bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acquisition of potential for sperm motility in rainbow trout and chum salmon
Authors: Morisawa S. , Morisawa M. 
Published: April 2021

ABSTRACT
The male reproductive organ of rainbow trout and chum salmon consists of a pair of testes and sperm ducts. Spermatozoa in the distal portion of the sperm ducts exhibit full motility in the K+-free medium. However, spermatozoa from the testis were almost immotile in this medium. This suggests that the spermatozoa acquire a capacity for movement during their passage from the testis along the sperm duct. In chum salmon migrating into a bay, the sperm duct was almost empty. However, after the fish have travelled upstream for 1 km to their spawning ground in the river, the spermatozoa have left the testis, moved into the sperm duct and are capable of becoming motile. Thus it is probable that the process of acquiring the ability to move occurs within a relatively short period in this simple reproductive organ. Additionally, testicular spermatozoa demembranated with Triton X-100 exhibited motility, although the motility was less than that of demembranated spermatozoa from the sperm duct, suggesting that the acquisition of motility may correspond with the development of some function of the plasma membrane.
Presynaptic Depolarization Mediates Presynaptic Inhibition at a Synapse Between an Identified Mechanosensory Neurone and Giant Interneurone 3 in the First Instar Cockroach, Periplaneta Americana
Authors: Blagburn Jonathan M. , Sattelle David B. 
Published: April 2021

ABSTRACT
Intracellular microelectrodes were used to study presynaptic inhibition at a cholinergic synapse between identified neurones: the lateral filiform hair sensory neurone (LFHSN) and giant interneurone 3 (GI 3) in the terminal ganglion of the first instar cockroach Periplaneta americana. The LFHSN-GI3 synapse was shown to fulfil physiological criteria for monosynaptic transmission : the latency of the EPSPs was 1·4ms and was constant during high-frequency firing of LFHSN; transmission was progressively and reversibly abolished by replacement of Ca2+ with Mg2+.
Movement of the lateral filiform hair towards the cereal tip produced a burst of spikes in LFHSN and a burst of EPSPs in GI 3. Movement of the medial filiform hair towards the base of the cercus produced a burst of spikes in the medial filiform hair sensory neurone (MFHSN) and a burst of EPSPs in GI2. EPSPs evoked in GI 3 by LFHSN spikes were inhibited during bursts of EPSPs in GI 2 which were evoked by MFHSN spikes. LFHSN was depolarized and its spikes were reduced in amplitude during spike bursts in MFHSN. Reduction in LFHSN spike amplitude reduced GI 3 EPSPs. This phenomenon was attributed, therefore, to presynaptic inhibition. The occurrence of presynaptic inhibition was dependent upon the degree of delayed rectification exhibited by the LFHSN axon. Hyperpolarization of LFHSN increased spike height, but did not increase the amplitude of GI 3 EPSPs.
The delay between the onset of MFHSN-evoked EPSPs in GI2 and MFHSN-evoked depolarizations in LFHSN suggested that MFHSN does not synapse directly onto LFHSN. Neither depolarization nor hyperpolarization of GI 2 had any effect on MFHSN-mediated presynaptic inhibition of LFHSN-GI 3 transmission, therefore it was considered unlikely that GI2 synapses onto LFHSN. Prolonged hyperpolarization lowered the LFHSN spike threshold and temporarily abolished presynaptic inhibition.
Bursts of spikes in LFHSN mediated presynaptic inhibition of MFHSN-GI2 EPSPs. Mutual presynaptic inhibition by the FHSNs may have a functional significance in sharpening the boundaries of the GIs’ directional sensitivities.
The Telson Flexor Neuromuscular System of the Crayfish: I. Homology with the Fast Flexor System
Authors: Dumont J. P. C. , Wine J. J. 
Published: April 2021

