bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Enforced Activity On Ventilation, Circulation and Blood Acid-Base Balance in the Aquatic Gill-Less Urodele, Cryptobranchus Alleganiensis; A Comparison with the Semi-Terrestrial Anuran, Bufo Marinus
Authors: Boutilier R. G. , McDonald D. G. , Toews D. P. 
Published: April 2021

ABSTRACT
A combined respiratory and metabolic acidosis occurs in the arterial blood immediately following 30 min of strenuous activity in the predominantly skin-breathing urodele, Cryptobranchus alleganiensis, and in the bimodal-breathing anuran, Bufo marinus, at 25 °C, In Bufo, the bulk of the post-exercise acidosis is metabolic in origin (principally lactic acid) and recovery is complete within 4-8 h. In the salamander, a lower magnitude, longer duration, metabolic acid component and a more pronounced respiratory acidosis prolong the recovery period for up to 22 h post-exercise. It is suggested that fundamental differences between the dominant sites for gas exchange (pulmonary versus cutaneous), and thus in the control of respiratory acid-base balance, may underline the dissimilar patterns of recovery from exercise in these two species.
The Giant Axon Escape System of A Hydrozoan Medusa, Aglantha Digitale
Authors: Roberts Alan , Mackie G. O. 
Published: April 2021

ABSTRACT
Aglantha digitale (Hydrozoa) has a ring giant axon, up to 35 μm in diameter, which runs all round the margin of the bell in the outer nerve-ring. Running from the margin, up the inside of the bell towards the apex are eight motor giant axons, up to 40 μm in diameter. These synapse with the sub-umbrellar myoepithelium and are therefore motoneurones. The myoepithelial cells line the inside of the bell and have striated muscular tails running circumferentially. Contraction of this circular musculature forces water out of the bell and propels the medusa through the water. A large axon (up to 7 μm in diameter) runs on the aboral side of each tentacle. The tentacles retract during swimming and contain longitudinally aligned striated muscle tails. Intra- and extracellular recordings from the giant axons indicate that they are involved in the rapid escape swimming response of Aglantha. Stimuli which evoke escape swimming lead to a brief burst of two to six impulses (2–3 ms in duration) in the ring giant axon. These propagate round the margin (at up to 2·6 m s−1). The large tentacle axons fire one-to-one with the ring giant axon and the tentacles contract. The motor giant axons are excited at chemical synapses (blocked by divalent cations and with a synaptic delay of 1·6 ± 1 ms), where large, facilitating epsps evoke an impulse which then propagates up the bell at up to 4 m s−1. The overshooting motor giant axon impulses are Na+ dependent, 2–3 ms in duration, and excite the myoepithelium at synapses with a 1·6 ± 1 ms synaptic delay. A regenerative muscle impulse is evoked. It is of long duration (15–70 ms), Ca2+ dependent, overshoots zero, and propagates through the myoepithelium at 0·22 to 0·29 ms−1. A nearly synchronous contraction of the whole subumbrellar circular musculature is evoked. Isolated strips of muscle can reach peak tension in 40 ms. In the absence of sarcoplasmic reticulum, Ca2+ for excitationcontraction coupling probably enters the muscle during the impulse. This preparation has allowed a clear understanding of how the two types of axon co-ordinate escape behaviour. It should also be valuable for the study of synaptic transmission, previously very inaccessible in Cnidarians.
Cockroach Giant Interneurones Stained by Cobalt-Backfilling of Dissected Axons
Authors: Harrow I. D. , Hue B. , Pelhate M. , Sattelle D. B. 
Published: April 2021

ABSTRACT
Detailed neuroanatomical information is an essential prerequisite for functional analysis of specific neurones in the central nervous system. In this investigation we have combined the dissection of single axons with cobalt-backfilling to reveal the structural organisation of a class of interganglionic giant intemeurones in the central nervous system of the cockroach, Periplaneta americana (L). Each giant interneurone possesses a cell body, neurite and dendrites within the sixth abdominal ganglion and also has a giant axon which ascends the ventral nerve cord (Harris & Smyth, 1971). Cereal sensory neurones provide monosynaptic input to at least some giant interneurones (Callec et al., 1974). Furthermore the cereal afferent, giant interneurone pathway has proved to be a useful system for quantitative pharmacology of putative cholinergic synapses (Callec & Sattelle, 1973; Callec, 1974).
Membrane Currents of Pawn Mutants of the Pwa Group in Paramecium Tetraurelia
Authors: Satow Youko , Kung Ching 
Published: April 2021

