bluuebunny/crossref_metadata_2025_split huggingface dataset:
NaCl adaptation in Rana ridibunda and a comparison with the euryhaline toad Bufo viridis
Authors: Katz U. 
Published: April 2021

ABSTRACT
The physiological adaptation of the frog Rana ridibunda to saline environment was studied. It was found that blood was always hypertonic to the external solution, but at the highest salinity tolerated (i.e. 300 mOsM) the osmotic gradient across the skin was nearly abolished. Water uptake by the living frog remained unchanged, whereas sodium transport across the skin decreased markedly. Neurohypophyseal hormone increased water uptake and sodium transport to levels similar to those in tap water frogs. Water content of the tissues was not affected by saline adaptation, although it varied appreciably under acute conditions. Oxygen consumption increased in dehydrated frogs, but not in adapted ones. The results are discussed and compared to the euryhaline toad Bufo viridis ; the importance of high urea levels for high salt adaptation is stressed.
An electrophysiological analysis of extra-axonal sodium and potassium concentrations in the central nervous system of the cockroach (Periplaneta americana L.)
Authors: Thomas M. V. , Treherne J. E. 
Published: April 2021

ABSTRACT
Simultaneous intracellular and sucrose-gap recordings showed, in contrast to previous findings, that the electrical parameters of giant axons were similar in intact and desheathed connectives bathed with the ‘extracellular Ringer’ of Yamasaki & Narahashi. This implies that the extra-axonal sodium concentration, in situ, is likely to be lower than had been previously supposed. Axonal responses showed that, despite the high blood concentration of 24·2 mM-K+ measured by flame photometry, the effective concentration in the blood was 10-15 mM-K+ which corresponds to the measurements made with potassium-selective electrodes. The activity of the blood potassium ions caused a marked reduction in the amplitude of the action potentials following surgical desheathing or disruption of the blood-brain barrier with hypertonic urea. It is suggested that a regulatory mechanism exists in the central nervous system which counteracts the effects of the high blood potassium level.
Energetics of swimming of a sea turtle
Authors: Prange H. D. 
Published: April 2021

ABSTRACT
Young (mean mass 735 g) green turtles (Chelonia my das) were able to swim in a water channel at sustained speeds between 0·14 and 0·35 m.s−1. Oxygen consumption at rest was 0·07kg−1. h−1; at maximum swimming speed oxygen consumption was 3–4 times greater than at rest for a given individual. In comparison with other animals of the same body mass the cost of transport for the green turtle (0·186 1 O2.kg−1. km−1) is less than that for flying birds but greater than that for fish. From drag measurements it was calculated that the aerobic efficiency of swimming was between 1 and 10 %; the higher efficiencies were found at the higher swimming speeds. Based upon the drag calculations for young turtles, it is estimated that adult turtles making the round-trip breeding migration between Brazil and Ascension Island (4800 km) would require the equivalent of about 21 % of their body mass in fat stores to account for the energetic cost of swimming.
Insect blood-brain barrier: an electrophysiological investigation of its permeability to the aliphatic alcohols
Authors: Thomas M. V. 
Published: April 2021

ABSTRACT
The anaesthetic effects of the aliphatic alcohols were used to measure their concentration at the neuronal surfaces of the cockroach central nervous system. The results were in most cases fairly closely described by first-order kinetics. The exchange half-times of the lower alcohols were only a few seconds, being little affected by the removal of the nerve sheath. The half-times for the higher alcohols were somewhat longer, and were more significantly reduced by desheathing; these observations were interpreted in terms of a reservoir effect resulting from their higher liposolubility. It was shown that the ionic diffusion barrier in intact nerve cords remained undamaged in the presence of the alcohols.
The pharmacology of an insect ganglion: actions of carbamylcholine and acetylcholine
Authors: Sattelle D. B. , McClay A. S. , Dowson R. J. , Callec J. J. 
Published: April 2021