ABSTRACT
We describe the phasic neuromuscular system of the crayfish telson and establish its homology with the abdominal flexor system that provides the power stroke for tailflip escape responses. Three paired phasic telson muscles are innervated by 11 paired neurones which have somata in the terminal (sixth) ganglion and axons in the sixth nerve. These are the posterior and ventral telson flexors and the anterior telson muscle. Studies of embryonic ganglia provide evidence that the sixth ganglion is a fusion product of two ancestral ganglia, plus a partial ganglion that is not homologous with the segmental ganglia. Two of the telson flexor motor neurones are homologues of the single motor giant found in each anterior hemiganglion. Among the shared features which led to this conclusion are: size, soma position, distribution of terminals to the muscles, dendrite morphology, pattern of direct inputs from the giant axons, and the marked tendency for low-frequency depression of the neuromuscular synapse. Two of the telson flexor neurones are homologues of the single flexor inhibitor found in each anterior hemiganglion. In addition to numerous morphological similarities, these two cells produce IPSPs in the telson flexor muscles. Six of the seven remaining motor neurones were identified as homologues of the non-giant fast flexor excitors of anterior ganglia. These can be divided into two uneven groups according to their ganglia of origin. The sixth segmental group of fast flexor motor neurones consists of four neurones (one less than expected) and the seventh segmental group consists of two neurones (three less than expected). The remaining neurone provides the sole innervation of the anterior telson muscle. Although previously classified as a telson flexor muscle, we found that the anterior telson muscle moves the uropod but not the telson. The innervation of this muscle and the pattern of inputs to the anterior telson motor neurone from identified interneurones are unlike that of any fast flexor muscle or motor neurone. We conclude that the anterior telson muscle and its motor neurone are not homologues of anterior components of the fast flexor system. In anterior ganglia, a prominent premotor neurone known as the segmental giant is presynaptic to all fast flexor motor neurones except the motor giants and flexor inhibitors. We identified a single paired cell in the sixth ganglion which appears to be the segmental giant homologue.
The Telson Flexor Neuromuscular System of the Crayfish: III. The Role of Feedforward Inhibition in Shaping a Stereotyped Behaviour Pattern
Authors: Dumont J. P. C. , Wine J. J. 
Published: April 2021

ABSTRACT
The telson flexor system is homologous to the fast flexor system of anterior ganglia (Dumont & Wine, 1986a), but important differences exist in connections to the telson motor giants (MoGs) (Dumont & Wine, 1986b). In this paper, we describe additional differences in connections to the telson non-giant fast flexor (FF) motor neurones and to the telson flexor inhibitor (FI). The telson FF motor neurones in ganglion 6 (G6) receive inputs similar to those in G4 and G5 (Miller, Hagiwara & Wine, 1985). The escape command neurones (lateral giants, LGs, and medial giants, MGs) in common provide weak disynaptic input via the telson segmental giant (SG6), and relatively strong tri-synaptic input via SG2, SG3 and the corollary discharge interneurones 12 and 13. There may also be some direct input from the MGs, but it, as well as the connections from SG6, appears to vary in different preparations. The compound PSP produced in telson FFs by a single LG or MG impulse was suprathreshold in only five of 55 experiments in isolated abdominal nerve cords, but the probability that a motor neurone would fire increased with additional giant axon impulses, showing that temporal summation of excitation outweighed the possible recruitment of inhibition. Firing probability was higher in semi-intact preparations, where at least one posterior telson FF was fired by a single LG impulse 50% of the time. As was pointed out previously (Dumont & Wine, 1986b), telson flexion would disrupt the behaviour pattern expected from LG commands. Two pathways of feedforward inhibition were found which prevent such disruption. The sensory input that recruits the LG also recruits powerful feedforward inhibition of the telson FF motor neurones, which reduces the probability that they will be fired by the LG. The same sensory stimulus also evokes inhibition of FFs in G5, excitation of FFs in G2 and G3, and mixed excitation and inhibition of FFs in G4. In addition, the telson FIs fire at short latency during LG-mediated tailflips. This occurs because the telson FIs are excited by sensory input. In fact, the firing threshold of the telson FIs to sensory input is lower than that of the LGs, at least for electrical stimulation of nerves. When the LGs do fire, they produce additional excitation of the FIs. The telson FIs also are excited by the LGs but not by the MGs. In contrast’ the anterior homologues of the telson FIs receive equivalent, delayed excitation from both MGs and LGs, and weaker sensory input, so that they tend to fire only after the peak of flexion (Wine & Mistick, 1977). The predicted net effect of these connections is that the telson flexor muscles should not contract during naturally elicited LG tailflips, and this is consistent with observed behaviour. The results can be interpreted as providing additional examples of potentially maladaptive central connections which are not expressed in behaviour because of feedforward inhibition.
Thermoregulation by Winter-Flying Endothermic Moths
Authors: Heinrich Bernd 
Published: April 2021