ABSTRACT
Membrane currents were recorded from the wild type and two pawn mutants of the pwA complementation group in Paramecium tetraurelia under a voltage clamp. Most currents are not changed by the mutations. Transient inward currents of a leaky mutant, puA132, upon step depolarizations are less than those in the wild type. The inward transient is completely lacking in a non-leaky mutant, pwA500. The time course of the residual inward currents in the leaky mutant is not significantly different from that of wild type. The voltage sensitivity of the Ca channels in the leaky mutant is also similar to that of wild type. The inward currents upon membrane hyperpolarizations in the mutants show normal characteristics in the presence or absence of external K+. With sufficiently large, prolonged depolarization, outward currents progressively develop in the wild type but decay in the mutants.
The simplest conclusion we can draw is that the pwA mutations reduce the number of functional Ca channels but do not change the channel characteristics. From the conductance measurements, 45 % of the Ca channels remain in the leaky mutant pwA132, and none remain in the non-leaky mutant pwA500..
By subtracting the outward currents of pwA132 from the slow and prolonged outward currents of the wild type, we have tentatively separated a Ca-induced K+ current from the voltage-dependent K+ current. The time courses of these two currents differ by two orders of magnitude.
The Mechanism of Fluid Absorption at Ecdysis in the American Lobster, Homarus Americanus
Authors: Mykles Donald L. 
Published: April 2021

ABSTRACT
The mechanism of fluid absorption at ecdysis was investigated in the stenohaline marine decapod, Homarus americanas. Sea-water uptake began approximately 1 h before ecdysis, increased rapidly during ecdysis, and was completed 2 h after ecdysis. Increased drinking rates were measured during and just after ecdysis. The quantity of water ingested was equal to the total amount of water absorbed during moult, indicating that fluid entered the haemolymph exclusively via the lining of the digestive tract. It was estimated that 91 % of the ingested sea water appeared in the haemolymph by 2·5 h postecdysis. The midgut appeared to be the principal part of the digestive tract involved in the absorption of fluid into the haemolymph. X-radiography of lobsters that ingested a suspension of barium sulphate during ecdysis demonstrated that accumulation and concentration of this compound occurred within the midgut during the 2·5 h of haemolymph expansion following ecdysis. Elevated net water fluxes across perfused midgut were observed in late proecdysis and 0-5 h after ecdysis.
A Micropuncture Study of Kidney Function in the River Lamprey, Lampetra Fluviatilis, Adapted to Fresh Water
Authors: Logan A. G. , Moriarty R. J. , Rankin J. C. 
Published: April 2021

ABSTRACT
Micropuncture techniques have been used to investigate the role of each nephron segment in the river lamprey. The proximal segment reabsorbed no more than 10% of filtered water and tubular fluid here was iso-osmotic to plasma, at about 250 m-osmol. Further water reabsorption occurred in later nephron segments so that 44% of all filtered water was reabsorbed. Dilution of tubular fluid began in the ascending limb of the nephron loop and continued in the distal and collecting segments, so that 96% and 97· 5% °f filtered sodium and chloride, respectively, was reabsorbed by the kidney. Lampreys produce 337 ml kg−1 day−1 of a dilute urine (31·2 m-osmol) and the urinary ducts appear not to modify the composition of this urine.
Oscillating Contractions in Protoplasmic Strands Of Physarum: Mechanical and Thermal Methods of Phase Shifting for Studying the Nature of the Synchronizing Factor and its Transmission*
Authors: Achenbach U. , Wohlfarth-Bottermann K. E. 
Published: April 2021