ABSTRACT
Methods for presenting dose-response data for the ganglionic actions of cholinergic agonists (e.g. carbamylcholine) are compared, using the mannitol-gap technique for electrophysiological recording of synaptic events at the cereal nerve, giant fibre synapse of the sixth abdominal ganglion of the cockroach Periplaneta americana. At concentrations around 10−5M, carbamylcholine has no effect on ganglionic polarization but potentiates the monosynaptic EPSP. At 10−4 M and higher concentrations, ganglionic depolarization is accompanied by a reduction of EPSP. Pretreatment with eserine ( 10−6 M) considerably shifts the dose-response curve for acetylcholine so that synaptic transmission is consistently sensitive to 10−8 M acetylcholine.
The Influence of the Hatching Factor on the Water Uptake of the Second Stage Larva of the Potato Cyst Nematode Heterodera Rostochiensis
Authors: Ellenby C. , Perry R. N. 
Published: April 2021

ABSTRACT
Larvae-containing eggs of the potato cyst nematode were soaked in root diffusate in artificial tap water or in artificial tap water alone. In one experiment, the eggs were still contained in intact cysts; in another experiment they were in a halved cyst. Eggs were ruptured after 0−5 days treatment and the water content of the liberated larvae immediately estimated by interference microscopy. Larvae from treated eggs from both the halved and intact cysts had a higher water content than controls. Larvae liberated from treated eggs from the halved cyst reached their maximum water content after 24 h treatment; those from intact cysts attained the same value after 2 days. The delay, for the intact cyst, is in keeping with the hatching response for intact cysts and supports the view that the results for water content are due to the activity of the hatching factor. Reasons are advanced for the view that the hatching factor may work via a neurosecretory mechanism.
The regulation of haemolymph calcium concentration of the crab Carcinus maenas (L.)
Authors: Greenaway P. 
Published: April 2021

ABSTRACT
After acclimation, Carcinus can maintain calcium balance in dilute (35–100%) but not in low calcium sea water. 71 % of total haemolymph calcium (9·54 ± 0·42 mm) was in ionic form as compared with 90·9 % (9·9 mm) in sea water. On acclimation to dilute sea water the calcium activity of the haemolymph was greater than that of the medium, the difference being maintained by active calcium uptake. Carcinus is highly permeable to Ca2+, influx from sea water being 0·513 ± 0·07 μmoles g−1 h−1 and the time constant for calcium influx 4·3 ± 0·48 h. Calcium space represented ca. 25 % wet body weight independent of body size or salinity of acclimation medium.
Connexions between hair-plate afferents and motoneurones in the cockroach leg
Authors: Pearson K. G. , Wong R. K. , Fourtner C. R. 
Published: April 2021

ABSTRACT
The trochanteral hair-plate afferents in the metathoracic leg of the cockroach, Periplaneta americana, were stimulated electrically and at the same time intracellular recordings were made from either motoneurones, interneurones or afferent terminals within the metathoracic ganglion. Activity in the hair-plate afferents evoked short latency excitatory postsynaptic potentials (EPSPs) in femur extensor motoneurones and inhibitory postsynaptic potentials (IPSPs) in femur flexor motoneurones. The latency of the IPSPs was on average 1·8 ms longer than the latency of the EPSPs. Intracellular recordings from terminal branches of the hair-plate afferents showed that the delay between the peak of the afferent terminal spike and the beginning of the EPSPs is about 0·4 ms. This finding, together with the observations that the amplitude of the EPSPs is increased by the passage of hyperpolarizing current and decreased following high-frequency stimulation, indicates that the EPSPs are evoked via monosynaptic chemical synaptic junctions. The observations of the long latency of the IPSPs, the need for a number of afferents to be simultaneously active for them to be evoked and the occasional variability in latency, all indicate that the IPSPs are evoked via a disynaptic pathway. These findings provide information on the synaptic mechanisms underlying the reflexes from the trochanteral hair plate to femur flexor and extensor motoneurones identified in a previous investigation (Wong & Pearson, 1976).
Cardiovascular dynamics of the chelonia during apnoea and lung ventilation
Authors: Shelton G. , Burggren W. 
Published: April 2021

