bursts, usually on the opposite side to the stimulus. Stronger bursts can alternate briefly between the two sides and are never synchronous on both. Episodes of sustained rhythmic activity can be evoked by touch, electrical stimulation of the skin or, rarely, dimming the lights. Cycle periods within each episode can vary considerably but often shorten as activity proceeds. Discharge on the two sides alternates (phase is approximately 0.5). Motor root burst duration correlates with cycle period, bursts being longer at longer cycle periods. Burst onset is delayed caudally, this delay being longer at longer cycle periods. Stimulating one side of the head evokes a large burst of discharge on the opposite side, often followed by sustained rhythmic discharge. These responses in immobilised animals are judged to constitute centrally generated correlates of the main behavioural responses of R. temporaria embryos.
Fibre Types in Leech Body Wall Muscle
Authors: Rowlerson A. M. , Blackshaw S. E. 
Published: April 2021

ABSTRACT
The fibre type composition of obliquely striated muscle of adult Hirudo medicinalis was investigated by enzyme histochemistry, by immunohistochemistry and by SDS-PAGE. The oxidative capacity of the fibres, assessed by succinate dehydrogenase activity, was similar in all three layers of body wall muscle (longitudinal, oblique and circular) and in dorsoventral muscles. Histochemical localisation of Mg2+-activated actomyosin ATPase activity gave stronger staining in the longitudinal muscle than in other layers. As muscle shortening speed is directly related to this form of ATPase activity, this suggests that the longitudinal layer fibres are faster contracting than the circular, oblique or dorsoventral muscles. Results with polyclonal antibodies specific for vertebrate myosins were consistent with the ATPase results, i.e. fibres with the lowest actomyosin ATPase activity reacted preferentially with an antibody for a slower myosin. Thus, anti-T2, selective for vertebrate tonic fibre myosin, bound preferentially to fibres in oblique, circular and dorsoventral muscles, whereas anti-S, selective for vertebrate slow twitch fibre myosin (faster than vertebrate tonic fibre myosin), bound preferentially to the bulk of longitudinal layer fibres. Whereas most of the longitudinal layer stained uniformly with the anti-S antibody, some fibres in the outermost bundles were negative for the anti-S antibody and were, therefore, different from the main mass of longitudinal fibres. SDS-PAGE analysis of contractile protein preparations from body wall muscle also revealed a difference in the composition of the oblique, circular and dorsoventral muscles compared to the longitudinal layer, supporting the conclusion that leech body wall muscle contains two fibre types.
Development of Segment- and Target-Related Neuronal Identity in the Medicinal Leech
Authors: Jellies John , Kopp Diane M. , Bledsoe James W. 
Published: April 2021

ABSTRACT
The rhythmic pumping of the paired heart tubes in the medicinal leech Hirudo medicinalis offers an excellent system for studying the development of a simple behavior in terms of its neuronal and muscular components. The present experiments examined the development of identified heart excitor (HE) motor neurons during normal embryogenesis. Using intracellular impalements and dyefilling, we found that the HE motor neurons could be identified at an early stage of development and that they initially elaborated axonal arborizations in inappropriate target fields in the ventral body wall. These inappropriate projections were retracted as those at the appropriate target (developing heart tube muscle) extended. This remodelling occurred at least 4 days before the HEs acquired the adult phenotype of being driven to fire action potentials in a rhythmic pattern. Although the HEs exhibited centrally driven rhythmic oscillations late in embryogenesis, at earlier stages they exhibited largely a tonic discharge interrupted by bursts of inhibitory potentials in a periodic, but not a rhythmic, pattern. We also found what appeared to be non-rhythmic HE homologs in anterior and posterior segments where HE neurons have not been previously described. These homologs may project along similarly patterned guidance cues early in development, since they are at first indistinguishable from the definitive HEs, but they continued to elaborate both lateral and medial body wall projections over the same period that definitive HEs were expanding their arborizations over the developing heart tube and retracting their body wall projections. In both adult and embryonic leeches the homologs exhibited mostly tonic activity that was interrupted by pronounced, but non-rhythmic, hyperpolarizing postsynaptic potentials. Thus, there appears to be early segmental specification directing the final phenotype of the iterated neuron that, in most segments, becomes the HE motor neuron.
The structure and function of the fungal V-ATPase
Authors: Stevens Tom H. 
Published: April 2021