ABSTRACT
Noctuid moths of the subfamily Cuculiinae fly in any month of the winter in the north-eastern United States when air temperatures are at least 0°C. At lower temperatures they hide under leaf litter rather than perching on trees like many summer-flying noctuid moths. Like moths of similar mass and wing-loading that fly in the summer or that reside in tropical regions, the nocturnal cuculinids fly with a thoracic temperature of 30–35°C. The generation and maintenance of such high thoracic temperatures at low air temperatures depends on (1) the ability to begin shivering at very low muscle temperatures, (2) a thick insulating pile, and (3) counter-current heat exchangers that retard heat flow to the head and to the abdomen, respectively.
The Effects of Reduced Gill Area and Hyperoxia on the Oxygen Consumption and Swimming Speed of Rainbow Trout
Authors: Duthie Garry G. , Hughes George M. 
Published: April 2021

ABSTRACT
Rainbow trout with a cautery-induced 30 % reduction in functional gill area showed significant proportional reductions in maximum oxygen consumption in comparison to controls, but oxygen consumption at rest and at subcritical swimming speeds was not affected. This corroborates suggestions that total gill area is utilized for oxygen uptake only under conditions of maximum aerobic demand. During swimming trials, hyperoxia (, 300mmHg) neither increased of control fish nor compensated for the reduced apparent in fish with reduced gill area. Therefore a direct limitation on oxygen uptake at the gills is implied.
A Comparative Study of the Flight Mechanism of Diptera
Authors: Ennos A. Roland 
Published: April 2021

ABSTRACT
The mechanism of dipteran flight has been investigated in a comparative study involving thorax manipulation, analysis of high-speed films and direct observation of tethered flies under stroboscopic illumination. The click action observed in CCl4-anaesthetized Calliphora was found to be due to an interaction between the radial stop and the pleural wing process at the top of the upstroke. The movements occurring during unanaesthetized tethered flight were quite different as these structures were vertically separated except towards the bottom of the downstroke (Miyan & Ewing, 1985a,b). Results of observations on tethered insect flight and on morphology did not give full support to either the click mechanism (Boettiger & Furshpan, 1952) or the model of Miyan & Ewing. A novel model for the wingbeat is proposed. Distortion of the thorax brought about by the flight muscles results in upward and outward movement of the lateral scutum during the downstroke and inward and downward movement during the upstroke. In more advanced flies flexion lines result in a differentiated scutellar lever and parascutal shelf. Distortion is thereby limited largely to the posterior scutum. The parascutal shelf moves as a part of the scutal distortion, not as an independent element in the articulation, and the system is not bistable. The automatic changes in angle of attack are caused by inertial and aerodynamic forces acting around the torsional axis of the wing during the beat, which twist the compliant wing base.
Hydric Conditions During Incubation Influence Locomotor Performance of Hatchling Snapping Turtles
Authors: Miller Kirk , Packard Gary C. , Packard Mary J. 
Published: April 2021

ABSTRACT
Locomotor performance of hatchling snapping turtles (Chelydra serpentina) was assessed while turtles were running on land and swimming in water. Hatchlings from eggs incubated on a relatively wet substrate were faster than hatchlings from eggs incubated on a drier medium, both in absolute distance and in body lengths moved per unit time. The superior performance of turtles from the wet substrate was not due to differences in hydration of tissues, because differences in performance persisted after turtles from both groups had been fully hydrated. The superior performance of turtles from the wet substrate may stem from a greater aerobic capacity, because these animals accumulated lactate more slowly during locomotion than did turtles from eggs incubated on the dry substrate. These observations may provide a physiological basis for the improved survival of larger hatchlings of many species of reptiles.
The Wake of a Kestrel (Falco Tinnunculus) in Gliding Flight
Authors: Spedding G. R. 
Published: April 2021

ABSTRACT
The wake of a kestrel gliding down a 36 m long corridor was examined using multiple-flash stereo photographs of small bubbles of helium in soap solution. Qualitatively and quantitatively, the wake is very similar to that which would be measured behind an elliptically loaded aerofoil of the same span. The significance of this close agreement with classical aerodynamic theory is briefly discussed and the results are compared with others measured or assumed in the bird flight literature.
The Wake of a Kestrel (Falco Tinnunculus) in Flapping Flight
Authors: Spedding G. R. 
Published: April 2021