ABSTRACT
In both Pseudemys and Testudo, blood pressures are identical in all chambers of the ventricle. Systolic pressures are not measurably different in the ventricle and systemic arteries but are 0·5–2·0 cm H2O lower in the pulmonary artery due to the resistance of the pulmonary outflow tract. Diastolic pressures are the same in all systemic arteries but are substantially lower in the pulmonary artery. It is concluded that the systemic and pulmonary circulations are perfused by a single pump during both apnoea and lung ventilation. Flow profiles in pulmonary and systemic arteries are characteristically different. Substantial changes in cardiac output may occur during intermittent breathing and apnoea, especially if there are large fluctuations in heart rate. Pulmonary flow increases during lung ventilation due to vasodilation of the lung vasculature. Systemic flow is also affected though the increase is usually smaller. Any separation in the blood pumped by the single ventricle must be maintained by laminar flow patterns and the composition of the blood in each of the major arteries should reflect their relationship to these patterns.
Activities of antennal and ocellar interneurones in the protocerebrum of the honey-bee
Authors: Suzuki H. , Tateda H. , Kuwabara M. 
Published: April 2021

ABSTRACT
Unit responses to olfactory and mechanical stimuli of the antennae, and illumination of the ocelli, were recorded extracellularly in the protocerebrum of the honey-bee. Bimodal units responded both to antennal and to ocellar stimuli; antennal units responded to the former and the ocellar units to the latter. Some antennal units responded to olfactory stimuli (olfactory units), and others responded to mechanical stimuli (mechanical units). Ocellar units in the brain showed phasic responses at the start and/or cessation of illumination. Six types of responses were found. About two-thirds of the bimodal units showed the same type of response to stimulation of the antennae as to stimulation of the ocelli. Most of them showed excitation by each stimulus. 5. Bimodal units were distributed around the a-lobe in the protocerebral lobe, whereas the antennal and the ocellar units were widely distributed. By turning off the ocellar illumination, background discharge frequency, and the pattern and magnitude of responses to antennal stimuli, were changed. The activities of the ocellar units were altered by inputs from the antenna. It was postulated that antennal and ocellar inputs converge and interact with each other in the protocerebral lobe of the honey-bee.
Control of shell settling in the swimming sea anemone Stomphia coccinea
Authors: Lawn I. D. , McFarlane I. D. 
Published: April 2021

ABSTRACT
Electrical activity has been recorded from Stomphia coccinea during the behavioural sequence in which the detached anemone settles on to a Modiolus shell. When a responsive tentacle contacts the shell, a short, complex burst of pulses is elicited. These remain confined to the region of contact. The endodermal slow-conduction system (SS2) then begins to fire repetitively (a typical example is 16 SS2 pulses at a mean interpulse interval of 5 s) until the pedal disc begins to inflate. Shell-tentacle contact is essential for stimulation of SS2 activity. The complete response, apart from local bending of the column, may be reproduced by electrical stimulation of the SS2 alone. As few as 10 stimuli at frequencies between 1 shock/s and 1 shock/10 s are required to elicit the response.
The different actions of chloride and potassium on postsynaptic inhibition of an isolated neurone
Authors: Meyer H. 
Published: April 2021

ABSTRACT
Isolated stretch receptor neurones from freshwater crayfish were examined in solutions containing different concentrations of chloride and potassium. In normal solution the inhibitory reversal potential (EIPSP) of this preparation was strictly negative with respect to the resting potential and even to the reversal potential of spike after-hyperpolarization. The time courses of resting potential and EIPSP following rapid solution change suggest that the current generating the IPSP is mainly carried by chloride ions and that the participation of potassium is very small. This has also been confirmed by the calculated conductances of the activated inhibitory membrane in the different solutions. The results add further evidence for an outwardly directed pumping of chloride ions which keeps the intracellular concentration of this anion at the low level necessary for hyperpolarizing inhibition.
On the interaction of NH4+ and Na+ fluxes in the isolated trout gill
Authors: Kerstetter T. H. , Keeler M. 
Published: April 2021