ABSTRACT
The fungal vacuole is a prominent organelle that functions as a storage site for amino acids, Ca2+, storage carbohydrates, inorganic phosphate and numerous hydrolases (Fig. 1) (Klionsky et al. 1990). A hallmark of fungal vacuoles is that they are acidic compartments involved in the turnover of cellular macromolecules. In the yeast Saccharomyces cerevisiae, the hydrolase activities in the vacuole are required for diploid cells to progress normally through sporulation and meiosis. The goal of this chapter is to present an overview of what is known about the enzyme complex responsible for acidifying the fungal vacuole and to summarize the current view of the function of acidification of the vacuolar network.
Lateral Bending During Lizard Locomotion
Authors: Ritter Dale 
Published: April 2021

ABSTRACT
Lateral bending of the trunk during terrestrial, quadrupedal locomotion was analyzed in four species of lizards, using high-speed videography and computerized motion analysis. The focus of the analysis was whether lizards produce a standing or a traveling wave of bending in the trunk during locomotion. Lizards with well-developed limbs (Cnemidophorus tigris and Dipsosaurus dorsalis) exhibit a standing wave of lateral bending at low speeds, which is replaced by a traveling wave of bending as velocity increases. Lizards with diminutive limbs (Gerrhonotus kingii and Eumeces multivirgatus) exhibit a traveling wave of lateral bending, even at the lowest speeds recorded. These results are not consistent with the ideas that lizards produce a standing wave of lateral bending during locomotion or that amniote vertebrates have lost the ability to produce a traveling wave of lateral flexion due to a change in the central pattern generator that controls locomotion.
The monosynaptic connections between the serotonin-containing LP3 and RPas neurones in Helix are serotonergic
Authors: Vehovszky Ágnes , Kemenes György , S.-Rózsa Katalin 
Published: April 2021

ABSTRACT
Monosynaptic connections between a giant serotonin-containing neurone and its serotonin-containing followers in the snail Helix pomatia were studied in isolated preparations of the central nervous system. The presynaptic cell was the LP3 cell in the left pedal ganglion and the followers were the RPas cells in the right parietal ganglion. The light microscopical morphology of the pre- and postsynaptic cells was investigated in whole-mount preparations following intracellular injection with a nickel-lysine complex. Axons from LP3 project towards the cerebral and suboesophageal ganglia or run in peripheral nerves which innervate feeding muscles and the foot. The follower neurones (RPas) project into nerves which innervate the heart and other visceral organs. The axons of LP3 and the RPas cells run in close proximity in the visceral ganglia. Ionophoretic application of serotonin onto the membrane of the postsynaptic RPas neurones mimicked the excitatory effect of the stimulation of the presynaptic LP3. Both the synaptic transmission between LP3 and its followers and the excitatory effect of exogenously applied serotonin on the RPas neurones decreased or were blocked in the presence of serotonin or the serotonin antagonists tryptamine, bufotenine, 7-methyltryptamine and MDL 72222-EFO2 in the bath. From this, we conclude that the excitatory neurotransmitter between LP3 and followers is serotonin and not some other neurotransmitter which might coexist with serotonin in LP3. The serotonergic monosynaptic connections between LP3 and its right parietal followers may play a role in a variety of serotonin-mediated physiological and behavioural responses, forming a link between feeding, locomotion and visceral functions.
Kidney and urinary bladder responses of freshwater rainbow trout to isosmotic NaCL and NaHCO3 infusion
Authors: Curtis B. James , Wood Chris M. 
Published: April 2021