ABSTRACT
The structure of the wake behind a kestrel in medium-speed flight down a 36 m length of corridor was analysed qualitatively and quantitatively by stereophoto grammetry of multiple flash photographs of the motion of small soap-covered helium bubbles. The wake consists of a pair of continuous, undulating trailing vortices. The upstroke is therefore aerodynamically active and the circulation appears to remain constant along the wing whose geometry is altered during the course of the wing stroke. It is argued that the flight kinematics, and so the wake structure, of the kestrel may be typical of flapping flight at medium speeds and a flight model based on this wake geometry is presented. Rough estimates of the rate of momentum generated in the wake balance the weight almost exactly and a direct estimate of the induced power requirement from the wake measurements is obtained. The significance of these results for the various alternative aerodynamic descriptions and energetic predictions of models of flapping animal flight is briefly assessed.
Discontinuous Carbon Dioxide Release and Metabolic Depression in Dormant Land Snails
Authors: Barnhart M. Christopher , McMahon B. R. 
Published: April 2021

ABSTRACT
The respiration of dormant land snails (Otala lactea Müller) is characterized by periodic retention and release of CO2. Rates of oxygen uptake and CO2 release of individuals were recorded continuously for up to 21 days. was usually low (5·6μlg−1tissueh−1) but increased up to five-fold at intervals between 20 and 50h. Snails hypoventilated and retained CO2 when was low, while periods of elevated commenced with hyperventilation and net CO2 release. The ratio varied between about 0·2 and 4·8 during these cycles. Calculated whole body CO2 content fluctuated over a range of about 4·3 mmol I−1 H2O, and was inversely correlated with .
Cycles of CO2 retention and release might be the result and/or the cause of changes in metabolic rate during dormancy. Ventilation is sensitive primarily to O2, and O2 transport appears to be diffusion-limited. A simple model based on these characteristics predicts hypoventilation and consequent CO2 retention when is reduced. Also, the close correlation of and whole-body CO2 content in snails suggests that CO2 or acid-base balance might influence metabolic rate during dormancy. The relationship between discontinuous CO2 release and respiratory water loss in insects and snails is discussed.
The effects of prolonged epinephrine infusion on the physiology of the rainbow trout, Salmo gairdneri: II. Branchial solute fluxes
Authors: Vermette M. G. , Perry S. F. 
Published: April 2021

ABSTRACT
Rainbow trout were infused continuously for 24 h with epinephrine in order to elevate circulating levels to those measured during periods of acute extracellular acidosis (about 5× 10−8 mol I−1). Concomitant effects on branchial solute fluxes were evaluated. Epinephrine infusion caused complex and differential adjustments of Na+ and Cl− unidirectional fluxes (influx and efflux) resulting in a significant elevation of the arithmetic difference between Na+ and Cl− net fluxes . A significant correlation existed between and net branchial acid excretion , thereby suggesting a role for epinephrine in piscine acid-base regulation. The stimulation of by epinephrine was due primarily to a reduction in the excretion of titratable acid (JTA) accompanied by non-significant changes in ammonia excretion (JAmm) The results are discussed with respect to a role for epinephrine in regulating acid-base disturbances by interacting with branchial ionic exchange mechanisms.
Mobilization of a Coordinated Escape Response by Giant Axons in the Ophiuroid, Ophiopteris Papillosa
Authors: Yee Audrey , Burkhardt James , Gilly W. F. 
Published: April 2021