ABSTRACT
Sodium influx was measured in isolated, previously perfused gill arches of rainbow trout, Salmo gairdneri, by measuring incorporation of 22Na into gill tissue following timed exposure to a 1 mm22NaCl medium. Transport rates approximated those estimated for intact fish and were linear for at least one min. NH4Cl-containing perfusates at pH 7 and 8 stimulated Na+ influx equally, indicating that only ionized ammonia is important in the transport process. A Na+/NH4+ exchange at basal and/or lateral membranes of the transporting cells is suggested. Low-sodium Ringer perfusate augmented Na+ influx; in one group of gills the transport rate was more than double that of NaCl Ringer controls. The increase in transport induced by internal NH4+ was not additive with the low sodium augmentation. A reduction in intracellular [Na+] is postulated as the mechanism operating in both cases. Ouabain had no appreciable effect on Na+ influx, either with or without NH4+ in the perfusate. Diamox partially blocked the augmented Na+ influx induced by NH4+. Amiloride completely inhibited Na+ influx, both with and without NH4+ in the perfusate.
Flight energetics in sphinx moths: heat production and heat loss in Hyles lineata during free flight
Authors: Casey T. M. 
Published: April 2021

ABSTRACT
Mean thoracic temperature of free-flying H. lineata in the field and in the laboratory increased from about 40 °C at Ta= 16 °C to 42·5 °C at Ta = 32°C. At a given Ta, thoracic temperature was independent of body weight and weakly correlated with wing loading. The difference between abdominal temperature and air temperature increased from 2 °C at low Ta to 4·2 °C at high Ta. At a given Ta, the difference between Tab and Ta was positively correlated with thoracic temperature. Oxygen consumption per unit weight did not appear to vary with Ta from 15 to 30 °C and was inversely proportional to body weight. Thermal conductance of the abdomen (Cab) was greater than thermal conductance of the thorax (Cth) in still air and at wind velocities up to 2·5 m/s. In moving air at speeds approximating flight, Cth was twice as high as in still air. Under the same conditions Cab was 3–4 times as high as in still air. Thoracic and abdominal conductance are inversely proportional to their respective weights. These data are consistent with the hypothesis that thoracic temperature is controlled by regulation of heat loss. However, a heat budget derived from these data suggests that heat dissipation may not be sufficient to offset the decrease in passive cooling of the thorax at high ambient temperatures.
The mobilization of calcium and bicarbonate by raised concentrations of potassium in the haemolymph of the snail, Helix pomatia
Authors: Burton R. F. , Jaufeerally F. R. 
Published: April 2021

ABSTRACT
After the concentration of potassium in the haemolymph of Helix pomatia has been raised by the infusion of KCl, it falls approximately exponentially for a time and then tends to rise. The accompanying rise and fall of calcium concentration can be fitted to a simple mathematical model. The mobilization of calcium is accompanied by the generation of bicarbonate in equivalent amounts, without much change in pH or . There is probably an increased production or retention of carbon dioxide at this time, but the main cause of the changes in calcium and bicarbonate is not respiratory acidosis. The concentration of potassium rises in snalis that have been infused with CaCl2. The adverse responses visible in snails infused with KCl are largely prevented when CaCl2 is infused at the same time. Homeostasis seems to involve the maintenance of a proper balance of calcium and potassium concentrations.
Osmotic and ionic regulation in different populations of the new zealand freshwater crayfish Paranephrops zealandicus
Authors: Wong T. M. , Freeman R. F. 
Published: April 2021

ABSTRACT
Some features of the osmoregulatory mechanism are compared in four populations of Paranephrops zealandicus White collected from freshwaters of different ionic concentrations. Crayfish from freshwaters of ca. 2·0 mm-NaCl concentration show a sustained decrease in blood concentration of ca. 8% when placed in 0·2 mm-NaCl. Populations from freshwaters of ca. o·2−0·4 mm-NaCl show lower rates of net salt loss in distilled water and higher rates of net salt uptake from dilute NaCl solutions than do populations from freshwaters of ca. o·8−2·0 mm-NaCl. Renal salt losses over the first 24 h in distilled water account for ca. 18% of the total salt loss. It is suggested that P. zealandicus from environments of lowest concentration shows a similar degree of adaptation to freshwater as do crayfish of the northern hemisphere. It differs in possessing a substantially higher blood concentration.
Evidence for A Synaptically Mediated Decrease in Conductance in A Crustacean Myocardium
Authors: Delaleu J. C. 
Published: April 2021