ABSTRACT
A new experimental investigation chamber was used to analyse the control of rhythmic contractile activity in Physarum. A strand was mounted in such a way that isometric tension measurements of contraction forces could be made on two regions independently, the two regions remaining connected. It was possible to disturb one region experimentally and to compare its behaviour with the other.
A short time after being set up in the apparatus, the isometric contraction cycles in the two regions became synchronous. Stretching one region by 50% of its original length induced a phase delay relative to the other. A brief unilateral cold shock (Δt = 5–15°C) had a similar phase-retarding effect. Synchrony was subsequently reattained, unless the connecting region was cut or, for example, treated with 30 mm benzamide.
In approximately 25% of the investigated strands, a rapid change to a higher temperature (Δt = 2–5 °C) caused the warmed side to be phase-advanced. However, 75 % of the strands did not show a phase shift, suggesting that a rapid phase regulation is supported by increased temperature.
The described experimental assay is suitable for analysing the pathway and the nature of signal transmission in plasmodial strands.
Carbon Dioxide Exchange and its Effects on pH and Bicarbonate Equilibria in the Blood of the Amphibian, Xenopus Laevis
Authors: Emilio M. G. , Shelton G. 
Published: April 2021

ABSTRACT
The elimination of CO2 through the lungs and skin of Xenopus laevis and its distribution between plasma and erythrocytes were determined during breathing and submergence periods. CO2 output does not decrease during submergence, as lack of lung ventilation is compensated by an increase in cutaneous exchange. The total CO2 carried in the blood decreases after a 30 min dive, but the fraction carried in red blood cells increases substantially, due to an increase in the haematocrit values. This increase is related to a decrease in plasma volume during diving. During short dives the blood shows changes characteristic of respiratory acidosis but longer dives result in a combination of respiratory and metabolic acidosis.
A Locust Wind and Ocellar Brain Neurone
Authors: Simmons Peter 
Published: April 2021

ABSTRACT
One of the large descending brain neurones in each half of the central nervous system of a locust is probably important in regulating the attitude of the locust’s flight in the pitch plane. This function is suggested by a consideration of the stimuli which excite the interneurones, and of the muscles whose motoneurones they excite. Each of these interneurones has its cell body in the protocerebrum and its axon descends the ipsilateral connective and has branches in all of the thoracic ganglia. The interneurones are excited by currents of air directed at the front of the head. An increase in the intensity of light falling on the median ocellus causes a reduction in the frequency of spikes produced by stimulation of the wind-sensitive hairs, and a reduction in the intensity of this light causes an increase in the frequency of these spikes. Each interneurone makes excitatory connexions with motoneurones of the subalar and dorsal longitudinal flight muscles ipsilateral to it.
Binaural Interaction in the Cod
Authors: Horner Kathleen , Sand Olav , Enger Per S. 
Published: April 2021

ABSTRACT
Recordings were made from 93 single units in the acoustical lobes and the torus semicircularis of the cod during sound stimulation and anodal blocking of the posterior saccular nerves. Most medullary sound responses were phase locked to the stimulus to some degree. The phase locking was less pronounced in the torus semicircularis, and sound stimulation sometimes caused clear inhibition of activity in this area. A large fraction of the units in both recording loci was insensitive to our sound stimuli, which acted mainly via the swimbladder. Peripheral blocking caused decreased activity and inhibition of sound responses in the acoustic lobes, indicating excitatory ascending input to this region. Binaural interaction was found in 8 of 29 medullary units tested during both ipsi- and contralateral block. Single-sided blocking experiments revealed both inhibitory and excitatory input to the torus semicircularis region. Binaural interaction was found in 3 of the 5 units tested during both ipsi- and contralateral block in this area.
Protein Synthesis Requirement of the Aplysia Circadian Clock Tested by Active and Inactive Derivatives of the Inhibitor Anisomycin
Authors: Jacklet Jon W. 
Published: April 2021