ABSTRACT
The relative roles of the kidney and urinary bladder in ion, fluid and acid-base regulation were examined in freshwater rainbow trout chronically infused with either 140 mmol I-1 NaCl or 140 mmol I-1 NaHCO3 (3mlkg-1h-1) for 32 h. NaCl had a negligible effect on blood ionic and acid-base status, whereas NaHCCh induced a metabolic alkalosis characterized by a rise in arterial pH and [HCO3-] and an equimolar fall in [Cl-]. Urine was collected via either an internal catheter, which bypassed bladder function, or an external urinary catheter, which collected naturally voided urine. As a percentage of the infusion rate, glomerular filtration rate increased by about 135%, but urine flow rate (UFR) by only 80 %, reflecting increased tubular reabsorption of H2O. During NaCl infusion, virtually all of the extra Na+ and Cl- filtered was reabsorbed by the kidney tubules, resulting in an increased UFR with largely unchanged composition. During Na HCO3- infusion, tubular Na+ and Cl- reabsorption again kept pace with filtration. HCO3- reabsorption also increased, but did not keep pace with filtration; an increased flow of HCO3--rich urine resulted, which excreted about 10% of the infused base load. At rest, fish fitted with external catheters voided in discrete bursts of about 0.85 ml kg-1 at 25 min intervals. During infusion, burst frequency increased by about 40 % and burst volume by about 20 %. Reabsorption by the bladder reduced UFR by 25 %, the excretion of Na+ and Cl - by 50 %, of K+ by 44 % and of urea by 25 %. These differences persisted on a relative basis during NaCl and NaHO3 infusion despite the decreased residence time. However, HCO3- was neither secreted nor reabsorbed by the bladder. We conclude that the freshwater kidney functions to remove as much NaCl as possible from the urine, regardless of the NaCl load, and this role is supplemented by bladder function. The bladder plays no role in acid-base regulation during metabolic alkalosis.
The Influence of Gas Gland Metabolism and Blood Flow on Gas Deposition into the Swimbladder of the European Eel Anguilla Anguilla
Authors: Pelster Bernd , Scheid Peter 
Published: April 2021

ABSTRACT
The effects of blood flow through, and metabolic activity in, the swimbladder epithelium on gas deposition into the swimbladder have been analysed in the European eel, Anguilla anguilla. Blood flow in the artery supplying the retia was measured by Doppler flow probes; measurement of O2 and CO2 content in arterial and venous blood samples from the swimbladder allowed calculation of the rates of O2 removal from, and CO2 addition to, swimbladder blood. 83% of the O2 removed from the blood was transferred into the swimbladder lumen and only 17% was metabolized in the tissue. In spite of the deposition of CO2 into the swimbladder lumen, the CO2 content in rete venous blood was higher than that in arterial blood, indicating production of CO2 in the swimbladder tissue. The respiratory exchange ratio, calculated from O2 consumption and CO2 production of the swimbladder tissue, was significantly greater than one. Gas deposition into the swimbladder increased with increasing swimbladder arteriovenous pH difference, indicating acid release from gas gland cells, and thus their metabolic activity. The rate of gas deposition into the swimbladder increased with increasing blood perfusion of the swimbladder tissue. Under hypoxic conditions, gas deposition was significantly reduced, as was blood flow through the swimbladder tissue. The decrease in gas deposition during hypoxia coincided with a reduction in the swimbladder arteriovenous pH difference. The results therefore demonstrate that the rate of gas deposition is dependent on blood perfusion of the swimbladder tissue and on metabolic activity of the swimbladder tissue, both of which are reduced under hypoxic conditions.
Actions of Ion-Transport Peptide From Locust Corpus Cardiacum on Several Hindgut Transport Processes
Authors: Audsley Neil , Mcintosh Chris , Phillips John E. 
Published: April 2021

ABSTRACT
Schistocerca gregaria ion-transport peptide (Scg-ITP), a neuropeptide isolated from locust corpora cardiaca, stimulates ileal Cl − transport (Isc) in a dose-dependent manner and causes increases in Na+, K+ (IK) and fluid reabsorption (Jv) as previously observed with crude extracts of corpus cardiacum and with cyclic AMP. Unlike cyclic AMP, Scg-ITP does not stimulate ileal NH4+ secretion. H+ secretion (JH) in the ileum, which is not affected by cyclic AMP, is almost completely abolished by Scg-ITP. Although ITP may act via cyclic AMP as second messenger to stimulate NaCl, KC1 and fluid reabsorption, it apparently acts through a different intracellular pathway to influence xJH. Scg-ITP is unlikely to be the chloride transport stimulating hormone previously reported to act on the rectum, because it did not produce a maximum rectal Isc response and had no effect on either rectal Jv (which is Cl− -depcndent) or IK.
Direct Measurement of Mass Loss During Discontinuous Ventilation in Two Species of Ants
Authors: Lighton John R. B. 
Published: April 2021