ABSTRACT
In the neurogenic heart of the isopod Porcellio dilatatus, electrical stimulation of the cardio-regulatory nerves at rates greater than 20-25 pulses/s elicited inhibitory junctional potentials (IJPs) in the myocardium. Its cessation was followed by a long lasting hyperpolarization of the myocardial membrane (post-stimulus hyperpolarization = PSH). During the PSH the membrane resistance of the heart muscle increased. The PSH was enhanced by myocardium hyperpolarization, decreased by depolarization and reversed around −50 mV. Picrotoxin inhibited the summated IJPs elicited by the stimulation and thus caused the membrane to maximally hyperpolarize during the inhibitory train, thus suggesting a composite nature of the inhibitory processes. The PSH was reversibly reduced in K+-free saline or in ouabain containing saline but partial restoration was obtained by injection of inward current to the myocardium. The PSH was abolished in lithium saline and reduced in Na+-deficient (choline) solution. Cl-deficient solution that markedly affected the summated IJPs shortly after its introduction did not affect the PSH. It is proposed that the PSH results from a decrease in conductance, presumably to both Na+ and K+. The implication of such a mechanism as a component of the inhibitory regulation of this crustacean heart is discussed.
Heat Transfer Between Fish and Ambient Water*
Authors: Stevens E. Don , Sutterlin A. M. 
Published: April 2021

ABSTRACT
The ability of fish gills to transfer heat was measured by applying a heat pulse to blood in the ventral aorta and measuring it before and after passing through the gills of a teleost, Hemitripterus americanus. 80–90 % of heat contained in the blood is lost during passage through the gills. The fraction of heat not lost during passage through the gills is due to direct transfer of heat between the afferent and efferent artery within the gill bar. The major fraction of metabolic heat (70–90%) is lost through the body wall and fins of the sea raven in sea water at 5 °C ; the remainder is lost through the gills.
Aerodynamics, Kinematics, and Energetics of Horizontal Flapping Flight in the Long-Eared Bat Plecotus Auritus
Authors: Norberg Ulla M. 
Published: April 2021

ABSTRACT
The kinematics, aerodynamics, and energetics of Plecotus auritus in slow horizontal flight, 2·35 m s−1, are analysed. At this speed the inclination of the stroke path is ca. 58° to the horizontal, the stroke angle ca. 91 °, and the stroke frequency ca. 11·9 Hz. A method, based on steady-state aerodynamic and momenthum theories, is derived to calculate the lift and drag coefficients as averaged over the whole wing and the whole wing-stroke for horizontal flapping flight. This is a further development of Pennycuick’s (1968) and Weis-Fogh’s (1972) expressions for calculating the lift coefficient. The lift coefficient obtained varies between 1·4 and 1·6, the drag coefficient between 0·4 and 1·2, and the lift: drag ratio between 1·2 and 4·0. The corresponding, calculated, total specific mechanical power output of the wing muscles varies between 27·0 and 40·4 W kg−1 body mass. A maximum estimate of mechanical efficiency is 0·26. The aerodynamic efficiency varies between 0·07 and 0·10. The force coefficients, total mechanical power output, and mechanical and aerodynamic efficiencies are all plausible, demonstrating that the slow flapping flight of Plecotus is thus explicable by steady-state aerodynamics. The downstroke is the power stroke for the vertical upward forces and the upstroke for the horizontal forward forces.
An Electrolytic Method for Determining Oxygen Dissociation Curves Using Small Blood Samples: the Effect of Temperature on Trout and Human Blood
Authors: Hughes G. M. , O’Neill J. G. , Van Aardt W. J. 
Published: April 2021

ABSTRACT
A detailed account is given of an electrolytic method for determining the oxygen dissociation curve of fish blood using a single sample of 50–100 μl for the whole curve. The accuracy and some of the problems arising from its uses are discussed. Oxygen dissociation curves have been determined for trout blood and human blood at temperatures of 15 and 37 °C. The relationship between P50 and temperature is similar to that obtained using other methods. Absolute values of P50 are generally lower than those obtained by other methods, especially in the case of fish blood. The effect of and pH on the oxygen dissociation curve of trout blood is tested and it is shown that , has a more marked effect than pH when the other factor is maintained at a constant level. The Bohr factor (Δlog P50/Δ pH) appears to be approximately the same and independent of the . The P50 of ray blood determined from fish during and after an operation showed an increased Bohr factor.