ABSTRACT
The circadian rhythm of compound action potential frequency recorded from the isolated eye of Aplysia in culture medium and darkness was subjected to 6 h pulse treatments with either anisomycin, a protein synthesis inhibitor, or inactive derivatives of anisomycin. Anisomycin caused phase-dependent phase shifts of the rhythm as expected from previous experiments, but none of the derivative molecules caused phase shifts or perturbed the rhythm. Anisomycin inhibited eye-protein synthesis by 75% at the concentrations (10-6 M) used in the phase shifting experiments but none of the derivatives inhibited synthesis. Only those molecules that actually inhibited protein synthesis caused phase shifts of the clock, although the inactive derivatives differed from anisomycin by only an acetyl group. The results strengthen the conclusion that the inhibition of protein synthesis caused by anisomycin is important in perturbing the timing of the circadian clock and not some other characteristic effect of the inhibitor molecule. Together with the results from other systems, these findings imply that the daily synthesis of protein is a general requirement for circadian clocks.
Postsynaptic Inhibition of Crayfish Tonic Flexor Motor Neurones By Escape Commands
Authors: Kuwada J. Y. , Hagiwara G. , Wine J. J. 
Published: April 2021

ABSTRACT
The crayfish abdomen contains separate slow and fast neuromuscular systems that mediate posture and escape tailflips (Kennedy & Takeda, 1965 a,b). It was recently demonstrated that impulses in the medial and lateral giant axons, which trigger escape responses, also inhibit both spontaneous and evoked activity in the tonic, or slow, flexor motor neurones (Kuwada & Wine, 1979). The evidence for inhibition was based exclusively on extracellular recordings of the spontaneously active tonic flexor motor neurones. We have now used intracellular recordings from the somata and neuropilar processes of the tonic flexor motor neurones to clarify the nature of inhibition.
Our main findings are that synaptic potentials (from unknown sources) appear to underlie the spontaneous activity of the tonic flexor motor neurones, and that impulses in the giant axons cause large-amplitude, hyperpolarizing IPSPs in the tonic flexor motor neurones and EPSPs or spikes in the peripheral inhibitor. Of the six tonic flexor neurones in each half ganglion, we have recorded from f 3, f5, f6 and possibly f4 (the motor neurones are numbered 1−6 according to increasing size, with f5 being the peripheral inhibitor). The motor neurones were identified by the size of their extracellularly recorded axon spikes and by the positions of their somata (Wine, Mittenthal & Kennedy, 1974). Results are from six preparations.
General methods were the same as those used earlier (Kuwada & Wine, 1979). For intracellular recordings we used 3 M-KCI electrodes of 15−80 MΩ, inserted into desheathed ganglia of isolated nerve cords. The giant axons were stimulated via focal suction electrodes placed directly over them in sheathed connectives. Examples of tonic flexor motor neurone activity and inhibition of it by giant axon spikes are shown in Fig. 1.
The following points can be made.
Use of an Operational Amplifier Signal Differentiator Reveals That Octopamine Increases the Rate of Development of Neurally Evoked Tension in Insect Muscle
Authors: Buchan P. B. , Evans P. D. 
Published: April 2021

ABSTRACT
Octopamine is a biogenic amine that is widespread in the insect nervous system (Evans, 1978; Dymond & Evans, 1979). In the locust, it potentiates the amplitude and increases the rate of relaxation of tension, in the extensor tibiae muscle of a hindleg, induced by the stimulation of the slow excitatory motoneurone (SETi) (Evans & O’Shea, 1977; O’Shea & Evans, 1979). O’Shea & Evans (1979) determined relaxation rates by graphical analysis of the data; a process which proved to be very time consuming and subject to error in the measurement at high relaxation rates. The device we describe here allows the continuous measurement of contraction and relaxation rates, and any changes in these parameters, during the course of an experiment. It was developed for use in a comparative pharmacological study of the octopamine receptors producing the above effects (Evans, 1980; P. D. Evans, in preparation).
Mechanisms of Body-Temperature Regulation in Honeybees, Apis Mellifera II. Regulation of Thoracic Temperature at High Air Temperatures
Authors: Heinrich Bernd 
Published: April 2021