ABSTRACT
A central controversy in the field of insect ventilation is the effect of the discontinuous ventilation cycle (DVC) on respiratory water loss rates. An accurate method of measuring water loss rates during the ventilation cycle would provide a direct means of resolving the controversy. It would also create opportunities for the comparative study of respiratory water loss rates in insects that employ different ventilation strategies and occupy different habitats.
Further Efforts at Training Pigeons to Discriminate Changes in the Geomagnetic Field
Authors: Couvillon P. A. , Asam Anne M. , Bitterman M. E. 
Published: April 2021

ABSTRACT
Although magnetic sensitivity in pigeons can reasonably be inferred from the impairment of homing by magnetic attachments to their heads (e.g. Keeton, 1971; Walcott and Green, 1974), which have been found to contain magnetite (Walcott et al. 1979), attempts to develop training methods suitable for systematic psychophysical analysis have been largely unsuccessful. Of four classical conditioning experiments with magnetic change as the conditioned stimulus, shock as the unconditioned stimulus and overt activity (Orgel and Smith, 1954) or cardiac acceleration (Beaugrand, 1976; Kreithen and Keeton, 1974; Reille, 1968) as the conditioned response, only one (Reille’s) gave any indication of conditioning. Of three experiments in which pigeons were rewarded with food or water for pecking a target in response to magnetic change (Alsop, 1987; Meyer and Lambe, 1966; Moore et al. 1987), all gave negative results. Bookman (1977) had some success with a flight tunnel in which his animals were rewarded for going to one or the other of two food boxes depending on the prevailing magnetic field, but the results of similar experiments by subsequent investigators were negative (Carman et al. 1987; Mclsaac and Kreithen, 1987).
Voltage-Activated Currents in Somatic Muscle of the Nematode Parasite Ascaris Suum
Authors: Martin R. J. , Thorn P. , Gration K. A. F. , Harrow I. D. 
Published: April 2021

ABSTRACT
Voltage-activated currents in cell bodies of the somatic muscle cells of Ascaris suum were studied using a two-microelectrode voltage-clamp technique. Cells recorded from had resting membrane potentials around −35 mV and had input conductances in the range 1–10 μS. In cells bathed in artificial perienteric fluid, depolarizing steps from a holding potential of −35 mV elicited outward currents at a threshold of − 15 mV. These currents had inwardly directed inflections on the rising phase, suggesting the presence of more than one current. Hyperpolarizing steps did not activate current. Tetraethylammonium (TEA+, 69 mmol l−1) blocked the outward currents and allowed a voltage-dependent inactivating Ca2+ current to be observed. The peak current-voltage relationship was U-shaped with a threshold around −15 mV and peak at +5 mV. The reversal potential of the Ca2+ current was estimated by extrapolation to be +45 mV. The permeability of the voltage-activated outward currents was studied by examining reversal potentials of tail currents. The reversal potentials were linearly dependent on the logarithm of the extracellular potassium concentration if extracellular [K+] was greater than 10 mmol 1−1. The Na+/K+ permeability ratio of the currents was 0.04. Inactivation, seen as a decline following the peak of the K+ current, was produced by maintained depolarization. The recovery from inactivation was complex and could be described by the sum of two exponentials with time constants of 0.67 s and 20.1 s. Steadystate inactivation of the K+ currents was observed at a range of holding potentials. Only a proportion (34%) of the total K+ current was inactivated by holding potentials more positive than −20 mV. Extracellular application of 5 mmol l−1 4-aminopyridine (4-AP) selectively abolished an early fast component of the K+ current (the peak). The 4-AP-sensitive current decayed quickly with a time constant of around 10 ms; a Boltzmann fit to its activation curve had a half-maximal activation voltage of +14 mV and a ‘slope’ of 10.5mV. The 4-AP-resistant current decayed with a time constant of around Is; a Boltzmann fit to its activation curve had a half-maximal activation voltage of +29 mV and a ‘slope’ of 12 mV. Depolarization activates a Ca2+ current and two K+ currents: the K+ currents were separated into lower-threshold, fast-inactivating (Ia-like) and higher-threshold, slowly inactivating (Ik-like) currents.