ABSTRACT
The escape response of Ophiopteris papillosa to contact by a predatory asteroid consists of a fast withdrawal of the stimulated arm, completed in less than 1 s, followed by rapid locomotion carried out by coordinated rowing of the two arms opposite the one stimulated. Electrical activity recorded from the radial nerve cord (RNC) during the locomotory phase consists of small-amplitude spikes (&lt;5μV). The initial arm jerk response is mediated by sequential activation of segmental intervertebral muscles, and the onset of activation progresses centrally at a rate of &lt;10cms-1 commencing 100-200ms after stimulation. Electrical activity recorded from the RNC immediately after tubefoot stimulation consists of a burst of large-amplitude spikes (50-100 μV) that propagate centrally at approximately 50cms-1. Electrical activity in the RNC with the lowest threshold to direct electrical stimulation consists of large spikes propagating at a mean velocity of 55cms-1 at 13 °C, and this activity persists in a Ca2+-free medium. Electrical and tubefoot stimulation of the arm tip in the same preparation both trigger a burst of large action potentials that propagate at approximately 50cms−1. The identity of the giant axons activated by tubefoot stimulation, the path-ways they follow and their role in mobilizing the coordinated escape response are discussed.
Pharyngeal movements during feeding sequences of Navanax inermis (Gastropoda: Opisthobranchia) in successive stages of dissection
Authors: Susswein A. J. , Achituv Y. , Cappell M. S. , Bennett M. V. 
Published: April 2021

ABSTRACT
Feeding in Navanax inermis Cooper was filmed and analysed after various dissections. In preparations with a cut through the body wall exposing the pharynx and buccal ganglia, completely normal feeding was observed. In addition to seven motor acts previously described in intact animals, an eighth act, peristalsis, was observed. In preparations with the pharynx excised from the animal but attached to the buccal ganglia, four motor acts were observed: flaring, expansion, contraction and peristalsis. In addition to increasing information about the nature of feeding movements in Navanax, these data indicate that preparations suitable for neuro-physiological studies are capable of producing a variety of feeding acts.
Short Communication: Critical Comments on a ‘Novel Mechanical Model of Dipteran Flight’ (Miyan & Ewing, 1985)
Authors: Pfau Hans K. 
Published: April 2021

ABSTRACT
According to the classical investigation of Boettiger & Furshpan (1952), the wing beat of flies is accompanied by a bistable mechanism, the ‘click mechanism’. This mechanism is controlled by the pleurosternal and tergopleural muscles (see Heide, 1971 ; Pfau, 1978; Pfau, Schroeter & Steitz, 1977). Recently doubts have been raised concerning the existence of the click mechanism during flight (Miyan & Ewing, 1985a,b). The authors suspect that the click mechanism is an artefact of CCl4 anaesthesia and propose a novel mechanical model of dipteran flight. In the following I analyse this model critically.
Suppression of sensory to motor synaptic transmission and narrowing of the sensory neurone action potential by arginine vasotocin in Aplysia californica
Authors: Goldberg J. , Colmers W. , Edstrom J. , Lukowiak K. 
Published: April 2021

ABSTRACT
The vertebrate neurohypophysial peptide arginine vasotocin (AVT), which may be endogenous to the Aplysia central nervous system, was tested for its effect on sensory to motor neurone synaptic transmission. In the semi-intact preparation, superfusion of AVT (10−6moll−1) over the abdominal ganglion decreased the amplitude of both the gill withdrawal reflex and the short-latency excitatory postsynaptic potentials (EPSPs) evoked in gill and siphon motor neurones by single action potentials elicited in sensory’ neurones. AVT slowed the rate of rise of the EPSP, enhanced the rate of homosynaptic depression, and reversibly decreased the duration of the action potential of mechanosensory neurones in isolated, perfused abdominal and pleural ganglia. Frequency-dependent prolongation of action potentials of pleural sensory cells was also decreased by application of AVT. Because this peptide has been shown to modulate the gill withdrawal reflex and its subsequent habituation, the hypothesis that AVT plays a physiological role in the expression of the suppressed behavioural state is proposed. In addition, it is proposed that modulation of the reflex by AVT occurs in part by shortening the duration of the sensory neurone action potential.
A New Field of Wing Campaniform Sensilla Essential for the Production of the Attractive Calling Song in Crickets
Authors: Schäffner Karl-Heinz , Koch Uwe T. 
Published: April 2021

ABSTRACT
A field of 10–15 campaniform sensilla located ventrally on the cubital vein of the cricket’s wing is described for the first time. This field of cubital campaniform sensilla (CCS) is only found in male crickets. When the afference from the CCS was removed by lesions of the cubital nerve, the syllable pattern was disturbed: syllables were shortened, shifted or omitted, resulting in severe irregularities of the song time pattern. The songs of crickets with lesions of the CCS are shown to be significantly less attractive to the female in quantitative phonotaxis experiments. In choice tests, the song of a lesioned male must be 20 dB louder to be as attractive as an intact song.