ABSTRACT
Honeybees could remain in continuous free flight at extremely high air temperatures (up to at least 46 °C). The metabolic rate in free flight, 80-85 ml O2 g body weight-1 h-1, was independent of air temperature (TA) over a span of at least 22 °C. The bees’ ability to fly at high TA was due to their ability to maintain thoracic temperature (TTh) near TA despite prodigious rates of heat production. Mechanisms of preventing TTh from overheating at high TA were investigated. Bees in flight at high TA regurgitated fluid from their honeycrop and large droplets sometimes spread over the anterior portion of the thorax. Bees without the first two sets of legs, or without a ‘tongue’, maintained as low TH and TTh as intact bees. The abdomen serves only a minor function as a heat exchanger. In tethered bees, heating of the thorax to 45-50 °C resulted in significant, yet relatively little, temperature increase of the abdomen above that of dead or non heat-stressed animals. Similarly, in free flight abdominal temperatures (TAb) were close to TA at all TA. Thoracic heating to near lethal temperatures did not result in droplet extrusion from the mouth nor in significant physiologically facilitated heat transfer to the head. Furthermore, it resulted in no, or in relatively small, changes in pulsation of the aorta and the heart. However, the bees prevented the head from overheating, and the head served as a heat sink for excess heat from the thorax. Keeping TH&lt; TA resulted in keeping TTh near TA. It is concluded that during flight at high TA regulation of TH by evaporative cooling is the primary mechanism of reducing TTh.
Mechanisms of Acid-Base Adjustment in Dogfish (Scyliorhinus Stell Aris) Subjected to Long-Term Temperature Acclimation
Authors: Heisler N. , Neumann P. , Holeton G. F. 
Published: April 2021

ABSTRACT
Specimens of Larger Spotted Dogfish (Scyliorhinus stellaris) were acclimated to a range of temperatures for 22–28 days. The relationships of pH to acclimation temperature in the extracellular space and in three intracellular compartments were essentially the same as previously observed in 24 h acclimated dogfish (Heisler, Weitz & Weitz, 1976).
In dogfish subjected to elevated inspired during acclimation to low temperature, there was an inversion in the relationship of acclimation temperature to plasma , and in that to plasma bicarbonate, whereas the relationships to pH values were unchanged.
It is concluded that the temperature adaptation of the acid-base parameters is complete after 24 h of temperature acclimation. At least the following mechanisms are involved in the adjustment of pH with changes of temperature: changes of changes of buffer pK values, and transmembrane transfer of bicarbonate. Apparently only one of them, the transmembrane transfer of bicarbonate, can be modulated in a sufficient range and is responsible for the final pH adjustment.
The Antennal Motor System of the Rock Lobster: Competitive Occurrence of Resistance and Assistance Reflex Patterns Originating From the Same Proprioceptor
Authors: Vedel Jean-Pierre 
Published: April 2021

ABSTRACT
Skeletal, muscular and neural organization of the two distal joints (J 2 and J3) of the antenna of the rock lobster Palinuros Palinurus has been described. Motor innervation (nine motoneurones) of the two distal joints of the antenna has been determined by anatomical and physiological methods. Extensor and flexor muscles of J2 and J3 are each innervated by one specific excitatory tonic motoneurone. One excitatory phasic motoneurone is common to both the J2 and J3 extensor muscles, another to the J2 and J3 flexor muscles. The J3 extensor muscle also receives a specific phasic motoneurone. An accessory extensor muscle which spans J2 and J3 is innervated by one excitatory motoneurone. A common inhibitory motoneurone innervates the two flexor and the two extensor muscles of J2 and J3. Movements of J2 and J3 are sensed by a proprioceptor (chordotonal organ). Reflex patterns involving this proprioceptor have been extensively studied. Sinusoidal extension-flexion movements imposed on the J3 joint induced intra-segmental reflexes (on the J3 muscle innervations) and intersegmental reflexes (on the J2 muscle innervations) which exclusively involved the tonic excitatory motoneurones and the common inhibitory motoneurone. Resistance reflexes (activation of the muscle stretched by the imposed movements) occurred whatever the excitability level of the animal and involved both flexor and extensor motoneurones. The motoneurones spiked at a higher frequency when the velocity of the imposed movement was increased. The common inhibitor motoneurone was activated during extension movements. In preparations which became ‘more excitable’, assistance reflexes could be induced by joint stimulations which formerly induced resistance reflexes. Sometimes assistance reflexes could be induced by increasing the velocity of the movements imposed on J3. Assistance reflexes mainly involved extensor motoneurones. The role of the tonic, phasic and inhibitory innervations and the functional significance of resistance and assistance reflexes are discussed in relation to the behavioural role of the rock lobster antenna.